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Search for "pyran" in Full Text gives 96 result(s) in Beilstein Journal of Organic Chemistry.
Microwave-assisted multicomponent reactions in heterocyclic chemistry and mechanistic aspects
- Shivani Gulati,
- Stephy Elza John and
- Nagula Shankaraiah
Beilstein J. Org. Chem. 2021, 17, 819–865, doi:10.3762/bjoc.17.71
- -methyl-2H-pyran-2-one and arylglyoxal to form intermediate A. Michael addition of amine to intermediate A gives B which further undergoes an intramolecular nucleophilic addition reaction to yield C which on cyclization and with subsequent loss of water from D produce the desired products 34. Meshram and
- ylide formation over the expected Strecker degradation. The azomethine ylide trapped by 3-alkenylindole undergoes 1,3-dipolar cycloaddition and led to the cycloadducts 44. 4 Pyrans Pyran is a six-membered heterocyclic, non-aromatic ring, consisting of five carbon atoms and one oxygen atom with two
- double bonds. Numerous natural compounds containing pyrans and benzopyrans (fused pyrans) are identified. Epicalyxin (45) is used as an anticancer agent against human HT-1080 fibrosarcoma and murine 26-L5 carcinoma. Laninamivir (46) is a pyran-based drug used as a neuraminidase inhibitor and zanamivir
Graphical Abstract
Figure 1: Marketed drugs with acridine moiety.
Scheme 1: Synthesis of 4-arylacridinediones.
Scheme 2: Proposed mechanism for acridinedione synthesis.
Scheme 3: Synthesis of tetrahydrodibenzoacridinones.
Scheme 4: Synthesis of naphthoacridines.
Scheme 5: Plausible mechanism for naphthoacridines.
Figure 2: Benzoazepines based potent molecules.
Scheme 6: Synthesis of azepinone.
Scheme 7: Proposed mechanism for azepinone formation.
Scheme 8: Synthesis of benzoazulenen-1-one derivatives.
Scheme 9: Proposed mechanism for benzoazulene-1-one synthesis.
Figure 3: Indole-containing pharmacologically active molecules.
Scheme 10: Synthesis of functionalized indoles.
Scheme 11: Plausible mechanism for the synthesis of functionalized indoles.
Scheme 12: Synthesis of spirooxindoles.
Scheme 13: Synthesis of substituted spirooxindoles.
Scheme 14: Plausible mechanism for the synthesis of substituted spirooxindoles.
Scheme 15: Synthesis of pyrrolidinyl spirooxindoles.
Scheme 16: Proposed mechanism for pyrrolidinyl spirooxindoles.
Figure 4: Pyran-containing biologically active molecules.
Scheme 17: Synthesis of functionalized benzopyrans.
Scheme 18: Plausible mechanism for synthesis of benzopyran.
Scheme 19: Synthesis of indoline-spiro-fused pyran derivatives.
Scheme 20: Proposed mechanism for indoline-spiro-fused pyran.
Scheme 21: Synthesis of substituted naphthopyrans.
Figure 5: Marketed drugs with pyrrole ring.
Scheme 22: Synthesis of tetra-substituted pyrroles.
Scheme 23: Mechanism for silica-supported PPA-SiO2-catalyzed pyrrole synthesis.
Scheme 24: Synthesis of pyrrolo[1,10]-phenanthrolines.
Scheme 25: Proposed mechanism for pyrrolo[1,10]-phenanthrolines.
Figure 6: Marketed drugs and molecules containing pyrimidine and pyrimidinones skeletons.
Scheme 26: MWA-MCR pyrimidinone synthesis.
Scheme 27: Two proposed mechanisms for pyrimidinone synthesis.
Scheme 28: MWA multicomponent synthesis of dihydropyrimidinones.
Scheme 29: Proposed mechanism for dihydropyrimidinones.
Figure 7: Biologically active fused pyrimidines.
Scheme 30: MWA- MCR for the synthesis of pyrrolo[2,3-d]pyrimidines.
Scheme 31: Proposed mechanism for pyrrolo[2,3-d]pyrimidines.
Scheme 32: Synthesis of substituted pyrrolo[2,3-d]pyrimidine-2,4-diones.
Scheme 33: Probable pathway for pyrrolo[2,3-d]pyrimidine-2,4-diones.
Scheme 34: Synthesis of pyridopyrimidines.
Scheme 35: Plausible mechanism for the synthesis of pyridopyrimidines.
Scheme 36: Synthesis of dihydropyridopyrimidine and dihydropyrazolopyridine.
Scheme 37: Proposed mechanism for the formation of dihydropyridopyrimidine.
Scheme 38: Synthesis of thiopyrano[4,3-d]pyrimidines.
Scheme 39: Plausible mechanism for the synthesis of thiopyrano[4,3-d]pyrimidines.
Scheme 40: Synthesis of decorated imidazopyrimidines.
Scheme 41: Proposed mechanism for imidazopyrimidine synthesis.
Figure 8: Pharmacologically active molecules containing purine bases.
Scheme 42: Synthesis of aza-adenines.
Scheme 43: Synthesis of 5-aza-7-deazapurines.
Scheme 44: Proposed mechanism for deazapurines synthesis.
Figure 9: Biologically active molecules containing pyridine moiety.
Scheme 45: Synthesis of steroidal pyridines.
Scheme 46: Proposed mechanism for steroidal pyridine.
Scheme 47: Synthesis of N-alkylated 2-pyridones.
Scheme 48: Two possible mechanisms for pyridone synthesis.
Scheme 49: Synthesis of pyridone derivatives.
Scheme 50: Postulated mechanism for synthesis of pyridone.
Figure 10: Biologically active fused pyridines.
Scheme 51: Benzimidazole-imidazo[1,2-a]pyridines synthesis.
Scheme 52: Mechanism for the synthesis of benzimidazole-imidazo[1,2-a]pyridines.
Scheme 53: Synthesis of pyrazolo[3,4-b]pyridine-5-spirocycloalkanedione derivatives.
Scheme 54: Proposed mechanism for spiro-pyridines.
Scheme 55: Functionalized macrocyclane-fused pyrazolo[3,4-b]pyridine derivatives.
Scheme 56: Mechanism postulated for macrocyclane-fused pyrazolo[3,4-b]pyridine.
Scheme 57: Generation of pyrazolo[3,4-b]pyridines.
Scheme 58: Proposed mechanism for the synthesis of pyrazolo[3,4-b]pyridines.
Scheme 59: Proposed mechanism for the synthesis of azepinoindole.
Figure 11: Pharmaceutically important molecules with quinoline moiety.
Scheme 60: Povarov-mediated quinoline synthesis.
Scheme 61: Proposed mechanism for Povarov reaction.
Scheme 62: Synthesis of pyrazoloquinoline.
Scheme 63: Plausible mechanism for pyrazoloquinoline synthesis.
Figure 12: Quinazolinones as pharmacologically significant scaffolds.
Scheme 64: Four-component reaction for dihydroquinazolinone.
Scheme 65: Proposed mechanism for dihydroquinazolinones.
Scheme 66: Synthesis purine quinazolinone and PI3K-δ inhibitor.
Scheme 67: Synthesis of fused benzothiazolo/benzoimidazoloquinazolinones.
Scheme 68: Proposed mechanism for fused benzothiazolo/benzoimidazoloquinazolinones.
Scheme 69: On-water reaction for synthesis of thiazoloquinazolinone.
Scheme 70: Proposed mechanism for the thiazoloquinazolinone synthesis.
Scheme 71: β-Cyclodextrin-mediated synthesis of indoloquinazolinediones.
Scheme 72: Proposed mechanism for synthesis of indoloquinazolinediones.
Figure 13: Triazoles-containing marketted drugs and pharmacologically active molecules.
Scheme 73: Cu(I) DAPTA-catalyzed 1,2,3-triazole formation.
Scheme 74: Mechanism for Cu(I) DAPTA-catalyzed triazole formation.
Scheme 75: Synthesis of β-hydroxy-1,2,3-triazole.
Scheme 76: Proposed mechanism for synthesis of β-hydroxy-1,2,3-triazoles.
Scheme 77: Synthesis of bis-1,2,4-triazoles.
Scheme 78: Proposed mechanism for bis-1,2,4-triazoles synthesis.
Figure 14: Thiazole containing drugs.
Scheme 79: Synthesis of a substituted thiazole ring.
Scheme 80: Synthesis of pyrazolothiazoles.
Figure 15: Chromene containing drugs.
Scheme 81: Magnetic nanocatalyst-mediated aminochromene synthesis.
Scheme 82: Proposed mechanism for the synthesis of chromenes.
Recent progress in the synthesis of homotropane alkaloids adaline, euphococcinine and N-methyleuphococcinine
- Dimas J. P. Lima,
- Antonio E. G. Santana,
- Michael A. Birkett and
- Ricardo S. Porto
Beilstein J. Org. Chem. 2021, 17, 28–41, doi:10.3762/bjoc.17.4
- a 6-step sequence from 3,4-dihydro-2-ethoxy-2H-pyran (58) [50]. Treatment of 58 with a mixture of butyllithium and potassium tert-butoxide in the presence of TMEDA and pentane, followed by reaction with the corresponding alkyl iodides in THF, and finally, acidic cleavage of the generated acetal
Graphical Abstract
Figure 1: Homotropane (azabicyclononane) systems.
Figure 2: Alkaloids (−)-adaline (1), (+)-euphococcinine (2) and (+)-N-methyleuphococcinine (3).
Scheme 1: Synthetic strategies before 1995.
Scheme 2: Synthesis (±)-adaline (1) and (±)-euphococcinine (2). Reagents and conditions: i) 1. dihydropyran, ...
Scheme 3: Synthesis (+)-euphococcinine (2). Reagents and conditions: i) H2O2, SeO2 (cat), acetone, rt, 88%; i...
Scheme 4: Synthesis (+)-euphococcinine (2). Reagents and conditions: i) 2,4-bis(4-phenoxyphenyl)-1,3-dithia-2...
Scheme 5: Synthesis of (±)-euphococcinine precursor (±)-42. Reagents and conditions: i) Bu3SnH, AIBN, toluene...
Scheme 6: Synthesis of (−)-adaline (1). Reagents and conditions: i) LiH2NBH3, THF, 40 °C, 88%; ii) TPAP, NMO,...
Scheme 7: Synthesis of (−)-adaline (1) and (−)-euphococcinine (2). Reagents and conditions: i) 1. BuLi, t-BuO...
Scheme 8: Synthesis of (−)-adaline (1). Reagents and conditions: i) Ref. [52]; ii) Et3N, TBDMSOTf, CH2Cl2, 0 °C t...
Scheme 9: Synthesis of (+)-euphococcinine (2). Reagents and conditions: i) 1. Cp2ZrCl2,AlMe3, CH2Cl2; 2. p-me...
Scheme 10: Synthesis of (−)-adaline 1. Reagents and conditions: i) 1. CuBr.DMS, Et2O/DMS, -42 ºC; 2. 1-heptyne...
Scheme 11: Synthesis of (−)-euphococcinine (2) and (−)-adaline (1). Reagents and conditions: i) 102, KHMDS, Et2...
Scheme 12: Synthesis of N-methyleuphococcinine 3. Reagents and conditions: i) 108 (1.5 equiv), 3,5-di-F-C6H3B(...
Ring-closing metathesis of prochiral oxaenediynes to racemic 4-alkenyl-2-alkynyl-3,6-dihydro-2H-pyrans
- Viola Kolaříková,
- Markéta Rybáčková,
- Martin Svoboda and
- Jaroslav Kvíčala
Beilstein J. Org. Chem. 2020, 16, 2757–2768, doi:10.3762/bjoc.16.226
- with CH2Cl2, and the organic solution was carefully evaporated to give the crude products. If necessary, the products were purified by column chromatography. 4-Ethenyl-(2-prop-2-yn-1-yl)-3,6-dihydro-2H-pyran (12a) According to general procedure A, from oxaenediyne 2a (243 mg, 1.64 mmol) in CH2Cl2 (6 mL
- ), 137.9 (s, 1C, CH=CH2); MS (CI+, m/z): 149.1 [M + H]+ (10), 109.1 [M − C3H3]+ (100), 91.1 [C7H7]+ (45), 81.1 [C5H5O]+ (50); HRMS (CI+, m/z): [M + H]+ calcd for C10H13O, 149.0966; found, 149.0964. 2-(But-2-yn-1-yl)-4-(prop-1-en-2-yl)-3,6-dihydro-2H-pyran (12b) According to general procedure A, from
- − CH2=O + H+]+ (95), 121.1 [M − CH2=O − CH≡CH + H]+ (100); HRMS (EI+, m/z): [M]+ calcd for C12H16O, 176.1201; found, 176.1208. 4-(But-1-en-2-yl)-2-(pent-2-yn-1-yl)-3,6-dihydro-2H-pyran (12c) According to general procedure A, from oxaenediyne 2c (31 mg, 0.15 mmol) in CH2Cl2 (1.2 mL) using G-I (6.2 mg
Graphical Abstract
Scheme 1: RCEYM with Ru and Mo catalysts.
Scheme 2: Beneficial effect of ethene atmosphere.
Scheme 3: Enantioselective dienyne metathesis [21].
Scheme 4: Diastereoselective endiyne metathesis [31].
Figure 1: Oxaenediynes considered for the study of desymmetrizing RCEYM.
Scheme 5: Synthesis of hepta-1,6-diyn-4-ol (4a).
Scheme 6: Protection of hepta-1,6-diyn-4-ol (4a).
Scheme 7: Alkylation of the protected diynols 7a and 8a.
Scheme 8: Deprotection of protected diynols 7b, 7c and 8b–d.
Scheme 9: Synthesis of the oxaenediynes 2 and 9 bearing an allyl or a methallyl group.
Scheme 10: Synthesis of oxaenediynes 2e and 2f bearing ester or silyl groups.
Scheme 11: Synthesis of alkadiynyl acrylates 10 and methacrylates 11.
Figure 2: The ruthenium precatalysts employed.
Scheme 12: RCEYM of oxaenediynes 2.
Figure 3: Examples of side products of CM with ethene.
Scheme 13: Attempted RCEYM of oxaenediynes 9, alkadiynyl acrylates 10 and methacrylates 11.
Scheme 14: Diels–Alder reaction of dihydropyran 12b with N-phenylmaleimide (13).
Figure 4: The four possible diastereoisomers of hexahydropyranoisoindole 14.
Figure 5: Conformations of dihydropyran 12b.
Figure 6: The two most stable s-trans (left) and s-cis (right) conformations of dihydropyran 12b.
Figure 7: The two most stable transition states endo-trans 15B and exo-cis 15C (hydrogens are omitted for cla...
Figure 8: PES of the Diels–Alder reaction of dihydropyran 12b and maleimide 13.
Convenient access to pyrrolidin-3-ylphosphonic acids and tetrahydro-2H-pyran-3-ylphosphonates with multiple contiguous stereocenters from nonracemic adducts of a Ni(II)-catalyzed Michael reaction
- Alexander N. Reznikov,
- Dmitry S. Nikerov,
- Anastasiya E. Sibiryakova,
- Victor B. Rybakov,
- Evgeniy V. Golovin and
- Yuri N. Klimochkin
Beilstein J. Org. Chem. 2020, 16, 2073–2079, doi:10.3762/bjoc.16.174
- ,6R)-13b. Intermolecular N-methylation of reduction product 7. Synthesis of pyrrolidinyl phosphonic acids 11a–d. Synthesis of tetrahydropyranylphosphonates 13a–f via diastereoselective Henry/acetalyzation reaction. Synthesis of (3,4-dihydro-2H-pyran-5-yl)phosphonate 14. Optimization of the conditions
Graphical Abstract
Figure 1: Pharmacologically active nonracemic phosphonates with heterocyclic moieties.
Figure 2: Starting nonracemic 4-nitro-2-oxophosphonates.
Scheme 1: Intermolecular N-methylation of reduction product 7.
Scheme 2: Synthesis of pyrrolidinyl phosphonic acids 11a–d.
Figure 3: ORTEP diagram of (2R,3R,4S)-10a.
Scheme 3: Synthesis of tetrahydropyranylphosphonates 13a–f via diastereoselective Henry/acetalyzation reactio...
Figure 4: ORTEP diagram of (2S,3R,4S,5S,6R)-13b.
Scheme 4: Synthesis of (3,4-dihydro-2H-pyran-5-yl)phosphonate 14.
Syntheses of spliceostatins and thailanstatins: a review
- William A. Donaldson
Beilstein J. Org. Chem. 2020, 16, 1991–2006, doi:10.3762/bjoc.16.166
- ) gave the C-phenyl glucoside 75 [36]. Notably, the use of oxidants other than BQ gave either the TMS enol ether or the 2,3-dihydro-6-phenyl-4H-pyran-4-one. The C-3 exocyclic methylene group was introduced by a Wittig olefination, and after the manipulation of the protecting groups, a VO(acac)2-catalyzed
Graphical Abstract
Figure 1: Structures of spliceostatins/thailanstatins.
Scheme 1: Synthetic routes to protected (2Z,4S)-4-hydroxy-2-butenoic acid fragments.
Scheme 2: Kitahara synthesis of the (all-cis)-2,3,5,6-tetrasubstituted tetrahydropyran.
Scheme 3: Koide synthesis of (all-cis)-2,3,5,6-tetrasubstituted tetrahydropyran.
Scheme 4: Nicolaou synthesis of the (all-cis)-2,3,5,6-tetrasubstituted tetrahydropyran.
Scheme 5: Jacobsen synthesis of the (all-cis)-2,3,5,6-tetrasubstituted tetrahydropyran.
Scheme 6: Unproductive attempt to generate the (all-cis)-tetrahydropyranone 50.
Scheme 7: Ghosh synthesis of the C-7–C-14 (all-cis)-tetrahydropyran segment.
Scheme 8: Ghosh’s alternative route to the (all-cis)-tetrahydropyranone 50.
Scheme 9: Alternative synthesis of the dihydro-3-pyrone 58.
Scheme 10: Kitahara’s 1st-generation synthesis of the C-1–C-6 fragment of FR901464 (1).
Scheme 11: Kitahara 1st-generation synthesis of the C-1–C-6 fragment of FR901464 (1).
Scheme 12: Nimura/Arisawa synthesis of the C-1-phenyl segment.
Scheme 13: Ghosh synthesis of the C-1–C-6 fragment of FR901464 (1) from (R)-glyceraldehyde acetonide.
Scheme 14: Jacobsen synthesis of the C-1–C-7 segment of FR901464 (1).
Scheme 15: Koide synthesis of the C-1–C-7 segment of FR901464 (1).
Scheme 16: Ghosh synthesis of the C-1–C-5 segment 102 of thailanstatin A (7).
Scheme 17: Nicolaou synthesis of the C-1–C-9 segments of spliceostatin D (9) and thailanstatins A (7) and B (5...
Scheme 18: Ghosh synthesis of the C-1–C-6 segment 115 of spliceostatin E (10).
Scheme 19: Fragment coupling via Wittig and modified Julia olefinations by Kitahara.
Scheme 20: Fragment coupling via cross-metathesis by Koide.
Scheme 21: The Ghosh synthesis of spliceostatin A (4), FR901464 (1), spliceostatin E (10), and thailanstatin m...
Scheme 22: Arisawa synthesis of a C-1-phenyl analog of FR901464 (1).
Scheme 23: Jacobsen fragment coupling by a Pd-catalyzed Negishi coupling.
Scheme 24: Nicolaou syntheses of thailanstatin A and B (7 and 5) and spliceostatin D (9) via a Pd-catalyzed Su...
Scheme 25: The Ghosh synthesis of spliceostatin G (11) via Suzuki–Miyaura coupling.
One-pot synthesis of substituted pyrrolo[3,4-b]pyridine-4,5-diones based on the reaction of N-(1-(4-hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)-2-oxo-2-arylethyl)acetamide with amines
- Valeriya G. Melekhina,
- Andrey N. Komogortsev,
- Boris V. Lichitsky,
- Vitaly S. Mityanov,
- Artem N. Fakhrutdinov,
- Arkady A. Dudinov,
- Vasily A. Migulin,
- Yulia V. Nelyubina,
- Elizaveta K. Melnikova and
- Michail M. Krayushkin
Beilstein J. Org. Chem. 2019, 15, 2840–2846, doi:10.3762/bjoc.15.277
- Federation Lomonosov Moscow State University, Moscow 119991, Russian Federation 10.3762/bjoc.15.277 Abstract The condensation of primary amines with N-(1-(4-hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)-2-oxo-2-arylethyl)acetamides was explored. Thus, a previously unknown recyclization of the starting material was
- strongly desirable. In this article, we describe a convenient synthetic method for the preparation of 6-alkyl-2-methyl-7-aryl-6,7-dihydro-1H-pyrrolo[3,4-b]pyridine-4,5-diones 1. Therein, the condensation of N-(1-(4-hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)-2-oxo-2-arylethyl)acetamides 2 with a diverse range of
- amines 3 did not only furnish the desired scaffolds in satisfactory yields but also allowed to use a variety of readily available substituted substrates (Scheme 1). Results and Discussion The published synthesis of acetamides 2 includes a one-pot three-component reaction of 4-hydroxy-6-methyl-2H-pyran-2
Graphical Abstract
Scheme 1: General synthetic pathway to 1.
Scheme 2: Synthesis of acetamides 2.
Scheme 3: Possible reaction pathways for the formation of enaminone 7.
Scheme 4: Possible reaction pathways for the formation of pyrrolo[3,4-b]pyridin-5-one derivatives 1.
Figure 1: View of the structure of 1e in the crystal (CCDC: 1921613). Thermal ellipsoids indicate 50% probabi...
Scheme 5: Tautomeric equilibrium of pyrrolo[3,4-b]pyridin-5-one derivatives 1 in solution.
Catalytic asymmetric oxo-Diels–Alder reactions with chiral atropisomeric biphenyl diols
- Chi-Tung Yeung,
- Wesley Ting Kwok Chan,
- Wai-Sum Lo,
- Ga-Lai Law and
- Wing-Tak Wong
Beilstein J. Org. Chem. 2019, 15, 955–962, doi:10.3762/bjoc.15.92
- diene in standard conditions. The reaction was found to be very sluggish when performed at −40 °C. However, at −20 °C, better yields were obtained. The reactions with organocatalysts 1–4 showed moderate yields (41–64%) of the catalytic product (2,3-dihydro-2-phenyl-4H-pyran-4-one). Unfortunately
- used as catalysts (Table 1, entries 8–11). With 1, the yield and enantioselectivity of the catalytic product (2,3-dihydro-2-tert-butyl-4H-pyran-4-one) were 50% and 12% ee (Table 1, entry 8). The reactivity and enantioselectivity were significantly increased to 66% yield and 72% ee when 2 was employed
Graphical Abstract
Scheme 1: Chiral biphenyl diol organocatalysts 1–6.
Scheme 2: Synthesis of 3.
Figure 1: (a) Single crystal X-ray structure of 3: showing intra- and intermolecular hydrogen bonds (green da...
Scheme 3: Synthesis of 4.
Scheme 4: Synthesis of 6.
Figure 2: X-ray crystal structure of (P)-(S,S)-6 at two different orientations to show (a) P atropselectiviti...
Synthesis of the aglycon of scorzodihydrostilbenes B and D
- Katja Weimann and
- Manfred Braun
Beilstein J. Org. Chem. 2019, 15, 610–616, doi:10.3762/bjoc.15.56
- , 152.5, 154.6, 158.1, 205.2; ESIMS m/z (%): 377.2 [M + 1] (100); HRMS (ESI): [M + H]+ calcd for C24H25O4, 377.1753; found, 377.1748. (2R,3R,4S,5R,6R)-2-(Acetoxymethyl)-6-[3-acetyl-2-(3,4-dimethoxyphenethyl)-4-hydroxyphenoxy]tetrahydro-2H-pyran-3,4,5-triyl triacetate (12): A 50 mL two-necked flask was
Graphical Abstract
Scheme 1: Structures of scorzodihydrostilbenes A–E (1–5) and resveratrol.
Scheme 2: Synthesis of dihydrostilbenes 8a–d by ruthenium-catalyzed addition of ketones 6 to styrenes 7. Yiel...
Scheme 3: Cleavage of benzyl protecting groups in ketones 8a and 8b. Synthesis of scorzodihydrostilbene aglyc...
Scheme 4: Synthesis of glycoside 12 and deprotected epi-scorzodihydrostilbene D (13). Yields of isolated prod...
Ring-closing-metathesis-based synthesis of annellated coumarins from 8-allylcoumarins
- Christiane Schultze and
- Bernd Schmidt
Beilstein J. Org. Chem. 2018, 14, 2991–2998, doi:10.3762/bjoc.14.278
- completely in this case (Table 4, entries 3 and 4). The beneficial effect of low initial substrate concentrations on RCM reactions with acrylates has previously been described [65] and was later systematically investigated by one of us [66]. A possible access to the pyran-2-one-annellated coumarin
- catalyze allylic and benzylic oxidation reactions through a radical mechanism [70]. To implement this tandem sequence in the synthesis of pyran-2-one-annellated coumarins 15 an isomerization of the 8-allyl substituent to a prop-1-enyl substituent was first required. When 8-allyl-7-hydroxycoumarin (8a) was
- -1-enyl)coumarins 16 were isolated in high overall yields and E-selectivities. Allylation of phenols 16 furnished the RCM precursors 17, which underwent the tandem RCM/allylic oxidation sequence to compounds 15 in fair yields (Table 5). All pyran-2-one-annellated coumarins 15 synthesized in the
Graphical Abstract
Figure 1: Illustration of coumarin taxonomy.
Scheme 1: Synthesis of oxepin-2-one-annellated coumarins 13 by RCM of acrylates 12.
Scheme 2: Attempted synthesis of pyran-2-one-annellated coumarin 15d via isomerization-RCM.
Scheme 3: Synthesis of aza-annellated coumarin 21 and attempted synthesis of indole 22.
Volatiles from the hypoxylaceous fungi Hypoxylon griseobrunneum and Hypoxylon macrocarpum
- Jan Rinkel,
- Alexander Babczyk,
- Tao Wang,
- Marc Stadler and
- Jeroen S. Dickschat
Beilstein J. Org. Chem. 2018, 14, 2974–2990, doi:10.3762/bjoc.14.277
- germination and to cause necrotic lesions in the plant tissue. In other cases, fungal volatiles can have beneficial effects and may even be involved in the induction of systemic resistance in plants, as can be assumed for 6-pentyl-2H-pyran-2-one (5) that is produced by many fungi from the genus Trichoderma
- ) 152.9 (Cq), 152.8 (Cq), 143.5 (Cq), 124.7 (CH), 124.3 (Cq), 108.0 (CH), 60.6 (CH3), 60.3 (CH3), 55.8 (CH3), 15.9 (CH3). Structures of fungal volatiles. Trichodiene (1), aristolochene (2), (R)-oct-1-en-3-ol (3), 3,4-dimethylpentan-4-olide (4), and 6-pentyl-2H-pyran-2-one (5). Total ion chromatogram of a
Graphical Abstract
Figure 1: Structures of fungal volatiles. Trichodiene (1), aristolochene (2), (R)-oct-1-en-3-ol (3), 3,4-dime...
Figure 2: Total ion chromatogram of a CLSA headspace extract from Hypoxylon griseobrunneum MUCL 53754. Peak n...
Figure 3: Volatiles from Hypoxylon griseobrunneum.
Figure 4: EI mass spectra of A) 2,4,5-trimethylanisole (24), B) the coeluting mixture of 3,4-dimethylanisole (...
Scheme 1: Synthesis of trimethylanisoles 24 and 24d.
Scheme 2: Hypothetical biosynthesis of 24. ACP: acyl carrier protein, AT: acyl transferase, KR: ketoreductase...
Figure 5: Biosynthesis of 24. Feeding of (methyl-2H3)methionine resulted in the incorporation of labelling in...
Scheme 3: Hypothetical biosynthesis of 25 and 26.
Figure 6: Total ion chromatogram of a CLSA headspace extract from Hypoxylon macrocarpum STMA 130423. Peak num...
Figure 7: Volatiles from Hypoxylon macrocarpum.
Figure 8: EI mass spectra of A) 3,4-dimethoxybenzaldehyde (42), B) 3,4,5-trimethoxytoluene (44), and C) 2,4,5...
Scheme 4: Synthesis of 2,3,4-trimethoxytoluene (44a).
An overview on recent advances in the synthesis of sulfonated organic materials, sulfonated silica materials, and sulfonated carbon materials and their catalytic applications in chemical processes
- Hashem Sharghi,
- Pezhman Shiri and
- Mahdi Aberi
Beilstein J. Org. Chem. 2018, 14, 2745–2770, doi:10.3762/bjoc.14.253
- -sulfo-1,4-diazabicyclo[2.2.2]octane-1,4-diium) chloride (C4(DABCO-SO3H)2·4Cl, 31) and its applications in the synthesis of spiro-oxindole derivatives 36 and 37 was described. C4(DABCO-SO3H)2·4Cl 31 acted as an efficient, cheap, and reusable nanocatalyst for synthesis of 2-amino-4H-pyran derivatives 36
- homogeneous conditions (Scheme 5). After this successful application, catalyst 31 was tested in the synthesis of bis(2-amino-4H-pyran) derivatives 39–44 via a one-pot multicomponent reaction of dialdehydes 38 (instead of isatin and acenaphthenequinone substrates), a variety of C–H activated acids 20a,b, 23
- , 34a–c and malononitrile (35) under the same reaction conditions. The observations showed that bis(2-amino-4H-pyran) derivatives 39–44 are constructed in excellent yields during very short reaction times with a higher amount of the catalyst (4 mol %, Scheme 6). The recyclability of this homogeneous
Graphical Abstract
Figure 1: Different types of sulfonated materials as acid catalysts.
Scheme 1: Synthetic route of 3-methyl-1-sulfo-1H-imidazolium metal chloride ILs and their catalytic applicati...
Scheme 2: Synthetic route of 1,3-disulfo-1H-imidazolium transition metal chloride ILs and their catalytic app...
Scheme 3: Synthetic route of 1,3-disulfoimidazolium carboxylate ILs and their catalytic applications in the s...
Scheme 4: Synthetic route of [BiPy](HSO3)2Cl2 and [Dsim]HSO4 ILs and their catalytic applications for the syn...
Scheme 5: The catalytic applications of (C4(DABCO-SO3H)2·4Cl) IL for the synthesis of spiro-isatin derivative...
Scheme 6: The catalytic applications of (C4(DABCO-SO3H)2·4Cl) IL for the synthesis of bis 2-amino-4H-pyran de...
Scheme 7: The synthetic route of N,N-disulfo-1,1,3,3-tetramethylguanidinium carboxylate ILs and their catalyt...
Scheme 8: The catalytic application of 1-methyl-3-sulfo-1H-imidazolium tetrachloroferrate IL in the synthesis...
Scheme 9: The synthetic route of 3-sulfo-1H-imidazolopyrimidinium hydrogen sulfate IL and its catalytic appli...
Scheme 10: The results for the synthesis of bis(indolyl)methanes and di(bis(indolyl)methyl)benzenes in the pre...
Scheme 11: The catalytic applications of 1-(1-sulfoalkyl)-3-methylimidazolium chloride acidic ILs for the hydr...
Scheme 12: The synthetic route of immobilized 1,4-diazabicyclo[2.2.2]octanesulfonic acid chloride on SiO2 and ...
Scheme 13: The catalytic application of a silica-bonded sulfoimidazolium chloride for the synthesis of 12-aryl...
Scheme 14: The synthetic route of the SBA-15-Ph-SO3H and its catalytic applications for the synthesis of 2H-in...
Scheme 15: The synthetic route for heteropolyanion-based ionic liquids immobilized on mesoporous silica SBA-15...
Scheme 16: Some mechanism aspects of SSA catalyst for the protection of amine derivatives.
Scheme 17: The synthetic route for MWCNT-SO3H and its catalytic application for the synthesis of N-substituted...
Scheme 18: The sulfonic acid-functionalized polymers (P-SO3H) covalently grafted on multi-walled carbon nanotu...
Scheme 19: The transesterification reaction in the presence of S-MWCNTs.
Scheme 20: The synthetic route for the new hypercrosslinked supermicroporous polymer via the Friedel–Crafts al...
Scheme 21: The synthetic route for a new microporous copolymer via the Friedel–Crafts alkylation reaction of t...
Scheme 22: The synthetic route for sulfonated polynaphthalene and its catalytic application for the amidoalkyl...
Scheme 23: The synthetic route of the acidic carbon material and its catalytic application in the etherificatio...
Scheme 24: The synthetic route of the acidic carbon materials and their catalytic applications for the esterif...
Scheme 25: The sulfonated MWCNTs.
Scheme 26: The sulfonated nanoscaled diamond powder for the dehydration of D-xylose into furfural.
Scheme 27: The synthetic route and catalytic application of the GR-SO3H.
Ring-opening metathesis of some strained bicyclic systems; stereocontrolled access to diolefinated saturated heterocycles with multiple stereogenic centers
- Zsanett Benke,
- Melinda Nonn,
- Márton Kardos,
- Santos Fustero and
- Loránd Kiss
Beilstein J. Org. Chem. 2018, 14, 2698–2707, doi:10.3762/bjoc.14.247
- , 100 MHz) δ 21.4, 25.3, 28.4, 46.8, 55.6, 78.7, 79.8, 125.9, 129.0, 154.6, 173.0; MS (ESI, pos) (m/z): 288 [M + 1], 168 [M – Boc]; anal. calcd for C14H21NO4: C, 62.90; H, 7.92; N, 5.24; found, C, 63.22; H, 7.59; N, 4.88. tert-Butyl ((S*)-1-((3R*,6S*)-2-oxo-6-vinyltetrahydro-2H-pyran-3-yl)but-3-en-1-yl
Graphical Abstract
Scheme 1: ROM of various bicyclic unsaturated β-lactams [14-16].
Scheme 2: ROM of various constrained bicyclic unsaturated systems (γ-lactones, δ-lactones, γ-lactam, isoxazol...
Figure 1: Commercial Ru-based catalysts used in the current work.
Scheme 3: ROM of lactones (±)-3 and (±)-4.
Scheme 4: ROM of lactones (±)-9.
Scheme 5: ROM of structurally constrained bicyclic lactones and lactams.
Scheme 6: ROM of bridged lactone (±)-14 and cyclooctene-fused isoxazoline (±)-16.
Scheme 7: ROM and transformations of lactam (±)-18.
Figure 2: Chelate intermediates in CM of (±)-19.
Synthesis of pyrimido[1,6-a]quinoxalines via intermolecular trapping of thermally generated acyl(quinoxalin-2-yl)ketenes by Schiff bases
- Svetlana O. Kasatkina,
- Ekaterina E. Stepanova,
- Maksim V. Dmitriev,
- Ivan G. Mokrushin and
- Andrey N. Maslivets
Beilstein J. Org. Chem. 2018, 14, 1734–1742, doi:10.3762/bjoc.14.147
- quinoxalin-2-ylideneacetates [9], multicomponent Mannich–Ritter transformations of quinoxalin-2(1H)-ones under the action of nitriles and 3,4-dihydro-2H-pyran [10] and a microwave-assisted cascade strategy via in situ-generated N-acyliminium ion precursors and amines [11] (Figure 2). To develop a new
Graphical Abstract
Figure 1: Quinoxaline-based 6/6/6-angularly fused scaffolds and respective examples of biologically active co...
Figure 2: Synthetic routes towards the pyrimido[1,6-a]quinoxaline scaffold.
Figure 3: Acyl(quinoxalin-2-yl)ketene.
Scheme 1: Thermolysis of five-membered 2,3-dioxoheterocycles resulting in acyl(quinoxalin-2-yl)ketenes.
Figure 4: STA plot of thermolysis of PQT 1a. Blue solid curve: DSC; green solid curve: TG; greed dashed curve...
Scheme 2: Side-reactions concurring with intermolecular trapping of ketene generated from PQT 1a by benzalani...
Figure 5: Scope of the intermolecular trapping of ketenes generated from PQTs 1a–h by Schiff bases 2a–d under...
Scheme 3: Formation of furoquinoxalines 6a,b via intramolecular cyclization in ketenes generated from PQTs 1g,...
Figure 6: ORTEP drawing of compound 3g (CCDC 1834011) showing thermal ellipsoids at the 30% probability level....
Figure 7: ORTEP drawing of compound 3j (CCDC 1834012) showing thermal ellipsoids at the 30% probability level....
Heterogeneous acidic catalysts for the tetrahydropyranylation of alcohols and phenols in green ethereal solvents
- Ugo Azzena,
- Massimo Carraro,
- Gloria Modugno,
- Luisa Pisano and
- Luigi Urtis
Beilstein J. Org. Chem. 2018, 14, 1655–1659, doi:10.3762/bjoc.14.141
- recycling of the catalyst. Results and Discussion Taking 2-phenylethanol (1a) as a model compound, we investigated its conversion into the corresponding THP ether 3a by reacting 4 M solutions of this alcohol with a slight excess (1.1 equiv) of 3,4-dihydro-2H-pyran (2, DHP) in the presence of several acidic
- starting materials, was detected. aNo reaction in the presence of comparable amounts of NH4Br or SiO2. b1e is almost insoluble in CPME. c1:1 mixture of diastereoisomers. Deprotection of THP ether 3i. One-pot synthesis of 3-[4-(tetrahydro-2H-pyran-2-yl)oxymethylphenyl]-3-pentanol (4fa). One-pot synthesis of
- 4-(tetrahydro-2H-pyran-2-yloxymethyl)benzyl alcohol (4fb). Synthesis of 2-(2-phenylethoxy)tetrahydro-2H-pyran (3a). Supporting Information Supporting Information File 256: Full experimental details, copies of IR spectra of fresh and recycled NH4HSO4@SiO2 and copies of 1H and 13C NMR spectra.
Graphical Abstract
Scheme 1: Synthesis of THP ether 3a.
Scheme 2: Synthesis of THP ethers 3b–l in the presence of NH4HSO4@SiO2. All reactions were run at rt, in the ...
Scheme 3: Deprotection of THP ether 3i.
Scheme 4: One-pot synthesis of 3-[4-(tetrahydro-2H-pyran-2-yl)oxymethylphenyl]-3-pentanol (4fa).
Scheme 5: One-pot synthesis of 4-(tetrahydro-2H-pyran-2-yloxymethyl)benzyl alcohol (4fb).
Glycosylation reactions mediated by hypervalent iodine: application to the synthesis of nucleosides and carbohydrates
- Yuichi Yoshimura,
- Hideaki Wakamatsu,
- Yoshihiro Natori,
- Yukako Saito and
- Noriaki Minakawa
Beilstein J. Org. Chem. 2018, 14, 1595–1618, doi:10.3762/bjoc.14.137
- oxocarbenium ion 101 to serve as an intermediate, giving a nucleoside 102. First, we attempted model reactions of the oxidative coupling to enol ether using a TMSOTf/PhI(OAc)2 system. After several attempts, we found that the reaction of 3,4-dihydro-2H-pyran (DHP, 103) with PhI(OAc)2 and TMSOTf, starting at
Graphical Abstract
Figure 1: Design of potential antineoplastic nucleosides.
Scheme 1: Synthesis of 4’-thioDMDC.
Scheme 2: Synthesis of 4’-thioribonucleosides by Minakawa and Matsuda.
Scheme 3: Synthesis of 4’-thioribonucleosides by Yoshimura.
Figure 2: Concept of the Pummerer-type glycosylation and hypervalent iodine-mediated glycosylation.
Scheme 4: Oxidative glycosylation of 4-thioribose mediated by hypervalent iodine.
Figure 3: Speculated mechanism of oxidative glycosylation mediated by hypervalent iodine.
Scheme 5: Synthesis of purine 4’-thioribonucleosides using hypervalent iodine-mediated glycosylation.
Scheme 6: Unexpected glycosylation of a thietanose derivative.
Scheme 7: Speculated mechanism of the ring expansion of a thietanose derivative.
Scheme 8: Synthesis of thietanonucleosides using the Pummerer-type glycosylation.
Scheme 9: First synthesis of 4’-selenonucleosides.
Scheme 10: The Pummerer-type glycosylation of 4-selenoxide 74.
Scheme 11: Synthesis of purine 4’-selenonucleosides using hypervalent iodine-mediated glycosylation.
Figure 4: Concept of the oxidative coupling reaction applicable to the synthesis of carbocyclic nucleosides.
Scheme 12: Oxidative coupling reaction mediated by hypervalent iodine.
Scheme 13: Synthesis of cyclohexenyl nucleosides using an oxidative coupling reaction.
Figure 5: Concept of the oxidative coupling reaction of glycal derivatives.
Scheme 14: Oxidative coupling reaction of silylated uracil and DHP using hypervalent iodine.
Scheme 15: Proposed mechanism of the oxidative coupling reaction mediated by hypervalent iodine.
Figure 6: Synthesis of 2’,3’-unsaturated nucleosides using hypervalent iodine and a co-catalyst.
Scheme 16: Synthesis of dihydropyranonucleoside.
Scheme 17: Synthesis of acetoxyacetals using hypervalent iodine and addition of silylated base.
Scheme 18: One-pot fragmentation-nucleophilic additions mediated by hypervalent iodine.
Figure 7: The reaction of thioglycoside with hypervalent iodine in the presence of Lewis acids.
Scheme 19: Synthesis of disaccharides employing thioglycosides under an oxidative coupling reaction mediated b...
Scheme 20: Synthesis of disaccharides using disarmed thioglycosides by hypervalent iodine-mediated glycosylati...
Scheme 21: Glycosylation using aryl(trifluoroethyl)iodium triflimide.
Figure 8: Expected mechanism of hypervalent iodine-mediated glycosylation with glycals.
Scheme 22: Synthesis of oligosaccharides by hypervalent iodine-mediated glycosylation with glycals.
Scheme 23: Synthesis of 2-deoxy amino acid glycosides.
Figure 9: Rationale for the intramolecular migration of the amino acid unit.
Bromide-assisted chemoselective Heck reaction of 3-bromoindazoles under high-speed ball-milling conditions: synthesis of axitinib
- Jingbo Yu,
- Zikun Hong,
- Xinjie Yang,
- Yu Jiang,
- Zhijiang Jiang and
- Weike Su
Beilstein J. Org. Chem. 2018, 14, 786–795, doi:10.3762/bjoc.14.66
- -2H-pyran-2-yl)-1H-indazole (3q) in 90% yield. Next, sequential two-step Heck coupling and Migita coupling under ball milling conditions selectively afforded THP-axitinib 7. Finally, deprotection of 7 with p-TsOH gave axitinib in a total yield of 44% (41% [66]). Comparing to previous synthetic
Graphical Abstract
Scheme 1: Representative pharmaceutically useful indazoles.
Scheme 2: Model Heck reaction of 3-bromo-N-methyl-1H-indazole (1a) and n-butyl acrylate (2a). (173 stainless-...
Figure 1: Investigation of additives in the Heck reaction: 1a (1.5 mmol), 2a (2.25 mmol), Pd(OAc)2 (5 mol %),...
Scheme 3: The control experiments. aTEA (1.8 mmol), silica gel (5.0 g), bPd(OAc)2 (5 mol %), PPh3 (10 mol %),...
Scheme 4: Plausible reaction pathway.
Figure 2: Influence of milling time and rotation speed on the Heck reaction: 1a (1.5 mmol), 2a (2.25 mmol), P...
Figure 3: Influence of the milling ball filling degree with different size on the Heck reaction: 1a (1.5 mmol...
Scheme 5: Examination of the substrate scope. Reaction conditions: 1 (1.5 mmol), 2 (2.25 mmol), Pd(OAc)2 (5 m...
Scheme 6: Synthesis of axitinib by mechanochemical Heck–Migita coupling. Reagents and conditions: (i) NBS, Na...
Volatiles from the xylarialean fungus Hypoxylon invadens
- Jeroen S. Dickschat,
- Tao Wang and
- Marc Stadler
Beilstein J. Org. Chem. 2018, 14, 734–746, doi:10.3762/bjoc.14.62
- , Agaricus bisporus, and other delicacies from the fungal world such as the oyster mushroom, the penny bun, and shiitake [2][3]. The ecological function of most fungal volatiles is unknown, but for the alcohol 1 (Figure 1) a germination inhibitory function has been reported [4]. For 6-pentyl-2H-pyran-2-one
- ; MS (EI, 70 eV) m/z (%): 218 (81) [M]+, 204 (13), 203 (100), 137 (53), 136 (17), 108 (21), 67 (26), 43 (23), 39 (13). Structures of the widespread fungal volatiles oct-1-en-3-ol (1) and 6-pentyl-2H-pyran-2-one (2), the stereoisomers α-muurolene (3), α-amorphene (4) and α-cadinene (5), and the
Graphical Abstract
Figure 1: Structures of the widespread fungal volatiles oct-1-en-3-ol (1) and 6-pentyl-2H-pyran-2-one (2), th...
Figure 2: Total-ion chromatogram of the bouquet from Hypoxylon invadens MUCL 54175 obtained by the CLSA heads...
Figure 3: Identified volatile organic compounds from Hypoxylon invadens MUCL 54175.
Figure 4: Mass spectra of volatiles from Hypoxylon invadens MUCL 54175. Mass spectra of A) 2,5-dimethylphenol...
Scheme 1: Proposed common biosynthetic pathway to volatile aromatic compounds from Hypoxylon invadens.
Scheme 2: Synthesis of 5-hydroxy-2-methyl-4H-chromen-4-one (19).
Electrochemical Corey–Winter reaction. Reduction of thiocarbonates in aqueous methanol media and application to the synthesis of a naturally occurring α-pyrone
- Ernesto Emmanuel López-López,
- José Alvano Pérez-Bautista,
- Fernando Sartillo-Piscil and
- Bernardo A. Frontana-Uribe
Beilstein J. Org. Chem. 2018, 14, 547–552, doi:10.3762/bjoc.14.41
- -(pent-1-enyl)-α-pyrone and trans-6-(pent-1,4-dienyl)-α-pyrone, which are naturally occurring metabolites isolated from Trichoderma viride and Penicillium, in high chemical yield and with excellent stereo selectivity. Keywords: Corey–Winter reaction; electrosynthesis; 6-pentyl-2H-pyran-2-ones; reduction
- (Scheme 1) [4]. Despite this advantage, the low availability and high cost of this reagent [5] makes this reaction difficult to be used in industry. Previously, starting from the versatile chiron 7,3-lactone-xylofuranose (7,3-LXF) [6], the first non-biological synthesis of chiral 6-pentyl-2H-pyran-2-ones
- convert thiocarbonates derived from 1,2-diols containing the 6-pentyl-2H-pyran-2-one framework to trans-alkenes by means of electrochemical reduction in an H-type separated cell was developed. The thiocarbonate functional group can be reduced using a vitreous carbon electrode in MeOH/H2O 80:20 with AcOH
Graphical Abstract
Scheme 1: The Corey–Winter reaction in general.
Scheme 2: Proposed route for the synthesis of metabolites isolated from Trichoderma and Penicillium species f...
Scheme 3: Preparation of thiocarbonate precursor 6 from pyrone dioxolane 7.
Figure 1: Cyclic voltammetry of thiocarbonates 4 (left) and 6 (right); c = 1 × 10−3 M, N2 bubbling 5 min, WE ...
Scheme 4: Putative reaction mechanism of the electrochemical Corey–Winter reaction.
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
- -pyrazolo[3,4-d]pyrimidin-6-yl)aniline 214 by NO2 group reduction with H2, Pd/C followed by Boc protection, coupling with tributyl(3,6-dihydro-2H-pyran-4-yl)stannane (213) and subsequent Boc deprotection with TFA in DCM. Pyrazolo[3,4-d]pyrimidinylaniline 214 was used to synthesize pyrazolo[3,4-d
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.
Volatiles from the tropical ascomycete Daldinia clavata (Hypoxylaceae, Xylariales)
- Tao Wang,
- Kathrin I. Mohr,
- Marc Stadler and
- Jeroen S. Dickschat
Beilstein J. Org. Chem. 2018, 14, 135–147, doi:10.3762/bjoc.14.9
- natural product is 6-nonyl-2H-pyran-2-one. The antimicrobial and cytotoxic effects of the synthetic volatiles are also reported. Keywords: enantioselective synthesis; gas chromatography; mass spectrometry; natural products; volatiles; Introduction A large variety of volatile organic compounds from
- widespread fungal volatile is 6-pentyl-2H-pyran-2-one (2) that was first isolated from Trichoderma and exhibits a strong coconut aroma [5]. For fungi producing 2 a plant-growth promoting effect and an induction of systemic resistance in plants has been observed which makes these fungi interesting as
- . clavata, showed a mass spectrum that was not included in our database (Figure 5A). However, the mass spectrum of 6-propyl-5,6-dihydro-2H-pyran-2-one (Figure 5B) is very similar, and the mass difference for the molecular ion of 28 Da suggested the structure of 6-methyl-5,6-dihydro-2H-pyran-2-one for
Graphical Abstract
Scheme 1: A selection of widespread fungal volatiles.
Figure 1: Total ion chromatogram of a representative headspace extract from Daldinia clavata MUCL 47436. Peak...
Scheme 2: Identified volatiles from Daldinia clavata MUCL 47436.
Figure 2: Mass spectra of volatiles from D. clavata that were identified by synthesis.
Scheme 3: Synthesis of manicone (10).
Scheme 4: Synthesis of a racemic mixture of all four diastereomers of 11.
Figure 3: Gas chromatographic analysis of 11 on a homochiral stationary phase. a) Synthetic mixture of all ei...
Scheme 5: Enantioselective synthesis of (4R,5S,6S)-11c and (4S,5R,6S)-11d.
Scheme 6: Epimerisations of (4R,5S,6S)-11c and (4S,5R,6S)-11d under basic conditions.
Figure 4: Gas chromatographic analysis of 11 on a homochiral stationary phase. a) Synthetic mixture of all ei...
Scheme 7: Proposed biosynthesis for (4R,5R,6S)-11a.
Figure 5: Mass spectra of a) 6-methyl-5,6-dihydro-2H-pyran-2-one (9), b) 6-propyl-5,6-dihydro-2H-pyran-2-one,...
Scheme 8: Synthesis of 6-methyl-5,6-dihydro-2H-pyran-2-one (9) and 6-nonyl-2H-pyran-2-one (17).
CF3SO2X (X = Na, Cl) as reagents for trifluoromethylation, trifluoromethylsulfenyl-, -sulfinyl- and -sulfonylation. Part 1: Use of CF3SO2Na
- Hélène Guyon,
- Hélène Chachignon and
- Dominique Cahard
Beilstein J. Org. Chem. 2017, 13, 2764–2799, doi:10.3762/bjoc.13.272
- allowing access to various β-trifluoromethyl ketones 24 featuring aryl, alkyl, functionalised alkyl, alkenyl, acetal, silylated alcohol, pyran, and piperidine functionalities (R group in 24). Mechanistic studies by 19F NMR allowed to identify CF3 complexes of copper(I) and copper(III) and the predominance
Graphical Abstract
Scheme 1: Trifluoromethylation of enol acetates by Langlois.
Scheme 2: Trifluoromethylation of (het)aryl enol acetates.
Scheme 3: Mechanism for the trifluoromethylation of enol acetates.
Scheme 4: Oxidative trifluoromethylation of unactivated olefins and mechanistic pathway.
Scheme 5: Oxidative trifluoromethylation of acetylenic substrates.
Scheme 6: Metal free trifluoromethylation of styrenes.
Scheme 7: Synthesis of α-trifluoromethylated ketones by oxytrifluoromethylation of heteroatom-functionalised ...
Scheme 8: Catalysed photoredox trifluoromethylation of vinyl azides.
Scheme 9: Oxidative difunctionalisation of alkenyl MIDA boronates.
Scheme 10: Synthesis of β-trifluoromethyl ketones from cyclopropanols.
Scheme 11: Aryltrifluoromethylation of allylic alcohols.
Scheme 12: Cascade multicomponent synthesis of nitrogen heterocycles via azotrifluoromethylation of alkenes.
Scheme 13: Photocatalytic azotrifluoromethylation of alkenes with aryldiazonium salts and CF3SO2Na.
Scheme 14: Copper-promoted intramolecular aminotrifluoromethylation of alkenes with CF3SO2Na.
Scheme 15: Oxytrifluoromethylation of alkenes with CF3SO2Na and hydroxamic acid.
Scheme 16: Manganese-catalysed oxytrifluoromethylation of styrene derivatives.
Scheme 17: Oxytrifluoromethylation of alkenes with NMP/O2 and CF3SO2Na.
Scheme 18: Intramolecular oxytrifluoromethylation of alkenes.
Scheme 19: Hydrotrifluoromethylation of styrenyl alkenes and unactivated aliphatic alkenes.
Scheme 20: Hydrotrifluoromethylation of electron-deficient alkenes.
Scheme 21: Hydrotrifluoromethylation of alkenes by iridium photoredox catalysis.
Scheme 22: Iodo- and bromotrifluoromethylation of alkenes by CF3SO2Na/I2O5 or CF3SO2Na / NaBrO3.
Scheme 23: N-methyl-9-mesityl acridinium and visible-light-induced chloro-, bromo- and SCF3 trifluoromethylati...
Scheme 24: Carbotrifluoromethylation of N-arylacrylamides with CF3SO2Na / TBHP by Lipshutz.
Scheme 25: Carbotrifluoromethylation of N-arylacrylamides with CF3SO2Na/TBHP reported by Lei.
Scheme 26: Carbotrifluoromethylation of N-arylacrylamides with CF3SO2Na/(NH4)2S2O8.
Scheme 27: Metal-free carbotrifluoromethylation of N-arylacrylamides with CF3SO2Na/K2S2O8 reported by Wang.
Scheme 28: Metal-free carbotrifluoromethylation of N-arylacrylamides with CF3SO2Na/PIDA reported by Fu.
Scheme 29: Metal-free cascade trifluoromethylation/cyclisation of N-arylmethacrylamides (a) and enynes (b) wit...
Scheme 30: Trifluoromethylation/cyclisation of N-arylcinnamamides: Synthesis of 3,4-disubstituted dihydroquino...
Scheme 31: Trifluoromethylation/cyclisation of aromatic-containing unsaturated ketones.
Scheme 32: Chemo- and regioselective cascade trifluoromethylation/heteroaryl ipso-migration of unactivated alk...
Scheme 33: Copper-mediated 1,2-bis(trifluoromethylation) of alkenes.
Scheme 34: Trifluoromethylation of aromatics with CF3SO2Na reported by Langlois.
Scheme 35: Baran’s oxidative C–H trifluoromethylation of heterocycles.
Scheme 36: Trifluoromethylation of acetanilides and anilines.
Scheme 37: Trifluoromethylation of heterocycles in water.
Scheme 38: Trifluoromethylation of coumarins in a continuous-flow reactor.
Scheme 39: Oxidative trifluoromethylation of coumarins, quinolines and pyrimidinones.
Scheme 40: Oxidative trifluoromethylation of pyrimidinones and pyridinones.
Scheme 41: Phosphovanadomolybdic acid-catalysed direct C−H trifluoromethylation.
Scheme 42: Oxidative trifluoromethylation of imidazopyridines and imidazoheterocycles.
Scheme 43: Oxidative trifluoromethylation of imidazoheterocycles and imidazoles in ionic liquid/water.
Scheme 44: Oxidative trifluoromethylation of 8-aminoquinolines.
Scheme 45: Oxidative trifluoromethylation of various 8-aminoquinolines using the supported catalyst CS@Cu(OAc)2...
Scheme 46: Oxidative trifluoromethylation of the naphthylamide 70.
Scheme 47: Oxidative trifluoromethylation of various arenes in the presence of CF3SO2Na and sodium persulfate.
Scheme 48: Trifluoromethylation of electron-rich arenes and unsymmetrical biaryls with CF3SO2Na in the presenc...
Figure 1: Trifluoromethylated coumarin and flavone.
Scheme 49: Metal-free trifluoromethylation catalysed by a photoredox organocatalyst.
Scheme 50: Quinone-mediated trifluoromethylation of arenes and heteroarenes.
Scheme 51: Metal- and oxidant-free photochemical trifluoromethylation of arenes.
Scheme 52: Copper-mediated trifluoromethylation of arenediazonium tetrafluoroborates.
Scheme 53: Oxidative trifluoromethylation of aryl- and heteroarylboronic acids.
Scheme 54: Oxidative trifluoromethylation of aryl- and vinylboronic acids.
Scheme 55: Oxidative trifluoromethylation of unsaturated potassium organotrifluoroborates.
Scheme 56: Oxidative trifluoromethylation of (hetero)aryl- and vinyltrifluoroborates.
Scheme 57: Copper−catalysed decarboxylative trifluoromethylation of cinnamic acids.
Scheme 58: Iron-mediated decarboxylative trifluoromethylation of α,β-unsaturated carboxylic acids.
Scheme 59: Cu/Ag-catalysed decarboxylative trifluoromethylation of cinnamic acids.
Scheme 60: I2O5-Promoted decarboxylative trifluoromethylation of cinnamic acids.
Scheme 61: Silver(I)-catalysed denitrative trifluoromethylation of β-nitrostyrenes.
Scheme 62: Copper-catalysed direct trifluoromethylation of styrene derivatives.
Scheme 63: Transition-metal-free synthesis of β-trifluoromethylated enamines.
Scheme 64: I2O5-mediated iodotrifluoromethylation of alkynes.
Scheme 65: Silver-catalysed tandem trifluoromethylation/cyclisation of aryl isonitriles.
Scheme 66: Photoredox trifluoromethylation of 2-isocyanobiphenyls.
Scheme 67: Trifluoromethylation of potassium alkynyltrifluoroborates with CF3SO2Na.
Scheme 68: N-trifluoromethylation of nitrosoarenes with CF3SO2Na (SQ: semiquinone).
Scheme 69: Trifluoromethylation of disulfides with CF3SO2Na.
Scheme 70: Trifluoromethylation of thiols with CF3SO2Na/I2O5.
Scheme 71: Electrophilic trifluoromethylsulfenylation by means of CF3SO2Na/(EtO)2P(O)H/CuCl/DMSO.
Scheme 72: Electrophilic trifluoromethylsulfenylation by means of CF3SO2Na/(EtO)2P(O)H/TMSCl.
Scheme 73: Electrophilic trifluoromethylsulfenylation by means of CF3SO2Na/PPh3/N-chlorophthalimide.
Scheme 74: Electrophilic trifluoromethylsulfenylation by means of CF3SO2Na/PCl3.
Scheme 75: Electrophilic trifluoromethylsulfenylation by means of CF3SO2Na/PCl3.
Scheme 76: Trifluoromethylsulfenylation of aryl iodides with in situ generated CuSCF3 (DMI: 1,3-dimethyl-2-imi...
Scheme 77: Pioneering trifluoromethylsulfinylation of N, O, and C-nucleophiles.
Scheme 78: Trifluoromethylsulfinylation of (1R,2S)-ephedrine (Im: imidazole; DIEA: N,N-diisopropylethylamine).
Scheme 79: Trifluoromethylsulfinylation of substituted benzenes with CF3SO2Na/CF3SO3H.
Scheme 80: Trifluoromethylsulfinylation of indoles with CF3SO2Na/P(O)Cl3.
Scheme 81: Trifluoromethylsulfinylation of indoles with CF3SO2Na/PCl3.
Scheme 82: Formation of triflones from benzyl bromides (DMA: dimethylacetamide).
Scheme 83: Formation of α-trifluoromethylsulfonyl ketones, esters, and amides.
Scheme 84: Allylic trifluoromethanesulfonylation of aromatic allylic alcohols.
Scheme 85: Copper-catalysed couplings of aryl iodonium salts with CF3SO2Na.
Scheme 86: Palladium-catalysed trifluoromethanesulfonylation of aryl triflates and chlorides with CF3SO2Na.
Scheme 87: Copper-catalysed coupling of arenediazonium tetrafluoroborates with CF3SO2Na.
Scheme 88: Synthesis of phenyltriflone via coupling of benzyne with CF3SO2Na.
Scheme 89: Synthesis of 1-trifluoromethanesulfonylcyclopentenes from 1-alkynyl-λ3-bromanes and CF3SO2Na.
Scheme 90: One-pot synthesis of functionalised vinyl triflones.
Scheme 91: Regioselective synthesis of vinyltriflones from styrenes.
Scheme 92: Trifluoromethanesulfonylation of alkynyl(phenyl) iodonium tosylates by CF3SO2Na.
Scheme 93: Synthesis of thio- and selenotrifluoromethanesulfonates.
Vinylphosphonium and 2-aminovinylphosphonium salts – preparation and applications in organic synthesis
- Anna Kuźnik,
- Roman Mazurkiewicz and
- Beata Fryczkowska
Beilstein J. Org. Chem. 2017, 13, 2710–2738, doi:10.3762/bjoc.13.269
- –71%, respectively (Scheme 29) [42]. An interesting example of the application of ylides derived from vinylphosphonium salts in the enantioselective synthesis of pyran derivatives was reported by Ley et al. in 2010. β-Hydroxyaldehyde 43 as the oxygen nucleophile was obtained here in the asymmetric
- , followed by the intramolecular Wittig reaction gave the corresponding 3,6-dihydropyran derivatives 44 in yields of 34–56% and a high enantioselectivity of 95–98% (Scheme 30) [43]. Pyran derivatives are structural elements of many natural biologically active compounds [44][45][46][47]. 2.2.2. Reactions with
Graphical Abstract
Scheme 1: Generation of phosphorus ylides from vinylphosphonium salts.
Scheme 2: Intramolecular Wittig reaction with the use of vinylphosphonium salts.
Scheme 3: Alkylation of diphenylvinylphosphine with methyl or benzyl iodide.
Scheme 4: Methylation of isopropenyldiphenylphosphine with methyl iodide.
Scheme 5: Alkylation of phosphines with allyl halide derivatives and subsequent isomerization of intermediate...
Scheme 6: Alkylation of triphenylphosphine with vinyl triflates in the presence of (Ph3P)4Pd.
Scheme 7: Mechanism of alkylation of triphenylphosphine with vinyl triflates in the presence of (Ph3P)4Pd as ...
Scheme 8: β-Elimination of phenol from β-phenoxyethyltriphenylphosphonium bromide.
Scheme 9: β-Elimination of phenol from β-phenoxyethylphosphonium salts in an alkaline environment.
Scheme 10: Synthesis and subsequent dehydrohalogenation of α-bromoethylphosphonium bromide.
Scheme 11: Synthesis of tributylvinylphosphonium iodides via Peterson-type olefination of α-trimethylsilylphos...
Scheme 12: Synthesis of 1-cycloalkenetriphenylphosphonium salts by electrochemical oxidation of triphenylphosp...
Scheme 13: Suggested mechanism for the electrochemical synthesis of 1-cycloalkenetriphenylphosphonium salts.
Scheme 14: Generation of α,β-(dialkoxycarbonyl)vinylphosphonium salts by addition of triphenylphosphine to ace...
Scheme 15: Synthesis of 2-(N-acylamino)vinylphosphonium halides by imidoylation of β-carbonyl ylides with imid...
Scheme 16: Imidoylation of β-carbonyl ylides with imidoyl halides generated in situ.
Scheme 17: Synthesis of 2-benzoyloxyvinylphosphonium bromide from 2-propynyltriphenylphosphonium bromide.
Scheme 18: Synthesis of 2-aminovinylphosphonium salts via nucleophilic addition of amines to 2-propynyltriphen...
Scheme 19: Deacylation of 2-(N-acylamino)vinylphosphonium chlorides to 2-aminovinylphosphonium salts.
Scheme 20: Resonance structures of 2-aminovinylphosphonium salts and tautomeric equilibrium between aminovinyl...
Scheme 21: Synthesis of 2-aminovinylphosphonium salts by reaction of (formylmethyl)triphenylphosphonium chlori...
Scheme 22: Generation of ylides by reaction of vinyltriphenylphosphonium bromide with nucleophiles and their s...
Scheme 23: Intermolecular Wittig reaction with the use of vinylphosphonium bromide and organocopper compounds ...
Scheme 24: Intermolecular Wittig reaction with the use of ylides generated from vinylphosphonium bromides and ...
Scheme 25: Direct transformation of vinylphosphonium salts into ylides in the presence of potassium tert-butox...
Scheme 26: A general method for synthesis of carbo- and heterocyclic systems by the intramolecular Wittig reac...
Scheme 27: Synthesis of 2H-chromene by reaction of vinyltriphenylphosphonium bromide with sodium 2-formylpheno...
Scheme 28: Synthesis of 2,5-dihydro-2,3-dimethylfuran by reaction of vinylphosphonium bromide with 3-hydroxy-2...
Scheme 29: Synthesis of 2H-chromene and 2,5-dihydrofuran derivatives in the intramolecular Wittig reaction wit...
Scheme 30: Enantioselective synthesis of 3,6-dihydropyran derivatives from vinylphosphonium bromide and enanti...
Scheme 31: Synthesis of 2,5-dihydrothiophene derivatives in the intramolecular Wittig reaction from vinylphosp...
Scheme 32: Synthesis of bicyclic pyrrole derivatives in the reaction of vinylphosphonium halides and 2-pyrrolo...
Scheme 33: Stereoselective synthesis of bicyclic 2-pyrrolidinone derivatives in the reaction of vinylphosphoni...
Scheme 34: Stereoselective synthesis of 3-pyrroline derivatives in the intramolecular Wittig reaction from vin...
Scheme 35: Synthesis of cyclic alkenes in the intramolecular Wittig reaction from vinylphosphonium bromide and...
Scheme 36: Synthesis of 1,3-cyclohexadienes by reaction of 1,3-butadienyltriphenylphosphonium bromide with eno...
Scheme 37: Synthesis of bicyclo[3.3.0]octenes by reaction of vinylphosphonium salts with cyclic diketoester.
Scheme 38: Synthesis of quinoline derivatives in the intramolecular Wittig reaction from 2-(2-acylphenylamino)...
Scheme 39: Stereoselective synthesis of γ-aminobutyric acid in the intermolecular Wittig reaction from chiral ...
Scheme 40: Synthesis of allylamines in the intermolecular Wittig reaction from 2-aminovinylphosphonium bromide...
Scheme 41: A general route towards α,β-di(alkoxycarbonyl)vinylphosphonium salts and their subsequent possible ...
Scheme 42: Generation of resonance-stabilized phosphorus ylides via the reaction of triphenylphosphine with di...
Scheme 43: Synthesis of resonance-stabilized phosphorus ylides in the reaction of triphenylphosphine, dialkyl ...
Scheme 44: Synthesis of resonance-stabilized phosphorus ylides via the reaction of triphenylphosphine with dia...
Scheme 45: Generation of resonance-stabilized phosphorus ylides in the reaction of acetylenedicarboxylate, tri...
Scheme 46: Synthesis of resonance-stabilized phosphorus ylides via the reaction of dialkyl acetylenedicarboxyl...
Scheme 47: Synthesis of resonance-stabilized ylides derived from semicarbazones, aromatic amides, and 3-(aryls...
Scheme 48: Synthesis of resonance-stabilized ylides via the reaction of triphenylphosphine with dialkyl acetyl...
Scheme 49: Synthesis of resonance-stabilized ylides in the reaction of triphenylphosphine, dialkyl acetylenedi...
Scheme 50: Synthesis of N-acylated α,β-unsaturated γ-lactams via resonance-stabilized phosphorus ylides derive...
Scheme 51: Synthesis of resonance-stabilized phosphorus ylides derived from 6-amino-N,N'-dimethyluracil and th...
Scheme 52: Generation of resonance-stabilized phosphorus ylides in the reaction of triphenylphosphine, dialkyl...
Scheme 53: Synthesis of resonance-stabilized phosphorus ylides via the reaction of triphenylphosphine with dia...
Scheme 54: Synthesis of 1,3-dienes via intramolecular Wittig reaction with the use of resonance-stabilized yli...
Scheme 55: Synthesis of 1,3-dienes in the intramolecular Wittig reaction from ylides generated from dimethyl a...
Scheme 56: Synthesis of 4-(2-quinolyl)cyclobutene-1,2,3-tricarboxylic acid triesters and isomeric cyclopenteno...
Scheme 57: Synthesis of 4-arylquinolines via resonance-stabilized ylides in the intramolecular Wittig reaction....
Scheme 58: Synthesis of furan derivatives via resonance-stabilized ylides in the intramolecular Wittig reactio...
Scheme 59: Synthesis of 1,3-indanedione derivatives via resonance-stabilized ylides in the intermolecular Witt...
Scheme 60: Synthesis of coumarin derivatives via nucleophilic displacement of the triphenylphosphonium group i...
Scheme 61: Synthesis of 6-formylcoumarin derivatives and their application in the synthesis of dyads.
Scheme 62: Synthesis of di- and tricyclic coumarin derivatives in the reaction of pyrocatechol with two vinylp...
Scheme 63: Synthesis of mono-, di-, and tricyclic derivatives in the reaction of pyrogallol with one or two vi...
Scheme 64: Synthesis of 1,4-benzoxazine derivative by nucleophilic displacement of the triphenylphosphonium gr...
Scheme 65: Synthesis of 7-oxo-7H-pyrido[1,2,3-cd]perimidine derivative via nucleophilic displacement of the tr...
Scheme 66: Application of vinylphosphonium salts in the Diels–Alder reaction with dienes.
Scheme 67: Synthesis of pyrroline derivatives from vinylphosphonium bromide and 5-(4H)-oxazolones.
Scheme 68: Synthesis of pyrrole derivatives in the reactions of vinyltriphenylphosphonium bromide with protona...
Scheme 69: Synthesis of dialkyl 2-(alkylamino)-5-aryl-3,4-furanedicarboxylates via intermediate α,β-di(alkoxyc...
Scheme 70: Synthesis of 1,4-benzoxazine derivatives from acetylenedicarboxylates, phosphines, and 1-nitroso-2-...
Dialkyl dicyanofumarates and dicyanomaleates as versatile building blocks for synthetic organic chemistry and mechanistic studies
- Grzegorz Mlostoń and
- Heinz Heimgartner
Beilstein J. Org. Chem. 2017, 13, 2235–2251, doi:10.3762/bjoc.13.221
- product [30] (Scheme 6). The analogous reaction with phenyl vinyl sulfide (22) gave the expected cyclobutane 23 exclusively. However, in the absence of ZnCl2, a mixture of 23 and 3,4-dihydro-2H-pyran 24 was obtained, with the latter compound formed through a competitive hetero-Diels–Alder reaction [30
- ]. The competitive formation of cyclobutane and pyran derivatives was also observed in reactions of E-1b or Z-1b with ethyl prop-1-enyl ether performed in CDCl3 at room temperature [31]. The reaction of N-vinylcarbazole (25) with E-1b or Z-1b in boiling benzene gave mixtures of four diastereoisomers of
- carried out [45][48][50][51]. A stepwise reaction has also been suggested for the formal [4 + 2]-cycloaddition of E- and Z-1b with ethyl prop-1-enyl ether leading to a mixture of the corresponding 3,4-dihydro-2H-pyran and cyclobutane derivatives in a non-stereospecific manner [31]. A mechanism with the
Graphical Abstract
Figure 1: Dialkyl dicyanofumarates E-1 and dicyanomaleates Z-1.
Scheme 1: Methods for the synthesis of dialkyl dicyanofumarates E-1 from alkyl cyanoacetates 2.
Scheme 2: Methods for the synthesis of dialkyl dicyanofumarates E-1 from alkyl bromoacetates 3.
Scheme 3: Reaction of dimethyl dicyanofumarate (E-1b) with dimethoxycarbene [(MeO)2C:] generated in situ from...
Scheme 4: Cyclopropanation of diethyl dicyanofumarate (E-1a) through reaction with the thiophene derived sulf...
Scheme 5: Cyclopropanation of dimethyl dicyanofumarate (E-1b) through a stepwise reaction with the in situ ge...
Scheme 6: The [2 + 2]-cycloadditions of dimethyl dicyanofumarate (E-1b) with electron-rich ethylenes 20 and 22...
Scheme 7: The [2 + 2]-cycloaddition of isomeric dimethyl dicyanofumarate (E-1b) and dicyanomaleate (Z-1b) wit...
Scheme 8: Non-concerted [2 + 2]-cycloaddition between E-1b and bicyclo[2.1.0]pentene (27).
Scheme 9: Stepwise [3 + 2]-cycloadditions of some thiocarbonyl S-methanides with dialkyl dicyanofumarates E-1...
Scheme 10: Stepwise [3 + 2]-cycloadditions of dimethyl dicyanofumarate (E-1b) and dimethyl dicyanomaleate (Z-1b...
Scheme 11: [3 + 2]-Cycloaddition of diazomethane with dimethyl dicyanofumarate (E-1b) leading to 1H-pyrazole d...
Scheme 12: Reversible Diels–Alder reaction of fulvenes 36 with diethyl dicyanofumarate (E-1a).
Scheme 13: [4 + 2]-Cycloaddition of 9,10-dimethylanthracene (39b) and E-1a.
Scheme 14: Stepwise [4 + 2]-cycloaddition of dimethyl dicyanofumarate (E-1b) with electron-rich 1,1-dimethoxy-...
Scheme 15: Formal [4 + 2]-cycloaddition of 3,4-di(α-styryl)furan (47) with dimethyl dicyanofumarate (E-1b).
Scheme 16: Acid-catalyzed Michael addition of enolizable ketones of type 49 to E-1.
Scheme 17: Reaction of diethyl dicyanofumarate (E-1a) with ammonia NH3.
Scheme 18: Reaction of dialkyl dicyanofumarates E-1 with primary and secondary amines.
Scheme 19: Reaction of dialkyl dicyanofumarates E-1 with 1-azabicyclo[1.1.0]butanes 55.
Scheme 20: Formation of pyrazole derivatives in the reaction of hydrazines with E-1.
Scheme 21: Formation of 5-aminopyrazole-3,4-dicarboxylate 65 via heterocyclization reactions.
Scheme 22: Reactions of aryl- and hetarylcarbohydrazides 67 with E-1a.
Scheme 23: Multistep reaction leading to perhydroquinoxaline derivative 73.
Scheme 24: Synthesis of ethyl 7-aminopteridin-6-carboxylates 75 via a domino reaction.
Scheme 25: Synthesis of morhpolin-2-ones 80 from E-1 and β-aminoalcohols 78 through an initial aza-Michael add...
Scheme 26: Reaction of 3-amino-5-arylpyrazoles 81 with dialkyl dicyanofumarates E-1 via competitive nucleophil...
Scheme 27: Heterocyclization reaction of thiosemicarbazone 86 with E-1a.
Scheme 28: Formation of diethyl 4-cyano-5-oxotetrahydro-4H-chromene-3,4-dicarboxylate (90) from E-1a via heter...
Scheme 29: Reaction of dialkyl dicyanofumarates E-1 with cysteamine (92).
Scheme 30: Formation of disulfides through reaction of thiols with E-1a.
Scheme 31: Formation of CT salts of E-1 with Mn2+ and Cr2+ metallocenes through one-electron transfer.
Scheme 32: Oxidation of diethyl dicyanofumarate (E-1a) with H2O2 to give oxirane 101.
Scheme 33: The aziridination of E-1b through nitrene addition.
Mechanochemical synthesis of small organic molecules
- Tapas Kumar Achar,
- Anima Bose and
- Prasenjit Mal
Beilstein J. Org. Chem. 2017, 13, 1907–1931, doi:10.3762/bjoc.13.186
- ]. Mechanochemical methods of the Mannich reaction, Paal–Knorr synthesis, Bigineli reaction, Hantzsch reaction, and syntheses of substituted pyran, thiophene, isoquinoline derivatives, etc. are also reported [104][107][112][113]. Isocyanide-based multi-component reactions are also well known [114][115]. Recently, in
- example, a) at higher frequency (800 min−1) for 45 min lower yield with less selectivity was observed and b) using lower frequency, 200 min−1 for 8 h led to 82% of yield with high selectivity. In the traditional method of pyran synthesis the use of transition metal catalyst, corrosive acid, longer
Graphical Abstract
Scheme 1: Mechanochemical aldol condensation reactions [48].
Scheme 2: Enantioselective organocatalyzed aldol reactions under mechanomilling. a) Based on binam-(S)-prolin...
Scheme 3: Mechanochemical Michael reaction [51].
Scheme 4: Mechanochemical organocatalytic asymmetric Michael reaction [52].
Scheme 5: Mechanochemical Morita–Baylis–Hillman (MBH) reaction [53].
Scheme 6: Mechanochemical Wittig reactions [55].
Scheme 7: Mechanochemical Suzuki reaction [56].
Scheme 8: Mechanochemical Suzuki–Miyaura coupling by LAG [57].
Scheme 9: Mechanochemical Heck reaction [59].
Scheme 10: a) Sonogashira coupling under milling conditions. b) The representative example of a double Sonogas...
Scheme 11: Copper-catalyzed CDC reaction under mechanomilling [67].
Scheme 12: Asymmetric alkynylation of prochiral sp3 C–H bonds via CDC [68].
Scheme 13: Fe(III)-catalyzed CDC coupling of 3-benzylindoles [69].
Scheme 14: Mechanochemical synthesis of 3-vinylindoles and β,β-diindolylpropionates [70].
Scheme 15: Mechanochemical C–N bond construction using anilines and arylboronic acids [78].
Scheme 16: Mechanochemical amidation reaction from aromatic aldehydes and N-chloramine [79].
Scheme 17: Mechanochemical CDC between benzaldehydes and benzyl amines [81].
Scheme 18: Mechanochemical protection of -NH2 and -COOH group of amino acids [85].
Scheme 19: Mechanochemical Ritter reaction [87].
Scheme 20: Mechanochemical synthesis of dialkyl carbonates [90].
Scheme 21: Mechanochemical transesterification reaction using basic Al2O3 [91].
Scheme 22: Mechanochemical carbamate synthesis [92].
Scheme 23: Mechanochemical bromination reaction using NaBr and oxone [96].
Scheme 24: Mechanochemical aryl halogenation reactions using NaX and oxone [97].
Scheme 25: Mechanochemical halogenation reaction of electron-rich arenes [88,98].
Scheme 26: Mechanochemical aryl halogenation reaction using trihaloisocyanuric acids [100].
Scheme 27: Mechanochemical fluorination reaction by LAG method [102].
Scheme 28: Mechanochemical Ugi reaction [116].
Scheme 29: Mechanochemical Passerine reaction [116].
Scheme 30: Mechanochemical synthesis of α-aminonitriles [120].
Scheme 31: Mechanochemical Hantzsch pyrrole synthesis [121].
Scheme 32: Mechanochemical Biginelli reaction by subcomponent synthesis approach [133].
Scheme 33: Mechanochemical asymmetric multicomponent reaction[134].
Scheme 34: Mechanochemical Paal–Knorr pyrrole synthesis [142].
Scheme 35: Mechanochemical synthesis of benzothiazole using ZnO nano particles [146].
Scheme 36: Mechanochemical synthesis of 1,2-di-substituted benzimidazoles [149].
Scheme 37: Mechanochemical click reaction using an alumina-supported Cu-catalyst [152].
Scheme 38: Mechanochemical click reaction using copper vial [155].
Scheme 39: Mechanochemical indole synthesis [157].
Scheme 40: Mechanochemical synthesis of chromene [158].
Scheme 41: Mechanochemical synthesis of azacenes [169].
Scheme 42: Mechanochemical oxidative C-P bond formation [170].
Scheme 43: Mechanochemical C–chalcogen bond formation [171].
Scheme 44: Solvent-free synthesis of an organometallic complex.
Scheme 45: Selective examples of mechano-synthesis of organometallic complexes. a) Halogenation reaction of Re...
Scheme 46: Mechanochemical activation of C–H bond of unsymmetrical azobenzene [178].
Scheme 47: Mechanochemical synthesis of organometallic pincer complex [179].
Scheme 48: Mechanochemical synthesis of tris(allyl)aluminum complex [180].
Scheme 49: Mechanochemical Ru-catalyzed olefin metathesis reaction [181].
Scheme 50: Rhodium(III)-catalyzed C–H bond functionalization under mechanochemical conditions [182].
Scheme 51: Mechanochemical Csp2–H bond amidation using Ir(III) catalyst [183].
Scheme 52: Mechanochemical Rh-catalyzed Csp2–X bond formation [184].
Scheme 53: Mechanochemical Pd-catalyzed C–H activation [185].
Scheme 54: Mechanochemical Csp2–H bond amidation using Rh catalyst.
Scheme 55: Mechanochemical synthesis of indoles using Rh catalyst [187].
Scheme 56: Mizoroki–Heck reaction of aminoacrylates with aryl halide in a ball-mill [58].
Scheme 57: IBX under mechanomilling conditions [8].
Scheme 58: Thiocarbamoylation of anilines; trapping of reactive aryl-N-thiocarbamoylbenzotriazole intermediate...
Pd(OAc)2/Ph3P-catalyzed dimerization of isoprene and synthesis of monoterpenic heterocycles
- Dominik Kellner,
- Maximilian Weger,
- Andrea Gini and
- Olga García Mancheño
Beilstein J. Org. Chem. 2017, 13, 1807–1815, doi:10.3762/bjoc.13.175
- simple screw cap vials or schlenks, leading to the desired dimer in good yields. Finally, the synthetic potential of this method for the synthesis of valuable heterocyclic terpenic derivatives was demonstrated with the preparation of several pyran, tetrahydroisobenzofurane and pyrrolidine derivatives by
- (gradient: hexane to hexanes/EtOAc 4:1) and distillation (90 °C, ≈6 mbar), to provide pyran 5 as colorless oil (106.0 mg, 0.64 mmol, 64%). 4-Methyl-2-(3-methylbut-3-en-1-yl)-5,6-dihydro-2H-pyran (5) [42] 1H NMR (400 MHz, CDCl3) δ 5.37–5.31 (m, 1H, H-2), 4.80–4.63 (m, 2H, H-11), 4.04–3.90 (m, 2H, H-2 + H-6a
Graphical Abstract
Figure 1: Isoprene as chemical building block in nature and organic synthesis.
Scheme 1: Pd-catalyzed dimerization of isoprene.
Scheme 2: Putative mechanism for the Pd(OAc)2-catalyzed dimerization of isoprene.
Scheme 3: Functionalization of the isoprene-dimer 2-TT to substituted O- and N-heterocycles.
