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Search for "spiro" in Full Text gives 196 result(s) in Beilstein Journal of Organic Chemistry.
Recent advances in phosphorescent platinum complexes for organic light-emitting diodes
- Cristina Cebrián and
- Matteo Mauro
Beilstein J. Org. Chem. 2018, 14, 1459–1481, doi:10.3762/bjoc.14.124
Graphical Abstract
Figure 1: Molecular structure of neutral platinum(II) complex 1 bearing four monodentate ligands; cy = cycloh...
Figure 2: Chemical structure of the dinuclear Pt complexes 2a–b and 3 [20].
Figure 3: Molecular structure of platinum(II) complexes bearing isoquinolinylpyrazolates; dip = 2,6-diisoprop...
Figure 4: Selected neutral platinum(II) complexes featuring dianionic biazolate and neutral bipyridines [27].
Figure 5: Selected neutral platinum(II) complexes from bipyrazolate and carbene-based chelates [34,35].
Figure 6: Cyclometalated thiazol-2-ylidene platinum(II) complexes with different acetylacetonate ligands [37].
Figure 7: Neutral platinum(II) complexes 13–15 bearing azolate ligands [13].
Figure 8: Chemical structure of neutral platinum(II) complexes 16–18 bearing azine-pyrazolato bidentate ligan...
Figure 9: Molecular structure of carbene-containing cyclometallated alkynylplatinum(II) complexes 19–21 [41].
Figure 10: Chemical structure of platinum(II) complexes 22a–d bearing asymmetric C^N^N tridentate ligands [53].
Figure 11: Chemical structure of platinum(II) complexes 23 bearing bis-cyclometalating 2,6-dipyridylbenzene ty...
Figure 12: Molecular structure of dendritic carbazole-containing alkynyl-platinum(II) complexes 24a–d [62].
Figure 13: Molecular structure of bipolar alkynyl-platinum(II) complexes 25 bearing carbazole and electron-acc...
Figure 14: Molecular structures of neutral platinum(II) complexes comprising donor-acceptor alkynyls (26) or e...
Figure 15: Chemical structure of the asymmetric Pt(II) derivatives 28 bearing triazole and tetrazole moieties ...
Figure 16: Molecular structure of the tetradentate platinum complexes 29–32 bearing N^C^C^N and C^C^C^N ligand...
Figure 17: Chemical structure of the tetradentate Pt complexes 33–38 based on N^C^C^N-type of ligands [80-84].
Figure 18: Chemical structure of the macrocyclic tetradentate platinum complexes reported by Wang and co-worke...
Figure 19: Molecular structure of complex 41–46 [88,89].
Figure 20: Molecular structure of asymmetric derivatives 47–49 based on triaryl-type of bridge [90].
Figure 21: Chemical structure of the asymmetric tetradentate derivatives 50 and 51 based on spirofluorene link...
Figure 22: Molecular structure of the pyridylazolate-based complexes 52–54 reported by Chi and co-workers [97].
Figure 23: Chemical structure of the red-to-NIR emitting complexes 55–57 bearing donor–acceptor triphenylamino...
Figure 24: Molecular structures of the Pt(IV) derivatives 58 and 59 employed as triplet emitters in solution-p...
Methyl isocyanide as a convertible functional group for the synthesis of spirocyclic oxindole γ-lactams via post-Ugi-4CR/transamidation/cyclization in a one-pot, three-step sequence
- Amarendar Reddy Maddirala and
- Peter R. Andreana
Beilstein J. Org. Chem. 2018, 14, 875–883, doi:10.3762/bjoc.14.74
- Amarendar Reddy Maddirala Peter R. Andreana Department of Chemistry and Biochemistry and School of Green Chemistry and Engineering, University of Toledo, 2801 W. Bancroft Street, Toledo, OH 43606, USA 10.3762/bjoc.14.74 Abstract The synthesis of spiro[indoline-3,2'-pyrrole]-2,5'(1'H)-diones and
- spiro[indoline-3,2'-pyrrolidine]-2,5'-diones, via a post-Ugi-domino transamidation/cyclization sequential process, has been achieved in three sequential steps utilizing a one-pot reaction protocol. The variation in carboxylic acid substrates allows for the generation of new chiral racemic quaternary
- synthetic method for these molecules that allows for structural diversity is also important but not necessarily trivial. For these and other reasons, we became interested in synthesizing spiro[indoline-3,2'-pyrrole]-2,5'(1'H)-dione and spiro[indoline-3,2'-pyrrolidine]-2,5'-dione scaffolds (a class of
Graphical Abstract
Scheme 1: Previously reported post-Ugi-4CR methods for the synthesis of 2-oxindoles and spirocyclic 2-oxindol...
Scheme 2: Post-Ugi-4CR/transamidation/cyclization sequence.
Scheme 3: Base-promoted intramolecular 5-endo-dig cyclization.
Figure 1: ORTEP diagram of compound 7a.
Figure 2: Readily and synthetically accessible starting materials.
Scheme 4: Reaction scope with varying combinations of substrates.
Scheme 5: Synthesis of 5-chloro-1'-phenylspiro[indoline-3,2'-pyrrolidine]-2,5'-dione (8a).
Figure 3: Small molecule library of spiro[indoline-3,2'-pyrrolidine]-2,5'-dione analogs.
Scheme 6: Method applicability for the one-pot synthesis of 5-HT6 receptor antagonist 8j [53].
Mannich base-connected syntheses mediated by ortho-quinone methides
- Petra Barta,
- Ferenc Fülöp and
- István Szatmári
Beilstein J. Org. Chem. 2018, 14, 560–575, doi:10.3762/bjoc.14.43
- are also known to undergo oligomerization in the absence of dienophiles and nucleophiles via an oxo-Diels–Alder protocol (Table 4). During the syntheses of 1,4,9,10-anthradiquinones with potential antitumor activity, Kucklaender et al. isolated new spiro derivatives 38 [77]. These latter spirocyclic
Graphical Abstract
Scheme 1: Formation of amidoalkylnaphthols 4 via o-QM intermediate 3.
Scheme 2: Asymmetric syntheses of triarylmethanes starting from diarylmethylamines.
Scheme 3: Proposed mechanism for the formation of 2,2-dialkyl-3-dialkylamino-2,3-dihydro-1H-naphtho[2,1-b]pyr...
Scheme 4: Cycloadditions of isoflavonoid-derived o-QMs and various dienophiles.
Scheme 5: [4 + 2] Cycloaddition reactions between aminonaphthols and cyclic amines.
Scheme 6: Brønsted acid-catalysed reaction between aza-o-QMs and 2- or 3-substituted indoles.
Scheme 7: Formation of 3-(α,α-diarylmethyl)indoles 52 in different synthetic pathways.
Scheme 8: Alkylation of o-QMs with N-, O- or S-nucleophiles.
Scheme 9: Formation of DNA linkers and o-QM mediated polymers.
One-pot preparation of 4-aryl-3-bromocoumarins from 4-aryl-2-propynoic acids with diaryliodonium salts, TBAB, and Na2S2O8
- Teppei Sasaki,
- Katsuhiko Moriyama and
- Hideo Togo
Beilstein J. Org. Chem. 2018, 14, 345–353, doi:10.3762/bjoc.14.22
- -alkynoates with N-bromosuccinimide (NBS) at rt [34], where those reactions proceed via radical spiro-cyclization and then radical 1,2-carboxyl group migration, were reported. On the other hand, diaryliodonium salts are very useful for the C-arylation of active CH groups, the O-arylation of OH groups, and the
- occurs to form aryl 3-aryl-2-propynoate 2 (1st step). The bromocyclization of aryl 3-aryl-2-propynoate 2 with TBAB and Na2S2O8 proceeds via a bromoradical addition to the triple bond to form very reactive vinyl radical I [47]. Ipso-cyclization of the vinyl radical I occurs to form spiro radical
- intermediate II. Then, β-cleavage of the spiro radical intermediate II proceeds to form carboxyl radical III. 6-Exo-trig cyclization of the carboxyl radical III onto the aromatic ring takes place to form adduct radical IV, which would be rapidly oxidized by Na2S2O8 to form cation intermediate V. Smooth
Graphical Abstract
Scheme 1: One-pot preparation of 4-aryl-3-bromocoumarins 3 from 3-aryl-2-propynoic acids 1 with diphenyliodon...
Scheme 2: One-pot preparation of 3-bromo-4-phenylcoumarins 3a from 3-phenyl-2-propynoic acid (1a) with daryli...
Scheme 3: Derivatization of 3-bromo-4-phenylcoumarin.
Figure 1: ORTEP of 3-bromo-7-chloro-4-phenylcoumarin (3Da).
Scheme 4: Possible reaction pathway.
Recent advances on organic blue thermally activated delayed fluorescence (TADF) emitters for organic light-emitting diodes (OLEDs)
- Thanh-Tuân Bui,
- Fabrice Goubard,
- Malika Ibrahim-Ouali,
- Didier Gigmes and
- Frédéric Dumur
Beilstein J. Org. Chem. 2018, 14, 282–308, doi:10.3762/bjoc.14.18
- % could be attained for the sky-blue B4-based devices. Still based on the combination of acridan and 10H-phenoxaborin units, a complete isolation of the two units could be realized in B6 by directly functionalizing the 10H-phenoxaborin core with a spiro-type acridan group [38]. Using this strategy, pure
Graphical Abstract
Figure 1: Radiative deactivation pathways existing in fluorescent, phosphorescent and TADF materials.
Figure 2: Boron-containing TADF emitters B1–B10.
Figure 3: Diphenylsulfone-based TADF emitters D1–D7.
Figure 4: Triazine-based TADF emitters T1–T3, T5–T7 and azasiline derivatives T3 and T4.
Figure 5: Triazine-based TADF emitters T8, T9, T11–T14 and carbazole derivative T10.
Figure 6: Triazine-based TADF emitters T15–T19.
Figure 7: Triazine- and pyrimidine-based TADF emitters T20–T26.
Figure 8: Pyrimidine-based TADF emitters T27–T30.
Figure 9: Triazine-based TADF polymers T31–T32.
Figure 10: Phenoxaphosphine oxide and phenoxathiin dioxide-based TADF emitters P1 and P2.
Figure 11: CN-Substituted pyridine and pyrimidine derivatives CN-P1–CN-P8.
Figure 12: CN-Substituted pyridine derivatives CN-P9 and CN-P10.
Figure 13: Phosphine oxide-based TADF blue emitters PO-1–PO-3.
Figure 14: Phosphine oxide-based TADF blue emitters PO-4–PO-9.
Figure 15: Benzonitrile-based emitters BN-1–BN-5.
Figure 16: Benzonitrile-based emitters BN-6–BN-11.
Figure 17: Benzoylpyridine-carbazole hybrid emitters BP-1–BP-6.
Figure 18: Benzoylpyridine-carbazole hybrid emitters BP-7–BP-10.
Figure 19: Triazole-based emitters Trz-1 and Trz-2.
Figure 20: Triarylamine-based emitters TPA-1–TPA-3.
Figure 21: Distribution of the CIE coordinates of ca. 90 blue TADF emitters listed in this review.
5-Aminopyrazole as precursor in design and synthesis of fused pyrazoloazines
- Ranjana Aggarwal and
- Suresh Kumar
Beilstein J. Org. Chem. 2018, 14, 203–242, doi:10.3762/bjoc.14.15
- product 4,5-dihydro-1H-pyrazolo[3,4-b]pyridine-6(7H)-one 53 was formed due to C–O bond cleavage from cyclic ester 51. Bazgir et al. [56] described the synthesis of spiro[indoline-3,4'-pyrazolo[3,4-b]pyridine]-2,6'(1'H)-diones 55 by an efficient three-component procedure from the reaction of 5
- described the construction of spiro[indoline-3,4'-pyrazolo[3,4-b]pyridine] derivatives 57 from the multicomponent reaction of 5-amino-3-hydroxy-1-phenyl-1H-pyrazole (46), ketones 56 and isatin 54 in water/acetic acid (3:1) at 90 °C (Scheme 12). Quiroga et al. [58] reported the synthesis of the pyrazolo[3,4
Graphical Abstract
Figure 1: Selected examples of drugs with fused pyrazole rings.
Figure 2: Typical structures of some fused pyrazoloazines from 5-aminopyrazoles.
Scheme 1: Regiospecific synthesis of 4 and 6-trifluoromethyl-1H-pyrazolo[3,4-b]pyridines.
Scheme 2: Synthesis of pyrazolo[3,4-b]pyridine-6-carboxylates.
Scheme 3: Synthesis of 1,4,6-triaryl-1H-pyrazolo[3,4-b]pyridines with ionic liquid .
Scheme 4: Synthesis of coumarin-based isomeric tetracyclic pyrazolo[3,4-b]pyridines.
Scheme 5: Synthesis of 6-substituted pyrazolo[3,4-b]pyridines under Heck conditions.
Scheme 6: Microwave-assisted palladium-catalyzed synthesis of pyrazolo[3,4-b]pyridines.
Scheme 7: Acid-catalyzed synthesis of pyrazolo[3,4-b]pyridines via enaminones.
Scheme 8: Synthesis of pyrazolo[3,4-b]pyridines via aza-Diels–Alder reaction.
Scheme 9: Synthesis of macrocyclane fused pyrazolo[3,4-b]pyridine derivatives.
Scheme 10: Three-component synthesis of 4,7-dihydro-1H-pyrazolo[3,4-b]pyridine derivatives.
Scheme 11: Ultrasonicated synthesis of spiro[indoline-3,4'-pyrazolo[3,4-b]pyridine]-2,6'(1'H)-diones.
Scheme 12: Synthesis of spiro[indoline-3,4'-pyrazolo[3,4-b]pyridine] derivatives under conventional heating co...
Scheme 13: Nanoparticle-catalyzed synthesis of pyrazolo[3,4-b]pyridine-spiroindolinones.
Scheme 14: Microwave-assisted multicomponent synthesis of spiropyrazolo[3,4-b]pyridines.
Scheme 15: Unexpected synthesis of naphthoic acid-substituted pyrazolo[3,4-b]pyridines.
Scheme 16: Multicomponent synthesis of variously substituted pyrazolo[3,4-b]pyridine derivatives.
Scheme 17: Three-component synthesis of 4,7-dihydropyrazolo[3,4-b]pyridines and pyrazolo[3,4-b]pyridines.
Scheme 18: Synthesis of pyrazolo[3,4-b]pyridine-5-spirocycloalkanediones.
Scheme 19: Ultrasound-mediated three-component synthesis of pyrazolo[3,4-b]pyridines.
Scheme 20: Multicomponent synthesis of 4-aryl-3-methyl-1-phenyl-4,6,8,9-tetrahydropyrazolo [3,4-b]thiopyrano[4...
Scheme 21: Synthesis of 2,3-dihydrochromeno[4,3-d]pyrazolo[3,4-b]pyridine-1,6-diones.
Scheme 22: FeCl3-catalyzed synthesis of o-hydroxyphenylpyrazolo[3,4-b]pyridine derivatives.
Scheme 23: Ionic liquid-mediated synthesis of pyrazolo[3,4-b]pyridines.
Scheme 24: Microwave-assisted synthesis of pyrazolo[3,4-b]pyridines.
Scheme 25: Multicomponent synthesis of pyrazolo[3,4-b]pyridine-5-carbonitriles.
Scheme 26: Unusual domino synthesis of 4,7-dihydropyrazolo[3,4-b]pyridine-5-nitriles.
Scheme 27: Synthesis of 4,5,6,7-tetrahydro-4H-pyrazolo[3,4-b]pyridines under conventional heating and ultrasou...
Scheme 28: L-Proline-catalyzed synthesis of of pyrazolo[3,4-b]pyridine.
Scheme 29: Microwave-assisted synthesis of 5-aminoarylpyrazolo[3,4-b]pyridines.
Scheme 30: Microwave-assisted multi-component synthesis of pyrazolo[3,4-e]indolizines.
Scheme 31: Synthesis of fluoropropynyl and fluoroalkyl substituted pyrazolo[1,5-a]pyrimidine.
Scheme 32: Acid-catalyzed synthesis of pyrazolo[1,5-a]pyrimidine derivatives.
Scheme 33: Chemoselective and regiospecific synthesis of 2-(3-methylpyrazol-1’-yl)-5-methylpyrazolo[1,5-a]pyri...
Scheme 34: Regioselective synthesis of 7-trifluoromethylpyrazolo[1,5-a]pyrimidines.
Scheme 35: Microwave-assisted synthesis of 7-trifluoromethylpyrazolo[1,5-a]pyrimidine carboxylates.
Scheme 36: Microwave and ultrasound-assisted synthesis of 7-trifluoromethylpyrazolo[1,5-a]pyrimidines.
Scheme 37: Base-catalyzed unprecedented synthesis of pyrazolo[1,5-a]pyrimidines via C–C bond cleavage.
Scheme 38: Synthesis of aminobenzothiazole/piperazine linked pyrazolo[1,5-a]pyrimidines.
Scheme 39: Synthesis of aminoalkylpyrazolo[1,5-a]pyrimidine-7-amines.
Scheme 40: Synthesis of pyrazolo[1,5-a]pyrimidines from condensation of 5-aminopyrazole 126 and ethyl acetoace...
Scheme 41: Synthesis of 7-aminopyrazolo[1,5-a]pyrimidines.
Scheme 42: Unexpected synthesis of 7-aminopyrazolo[1,5-a]pyrimidines under solvent free and solvent-mediated c...
Scheme 43: Synthesis of N-(4-aminophenyl)-7-aryloxypyrazolo[1,5-a]pyrimidin-5-amines.
Scheme 44: Base-catalyzed synthesis of 5,7-diarylpyrazolo[1,5-a]pyrimidines.
Scheme 45: Synthesis of 6,7-dihydropyrazolo[1,5-a]pyrimidines in PEG-400.
Scheme 46: Synthesis of 7-heteroarylpyrazolo[1,5-a]pyrimidine-3-carboxamides.
Scheme 47: Synthesis of 7-heteroarylpyrazolo[1,5-a]pyrimidine derivatives under conventional heating and micro...
Scheme 48: Synthesis of N-aroylpyrazolo[1,5-a]pyrimidine-5-amines.
Scheme 49: Regioselective synthesis of ethyl pyrazolo[1,5-a]pyrimidine-7-carboxylate.
Scheme 50: Sodium methoxide-catalyzed synthesis of 3-cyano-6,7-diarylpyrazolo[1,5-a]pyrimidines.
Scheme 51: Synthesis of various pyrazolo[3,4-d]pyrimidine derivatives.
Scheme 52: Synthesis of hydrazinopyrazolo[3,4-d]pyrimidine derivatives.
Scheme 53: Synthesis of N-arylidinepyrazolo[3,4-d]pyrimidin-5-amines.
Scheme 54: Synthesis of pyrazolo[3,4-d]pyrimidinyl-4-amines.
Scheme 55: Iodine-catalyzed synthesis of pyrazolo[3,4-d]pyrimidinones.
Scheme 56: Synthesis of ethyl 6-amino-2H-pyrazolo[3,4-d]pyrimidine-4-carboxylate.
Scheme 57: Synthesis of 4-substituted-(3,6-dihydropyran-4-yl)-1H-pyrazolo[3,4-d]pyrimidines.
Scheme 58: Synthesis of 1-(2,4-dichlorophenyl)pyrazolo[3,4-d]pyrimidin-4-yl carboxamides.
Scheme 59: Synthesis of 5-(1,3,4-thidiazol-2-yl)pyrazolo[3,4-d]pyrimidine.
Scheme 60: One pot POCl3-catalyzed synthesis of 1-arylpyrazolo[3,4-d]pyrimidin-4-ones.
Scheme 61: Synthesis of 4-amino-N1,C3-dialkylpyrazolo[3,4-d]pyrimidines under Suzuki conditions.
Scheme 62: Microwave-assisted synthesis of pyrazolo[3,4-b]pyrazines.
Scheme 63: Synthesis and derivatization of pyrazolo[3,4-b]pyrazine-5-carbonitriles.
Scheme 64: Synthesis of 2-thioxo-pyrazolo[1,5-a][1,3,5]triazin-4-ones.
Scheme 65: Synthesis of 2,3-dihydropyrazolo[1,5-a][1,3,5]triazin-4(1H)-one.
Scheme 66: Synthesis of pyrazolo[1,5-a][1,3,5]triazine-8-carboxylic acid ethyl ester.
Scheme 67: Microwave-assisted synthesis of 4,7-dihetarylpyrazolo[1,5-a][1,3,5]triazines.
Scheme 68: Alternative synthetic route to 4,7-diheteroarylpyrazolo[1,5-a][1,3,5]triazines.
Scheme 69: Synthesis of 4-aryl-2-ethylthio-7-methylpyrazolo[1,5-a][1,3,5]triazines.
Scheme 70: Microwave-assisted synthesis of 4-aminopyrazolo[1,5-a][1,3,5]triazine.
Scheme 71: Synthesis of pyrazolo[3,4-d][1,2,3]triazines from pyrazol-5-yl diazonium salts.
Scheme 72: Synthesis of 2,5-dihydropyrazolo[3,4-e][1,2,4]triazines.
Scheme 73: Synthesis of pyrazolo[5,1-c][1,2,4]triazines via diazopyrazolylenaminones.
Scheme 74: Synthesis of pyrazolo[5,1-c][1,2,4]triazines in presence of sodium acetate.
Scheme 75: Synthesis of various 7-diazopyrazolo[5,1-c][1,2,4]triazine derivatives.
Scheme 76: One pot synthesis of pyrazolo[5,1-c][1,2,4]triazines.
Scheme 77: Synthesis of 4-amino-3,7,8-trinitropyrazolo-[5,1-c][1,2,4]triazines.
Scheme 78: Synthesis of tricyclic pyrazolo[5,1-c][1,2,4]triazines by azocoupling reaction.
Regiodivergent condensation of 5-alkoxycarbonyl-1H-pyrrol-2,3-diones with cyclic ketazinones en route to spirocyclic scaffolds
- Alexey Yu. Dubovtsev,
- Maksim V. Dmitriev,
- Аndrey N. Maslivets and
- Michael Rubin
Beilstein J. Org. Chem. 2017, 13, 2179–2185, doi:10.3762/bjoc.13.218
- ; spiro compounds; synthetic methods; Introduction Molecular structures based on partially or exhaustively hydrogenated indole and benzofuran cores are omnipresent in nature. Both types of ring systems are found in a variety of important biologically active natural products [1][2][3][4][5][6][7][8][9][10
- spirocondensation of 5-alkoxycarbonyl-1H-pyrrole-2,3-diones (serving as 1,2-bis-electrophiles) with cyclic ketazinones (serving as either 1,3-C,N- or 1,3-C,O-bis-nucleophiles). Results and Discussion Previously, we demonstrated a convenient approach towards spiro[indole-3,2’-pyrroles] 3 based on catalyst-free
- in tautomeric form 18 (Scheme 5). Surprisingly, an alternative direction of spirocyclization involving the reaction of tautomeric form 19 and affording lactam rings proceeded exclusively. The corresponding spiro[indole-3,2’-pyrroles] 21 were obtained exclusively in good yields (Scheme 5). The
Graphical Abstract
Scheme 1: Spirocyclization of enamines with 5-methoxycarbonyl-1H-pyrrolediones.
Scheme 2: Non-catalyzed spirocyclization of enoles (vinylogous carbonates and carbamates) with 5-methoxycarbo...
Scheme 3: Acid-catalyzed spirocyclization of enoles (vinylogous carboxylates) with 5-alkoxycarbonyl-1H-pyrrol...
Figure 1: ORTEP drawing of compound 12ab (CCDC 1546062) showing 50% probability amplitude displacement ellips...
Scheme 4: Formation of mono-imines and mono-hydrazones of 1,3-cyclohexanediones and tautomeric equilibrium be...
Scheme 5: Spirocyclizations involving non-bulky ketazinones 17 and 5-alkoxycarbonyl-1H-pyrrolediones 9.
Figure 2: ORTEP drawing of compound 21ab (CCDC 1546063) showing 50% probability amplitude displacement ellips...
Figure 3: ORTEP drawing of compound 22a (CCDC 1546065) showing 50% probability amplitude displacement ellipso...
Scheme 6: Spirocyclizations involving bulky ketazinones 22 and 5-alkoxycarbonyl-1H-pyrrolediones 9.
Figure 4: ORTEP drawing of compound 23aa (CCDC 1546064) showing 50% probability amplitude displacement ellips...
Enzymatic separation of epimeric 4-C-hydroxymethylated furanosugars: Synthesis of bicyclic nucleosides
- Neha Rana,
- Manish Kumar,
- Vinod Khatri,
- Jyotirmoy Maity and
- Ashok K. Prasad
Beilstein J. Org. Chem. 2017, 13, 2078–2086, doi:10.3762/bjoc.13.205
- , which is a key precursor for the synthesis of different types of bicyclic/spiro nucleosides, led to the formation of an inseparable 1:1 mixture of the desired product and 4-C-hydroxymethyl-1,2-O-isopropylidene-α-D-xylofuranose. A convenient environment friendly Novozyme®-435 catalyzed selective
Graphical Abstract
Scheme 1: Formation of a 1:1 epimeric mixture of 3a and 3b.
Scheme 2: Lipase-catalysed separation of a mixture of ribo- and xylotrihydroxyfuranosides.
Figure 1: Screening of Novozyme®-435 and Lipozyme TL IM in different organic solvents at 35 °C for regioselec...
Figure 2: ORTEP diagram of tosylated sugar derivatives 5 and 10.
Scheme 3: Convergent synthesis of 3′-O,4′-C-methyleneuridine.
Scheme 4: Convergent synthesis of 2′-O,4′-C-methylene-xylouridine.
Figure 3: ORTEP diagram and preferential N-type sugar ring puckering of 2′-O,4′-C-methylene-xylouridine (14).
Chiral phase-transfer catalysis in the asymmetric α-heterofunctionalization of prochiral nucleophiles
- Johannes Schörgenhumer,
- Maximilian Tiffner and
- Mario Waser
Beilstein J. Org. Chem. 2017, 13, 1753–1769, doi:10.3762/bjoc.13.170
- -workers demonstrated the potential of asymmetric cation-based phase-transfer catalysis to control the absolute configuration of the newly-installed stereogenic centre in this rearrangement reaction [141]. By using their spiro-quaternary ammonium salt catalyst B5 they were able to control the Neber
Graphical Abstract
Scheme 1: Generally accepted ion-pairing mechanism between the chiral cation Q+ of a PTC and an enolate and s...
Scheme 2: Reported asymmetric α-fluorination of β-ketoesters 1 using different chiral PTCs.
Scheme 3: Asymmetric α-fluorination of benzofuranones 4 with phosphonium salt PTC F1.
Scheme 4: Asymmetric α-fluorination of 1 with chiral phosphate-based catalysts.
Scheme 5: Anionic PTC-catalysed α-fluorination of enamines 7 and ketones 10.
Scheme 6: PTC-catalysed α-chlorination reactions of β-ketoesters 1.
Scheme 7: Shioiri’s seminal report of the asymmetric α-hydroxylation of 15 with chiral ammonium salt PTCs.
Scheme 8: Asymmetric ammonium salt-catalysed α-hydroxylation using oxygen together with a P(III)-based reduct...
Scheme 9: Asymmetric ammonium salt-catalysed α-photooxygenations.
Scheme 10: Asymmetric ammonium salt-catalysed α-hydroxylations using organic oxygen-transfer reagents.
Scheme 11: Asymmetric triazolium salt-catalysed α-hydroxylation with in situ generated peroxy imidic acid 24.
Scheme 12: Phase-transfer-catalysed dearomatization of phenols and naphthols.
Scheme 13: Ishihara’s ammonium salt-catalysed oxidative cycloetherification.
Scheme 14: Chiral phase-transfer-catalysed α-sulfanylation reactions.
Scheme 15: Chiral phase-transfer-catalysed α-trifluoromethylthiolation of β-ketoesters 1.
Scheme 16: Chiral phase-transfer-catalysed α-amination of β-ketoesters 1 using diazocarboxylates 38.
Scheme 17: Asymmetric α-fluorination of benzofuranones 4 using diazocarboxylates 38 in the presence of phospho...
Scheme 18: Anionic phase-transfer-catalysed α-amination of β-ketoesters 1 with aryldiazonium salts 41.
Scheme 19: Triazolium salt L-catalysed α-amination of different prochiral nucleophiles with in situ activated ...
Scheme 20: Phase-transfer-catalysed Neber rearrangement.
Oxidative dehydrogenation of C–C and C–N bonds: A convenient approach to access diverse (dihydro)heteroaromatic compounds
- Santanu Hati,
- Ulrike Holzgrabe and
- Subhabrata Sen
Beilstein J. Org. Chem. 2017, 13, 1670–1692, doi:10.3762/bjoc.13.162
- combination of heterogeneous polymer-supported bi-metallic platinum/iridium alloyed nanoclusters and 5,5’,6,6’-tetrahydroxy-3,3,3’,3’-tetramethyl-1,1’-spiro-bisindane (TTSBI) facilitated a one-pot condensation and oxidative dehydrogenation of o-aminobenzylamine to generate quinazoline derivatives 79 under
- dehydrogenation of tetrahydroisoquinolines. Ruthenium-catalyzed polycyclic heteroarenes. Plausible mechanism of the ruthenium-catalyzed dehydrogenation. Bi-metallic platinum/iridium alloyed nanoclusters and 5,5’,6,6’-tetrahydroxy-3,3,3’,3’-tetramethyl-1,1’-spiro-bisindane (TTSBI) for the synthesis of quinazolines
Graphical Abstract
Figure 1: Representative bioactive heterocycles.
Scheme 1: The concept of oxidative dehydrogenation.
Scheme 2: IBX-mediated oxidative dehydrogenation of various heterocycles [31-34].
Scheme 3: Potential mechanism of IBX-mediated oxidative dehydrogenation of N-heterocycles [31-34].
Scheme 4: IBX-mediated room temperature one-pot condensation–oxidative dehydrogenation of o-aminobenzylamines....
Scheme 5: Anhydrous cerium chloride-catalyzed, IBX-mediated oxidative dehydrogenation of various heterocycles...
Scheme 6: Oxidative dehydrogenation of quinazolinones with I2 and DDQ [37-40].
Scheme 7: DDQ-mediated oxidative dehydrogenation of thiazolidines and oxazolidines.
Scheme 8: Oxone-mediated oxidative dehydrogenation of intermediates from o-phenylenediamine and o-aminobenzyl...
Scheme 9: Transition metal-free oxidative cross-dehydrogenative coupling.
Scheme 10: NaOCl-mediated oxidative dehydrogenation.
Scheme 11: NBS-mediated oxidative dehydrogenation of tetrahydro-β-carbolines.
Scheme 12: One-pot synthesis of various methyl(hetero)arenes from o-aminobenzamide in presence of di-tert-buty...
Scheme 13: Oxidative dehydrogenation of 1, 4-DHPs.
Scheme 14: Synthesis of quinazolines in the presence of MnO2.
Scheme 15: Selenium dioxide and potassium dichromate-mediated oxidative dehydrogenation of tetrahydro-β-carbol...
Scheme 16: Synthesis of substituted benzazoles in the presence of barium permanganate.
Scheme 17: Oxidative dehydrogenation with phenanthroline-based catalysts. PPTS = pyridinium p-toluenesulfonic ...
Scheme 18: Oxidative dehydrogenation with Flavin mimics.
Scheme 19: o-Quinone based bioinspired catalysts for the synthesis of dihydroisoquinolines.
Scheme 20: Cobalt-catalyzed aerobic dehydrogenation of Hantzch 1,4-DHPs and pyrazolines.
Scheme 21: Mechanism of cobalt-catalyzed aerobic dehydrogenation of Hantzch 1,4-DHPs.
Scheme 22: DABCO and TEMPO-catalyzed aerobic oxidative dehydrogenation of quinazolines and 4H-3,1-benzoxazines....
Scheme 23: Putative mechanism for Cu(I)–DABCO–TEMPO catalyzed aerobic oxidative dehydrogenation of tetrahydroq...
Scheme 24: Potassium triphosphate modified Pd/C catalysts for the oxidative dehydrogenation of tetrahydroisoqu...
Scheme 25: Ruthenium-catalyzed polycyclic heteroarenes.
Scheme 26: Plausible mechanism of the ruthenium-catalyzed dehydrogenation.
Scheme 27: Bi-metallic platinum/iridium alloyed nanoclusters and 5,5’,6,6’-tetrahydroxy-3,3,3’,3’-tetramethyl-...
Scheme 28: Magnesium iodide-catalyzed synthesis of quinazolines.
Scheme 29: Ferrous chloride-catalyzed aerobic dehydrogenation of 1,2,3,4-tetrahydroquinolines.
Scheme 30: Cu(I)-catalyzed oxidative aromatization of indoles.
Scheme 31: Putative mechanism of the transformation.
Scheme 32: Oxidative dehydrogenation of pyrimidinones and pyrimidines.
Scheme 33: Putative mechanisms (radical and metal-catalyzed) of the transformation.
Scheme 34: Ferric chloride-catalyzed, TBHP-oxidized synthesis of substituted quinazolinones and arylquinazolin...
Scheme 35: Iridium-catalyzed oxidative dehydrogenation of quinolines.
Scheme 36: Microwave-assisted synthesis of β-carboline with a catalytic amount of Pd/C in lithium carbonate at...
Scheme 37: 4-Methoxy-TEMPO-catalyzed aerobic oxidative synthesis of 2-substituted benzazoles.
Scheme 38: Plausible mechanism of the 4-methoxy-TEMPO-catalyzed transformation.
Scheme 39: One-pot synthesis of 2-arylquinazolines, catalyzed by 4-hydroxy-TEMPO.
Scheme 40: Oxidative dehydrogenation – a key step in the synthesis of AZD8926.
Scheme 41: Catalytic oxidative dehydrogenation of tetrahydroquinolines to afford bioactive molecules.
Scheme 42: Iodobenzene diacetate-mediated synthesis of β-carboline natural products.
Synthesis and metal binding properties of N-alkylcarboxyspiropyrans
- Alexis Perry and
- Christina J. Kousseff
Beilstein J. Org. Chem. 2017, 13, 1542–1550, doi:10.3762/bjoc.13.154
- for binding divalent metal cations and a modest increase in M2+ binding affinity correlated with increased alkycarboxylate tether length. Keywords: carboxylate ligand; merocyanine; metal binding; photochromism; spiropyran; Introduction Spiropyrans are a class of spiro-fused indolochromene (e.g
Graphical Abstract
Figure 1: General uses of N-alkylcarboxyspiropyrans.
Scheme 1: C4SP–C4MC spiropyran-merocyanine equilibrium and M2+ binding.
Scheme 2: General synthesis of N-alkylcarboxyspiropyrans.
Scheme 3: Decarboxylation of N-ethanoic acid indolium salt 3a.
Scheme 4: Lactonisation of 4-bromobutyric acid 2c.
Figure 2: N-methyl spiropyran 9.
Figure 3: Example spectra illustrating binding studies of spiropyrans with M2+. (a) 1H NMR spectrum of C10SP ...
Figure 4: ε for MC–M2+ complexes of C2SP–C12SP and 9: (left) with Zn2+; (right) with Mg2+. Values for ε were ...
Figure 5: [MC] for compounds C2SP–C12SP and 9 in the presence of various metal cations. Solutions of spiropyr...
Figure 6: [MC] for spiropyrans C2SP–C12SP, 9 and 10 (0.1 mM) in CH3CN–H2O (99.9% v/v). Samples were kept in d...
Figure 7: C6 ester derivative 10.
Synthesis of 1-indanones with a broad range of biological activity
- Marika Turek,
- Dorota Szczęsna,
- Marek Koprowski and
- Piotr Bałczewski
Beilstein J. Org. Chem. 2017, 13, 451–494, doi:10.3762/bjoc.13.48
- spiroindanone 50 has been proposed by Estévez et al. [38]. Thus, starting from 2,2-disubstituted-1-indanone 49, the spiro-1-indanone 50 was formed via cyclization using HBr/AcOH and next converted in a sequence of reactions to the biologically active benzopyronaphthoquinone 51 (Scheme 18). Endothelins are 21
- carbene is an outstanding protocol for the synthesis of polyhydroxylated spiro- or fused 1-indanones [49]. Thus, the imidazole-based carbene catalyzed the conversion of phthalaldehydes 72 to dihydroxyspiro[indane-2,1′-isobenzofuran]-3-ones 73, whereas triazole-based carbene catalyzed the conversion of 72
- quaternary center with high diastereoselectivity as a consequence of the Stetter–Aldol–Aldol (SAA) reaction sequence. The Stetter–Aldol–Aldol conversion of the phthaldialdehyde derivatives 75 and o-formyl substituted chalcones 76 using the thiazole based carbene 78 as a precatalyst allowed to obtain spiro
Graphical Abstract
Figure 1: Biologically active 1-indanones and their structural analogues.
Figure 2: Number of papers about (a) 1-indanones, (b) synthesis of 1-indanones.
Scheme 1: Synthesis of 1-indanone (2) from hydrocinnamic acid (1).
Scheme 2: Synthesis of 1-indanone (2) from 3-(2-bromophenyl)propionic acid (3).
Scheme 3: Synthesis of 1-indanones 5 from 3-arylpropionic acids 4.
Scheme 4: Synthesis of kinamycin (9a) and methylkinamycin C (9b).
Scheme 5: Synthesis of trifluoromethyl-substituted arylpropionic acids 12, 1-indanones 13 and dihydrocoumarin...
Scheme 6: Synthesis of 1-indanones 16 from benzoic acids 15.
Scheme 7: Synthesis of 1-indanones 18 from arylpropionic and 3-arylacrylic acids 17.
Scheme 8: The NbCl5-induced one-step synthesis of 1-indanones 22.
Scheme 9: Synthesis of biologically active 1-indanone derivatives 26.
Scheme 10: Synthesis of enantiomerically pure indatraline ((−)-29).
Scheme 11: Synthesis of 1-indanone (2) from the acyl chloride 30.
Scheme 12: Synthesis of the mechanism-based inhibitors 33 of coelenterazine.
Scheme 13: Synthesis of the indane 2-imidazole derivative 37.
Scheme 14: Synthesis of fluorinated PAHs 41.
Scheme 15: Synthesis of 1-indanones 43 via transition metal complexes-catalyzed carbonylative cyclization of m...
Scheme 16: Synthesis of 6-methyl-1-indanone (46).
Scheme 17: Synthesis of 1-indanone (2) from ester 48.
Scheme 18: Synthesis of benzopyronaphthoquinone 51 from the spiro-1-indanone 50.
Scheme 19: Synthesis of the selective endothelin A receptor antagonist 55.
Scheme 20: Synthesis of 1-indanones 60 from methyl vinyl ketone (57).
Scheme 21: Synthesis of 1-indanones 64 from diethyl phthalate 61.
Scheme 22: Synthesis of 1-indanone derivatives 66 from various Meldrum’s acids 65.
Scheme 23: Synthesis of halo 1-indanones 69.
Scheme 24: Synthesis of substituted 1-indanones 71.
Scheme 25: Synthesis of spiro- and fused 1-indanones 73 and 74.
Scheme 26: Synthesis of spiro-1,3-indanodiones 77.
Scheme 27: Mechanistic pathway for the NHC-catalyzed Stetter–Aldol–Michael reaction.
Scheme 28: Synthesis of 2-benzylidene-1-indanone derivatives 88a–d.
Scheme 29: Synthesis of 1-indanone derivatives 90a–i.
Scheme 30: Synthesis of 1-indanones 96 from o-bromobenzaldehydes 93 and alkynes 94.
Scheme 31: Synthesis of 3-hydroxy-1-indanones 99.
Scheme 32: Photochemical preparation of 1-indanones 103 from ketones 100.
Scheme 33: Synthesis of chiral 3-aryl-1-indanones 107.
Scheme 34: Photochemical isomerization of 2-methylbenzil 108.
Scheme 35: Synthesis of 2-hydroxy-1-indanones 111a–c.
Scheme 36: Synthesis of 1-indanone derivatives 113 and 114 from η6-1,2-dioxobenzocyclobutene complex 112.
Scheme 37: Synthesis of nakiterpiosin (117).
Scheme 38: Synthesis of 2-alkyl-1-indanones 120.
Scheme 39: Synthesis of fluorine-containing 1-indanone derivatives 123.
Scheme 40: Synthesis of 2-benzylidene and 2-benzyl-1-indanones 126, 127 from the chalcone 124.
Scheme 41: Synthesis of 2-bromo-6-methoxy-3-phenyl-1-indanone (130).
Scheme 42: Synthesis of combretastatin A-4-like indanones 132a–s.
Figure 3: Chemical structures of investigated dienones 133 and synthesized cyclic products 134–137.
Figure 4: Chemical structures of 1-indanones and their heteroatom analogues 138–142.
Scheme 43: Synthesis of 2-phosphorylated and 2-non-phosphorylated 1-indanones 147 and 148 from β-ketophosphona...
Scheme 44: Photochemical synthesis of 1-indanone derivatives 150, 153a, 153b.
Scheme 45: Synthesis of polysubstituted-1-indanones 155, 157.
Scheme 46: Synthesis of 1-indanones 159a–g from α-arylpropargyl alcohols 158 using RhCl(PPh3)3 as a catalyst.
Scheme 47: Synthesis of optically active 1-indanones 162 via the asymmetric Rh-catalyzed isomerization of race...
Scheme 48: Mechanism of the Rh-catalyzed isomerization of α-arylpropargyl alcohols 161 to 1-indanones 162.
Figure 5: Chemical structure of abicoviromycin (168) and its new benzo derivative 169.
Scheme 49: Synthesis of racemic benzoabicoviromycin 172.
Scheme 50: Synthesis of [14C]indene 176.
Scheme 51: Synthesis of indanone derivatives 178–180.
Scheme 52: Synthesis of racemic pterosin A 186.
Scheme 53: Synthesis of trans-2,3-disubstituted 1-indanones 189.
Scheme 54: Synthesis of 3-aryl-1-indanone derivatives 192.
Scheme 55: Synthesis of 1-indanone derivatives 194 from 3-(2-iodoaryl)propanonitriles 193.
Scheme 56: Synthesis of 1-indanones 200–204 by cyclization of aromatic nitriles.
Scheme 57: Synthesis of 1,1’-spirobi[indan-3,3’-dione] derivative 208.
Scheme 58: Total synthesis of atipamezole analogues 211.
Scheme 59: Synthesis of 3-[4-(1-piperidinoethoxy)phenyl]spiro[indene-1,1’-indan]-5,5’-diol hydrochloride 216.
Scheme 60: Synthesis of 3-arylindan-1-ones 219.
Scheme 61: Synthesis of 2-hydroxy-1-indanones 222.
Scheme 62: Synthesis of the 1-indanone 224 from the THP/MOM protected chalcone epoxide 223.
Scheme 63: Synthesis of 1-indanones 227 from γ,δ-epoxy ketones 226.
Scheme 64: Synthesis of 2-hydroxy-2-methylindanone (230).
Scheme 65: Synthesis of 1-indanone derivatives 234 from cyclopropanol derivatives 233.
Scheme 66: Synthesis of substituted 1-indanone derivatives 237.
Scheme 67: Synthesis of 7-methyl substituted 1-indanone 241 from 1,3-pentadiene (238) and 2-cyclopentenone (239...
Scheme 68: Synthesis of disubstituted 1-indanone 246 from the siloxydiene 244 and 2-cyclopentenone 239.
Scheme 69: Synthesis of 5-hydroxy-1-indanone (250) via the Diels–Alder reaction of 1,3-diene 248 with sulfoxid...
Scheme 70: Synthesis of halogenated 1-indanones 253a and 253b.
Scheme 71: Synthesis of 1-indanones 257 and 258 from 2-bromocyclopentenones 254.
Scheme 72: Synthesis of 1-indanone 261 from 2-bromo-4-acetoxy-2-cyclopenten-1-one (260) and 1,2-dihydro-4-viny...
Scheme 73: Synthesis of 1-indanone 265 from 1,2-dihydro-7-methoxy-4-vinylnaphthalene (262) and bromo-substitut...
Scheme 74: Synthesis of 1-indanone 268 from dihydro-3-vinylphenanthrene 266 and 4-acetoxy-2-cyclopenten-1-one (...
Scheme 75: Synthesis of 1-indanone 271 from phenylselenyl-substituted cyclopentenone 268.
Scheme 76: Synthesis of 1-indanone 272 from the trienone 270.
Scheme 77: Synthesis of the 1-indanone 276 from the aldehyde 273.
Scheme 78: Synthesis of 1-indanones 278 and 279.
Scheme 79: Synthesis of 1-indanone 285 from octa-1,7-diyne (282) and cyclopentenone 239.
Scheme 80: Synthesis of benz[f]indan-1-one (287) from cyclopentenone 239 and o-bis(dibromomethyl)benzene (286)....
Scheme 81: Synthesis of 3-methyl-substituted benz[f]indan-1-one 291 from o-bis(dibromomethyl)benzene (286) and...
Scheme 82: Synthesis of benz[f]indan-1-one (295) from the anthracene epidioxide 292.
Scheme 83: Synthesis of 1-indanone 299 from homophthalic anhydride 298 and cyclopentynone 297.
Scheme 84: Synthesis of cyano-substituted 1-indanone derivative 301 from 2-cyanomethylbenzaldehyde (300) and c...
Scheme 85: Synthesis of 1-indanone derivatives 303–305 from ketene dithioacetals 302.
Scheme 86: Synthesis of 1-indanones 309–316.
Scheme 87: Mechanism of the hexadehydro-Diels–Alder (HDDA) reaction.
Scheme 88: Synthesis of 1-indenone 318 and 1-indanones 320 and 321 from tetraynes 317 and 319.
Scheme 89: Synthesis of 1-indanone 320 from the triyn 319.
Scheme 90: Synthesis 1-indanone 328 from 2-methylfuran 324.
Scheme 91: Synthesis of 1-indanones 330 and 331 from furans 329.
Scheme 92: Synthesis of 1-indanone 333 from the cycloadduct 332.
Scheme 93: Synthesis of (S)-3-arylindan-1-ones 335.
Scheme 94: Synthesis of (R)-2-acetoxy-1-indanone 338.
Figure 6: Chemical structures of obtained cyclopenta[α]phenanthrenes 339.
Scheme 95: Synthesis of the benzoindanone 343 from arylacetaldehyde 340 with 1-trimethylsilyloxycyclopentene (...
Multicomponent synthesis of spiropyrrolidine analogues derived from vinylindole/indazole by a 1,3-dipolar cycloaddition reaction
- Manjunatha Narayanarao,
- Lokesh Koodlur,
- Vijayakumar G. Revanasiddappa,
- Subramanya Gopal and
- Susmita Kamila
Beilstein J. Org. Chem. 2016, 12, 2893–2897, doi:10.3762/bjoc.12.288
- stereospecific cyclic adducts. Keywords: L-proline; ninhydrin; sarcosine; spiropyrrolidine; 5-vinylindazole; 5-vinylindole; Introduction The [3 + 2] cycloaddition between azomethine ylides and olefins/acetylene as dipolarophiles is an important reaction to access a number of novel heterocyclic spiro scaffolds
- of biological importance [1][2]. The regio- and stereoselective construction of spiro compounds by utilizing the 1,3-dipolar cycloaddition reaction of azomethine ylides has been reported [3][4][5][6]. However, unlike the previous reports, the present method is concise and facilitates the one-pot
- in the construction of functionalized spiro compounds. We report herein the facile synthesis of novel spiropyrrolidine compounds through a one-pot three-component reaction involving N-substituted vinylindole/indazole, ninhydrin and sarcosine/L-proline. The present multicomponent reaction (MCR) leads
Graphical Abstract
Scheme 1: Synthesis of N-alkyl vinylindoles and N-alkyl vinylindazoles (3).
Scheme 2: Retrosynthetic strategy used for the synthesis of 7 and 8.
Figure 1: NOE interactions in compound 8c supporting the stereochemical assignments for 8a–k. H1 and H2 on th...
Figure 2: ORTEP representation of compounds 7a and 7f obtained by single crystal XRD study.
Synthesis of spiro[isoindole-1,5’-isoxazolidin]-3(2H)-ones as potential inhibitors of the MDM2-p53 interaction
- Salvatore V. Giofrè,
- Santa Cirmi,
- Raffaella Mancuso,
- Francesco Nicolò,
- Giuseppe Lanza,
- Laura Legnani,
- Agata Campisi,
- Maria A. Chiacchio,
- Michele Navarra,
- Bartolo Gabriele and
- Roberto Romeo
Beilstein J. Org. Chem. 2016, 12, 2793–2807, doi:10.3762/bjoc.12.278
- Farmaco, Università di Catania, Viale A. Doria, 95100 Catania, Italy Dipartimento di Chimica, Università di Pavia, Via Taramelli 12, 27100 Pavia, Italy 10.3762/bjoc.12.278 Abstract A series of spiro[isoindole-1,5-isoxazolidin]-3(2H)-ones has been synthesized by 1,3-dipolar cycloaddition of N
- be linked to the inhibition of the protein–protein p53-MDM2 interaction. Docking measurements support the biological data. Keywords: antitumor agents; DFT studies; 1,3-dipolar cycloaddition; docking studies; spiro-compounds; Introduction The p53 tumor suppressor protein is a transcriptional factor
- construction of the spiro[isoxazolidin-isoindolinone] system. The synthetic scheme (Figure 2) exploits the strategy of the 1,3-dipolar cycloaddition of nitrones on the substrate isoindolin-3-methylene-1-one 2, obtained by a recent methodology of a PdI2 catalyzed aminocarbonylation-N-heterocyclization of 2
Graphical Abstract
Figure 1: Some relevant MDM2-p53 interaction inhibitors.
Figure 2: Retrosynthetic route to spiro[isoindole-1,5-isoxazolidin]-3(2H)-ones 3.
Scheme 1: Synthesis of compounds 2.
Scheme 2: Synthesis of 6a–f by 1,3-dipolar cycloaddition.
Figure 3: Selected NOESY observed for compounds 6a and 7a.
Figure 4: ORTEP drawing of the X-ray crystal structure of 7a showing the model atomic numbering scheme (C10 a...
Scheme 3: Reaction pathway.
Figure 5: Three-dimensional plots of TSs of reaction of dipolarophiles (Z)-8 and (E)-8 with nitrone 4. The la...
Figure 6: Free energy profiles for the cycloaddition reaction of the two isomers Z (A) or E (B) of dipolaroph...
Figure 7: Compound 6e reduces cancer cell proliferation. Treatment of SH-SY5Y, HT-29 and HepG2 cells with 6e ...
Figure 8: Cytotoxic effect of 6e. The cytotoxic activity of 6e was assessed in terms of both LDH release (a) ...
Figure 9: 6e modulate the levels of p53 in SH-SY5Y cells. (a) The SH-SY5Y cells were treated for 24 h with th...
Figure 10: (A) Representative Western Blots and (B) semiquantitative analyses of p53, MDM2, p21 expression lev...
Figure 11: (A) Representative Western Blots and (B) densitometric analysis of caspase-3 and PARP cleavage in t...
Figure 12: Compounds 6a (green) and 6c (blue) docked into MDM2 structure (PDB-ID: 3LBL) superimposed on the ke...
Figure 13: A) Compounds 6e (green) docked into MDM2 structure (PDB-ID: 3LBL); His96 and p53 residue (yellow st...
An effective one-pot access to polynuclear dispiroheterocyclic structures comprising pyrrolidinyloxindole and imidazothiazolotriazine moieties via a 1,3-dipolar cycloaddition strategy
- Alexei N. Izmest’ev,
- Galina A. Gazieva,
- Natalya V. Sigay,
- Sergei A. Serkov,
- Valentina A. Karnoukhova,
- Vadim V. Kachala,
- Alexander S. Shashkov,
- Igor E. Zanin,
- Angelina N. Kravchenko and
- Nina N. Makhova
Beilstein J. Org. Chem. 2016, 12, 2240–2249, doi:10.3762/bjoc.12.216
- ; nitrogen heterocycles; spiro compounds; Introduction A global trend in modern organic chemistry is the design of molecular systems with various degrees of complexity to maximize the incorporation of useful properties while optimizing cost and efficiency [1]. A very extended and powerful approach for
- interest to synthesize the other types of spiro compounds such as the 2,3’-spiropyrrolidinyloxindole structure which is isosteric with the 3,3’-spiropyrrolidinyloxindole and to study the diastereoselectivity of its formation. It could be expected that the cycloaddition of more bulky azomethine ylides
- the {1H-13C}HMBC spectrum of 4f, the N(1’)Me protons (2.17 ppm) correlate with the C-5’ (57.52 ppm) and spiro C-2’ (80.29 ppm) carbons; the proton of C(4’)H (4.63 ppm) of the pyrrolidine ring correlates with the spiro carbon C-3’ (68.47 ppm) and the carbon atoms of the C(5’)H2 and C(7)=O (167.31 ppm
Graphical Abstract
Figure 1: Bioactive 2,3’-spiropyrrolidinyloxindoles.
Scheme 1: Earlier studied cycloaddition reaction.
Scheme 2: Synthesis of dipolarophiles 1a–c.
Scheme 3: Synthesis of dispirocompounds 4a–o.
Figure 2: Synthesis of dispiro compounds 4a–o. Reaction conditions: heating the mixture of compounds 1 (0.5 m...
Scheme 4: Synthesis of dipolarophiles 1d–f.
Figure 3: Synthesis of dispiro compounds 4p–t. Reaction conditions: heating the solution of compounds 1 (0.5 ...
Figure 4: Key interactions in {1H-13C}HMBC spectrum of 4f.
Figure 5: General view of 4c in the crystal in thermal ellipsoids representation (50% probability). Hydrogen ...
Figure 6: General view of 4e in the crystal in thermal ellipsoids representation (40% probability). Hydrogen ...
Figure 7: General view of 4r in the crystal in thermal ellipsoids representation (50% probability). Hydrogen ...
Figure 8: Modes of approach of azomethine ylide (R = H, Ph).
Enantioconvergent catalysis
- Justin T. Mohr,
- Jared T. Moore and
- Brian M. Stoltz
Beilstein J. Org. Chem. 2016, 12, 2038–2045, doi:10.3762/bjoc.12.192
- nucleophilic, but in this case the stereoablative step in the mechanism leads to an electrophilic intermediate. The use of Cu(box) complex 9 rendered the reaction enantioselective, forming C-3 quaternary oxindole 12 in 91% ee (up to 94% ee for related substrates). This strategy is useful for constructing spiro
Graphical Abstract
Figure 1: Enantioconvergent methods.
Figure 2: Stereomutative enantioconvergent catalysis.
Scheme 1: Dynamic kinetic resolution by hydrogenation.
Scheme 2: Enantioconvergent synthesis of phosphines governed by Curtin–Hammett/Winstein–Holness kinetics (TMS...
Figure 3: Stereoablative enantioconvergent catalysis.
Scheme 3: Stoltz’ stereoablative oxindole functionalization.
Scheme 4: Fu’s type II enantioconvergent Cu-catalyzed photoredox reaction.
Scheme 5: Stereoablative enantioconvergent allylation and protonation (dba = dibenzylideneacetone).
Scheme 6: Enantioconvergent allylic alkylation with two racemic starting materials.
Figure 4: Enantioconvergent parallel kinetic resolution.
Scheme 7: Enantioconvergent parallel kinetic resolution by two complementary biocatalysts.
Scheme 8: Enantioconvergent PKR by Nocardia EH1.
Rearrangements of organic peroxides and related processes
- Ivan A. Yaremenko,
- Vera A. Vil’,
- Dmitry V. Demchuk and
- Alexander O. Terent’ev
Beilstein J. Org. Chem. 2016, 12, 1647–1748, doi:10.3762/bjoc.12.162
- of homoallylic brosylates 174a–c or spiro cyclopropyl carbinols 175a–c in the THF/H2O2 system, resulting in the increase in the ring size by two atoms and the formation of hydroperoxy oxabicyclo derivatives 176a–c (Table 11). The mechanism of the solvolysis of 174 or 175 in the THF/H2O2 system
Graphical Abstract
Figure 1: The named transformations considered in this review.
Scheme 1: The Baeyer–Villiger oxidation.
Scheme 2: The general mechanism of the peracid-promoted Baeyer–Villiger oxidation.
Scheme 3: General mechanism of the Lewis acid-catalyzed Baeyer–Villiger rearrangement.
Scheme 4: The theoretically studied mechanism of the BV oxidation reaction promoted by H2O2 and the Lewis aci...
Scheme 5: Proton movements in the transition states of the Baeyer–Villiger oxidation.
Scheme 6: The dependence of the course of the Baeyer–Villiger oxidation on the type of O–O-bond cleavage in t...
Scheme 7: The acid-catalyzed Baeyer–Villiger oxidation of cyclic epoxy ketones 22.
Scheme 8: Oxidation of isophorone oxide 29.
Scheme 9: Synthesis of acyl phosphate 32 from acyl phosphonate 31.
Scheme 10: Synthesis of aflatoxin B2 (36).
Scheme 11: The Baeyer–Villiger rearrangement of ketones 37 to lactones 38.
Scheme 12: Synthesis of 3,4-dimethoxybenzoic acid (40) via Baeyer–Villiger oxidation.
Scheme 13: Oxone transforms α,β-unsaturated ketones 43 into vinyl acetates 44.
Scheme 14: The Baeyer–Villiger oxidation of ketones 45 using diaryl diselenide and hydrogen peroxide.
Scheme 15: Baeyer–Villiger oxidation of (E)-2-methylenecyclobutanones.
Scheme 16: Oxidation of β-ionone (56) by H2O2/(BnSe)2 with formation of (E)-2-(2,6,6-trimethylcyclohex-1-en-1-...
Scheme 17: The mechanism of oxidation of ketones 58a–f by hydrogen peroxide in the presence of arsonated polys...
Scheme 18: Oxidation of ketone (58b) by H2O2 to 6-methylcaprolactone (59b) catalyzed by Pt complex 66·BF4.
Scheme 19: Oxidation of ketones 67 with H2O2 in the presence of [(dppb}Pt(µ-OH)]22+.
Scheme 20: The mechanism of oxidation of ketones 67 in the presence of [(dppb}Pt(µ-OH)]22+ and H2O2.
Scheme 21: Oxidation of benzaldehydes 69 in the presence of the H2O2/MeReO3 system.
Scheme 22: Oxidation of acetophenones 72 in the presence of the H2O2/MeReO3 system.
Scheme 23: Baeyer–Villiger oxidation of 2-adamantanone (45c) in the presence of Sn-containing mesoporous silic...
Scheme 24: Aerobic Baeyer–Villiger oxidation of ketones 76 using metal-free carbon.
Scheme 25: A regioselective Baeyer-Villiger oxidation of functionalized cyclohexenones 78 into a dihydrooxepin...
Scheme 26: The oxidation of aldehydes and ketones 80 by H2O2 catalyzed by Co4HP2Mo15V3O62.
Scheme 27: The cleavage of ketones 82 with hydrogen peroxide in alkaline solution.
Scheme 28: Oxidation of ketones 85 to esters 86 with H2O2–urea in the presence of KHCO3.
Scheme 29: Mechanism of the asymmetric oxidation of cyclopentane-1,2-dione 87a with the Ti(OiPr)4/(+)DET/t-BuO...
Scheme 30: The oxidation of cis-4-tert-butyl-2-fluorocyclohexanone (93) with m-chloroperbenzoic acid.
Scheme 31: The mechanism of the asymmetric oxidation of 3-substituted cyclobutanone 96a in the presence of chi...
Scheme 32: Enantioselective Baeyer–Villiger oxidation of cyclic ketones 98.
Scheme 33: Regio- and enantioselective Baeyer–Villiger oxidation of cyclic ketones 101.
Scheme 34: The proposed mechanism of the Baeyer–Villiger oxidation of acetal 105f.
Scheme 35: Synthesis of hydroxy-10H-acridin-9-one 117 from tetramethoxyanthracene 114.
Scheme 36: The Baeyer–Villiger oxidation of the fully substituted pyrrole 120.
Scheme 37: The Criegee rearrangement.
Scheme 38: The mechanism of the Criegee reaction of a peracid with a tertiary alcohol 122.
Scheme 39: Criegee rearrangement of decaline ethylperoxoate 127 into ketal 128.
Scheme 40: The ionic cleavage of 2-methoxy-2-propyl perester 129.
Scheme 41: The Criegee rearrangement of α-methoxy hydroperoxide 136.
Scheme 42: Synthesis of enol esters and acetals via the Criegee rearrangement.
Scheme 43: Proposed mechanism of the transformation of 1-hydroperoxy-2-oxabicycloalkanones 147a–d.
Scheme 44: Transformation of 3-hydroxy-1,2-dioxolanes 151 into diketone derivatives 152.
Scheme 45: Criegee rearrangement of peroxide 153 with the mono-, di-, and tri-O-insertion.
Scheme 46: The sequential Criegee rearrangements of adamantanes 157a,b.
Scheme 47: Synthesis of diaryl carbonates 160a–d from triarylmethanols 159a–d through successive oxygen insert...
Scheme 48: The synthesis of sesquiterpenes 162 from ketone 161 with a Criegee rearrangement as one key step.
Scheme 49: Synthesis of trans-hydrindan derivatives 164, 165.
Scheme 50: The Hock rearrangement.
Scheme 51: The general scheme of the cumene process.
Scheme 52: The Hock rearrangement of aliphatic hydroperoxides.
Scheme 53: The mechanism of solvolysis of brosylates 174a–c and spiro cyclopropyl carbinols 175a–c in THF/H2O2....
Scheme 54: The fragmentation mechanism of hydroperoxy acetals 178 to esters 179.
Scheme 55: The acid-catalyzed rearrangement of phenylcyclopentyl hydroperoxide 181.
Scheme 56: The peroxidation of tertiary alcohols in the presence of a catalytic amount of acid.
Scheme 57: The acid-catalyzed reaction of bicyclic secondary alcohols 192 with hydrogen peroxide.
Scheme 58: The photooxidation of 5,6-disubstituted 3,4-dihydro-2H-pyrans 196.
Scheme 59: The oxidation of tertiary alcohols 200a–g, 203a,b, and 206.
Scheme 60: Transformation of functional peroxide 209 leading to 2,3-disubstitued furans 210 in one step.
Scheme 61: The synthesis of carbazoles 213 via peroxide rearrangement.
Scheme 62: The construction of C–N bonds using the Hock rearrangement.
Scheme 63: The synthesis of moiety 218 from 217 which is a structural motif in the antitumor–antibiotic of CC-...
Scheme 64: The in vivo oxidation steps of cholesterol (219) by singlet oxygen.
Scheme 65: The proposed mechanism of the rearrangement of cholesterol-5α-OOH 220.
Scheme 66: Photochemical route to artemisinin via Hock rearrangement of 223.
Scheme 67: The Kornblum–DeLaMare rearrangement.
Scheme 68: Kornblum–DeLaMare transformation of 1-phenylethyl tert-butyl peroxide (225).
Scheme 69: The synthesis 4-hydroxyenones 230 from peroxide 229.
Scheme 70: The Kornblum–DeLaMare rearrangement of peroxide 232.
Scheme 71: The reduction of peroxide 234.
Scheme 72: The Kornblum–DeLaMare rearrangement of endoperoxide 236.
Scheme 73: The rearrangement of peroxide 238 under Kornblum–DeLaMare conditions.
Scheme 74: The proposed mechanism of rearrangement of peroxide 238.
Scheme 75: The Kornblum–DeLaMare rearrangement of peroxides 242a,b.
Scheme 76: The base-catalyzed rearrangements of bicyclic endoperoxides having electron-withdrawing substituent...
Scheme 77: The base-catalyzed rearrangements of bicyclic endoperoxides 249a,b having electron-donating substit...
Scheme 78: The base-catalyzed rearrangements of bridge-head substituted bicyclic endoperoxides 251a,b.
Scheme 79: The Kornblum–DeLaMare rearrangement of hydroperoxide 253.
Scheme 80: Synthesis of β-hydroxy hydroperoxide 254 from endoperoxide 253.
Scheme 81: The amine-catalyzed rearrangement of bicyclic endoperoxide 263.
Scheme 82: The base-catalyzed rearrangement of meso-endoperoxide 268 into 269.
Scheme 83: The photooxidation of 271 and subsequent Kornblum–DeLaMare reaction.
Scheme 84: The Kornblum–DeLaMare rearrangement as one step in the oxidation reaction of enamines.
Scheme 85: The Kornblum–DeLaMare rearrangement of 3,5-dihydro-1,2-dioxenes 284, 1,2-dioxanes 286, and tert-but...
Scheme 86: The Kornblum–DeLaMare rearrangement of epoxy dioxanes 290a–d.
Scheme 87: Rearrangement of prostaglandin H2 292.
Scheme 88: The synthesis of epicoccin G (297).
Scheme 89: The Kornblum–DeLaMare rearrangement used in the synthesis of phomactin A.
Scheme 90: The Kornblum–DeLaMare rearrangement in the synthesis of 3H-quinazolin-4-one 303.
Scheme 91: The Kornblum–DeLaMare rearrangement in the synthesis of dolabriferol (308).
Scheme 92: Sequential transformation of 3-substituted 2-pyridones 309 into 3-hydroxypyridine-2,6-diones 311 in...
Scheme 93: The Kornblum–DeLaMare rearrangement of peroxide 312 into hydroxy enone 313.
Scheme 94: The Kornblum–DeLaMare rearrangement in the synthesis of polyfunctionalized carbonyl compounds 317.
Scheme 95: The Kornblum–DeLaMare rearrangement in the synthesis of (Z)-β-perfluoroalkylenaminones 320.
Scheme 96: The Kornblum–DeLaMare rearrangement in the synthesis of γ-ketoester 322.
Scheme 97: The Kornblum–DeLaMare rearrangement in the synthesis of diterpenoids 326 and 328.
Scheme 98: The synthesis of natural products hainanolidol (331) and harringtonolide (332) from peroxide 329.
Scheme 99: The synthesis of trans-fused butyrolactones 339 and 340.
Scheme 100: The synthesis of leucosceptroid C (343) and leucosceptroid P (344) via the Kornblum–DeLaMare rearra...
Scheme 101: The Dakin oxidation of arylaldehydes or acetophenones.
Scheme 102: The mechanism of the Dakin oxidation.
Scheme 103: A solvent-free Dakin reaction of aromatic aldehydes 356.
Scheme 104: The organocatalytic Dakin oxidation of electron-rich arylaldehydes 358.
Scheme 105: The Dakin oxidation of electron-rich arylaldehydes 361.
Scheme 106: The Dakin oxidation of arylaldehydes 358 in water extract of banana (WEB).
Scheme 107: A one-pot approach towards indolo[2,1-b]quinazolines 364 from indole-3-carbaldehydes 363 through th...
Scheme 108: The synthesis of phenols 367a–c from benzaldehydes 366a-c via acid-catalyzed Dakin oxidation.
Scheme 109: Possible transformation paths of the highly polarized boric acid coordinated H2O2–aldehyde adduct 3...
Scheme 110: The Elbs oxidation of phenols 375 to hydroquinones.
Scheme 111: The mechanism of the Elbs persulfate oxidation of phenols 375 affording p-hydroquinones 376.
Scheme 112: Oxidation of 2-pyridones 380 under Elbs persulfate oxidation conditions.
Scheme 113: Synthesis of 3-hydroxy-4-pyridone (384) via an Elbs oxidation of 4-pyridone (382).
Scheme 114: The Schenck rearrangement.
Scheme 115: The Smith rearrangement.
Scheme 116: Three main pathways of the Schenck rearrangement.
Scheme 117: The isomerization of hydroperoxides 388 and 389.
Scheme 118: Trapping of dioxacyclopentyl radical 392 by oxygen.
Scheme 119: The hypothetical mechanism of the Schenck rearrangement of peroxide 394.
Scheme 120: The autoxidation of oleic acid (397) with the use of labeled isotope 18O2.
Scheme 121: The rearrangement of 18O-labeled hydroperoxide 400 under an atmosphere of 16O2.
Scheme 122: The rearrangement of the oleate-derived allylic hydroperoxides (S)-421 and (R)-425.
Scheme 123: Mechanisms of Schenck and Smith rearrangements.
Scheme 124: The rearrangement and cyclization of 433.
Scheme 125: The Wieland rearrangement.
Scheme 126: The rearrangement of bis(triphenylsilyl) 439 or bis(triphenylgermyl) 441 peroxides.
Scheme 127: The oxidative transformation of cyclic ketones.
Scheme 128: The hydroxylation of cyclohexene (447) in the presence of tungstic acid.
Scheme 129: The oxidation of cyclohexene (447) under the action of hydrogen peroxide.
Scheme 130: The reaction of butenylacetylacetone 455 with hydrogen peroxide.
Scheme 131: The oxidation of bridged 1,2,4,5-tetraoxanes.
Scheme 132: The proposed mechanism for the oxidation of bridged 1,2,4,5-tetraoxanes.
Scheme 133: The rearrangement of ozonides.
Scheme 134: The acid-catalyzed oxidative rearrangement of malondialdehydes 462 under the action of H2O2.
Scheme 135: Pathways of the Lewis acid-catalyzed cleavage of dialkyl peroxides 465 and ozonides 466.
Scheme 136: The mechanism of the transformation of (tert-butyldioxy)cyclohexanedienones 472.
Scheme 137: The synthesis of Vitamin K3 from 472a.
Scheme 138: Proposed mechanism for the transformation of 478d into silylated endoperoxide 479d.
Scheme 139: The rearrangement of hydroperoxide 485 to form diketone 486.
Scheme 140: The base-catalyzed rearrangement of cyclic peroxides 488a–g.
Scheme 141: Synthesis of chiral epoxides and aldols from peroxy hemiketals 491.
Scheme 142: The multistep transformation of (R)-carvone (494) to endoperoxides 496a–e.
Scheme 143: The decomposition of anthracene endoperoxide 499.
Scheme 144: Synthesis of esters 503 from aldehydes 501 via rearrangement of peroxides 502.
Scheme 145: Two possible paths for the base-promoted decomposition of α-azidoperoxides 502.
Scheme 146: The Story decomposition of cyclic diperoxide 506a.
Scheme 147: The Story decomposition of cyclic triperoxide 506b.
Scheme 148: The thermal rearrangement of endoperoxides A into diepoxides B.
Scheme 149: The transformation of peroxide 510 in the synthesis of stemolide (511).
Scheme 150: The possible mechanism of the rearrangement of endoperoxide 261g.
Scheme 151: The photooxidation of indene 517.
Scheme 152: The isomerization of ascaridole (523).
Scheme 153: The isomerization of peroxide 525.
Scheme 154: The thermal transformation of endoperoxide 355.
Scheme 155: The photooxidation of cyclopentadiene (529) at a temperature higher than 0 °C.
Scheme 156: The thermal rearrangement of endoperoxides 538a,b.
Scheme 157: The transformation of peroxides 541.
Scheme 158: The thermal rearrangements of strained cyclic peroxides.
Scheme 159: The thermal rearrangement of diacyl peroxide 551 in the synthesis of C4-epi-lomaiviticin B core 553....
Scheme 160: The 1O2 oxidation of tryptophan (554) and rearrangement of dioxetane intermediate 555.
Scheme 161: The Fe(II)-promoted cleavage of aryl-substituted bicyclic peroxides.
Scheme 162: The proposed mechanism of the Fe(II)-promoted rearrangement of 557a–c.
Scheme 163: The reaction of dioxolane 563 with Fe(II) sulfate.
Scheme 164: Fe(II)-promoted rearrangement of 1,2-dioxane 565.
Scheme 165: Fe(II) cysteinate-promoted rearrangement of 1,2-dioxolane 568.
Scheme 166: The transformation of 1,2-dioxanes 572a–c under the action of FeCl2.
Scheme 167: Fe(II) cysteinate-promoted transformation of tetraoxane 574.
Scheme 168: The CoTPP-catalyzed transformation of bicyclic endoperoxides 600a–d.
Scheme 169: The CoTPP-catalyzed transformation of epoxy-1,2-dioxanes.
Scheme 170: The Ru(II)-catalyzed reactions of 1,4-endoperoxide 261g.
Scheme 171: The Ru(II)-catalyzed transformation as a key step in the synthesis of elyiapyrone A (610) from 1,4-...
Scheme 172: Peroxides with antimalarial activity.
Scheme 173: The interaction of iron ions with artemisinin (616).
Scheme 174: The interaction of FeCl2 with 1,2-dioxanes 623, 624.
Scheme 175: The mechanism of reaction 623 and 624 with Fe(II)Cl2.
Scheme 176: The reaction of bicyclic natural endoperoxides G3-factors 631–633 with FeSO4.
Scheme 177: The transformation of terpene cardamom peroxide 639.
Scheme 178: The different ways of the cleavage of tetraoxane 643.
Scheme 179: The LC–MS analysis of interaction of tetraoxane 646 with iron(II)heme 647.
Scheme 180: The rearrangement of 3,6-epidioxy-1,10-bisaboladiene (EDBD, 649).
Scheme 181: Easily oxidized substrates.
Scheme 182: Biopathway of synthesis of prostaglandins.
Scheme 183: The reduction and rearrangements of isoprostanes.
Scheme 184: The partial mechanism for linoleate 658 oxidation.
Scheme 185: The transformation of lipid hydroperoxide.
Scheme 186: The acid-catalyzed cleavage of the product from free-radical oxidation of cholesterol (667).
Scheme 187: Two pathways of catechols oxidation.
Scheme 188: Criegee-like or Hock-like rearrangement of the intermediate hydroperoxide 675 in dioxygenase enzyme...
Scheme 189: Carotinoides 679 cleavage by carotenoid cleavage dioxygenases.
Biosynthesis of oxygen and nitrogen-containing heterocycles in polyketides
- Franziska Hemmerling and
- Frank Hahn
Beilstein J. Org. Chem. 2016, 12, 1512–1550, doi:10.3762/bjoc.12.148
- , 3,4-dihydroxy-L-phenylalanine (L-DOPA), 4-coumaric acid or caffeic acid. Grisanes. Many fungal spirobenzofuranones contain the grisane (191) moiety as the central structural motif (Scheme 26a). The spiro linkage between the B and C rings is installed by oxidative phenol coupling starting from type II
Graphical Abstract
Scheme 1: Schematic description of the cyclisation reaction catalysed by TE domains. In most cases, the nucle...
Scheme 2: Mechanisms for the formation of oxygen heterocycles. The degree of substitution can differ from tha...
Scheme 3: Pyran-ring formation in pederin (24) biosynthesis. Incubation of recombinant PedPS7 with substrate ...
Scheme 4: The domain AmbDH3 from ambruticin biosynthesis catalyses the dehydration of 25 and subsequent cycli...
Scheme 5: SalBIII catalyses dehydration of 29 and subsequent cyclisation to tetrahydropyran 30 [18].
Figure 1: All pyranonaphtoquinones contain either the naphtha[2,3-c]pyran-5,10-dione (32) or the regioisomeri...
Scheme 6: Pyran-ring formation in actinorhodin (34) biosynthesis. DNPA: 4-dihydro-9-hydroxy-1-methyl-10-oxo-3H...
Scheme 7: Pyran formation in granaticin (36) biosynthesis. DNPA: 4-dihydro-9-hydroxy-1-methyl-10-oxo-3H-napht...
Scheme 8: Pyran formation in alnumycin (37) biosynthesis. Adapted from [21].
Scheme 9: Biosynthesis of pseudomonic acid A (61). The pyran ring is initially formed in 57 after dehydrogena...
Scheme 10: Epoxidation–cyclisation leads to the formation of the tetrahydropyran ring in the western part of t...
Scheme 11: a) Nonactin (70) is formed from heterodimers of (−)(+)-dimeric nonactic acid and (+)(−)-dimeric non...
Figure 2: Pamamycins (73) are macrodiolide antibiotics containing three tetrahydrofuran moieties, which are a...
Scheme 12: A PS domain homolog in oocydin A (76) biosynthesis is proposed to catalyse furan formation via an o...
Scheme 13: Mechanism of oxidation–furan cyclisation by AurH, which converts (+)-deoxyaureothin (77) into (+)-a...
Scheme 14: Leupyrrin A2 (80) and the proposed biosynthesis of its furylidene moiety [69,70].
Scheme 15: Asperfuranone (93) biosynthesis, adapted from [75].
Figure 3: The four major aflatoxins produced by Aspergilli are the types B1, B2, G1 and G2 (94–97). In the di...
Scheme 16: Overview on aflatoxin B1 (94) biosynthesis. HOMST = 11-hydroxy-O-methylsterigmatocystin [78,79,82-106].
Scheme 17: A zipper mechanism leads to the formation of oxygen heterocycles in monensin biosynthesis [109-111].
Scheme 18: Formation of the 2,6-dioxabicyclo[3.2.1]octane (DBO) ring system in aurovertin B (118) biosynthesis ...
Figure 4: Structures of the epoxide-containing polyketides epothilone A (119) and oleandomycin (120) [123-125].
Scheme 19: Structures of phoslactomycin B (121) (a) and jerangolid A (122) (b). The heterocycle-forming steps ...
Scheme 20: a) Structures of rhizoxin (130) and cycloheximide (131). Model for the formation of δ-lactones (b) ...
Scheme 21: EncM catalyses a dual oxidation sequence and following processing of the highly reactive intermedia...
Figure 5: Mesomeric structures of tetronates [138,139].
Figure 6: Structures of tetronates for which gene clusters have been sequenced. The tetronate moiety is shown...
Scheme 22: Conserved steps for formation and processing in several 3-acyl-tetronate biosynthetic pathways were...
Scheme 23: In versipelostatin A (153) biosynthesis, VstJ is a candidate enzyme for catalysing the [4 + 2] cycl...
Scheme 24: a) Structures of some thiotetronate antibiotics. b) Biosynthesis of thiolactomycin (165) as propose...
Scheme 25: Aureusidine synthase (AS) catalyses phenolic oxidation and conjugate addition of chalcones leading ...
Scheme 26: a) Oxidative cyclisation is a key step in the biosynthesis of spirobenzofuranes 189, 192 and 193. b...
Scheme 27: A bicyclisation mechanism forms a β-lactone and a pyrrolidinone and removes the precursor from the ...
Scheme 28: Spontaneous cyclisation leads to off-loading of ebelactone A (201) from the PKS machinery [163].
Scheme 29: Mechanisms for the formation of nitrogen heterocycles.
Scheme 30: Biosynthesis of highly substituted α-pyridinones. a) Feeding experiments confirmed the polyketide o...
Scheme 31: Acridone synthase (ACS) catalyses the formation of 1,3-dihydroxy-N-methylacridone (224) by condensa...
Scheme 32: A Dieckmann condensation leads to the formation of a 3-acyl-4-hydroxypyridin-2-one 227 and removes ...
Scheme 33: a) Biosynthesis of the pyridinone tenellin (234). b) A radical mechanism was proposed for the ring-...
Scheme 34: a) Oxazole-containing PKS–NRPS-derived natural products oxazolomycin (244) and conglobatin (245). b...
Scheme 35: Structure of tetramic acids 251 (a) and major tautomers of 3-acyltetramic acids 252a–d (b). Adapted...
Scheme 36: Equisetin biosynthesis. R*: terminal reductive domain. Adapted from [202].
Scheme 37: a) Polyketides for which a similar biosynthetic logic was suggested. b) Pseurotin A (256) biosynthe...
Figure 7: Representative examples of PTMs with varying ring sizes and oxidation patterns [205,206].
Scheme 38: Ikarugamycin biosynthesis. Adapted from [209-211].
Scheme 39: Tetramate formation in pyrroindomycin aglycone (279) biosynthesis [213-215].
Scheme 40: Dieckmann cyclases catalyse tetramate or 2-pyridone formation in the biosynthesis of, for example, ...
One-pot synthesis of tetracyclic fused imidazo[1,2-a]pyridines via a three-component reaction
- Bo Yang,
- Chuanye Tao,
- Taofeng Shao,
- Jianxian Gong and
- Chao Che
Beilstein J. Org. Chem. 2016, 12, 1487–1492, doi:10.3762/bjoc.12.145
- species from 2-aminopyridine and isatin which then undergoes a formal [4 + 1] cycloaddition with isocyanide to generate a spiro intermediate b. The spiro compound then undergoes a retro-aza–ene reaction via a [1,5]-hydride shift resulting in an aromatic imidazo[1,2-a]pyridine having an isocyanate
Graphical Abstract
Scheme 1: MCR to polycyclic fused imidazo[1,2-a]pyridine derivatives.
Figure 1: Syntheses of imidazo[1,2-a]pyridine derivatives. Reaction conditions: 2 (1.35 mmol), 3 (1 mmol), 4 ...
Figure 2: Mechanistic rationale for the MCR [36].
Synthesis of ferrocenyl-substituted 1,3-dithiolanes via [3 + 2]-cycloadditions of ferrocenyl hetaryl thioketones with thiocarbonyl S-methanides
- Grzegorz Mlostoń,
- Róża Hamera-Fałdyga,
- Anthony Linden and
- Heinz Heimgartner
Beilstein J. Org. Chem. 2016, 12, 1421–1427, doi:10.3762/bjoc.12.136
- -Tetramethyl-8-thia-5,6-diazaspiro[3.4]oct-5-en-2-one (3c) [20] and spiro[1,3,4-thiadiazole-2(5H),2’-tricyclo[3.3.1.13,7]decane] (3d) [21] were obtained by known methods according to the literature protocols. Diazomethane was prepared in a 5 mmol scale either from N-nitroso-N-methylurea or from N
- -Ferrocenyl-5-(selenophen-2-yl)spiro[1,3-dithiolane-4,2’-tricyclo[3.3.1.13,7]decane] (5l); 4-Ferrocenyl-4-(selenophen-2-yl)spiro[1,3-dithiolane-2,2’-tricyclo[3.3.1.13,7]decane] (6l): Isolated as a mixture of regioisomers. Yield: 393 mg (73%; crude product ratio 67:33). Yellow solid; IR (KBr) ν: 3085 (w), 3072
Graphical Abstract
Scheme 1: Reactions of aromatic thiocarbonyl S-methanides 2a,b with ferrocenyl thioketones 1 (Table 1).
Figure 1: ORTEP Plot [16] of the molecular structures of the ferrocenyl-substituted 1,3-dithiolanes 5b and 5f (wi...
Scheme 2: Reactions of cycloaliphatic thiocarbonyl S-methanides with ferrocenyl hetaryl thioketones 1 (Table 1).
Scheme 3: Reaction of 3c with ferrocenyl methyl thioketone 1e.
Scheme 4: Mesomeric stabilization of the 1,5-diradical intermediate in the reaction of aromatic thiocarbonyl S...
3,6-Carbazole vs 2,7-carbazole: A comparative study of hole-transporting polymeric materials for inorganic–organic hybrid perovskite solar cells
- Wei Li,
- Munechika Otsuka,
- Takehito Kato,
- Yang Wang,
- Takehiko Mori and
- Tsuyoshi Michinobu
Beilstein J. Org. Chem. 2016, 12, 1401–1409, doi:10.3762/bjoc.12.134
- performances. So far, 2,2’,7,7’-tetrakis(N,N-di(p-methoxyphenyl)amino)-9,9-spirobifluorene (spiro-OMeTAD) is regarded as the most conventional solid state hole transporter for the PSCs [6][7][8][9][10]. Despite the high PCEs conferred by this hole transporting layer, spiro-OMeTAD has several limitations, such
Graphical Abstract
Scheme 1: Synthesis of 3,6-Cbz-EDOT and 2,7-Cbz-EDOT by Stille polycondensation.
Figure 1: (a) Normalized UV–vis absorption of Cbz-EDOT polymers in CH2Cl2 measured at 10−5 M repeat unit−1 an...
Figure 2: Energy level diagram of PSC components including P3HT, 3,6-Cbz-EDOT, and 2,7-Cbz-EDOT.
Figure 3: (a) Current density–voltage curves and (b) incident photon to current conversion efficiency (IPCE) ...
Figure 4: Impedance spectroscopy characterization of the PSCs with different HTMs over the frequency range fr...
From N-vinylpyrrolidone anions to modified paraffin-like oligomers via double alkylation with 1,8-dibromooctane: access to covalent networks and oligomeric amines for dye attachment
- Daniela Obels,
- Melanie Lievenbrück and
- Helmut Ritter
Beilstein J. Org. Chem. 2016, 12, 1395–1400, doi:10.3762/bjoc.12.133
- . However, in contrast to the restricted monoalkylation of N-vinylcaprolactam [24], the five-membered ring of N-VP can be double alkylated in α-position. In this connection, 1-bromo-2-(2-bromoethoxy)ethane was used as alkylation reagent to allow the preparation of a spiro-type monomer [25] due to
Graphical Abstract
Scheme 1: Alkylation of N-VP with 1,8-dibromooctane yielding paraffin-like oligomers 2a–c.
Figure 1: Chemical structure of water swellable network 3a and 3b. Photographs of water-swollen polymer disks...
Scheme 2: Synthesis of the branched oligomeric dye 6: a) radical thiol–ene click reaction of 2a with 2-aminoe...
Figure 2: UV–vis spectra of oligomers 5 (c = 0.16 g/mL, red), 6 (c = 0.63 g/mL, blue) and DFA (c = 0.016 g/mL...
Synthesis of 2-oxindoles via 'transition-metal-free' intramolecular dehydrogenative coupling (IDC) of sp2 C–H and sp3 C–H bonds
- Nivesh Kumar,
- Santanu Ghosh,
- Subhajit Bhunia and
- Alakesh Bisai
Beilstein J. Org. Chem. 2016, 12, 1153–1169, doi:10.3762/bjoc.12.111
- synthetic methodology was further explored in the construction of spiro-fused oxindole ring systems (Scheme 3). The spiro-fused oxindoles such as coerulescine (15a) [68][69][70][71][72], horsfiline (15b) [73], and elacomine (16), are prevalently found in a huge number of indole-based alkaloids having
Graphical Abstract
Scheme 1: Synthesis of 2-oxindoles via oxidative processes.
Figure 1: Substrates scope of one-pot ‘transition-metal-free’ IDC. The syntheses of compounds 4a–s according ...
Figure 2: Further substrates scope of one-pot ‘transition metal-free’ IDC. Conditions A: KOt-Bu, iodine; cond...
Figure 3: Substrates scope of ‘transition-metal-free’ IDC using KOt-Bu/I2. Reproduced from [46].
Figure 4: C-Alkylation of anilides using KOt-Bu.
Figure 5: Substrates scope of ‘transition-metal-free’ IDC of C-alkylated anilides using DBU/I2.
Scheme 2: Oxidative coupling of C-arylated anilides (±)-11a–d. The synthesis of 12b as per method A has been ...
Scheme 3: Synthesis of spirocyclic product through IDC The synthesis of 14 as per method A has been reproduce...
Scheme 4: Dimerization of β-N-aryl-amidoesters 3a and b. Reproduced from [46].
Scheme 5: Synthesis of dimeric 2-oxindoles utilizing IDC. The syntheses of 19a and b have been reproduced fro...
Scheme 6: Plausible mechanism of ‘transition-metal-free’ IDC The mechanistic consideration in Scheme 6 has been repro...
Scheme 7: Intramolecular-dehydrogenative-coupling (IDC) of 3a and 5a. Reproduced from [46].
Scheme 8: IDC of 3a and 5a using different oxidants. Reproduced from [46].
Scheme 9: Synthesis of 3-substituted-2-oxindoles from benzyl esters.
Scheme 10: 3-Substituted-2-oxindoles from p-methoxybenzyl esters.
Scheme 11: Synthetic elaboration using Tsuji–Trost reactions. Reproduced from [46].
Catalytic asymmetric synthesis of biologically important 3-hydroxyoxindoles: an update
- Bin Yu,
- Hui Xing,
- De-Quan Yu and
- Hong-Min Liu
Beilstein J. Org. Chem. 2016, 12, 1000–1039, doi:10.3762/bjoc.12.98
- -workers also established a CPA (cat. 38)-catalyzed asymmetrc [3 + 2] cycloaddition of 3-indolylmethanols with 3-methyl-2-vinylindoles, affording spiro[cyclopenta[b]indole-1,3’-oxindole] scaffolds in moderate to good yields (72–99% yield) and with excellent diastereoselectivities (>95:5 dr) and
Graphical Abstract
Figure 1: 3-Hydroxyoxindole-containing natural products and biologically active molecules.
Scheme 1: Chiral CNN pincer Pd(II) complex 1 catalyzed asymmetric allylation of isatins.
Scheme 2: Asymmetric allylation of ketimine catalyzed by the chiral CNN pincer Pd(II) complex 2.
Scheme 3: Pd/L1 complex-catalyzed asymmetric allylation of 3-O-Boc-oxindoles.
Scheme 4: Cu(OTf)2-catalyzed asymmetric direct addition of acetonitrile to isatins.
Scheme 5: Chiral tridentate Schiff base/Cu complex catalyzed asymmetric Friedel–Crafts alkylation of isatins ...
Scheme 6: Guanidine/CuI-catalyzed asymmetric alkynylation of isatins with terminal alkynes.
Scheme 7: Asymmetric intramolecular direct hydroarylation of α-ketoamides.
Scheme 8: Plausible catalytic cycle for the direct hydroarylation of α-ketoamides.
Scheme 9: Ir-catalyzed asymmetric arylation of isatins with arylboronic acids.
Scheme 10: Enantioselective decarboxylative addition of β-ketoacids to isatins.
Scheme 11: Ruthenium-catalyzed hydrohydroxyalkylation of olefins and 3-hydroxy-2-oxindoles.
Scheme 12: Proposed catalytic mechanism and stereochemical model.
Scheme 13: In-catalyzed allylation of isatins with stannylated reagents.
Scheme 14: Modified protocol for the synthesis of allylated 3-hydroxyoxindoles.
Scheme 15: Hg-catalyzed asymmetric allylation of isatins with allyltrimethylsilanes.
Scheme 16: Enantioselective additions of organoborons to isatins.
Scheme 17: Asymmetric aldol reaction of isatins with cyclohexanone.
Scheme 18: Enantioselective aldol reactions of aliphatic aldehydes with isatin derivatives and the plausible t...
Scheme 19: Enantioselective aldol reaction of isatins and 2,2-dimethyl-1,3-dioxan-5-one.
Scheme 20: Asymmetric aldol reactions between ketones and isatins.
Scheme 21: Phenylalanine lithium salt-catalyzed asymmetric synthesis of 3-alkyl-3-hydroxyoxindoles.
Scheme 22: Aldolization between isatins and dihydroxyacetone derivatives.
Scheme 23: One-pot asymmetric synthesis of convolutamydine A.
Scheme 24: Asymmetric aldol reactions of cyclohexanone and acetone with isatins.
Scheme 25: Aldol reactions of acetone with isatins.
Scheme 26: Aldol reactions of ketones with isatins.
Scheme 27: Enantioselective allylation of isatins.
Scheme 28: Asymmetric aldol reaction of trifluoromethyl α-fluorinated β-keto gem-diols with isatins.
Scheme 29: Plausible mechanism proposed for the asymmetric aldol reaction.
Scheme 30: Asymmetric aldol reaction of 1,1-dimethoxyacetone with isatins.
Scheme 31: Enantioselective Friedel-Crafts reaction of phenols with isatins.
Scheme 32: Enantioselective addition of 1-naphthols with isatins.
Scheme 33: Enantioselective aldol reaction between 3-acetyl-2H-chromen-2-ones and isatins.
Scheme 34: Stereoselective Mukaiyama–aldol reaction of fluorinated silyl enol ethers with isatins.
Scheme 35: Asymmetric vinylogous Mukaiyama–aldol reaction between 2-(trimethylsilyloxy)furan and isatins.
Scheme 36: β-ICD-catalyzed MBH reactions of isatins with maleimides.
Scheme 37: β-ICD-catalyzed MBH reactions of 7-azaisatins with maleimides and activated alkenes.
Scheme 38: Enantioselective aldol reaction of isatins with ketones.
Scheme 39: Direct asymmetric vinylogous aldol reactions of allyl ketones with isatins.
Scheme 40: Enantioselective aldol reactions of ketones with isatins.
Scheme 41: The MBH reaction of isatins with α,β-unsaturated γ-butyrolactam.
Scheme 42: Reactions of tert-butyl hydrazones with isatins followed by oxidation.
Scheme 43: Aldol reactions of isatin derivatives with ketones.
Scheme 44: Enantioselective decarboxylative cyanomethylation of isatins.
Scheme 45: Catalytic kinetic resolution of 3-hydroxy-3-substituted oxindoles.
Scheme 46: Lewis acid catalyzed Friedel–Crafts alkylation of 3-hydroxy-2-oxindoles with electron-rich phenols.
Scheme 47: Lewis acid catalyzed arylation of 3-hydroxyoxindoles with aromatics.
Scheme 48: Synthetic application of 3-arylated disubstituted oxindoles in the construction of core structures ...
Scheme 49: CPA-catalyzed dearomatization and arylation of 3-indolyl-3-hydroxyoxindoles with tryptamines and 3-...
Scheme 50: CPA-catalyzed enantioselective decarboxylative alkylation of β-keto acids with 3-hydroxy-3-indolylo...
Scheme 51: BINOL-derived imidodiphosphoric acid-catalyzed enantioselective Friedel–Crafts reactions of indoles...
Scheme 52: CPA-catalyzed enantioselective allylation of 3-indolylmethanols.
Scheme 53: 3-Indolylmethanol-based substitution and cycloaddition reactions.
Scheme 54: CPA-catalyzed asymmetric [3 + 3] cycloaddtion reactions of 3-indolylmethanols with azomethine ylide...
Scheme 55: CPA-catalyzed three-component cascade Michael/Pictet–Spengler reactions of 3-indolylmethanols and a...
Scheme 56: Acid-promoted chemodivergent and stereoselective synthesis of diverse indole derivatives.
Scheme 57: CPA-catalyzed asymmetric formal [3 + 2] cycloadditions.
Scheme 58: CPA-catalyzed enantioselective cascade reactions for the synthesis of C7-functionlized indoles.
Scheme 59: Lewis acid-promoted Prins cyclization of 3-allyl-3-hydroxyoxindoles with aldehydes.
Scheme 60: Ga(OTf)3-catalyzed reactions of allenols and phenols.
Scheme 61: I2-catalyzed construction of pyrrolo[2.3.4-kl]acridines from enaminones and 3-indolyl-3-hydroxyoxin...
Scheme 62: CPA-catalyzed asymmetric aza-ene reaction of 3-indolylmethanols with cyclic enaminones.
Scheme 63: Asymmetric α-alkylation of aldehydes with 3-indolyl-3-hydroxyoxindoles.
Scheme 64: Organocatalytic asymmetric α-alkylation of enolizable aldehydes with 3-indolyl-3-hydroxyoxindoles a...
(Thio)urea-mediated synthesis of functionalized six-membered rings with multiple chiral centers
- Giorgos Koutoulogenis,
- Nikolaos Kaplaneris and
- Christoforos G. Kokotos
Beilstein J. Org. Chem. 2016, 12, 462–495, doi:10.3762/bjoc.12.48
- prochiral ketones 35 or 36, catalyzed by a primary amine-thiourea 37 developed by Jacobsen. The proposed pathway is based on desymmetrization of 35 or 36 by an intramolecular Michael addition of the corresponding enamines to an α,β-unsaturated ester, to yield bicyclic or spiro-bicyclic products 38 and 39
- malononitriles 104 and α,α-dicyanoalkenes 105. The process yielded highly functionalized spiro-oxindole dienes 106. The products were obtained in good to excellent yields (up to 97%) and enantioselectivities (up to 96%), but the diastereoselectivities were moderate (up to 7.9:1) (Scheme 34) [53]. In 2015, Soós
- -dioxocyclohexanecarboxyalate 124 to produce bicyclo[3.2.1]octane unit (Scheme 40) [60]. The reaction proceeded smoothly to afford a wide variety of products 125 in good to excellent yields and selectivities. In 2010, Gong and co-workers developed an asymmetric process en route to spiro[4-cyclohexanone-1,3’-oxindoline] 126
Graphical Abstract
Scheme 1: Activation of carbonyl compounds via enamine and iminium intermediates [2].
Scheme 2: Electronic and steric interactions present in enamine activation mode [2].
Scheme 3: Electrophilic activation of carbonyl compounds by a thiourea moiety.
Scheme 4: Asymmetric synthesis of dihydro-2H-pyran-6-carboxylate 3 using organocatalyst 4 [16].
Scheme 5: Possible hydrogen-bonding for the reaction of (E)-methyl 2-oxo-4-phenylbut-3-enoate [16].
Scheme 6: Asymmetric desymmetrization of 4,4-cyclohexadienones using the Michael addition reaction with malon...
Scheme 7: The enantioselective synthesis of α,α-disubstituted cycloalkanones using catalyst 11 [18].
Scheme 8: The enantioselective synthesis of indolo- and benzoquinolidine compounds through aza-Diels–Alder re...
Scheme 9: Enantioselective [5 + 2] cycloaddition [20].
Scheme 10: Asymmetric synthesis of oxazine derivatives 26 [21].
Scheme 11: Asymmetric synthesis of bicyclo[3.3.1]nonadienone, core 30 present in (−)-huperzine [22].
Scheme 12: Asymmetric inverse electron-demand Diels-Alder reaction catalyzed by amine-thiourea 34 [23].
Scheme 13: Asymmetric entry to morphan skeletons, catalyzed by amine-thiourea 37 [24].
Scheme 14: Asymmetric transformation of (E)-2-nitroallyl acetate [25].
Scheme 15: Proposed way of activation.
Scheme 16: Asymmetric synthesis of nitrobicyclo[3.2.1]octan-2-one derivatives [26].
Scheme 17: Asymmetric tandem Michael–Henry reaction catalyzed by 50 [27].
Scheme 18: Asymmetric Diels–Alder reactions of 3-vinylindoles 51 [29].
Scheme 19: Proposed transition state and activation mode of the asymmetric Diels–Alder reactions of 3-vinylind...
Scheme 20: Desymmetrization of meso-anhydrides by Chin, Song and co-workers [30].
Scheme 21: Desymmetrization of meso-anhydrides by Connon and co-workers [31].
Scheme 22: Asymmetric intramolecular Michael reaction [32].
Scheme 23: Asymmetric addition of malonate to 3-nitro-2H-chromenes 67 [33].
Scheme 24: Intramolecular desymmetrization through an intramolecular aza-Michael reaction [34].
Scheme 25: Enantioselective synthesis of (−)-mesembrine [34].
Scheme 26: A novel asymmetric Michael–Michael reaction [35].
Scheme 27: Asymmetric three-component reaction catalyzed by Takemoto’s catalyst 77 [46].
Scheme 28: Asymmetric domino Michael–Henry reaction [47].
Scheme 29: Asymmetric domino Michael–Henry reaction [48].
Scheme 30: Enantioselective synthesis of derivatives of 3,4-dihydro-2H-pyran 89 [49].
Scheme 31: Asymmetric addition of α,α-dicyano olefins 90 to 3-nitro-2H-chromenes 91 [50].
Scheme 32: Asymmetric three-component reaction producing 2,6-diazabicyclo[2.2.2]octanones 95 [51].
Scheme 33: Asymmetric double Michael reaction producing substituted chromans 99 [52].
Scheme 34: Enantioselective synthesis of multi-functionalized spiro oxindole dienes 106 [53].
Scheme 35: Organocatalyzed Michael aldol cyclization [54].
Scheme 36: Asymmetric synthesis of dihydrocoumarins [55].
Scheme 37: Asymmetric double Michael reaction en route to tetrasubstituted cyclohexenols [56].
Scheme 38: Asymmetric synthesis of α-trifluoromethyl-dihydropyrans 121 [58].
Scheme 39: Tyrosine-derived tertiary amino-thiourea 123 catalyzed Michael hemiaketalization reaction [59].
Scheme 40: Enantioselective entry to bicyclo[3.2.1]octane unit [60].
Scheme 41: Asymmetric synthesis of spiro[4-cyclohexanone-1,3’-oxindoline] 126 [61].
Scheme 42: Kinetic resolution of 3-nitro-2H-chromene 130 [62].
Scheme 43: Asymmetric synthesis of chromanes 136 [63].
Scheme 44: Wang’s utilization of β-unsaturated α-ketoesters 87 [64,65].
Scheme 45: Asymmetric entry to trifluoromethyl-substituted dihydropyrans 144 [66].
Scheme 46: Phenylalanine-derived thiourea-catalyzed domino Michael hemiaketalization reaction [67].
Scheme 47: Asymmetric synthesis of α-trichloromethyldihydropyrans 149 [68].
Scheme 48: Takemoto’s thiourea-catalyzed domino Michael hemiaketalization reaction [69].
Scheme 49: Asymmetric synthesis of densely substituted cyclohexanes [70].
Scheme 50: Enantioselective synthesis of polysubstituted chromeno [4,3-b]pyrrolidine derivatines 157 [71].
Scheme 51: Enantioselective synthesis of spiro-fused cyclohexanone/5-oxazolone scaffolds 162 [72].
Scheme 52: Utilizing 2-mercaptobenzaldehydes 163 in cascade processes [73,74].
Scheme 53: Proposed transition state of the initial sulfa-Michael step [74].
Scheme 54: Asymmetric thiochroman synthesis via dynamic kinetic resolution [75].
Scheme 55: Enantioselective synthesis of thiochromans [76].
Scheme 56: Enantioselective synthesis of chromans and thiochromans synthesis [77].
Scheme 57: Enantioselective sulfa-Michael aldol reaction en route to spiro compounds [78].
Scheme 58: Enantioselective synthesis of 4-aminobenzo(thio)pyrans 179 [79].
Scheme 59: Asymmetric synthesis of tetrahydroquinolines [80].
Scheme 60: Novel asymmetric Mannich–Michael sequence producing tetrahydroquinolines 186 [81].
Scheme 61: Enantioselective synthesis of biologically interesting chromanes 190 and 191 [82].
Scheme 62: Asymmetric tandem Henry–Michael reaction [83].
Scheme 63: An asymmetric synthesis of substituted cyclohexanes via a dynamic kinetic resolution [84].
Scheme 64: Three component-organocascade initiated by Knoevenagel reaction [85].
Scheme 65: Asymmetric Michael reaction catalyzed by catalysts 57 and 211 [86].
Scheme 66: Proposed mechanism for the asymmetric Michael reaction catalyzed by catalysts 57 and 211 [86].
Scheme 67: Asymmetric facile synthesis of hexasubstituted cyclohexanes [87].
Scheme 68: Dual activation catalytic mechanism [87].
Scheme 69: Asymmetric Michael–Michael/aldol reaction catalyzed by catalysts 57, 219 and 214 [88].
Scheme 70: Asymmetric synthesis of substituted cyclohexane derivatives, using catalysts 57 and 223 [89].
Scheme 71: Asymmetric synthesis of substituted piperidine derivatives, using catalysts 223 and 228 [90].
Scheme 72: Asymmetric synthesis of endo-exo spiro-dihydropyran-oxindole derivatives catalyzed by catalyst 232 [91]....
Scheme 73: Asymmetric synthesis of carbazole spiroxindole derivatives, using catalyst 236 [92].
Scheme 74: Enantioselective formal [2 + 2] cycloaddition of enal 209 with nitroalkene 210, using catalysts 23 ...
Scheme 75: Asymmetric synthesis of polycyclized hydroxylactams derivatives, using catalyst 242 [94].
Scheme 76: Asymmetric synthesis of product 243, using catalyst 246 [95].
Scheme 77: Formation of the α-stereoselective acetals 248 from the corresponding enol ether 247, using catalys...
Scheme 78: Selective glycosidation, catalyzed by Shreiner’s catalyst 23 [97].
