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Search for "hydride" in Full Text gives 490 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.
Syntheses of spliceostatins and thailanstatins: a review
- William A. Donaldson
Beilstein J. Org. Chem. 2020, 16, 1991–2006, doi:10.3762/bjoc.16.166
- -tert-butylsilylene protecting group and the selective arylsulfonylation of the primary alcohol was effected with the bulky 2,4,6-triisopropylsulfonyl chloride, which upon reduction with aluminum hydride, followed by the oxidation of the remaining alcohol group gave the dihydropyran-3-one 65. In a
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.
Regiodivergent synthesis of functionalized pyrimidines and imidazoles through phenacyl azides in deep eutectic solvents
- Paola Vitale,
- Luciana Cicco,
- Ilaria Cellamare,
- Filippo M. Perna,
- Antonio Salomone and
- Vito Capriati
Beilstein J. Org. Chem. 2020, 16, 1915–1923, doi:10.3762/bjoc.16.158
- reactions of α-azido ketones with tributyltin hydride [31], or (e) by a modified Radziszewski’s synthesis when using phenylglyoxals, benzaldeydes, and ammonium acetate as ammonia source in acetic acid or methylene chloride or N,N-dimethylformamide as the solvent [32], there are no adequate studies covering
Graphical Abstract
Scheme 1: One-pot synthesis of 2,5-diarylpyrazines (A) (path a) or 2-aroyl-(4 or 5)-aryl-(1H)-imidazoles (B) ...
Scheme 2: Transformation of phenacyl bromide (1a) in ChCl/Gly into phenacyl azide (2a) and 2-benzoyl-(4 or 5)...
Scheme 3: Synthesis of 2-aroyl-(4 or 5)-aryl-(1H)-imidazoles 3. Scope of the reaction. Typical conditions: 1 ...
Scheme 4: Proposed mechanism for the formation of 2-aroyl-(4 or 5)-aryl-(1H)-imidazoles 3/3' from α-phenacyl ...
Scheme 5: Proposed mechanism for the formation of 2-benzoyl-(4 or 5)-phenyl-(1H)-imidazoles 3a/3a' and 2,4-di...
Scheme 6: Scope of the synthesis of 2,4-diaroyl-6-arylpyrimidines 7. Typical conditions: 2 (0.3 mmol), Et3N (...
Stereoselective Biginelli-like reaction catalyzed by a chiral phosphoric acid bearing two hydroxy groups
- Xiaoyun Hu,
- Jianxin Guo,
- Cui Wang,
- Rui Zhang and
- Victor Borovkov
Beilstein J. Org. Chem. 2020, 16, 1875–1880, doi:10.3762/bjoc.16.155
- ), sodium hydride (0.105 g, 4.2 mmol), and dried THF (16 mL). The mixture was stirred at rt for 2 h, and then methyl iodide (0.61 g, 4.3 mmol) was added and the mixture stirred at rt for 6 h. Then, distilled water (12 mL) and diethyl ether (15 mL) were added, the organic phase was separated, dried, and
Graphical Abstract
Scheme 1: Synthesis of chiral phosphoric acid 3.
Scheme 2: Synthesis of methylated chiral phosphoric acid 7.
Scheme 3: Control experiment with catalyst 7.
Figure 1: A plausible chiral transition-state structure in the Biginelli-like reaction catalyzed by phosphori...
When metal-catalyzed C–H functionalization meets visible-light photocatalysis
- Lucas Guillemard and
- Joanna Wencel-Delord
Beilstein J. Org. Chem. 2020, 16, 1754–1804, doi:10.3762/bjoc.16.147
- metal catalyst X2M into an aromatic C–H bond of a substrate (generally facilitated by the presence of a directing group (DG)), delivers a metal–aryl complex. Coordination and subsequent insertion of an alkene into the M–aryl bond then provides the desired coupling product after β-hydride elimination
- , together with a metal hydride or a low-valent metal complex. Hence, in order to reoxidize the metal catalyst, excess of an external oxidant, such as Cu(II) or Ag(I) salts, was frequently used. On the other hand, photoredox catalysis has been mainly employed for electron-transfer reactions and, remarkably
- towards various functional groups such as aldehydes, ketones, and esters. Of note is that in some cases, partial hydrogenation of the double bond was observed, resulting probably from the generation of a ruthenium–hydride complex. However, this consecutive reactivity and the ratio between the olefin and
Graphical Abstract
Figure 1: Concept of dual synergistic catalysis.
Figure 2: Classification of catalytic systems involving two catalysts.
Figure 3: General mechanism for the dual nickel/photoredox catalytic system.
Figure 4: General mechanisms for C–H activation catalysis involving different reoxidation strategies.
Figure 5: Indole synthesis via dual C–H activation/photoredox catalysis.
Figure 6: Proposed mechanism for the indole synthesis via dual catalysis.
Figure 7: Oxidative Heck reaction on arenes via the dual catalysis.
Figure 8: Proposed mechanism for the Heck reaction on arenes via dual catalysis.
Figure 9: Oxidative Heck reaction on phenols via the dual catalysis.
Figure 10: Proposed mechanism for the Heck reaction on phenols via dual catalysis.
Figure 11: Carbazole synthesis via dual C–H activation/photoredox catalysis.
Figure 12: Proposed mechanism for the carbazole synthesis via dual catalysis.
Figure 13: Carbonylation of enamides via the dual C–H activation/photoredox catalysis.
Figure 14: Proposed mechanism for carbonylation of enamides via dual catalysis.
Figure 15: Annulation of benzamides via the dual C–H activation/photoredox catalysis.
Figure 16: Proposed mechanism for the annulation of benzamides via dual catalysis.
Figure 17: Synthesis of indoles via the dual C–H activation/photoredox catalysis.
Figure 18: Proposed mechanism for the indole synthesis via dual catalysis.
Figure 19: General concept of dual catalysis merging C–H activation and photoredox catalysis.
Figure 20: The first example of dual catalysis merging C–H activation and photoredox catalysis.
Figure 21: Proposed mechanism for the C–H arylation with diazonium salts via dual catalysis.
Figure 22: Dual catalysis merging C–H activation/photoredox using diaryliodonium salts.
Figure 23: Direct arylation via the dual catalytic system reported by Xu.
Figure 24: Direct arylation via dual catalytic system reported by Balaraman.
Figure 25: Direct arylation via dual catalytic system reported by Guo.
Figure 26: C(sp3)–H bond arylation via the dual Pd/photoredox catalytic system.
Figure 27: Acetanilide derivatives acylation via the dual C–H activation/photoredox catalysis.
Figure 28: Proposed mechanism for the C–H acylation with α-ketoacids via dual catalysis.
Figure 29: Acylation of azobenzenes via the dual catalysis C–H activation/photoredox.
Figure 30: C2-acylation of indoles via the dual C–H activation/photoredox catalysis.
Figure 31: Proposed mechanism for the C2-acylation of indoles with aldehydes via dual catalysis.
Figure 32: C2-acylation of indoles via the dual C–H activation/photoredox catalysis.
Figure 33: Perfluoroalkylation of arenes via the dual C–H activation/photoredox catalysis.
Figure 34: Proposed mechanism for perfluoroalkylation of arenes via dual catalysis.
Figure 35: Sulfonylation of 1-naphthylamides via the dual C–H activation/photoredox catalysis.
Figure 36: Proposed mechanism for sulfonylation of 1-naphthylamides via dual catalysis.
Figure 37: meta-C–H Alkylation of arenes via visible-light metallaphotocatalysis.
Figure 38: Alternative procedure for meta-C–H alkylation of arenes via metallaphotocatalysis.
Figure 39: Proposed mechanism for meta-C–H alkylation of arenes via metallaphotocatalysis.
Figure 40: C–H borylation of arenes via visible-light metallaphotocatalysis.
Figure 41: Proposed mechanism for C–H borylation of arenes via visible-light metallaphotocatalysis.
Figure 42: Undirected C–H aryl–aryl cross coupling via dual gold/photoredox catalysis.
Figure 43: Proposed mechanism for the undirected C–H aryl–aryl cross-coupling via dual catalysis.
Figure 44: Undirected C–H arylation of (hetero)arenes via dual manganese/photoredox catalysis.
Figure 45: Proposed mechanism for the undirected arylation of (hetero)arenes via dual catalysis.
Figure 46: Photoinduced C–H arylation of azoles via copper catalysis.
Figure 47: Photo-induced C–H chalcogenation of azoles via copper catalysis.
Figure 48: Decarboxylative C–H adamantylation of azoles via dual cobalt/photoredox catalysis.
Figure 49: Proposed mechanism for the C–H adamantylation of azoles via dual catalysis.
Figure 50: General mechanisms for the “classical” (left) and Cu-free variant (right) Sonogoshira reaction.
Figure 51: First example of a dual palladium/photoredox catalysis for Sonogashira-type couplings.
Figure 52: Arylation of terminal alkynes with diazonium salts via dual gold/photoredox catalysis.
Figure 53: Proposed mechanism for the arylation of terminal alkynes via dual catalysis.
Figure 54: C–H Alkylation of alcohols promoted by H-atom transfer (HAT).
Figure 55: Proposed mechanism for the C–H alkylation of alcohols promoted by HAT.
Figure 56: C(sp3)–H arylation of latent nucleophiles promoted by H-atom transfer.
Figure 57: Proposed mechanism for the C(sp3)–H arylation of latent nucleophiles promoted by HAT.
Figure 58: Direct α-arylation of alcohols promoted by H-atom transfer.
Figure 59: Proposed mechanism for the direct α-arylation of alcohols promoted by HAT.
Figure 60: C–H arylation of amines via dual Ni/photoredox catalysis.
Figure 61: Proposed mechanism for the C–H arylation of amines via dual Ni/photoredox catalysis.
Figure 62: C–H functionalization of nucleophiles via excited ketone/nickel dual catalysis.
Figure 63: Proposed mechanism for the C–H functionalization enabled by excited ketones.
Figure 64: Selective sp3–sp3 cross-coupling promoted by H-atom transfer.
Figure 65: Proposed mechanism for the selective sp3–sp3 cross-coupling promoted by HAT.
Figure 66: Direct C(sp3)–H acylation of amines via dual Ni/photoredox catalysis.
Figure 67: Proposed mechanism for the C–H acylation of amines via dual Ni/photoredox catalysis.
Figure 68: C–H hydroalkylation of internal alkynes via dual Ni/photoredox catalysis.
Figure 69: Proposed mechanism for the C–H hydroalkylation of internal alkynes.
Figure 70: Alternative procedure for the C–H hydroalkylation of ynones, ynoates, and ynamides.
Figure 71: Allylic C(sp3)–H activation via dual Ni/photoredox catalysis.
Figure 72: Proposed mechanism for the allylic C(sp3)–H activation via dual Ni/photoredox catalysis.
Figure 73: Asymmetric allylation of aldehydes via dual Cr/photoredox catalysis.
Figure 74: Proposed mechanism for the asymmetric allylation of aldehydes via dual catalysis.
Figure 75: Aldehyde C–H functionalization promoted by H-atom transfer.
Figure 76: Proposed mechanism for the C–H functionalization of aldehydes promoted by HAT.
Figure 77: Direct C–H arylation of strong aliphatic bonds promoted by HAT.
Figure 78: Proposed mechanism for the C–H arylation of strong aliphatic bonds promoted by HAT.
Figure 79: Direct C–H trifluoromethylation of strong aliphatic bonds promoted by HAT.
Figure 80: Proposed mechanism for the C–H trifluoromethylation of strong aliphatic bonds.
Facile synthesis of 7-alkyl-1,2,3,4-tetrahydro-1,8-naphthyridines as arginine mimetics using a Horner–Wadsworth–Emmons-based approach
- Rhys A. Lippa,
- John A. Murphy and
- Tim N. Barrett
Beilstein J. Org. Chem. 2020, 16, 1617–1626, doi:10.3762/bjoc.16.134
- (1.5–2.4 equiv) and proceeded in <1 h. Sodium hydride was investigated as a heterogeneous alternative to potassium tert-butoxide, although a lower isolated yield of the final amine was obtained. All amines were formed in high NMR and LC–MS purity without the need for purification by column
Graphical Abstract
Figure 1: The Arg–Gly–Asp tripeptide sequence and examples of tetrahydro-1,8-naphthyridine-containing integri...
Scheme 1: Commonly used synthetic routes to tetrahydro-1,8-naphthyridine moieties by hydrogenation of saturat...
Scheme 2: Previous synthetic route to fluoropyrrolidine 6 utilising a Wittig reaction and the novel, higher y...
Scheme 3: Synthesis of phosphoramidate 9 from tetrahydro-1,8-naphthyridine 8. Conditions: s-BuLi (3 equiv), d...
Scheme 4: Mono- and diphosphorylation of tetrahydro-1,8-naphthyridine 11. Conditions: (i) s-BuLi (2 equiv), d...
Scheme 5: Synthesis of amine 6 from phosphonate 7 and aldehyde 5. Conditions: (i) T3P® (50% w/w in DCM, 3 equ...
Scheme 6: Monodeuteration of 13 as observed by 1H and 13C NMR. Conditions: s-BuLi (3 equiv), THF, −42 °C, 20 ...
Scheme 7: Sequential diphosphorylation of tetrahydronaphthyridine 11. Conditions: (i) iPrMgCl (1.5 equiv), TH...
Scheme 8: Possible mechanistic pathways for the formation of dimer 28. Conditions: KOt-Bu, THF, 1 h, 68% yiel...
Scheme 9: Alkylation of phosphoramidate 13 by iodide 29 to afford compound 30 and byproducts alcohol 31 and d...
Synthesis of new dihydroberberine and tetrahydroberberine analogues and evaluation of their antiproliferative activity on NCI-H1975 cells
- Giacomo Mari,
- Lucia De Crescentini,
- Serena Benedetti,
- Francesco Palma,
- Stefania Santeusanio and
- Fabio Mantellini
Beilstein J. Org. Chem. 2020, 16, 1606–1616, doi:10.3762/bjoc.16.133
- interest, the hydrazono-DHBERs 2a–n were further treated with 2.0 equivalents of sodium boron hydride at room temperature in methanol. The reaction furnishes the corresponding hydrazono-THBERs 3a–n in good yields (77–96%, Scheme 3). It is noteworthy that in these conditions, only the iminium moiety is
Graphical Abstract
Scheme 1: Preparation of functionalized-BER, -DHBER and -THBER derivatives.
Scheme 2: Substrate scope of hydrazono-DHBER. Reaction conditions: DHBER (1.0 mmol), 1 (1.0 mmol), DCM 3.0 mL...
Figure 1: 1H,1H-COSY spectrum of DHBER 2a [65].
Scheme 3: Synthesis of hydrazono-THBERs 3a–n. Reaction conditions: DHBER (0.5 mmol), NaBH4 (2.0 mmol), MeOH, ...
Figure 2: Detail of the hydrazone signal in the HMBC spectrum of THBER 3a.
Figure 3: Comparison between 1H NMR spectra of DHBER 2a and of THBER 3a.
Figure 4: NOE correlation between C13−H and C13a−H of THBER 3a.
Figure 5: Effects of 25 µM hydrazono-DHBERs 2a–n (A) and hydrazono-THBERs 3a–g,i–n [70] (B) on NCI-H1975 cell pro...
Figure 6: Effects of 25 µM hydrazono-DHBERs 2a–n and hydrazono-THBERs 3a–g,i–n [70] on NCI-H1975 cell proliferati...
Photoredox-catalyzed silyldifluoromethylation of silyl enol ethers
- Vyacheslav I. Supranovich,
- Vitalij V. Levin and
- Alexander D. Dilman
Beilstein J. Org. Chem. 2020, 16, 1550–1553, doi:10.3762/bjoc.16.126
- silane is very sensitive to Lewis bases and accordingly it was used as a precursor of difluorocarbene, which can react with enol ethers [19][20] (Scheme 1). We showed that this silane could be involved in the radical chain hydrofluoroalkylation of electron-deficient alkenes, using a boron hydride as a
Graphical Abstract
Scheme 1: Reactions of (bromodifluoromethyl)trimethylsilane (1).
Scheme 2: Optimization studies. Yield determined by 19F NMR spectroscopy using an internal standard.
Figure 1: Reaction of silyl enol ethers. Yields refer to isolated yields. aReaction time 24 h; b1.0 equiv of ...
Scheme 3: Proposed mechanism of the fluoroalkylation reaction.
Recent synthesis of thietanes
- Jiaxi Xu
Beilstein J. Org. Chem. 2020, 16, 1357–1410, doi:10.3762/bjoc.16.116
- [22] (Scheme 93). The reaction mechanism was proposed as following. The treatment of trimethyloxosulfonium iodide (424) with sodium hydride generated dimethyloxosulfonium methylide (426) as the one carbon-containing nucleophile with DMSO (379) as a good leaving group. The nucleophilic attack of 426 on
Graphical Abstract
Figure 1: Examples of biologically active thietane-containing molecules.
Figure 2: The diverse methods for the synthesis of thietanes.
Scheme 1: Synthesis of 1-(thietan-2-yl)ethan-1-ol (10) from 3,5-dichloropentan-2-ol (9).
Scheme 2: Synthesis of thietanose nucleosides 2,14 from 2,2-bis(bromomethyl)propane-1,3-diol (11).
Scheme 3: Synthesis of methyl 3-vinylthietane-3-carboxylate (19).
Scheme 4: Synthesis of 1,6-thiazaspiro[3.3]heptane (24).
Scheme 5: Synthesis of 6-amino-2-thiaspiro[3.3]heptane hydrochloride (28).
Scheme 6: Synthesis of optically active thietane 31 from vitamin C.
Scheme 7: Synthesis of an optically active thietane nucleoside from diethyl L-tartrate (32).
Scheme 8: Synthesis of thietane-containing spironucleoside 40 from 5-aldo-3-O-benzyl-1,2-O-isopropylidene-α-D...
Scheme 9: Synthesis of optically active 2-methylthietane-containing spironucleoside 43.
Scheme 10: Synthesis of a double-linked thietane-containing spironucleoside 48.
Scheme 11: Synthesis of two diastereomeric thietanose nucleosides via 2,4-di(benzyloxymethyl)thietane (49).
Scheme 12: Synthesis of the thietane-containing PI3k inhibitor candidate 54.
Scheme 13: Synthesis of the spirothietane 57 as the key intermediate to Nuphar sesquiterpene thioalkaloids.
Scheme 14: Synthesis of spirothietane 61 through a direct cyclic thioetherification of 3-mercaptopropan-1-ol.
Scheme 15: Synthesis of thietanes 66 from 1,3-diols 62.
Scheme 16: Synthesis of thietanylbenzimidazolone 75 from (iodomethyl)thiazolobenzimidazole 70.
Scheme 17: Synthesis of 2-oxa-6-thiaspiro[3.3]heptane (80) from bis(chloromethyl)oxetane 76 and thiourea.
Scheme 18: Synthesis of the thietane-containing glycoside, 2-O-p-toluenesulfonyl-4,6-thioanhydro-α-D-gulopyran...
Scheme 19: Synthesis of methyl 4,6-thioanhydro-α-D-glucopyranoside (89).
Scheme 20: Synthesis of thietane-fused α-D-galactopyranoside 93.
Scheme 21: Synthesis of thietane-fused α-D-gulopyranoside 100.
Scheme 22: Synthesis of 3,5-anhydro-3-thiopentofuranosides 104.
Scheme 23: Synthesis of anhydro-thiohexofuranosides 110, 112 and 113 from from 1,2:4,5-di-O-isopropylidene D-f...
Scheme 24: Synthesis of optically active thietanose nucleosides from D- and L-xyloses.
Scheme 25: Synthesis of thietane-fused nucleosides.
Scheme 26: Synthesis of 3,5-anhydro-3-thiopentofuranosides.
Scheme 27: Synthesis of 2-amino-3,5-anhydro-3-thiofuranoside 141.
Scheme 28: Synthesis of thietane-3-ols 145 from (1-chloromethyl)oxiranes 142 and hydrogen sulfide.
Scheme 29: Synthesis of thietane-3-ol 145a from chloromethyloxirane (142a).
Scheme 30: Synthesis of thietane-3-ols 145 from 2-(1-haloalkyl)oxiranes 142 and 147 with ammonium monothiocarb...
Scheme 31: Synthesis of 7-deoxy-5(20)thiapaclitaxel 154a, a thietane derivative of taxoids.
Scheme 32: Synthesis of 5(20)-thiadocetaxel 158 from 10-deacetylbaccatin III (155).
Scheme 33: Synthesis of thietane derivatives 162 as precursors for deoxythiataxoid synthesis through oxiraneme...
Scheme 34: Synthesis of 7-deoxy 5(20)-thiadocetaxel 154b.
Scheme 35: Mechanism for the formation of the thietane ring in 171 from oxiranes with vicinal leaving groups 1...
Scheme 36: Synthesis of cis-2,3-disubstituted thietane 175 from thiirane-2-methanol 172.
Scheme 37: Synthesis of a bridged thietane 183 from aziridine cyclohexyl tosylate 179 and ammonium tetrathiomo...
Scheme 38: Synthesis of thietanes via the photochemical [2 + 2] cycloaddition of thiobenzophenone 184a with va...
Scheme 39: Synthesis of spirothietanes through the photo [2 + 2] cycloaddition of cyclic thiocarbonyls with ol...
Scheme 40: Photochemical synthesis of spirothietane-thioxanthenes 210 from thioxanthenethione (208) and butatr...
Scheme 41: Synthesis of thietanes 213 from 2,4,6-tri(tert-butyl)thiobenzaldehyde (211) with substituted allene...
Scheme 42: Photochemical synthesis of spirothietanes 216 and 217 from N-methylthiophthalimide (214) with olefi...
Scheme 43: Synthesis of fused thietanes from quadricyclane with thiocarbonyl derivatives 219.
Scheme 44: Synthesis of tricyclic thietanes via the photo [2 + 2] cycloaddition of N-methyldithiosuccinimides ...
Scheme 45: Synthesis of tricyclic thietanes via the photo [2 + 2] cycloaddition of N-methylthiosuccinimide/thi...
Scheme 46: Synthesis of tricyclic thietanes via the photo [2 + 2] cycloaddition of N-alkylmonothiophthalimides...
Scheme 47: Synthesis of spirothietanes from dithiosuccinimides 223 with 2,3-dimethyl-2-butene (215a).
Scheme 48: Synthesis of thietanes 248a,b from diaryl thione 184b and ketene acetals 247a,b.
Scheme 49: Photocycloadditions of acridine-9-thiones 249 and pyridine-4(1H)-thione (250) with 2-methylacrynitr...
Scheme 50: Synthesis of thietanes via the photo [2 + 2] cycloaddition of mono-, di-, and trithiobarbiturates 2...
Scheme 51: Synthesis of spirothietanes via the photo [2 + 2] cycloaddition of 1,1,3-trimethyl-2-thioxo-1,2-dih...
Scheme 52: Synthesis of spirothietanes via the photo [2 + 2] cycloaddition of thiocoumarin 286 with olefins.
Scheme 53: Photochemical synthesis of thietanes 296–299 from semicyclic and acyclic thioimides 292–295 and 2,3...
Scheme 54: Photochemical synthesis of spirothietane 301 from 1,3,3-trimethylindoline-2-thione (300) and isobut...
Scheme 55: Synthesis of spirobenzoxazolethietanes 303 via the photo [2 + 2] cycloaddition of alkyl and aryl 2-...
Scheme 56: Synthesis of spirothietanes from tetrahydrothioxoisoquinolines 306 and 307 with olefins.
Scheme 57: Synthesis of spirothietanes from 1,3-dihydroisobenzofuran-1-thiones 311 and benzothiophene-1-thione...
Scheme 58: Synthesis of 2-triphenylsilylthietanes from phenyl triphenylsilyl thioketone (316) with electron-po...
Scheme 59: Diastereoselective synthesis of spiropyrrolidinonethietanes 320 via the photo [2 + 2] cycloaddition...
Scheme 60: Synthesis of bicyclic thietane 323 via the photo [2 + 2] cycloaddition of 2,4-dioxo-3,4-dihydropyri...
Scheme 61: Photo-induced synthesis of fused thietane-2-thiones 325 and 326 from silacyclopentadiene 324 and ca...
Scheme 62: Synthesis of highly strained tricyclic thietanes 328 via the intramolecular photo [2 + 2] cycloaddi...
Scheme 63: Synthesis of tri- and pentacyclic thietanes 330 and 332, respectively, through the intramolecular p...
Scheme 64: Synthesis of tricyclic thietanes 334 via the intramolecular photo [2 + 2] cycloaddition of N-vinylt...
Scheme 65: Synthesis of tricyclic thietanes 336 via the intramolecular photo [2 + 2] cycloaddition of N-but-3-...
Scheme 66: Synthesis of tricyclic thietanes via the intramolecular photo [2 + 2] cycloaddition of N-but-3-enyl...
Scheme 67: Synthesis of tetracyclic thietane 344 through the intramolecular photo [2 + 2] cycloaddition of N-[...
Scheme 68: Synthesis of tri- and tetracyclic thietanes 348, 350, and 351, through the intramolecular photo [2 ...
Scheme 69: Synthesis of tetracyclic fused thietane 354 via the photo [2 + 2] cycloaddition of vinyl 2-thioxo-3H...
Scheme 70: Synthesis of highly rigid thietane-fused β-lactams via the intramolecular photo [2 + 2] cycloadditi...
Scheme 71: Asymmetric synthesis of a highly rigid thietane-fused β-lactam 356a via the intramolecular photo [2...
Scheme 72: Diastereoselective synthesis of the thietane-fused β-lactams via the intramolecular photo [2 + 2] c...
Scheme 73: Asymmetric synthesis of thietane-fused β-lactams 356 via the intramolecular photo [2 + 2] cycloaddi...
Scheme 74: Synthesis of the bridged bis(trifluoromethyl)thietane from 2,2,4,4-tetrakis(trifluoromethyl)-1,3-di...
Scheme 75: Synthesis of the bridged-difluorothietane 368 from 2,2,4,4-tetrafluoro-1,3-dithietane (367) and qua...
Scheme 76: Synthesis of bis(trifluoromethyl)thietanes from 2,2,4,4-tetrakis(trifluoromethyl)-1,3-dithietane (3...
Scheme 77: Synthesis of 2,2-dimethylthio-4,4-di(trifluoromethyl)thietane (378) from 2,2,4,4-tetrakis(trifluoro...
Scheme 78: Formation of bis(trifluoromethyl)thioacetone (381) through nucleophilic attack of dithietane 363 by...
Scheme 79: Synthesis of 2,2-bis(trifluoromethyl)thietanes from 2,2,4,4-tetrakis(trifluoromethyl)-1,3-dithietan...
Scheme 80: Synthesis of the bridged bis(trifluoromethyl)thietane 364 from of 2,2,4,4-tetrakis(trifluoromethyl)...
Scheme 81: Synthesis of 2,4-diiminothietanes 390 from alkenimines and 4-methylbenzenesulfonyl isothiocyanate (...
Scheme 82: Synthesis of arylidene 2,4-diiminothietanes 393 starting from phosphonium ylides 391 and isothiocya...
Scheme 83: Synthesis of thietane-2-ylideneacetates 397 through a DABCO-catalyzed formal [2 + 2] cycloaddition ...
Scheme 84: Synthesis of 3-substituted thietanes 400 from (1-chloroalkyl)thiiranes 398.
Scheme 85: Synthesis of N-(thietane-3-yl)azaheterocycles 403 and 404 through reaction of chloromethylthiirane (...
Scheme 86: Synthesis of 3-sulfonamidothietanes 406 from sulfonamides and chloromethylthiirane (398a).
Scheme 87: Synthesis of N-(thietane-3-yl)isatins 408 from chloromethylthiirane (398a) and isatins 407.
Scheme 88: Synthesis of 3-(nitrophenyloxy)thietanes 410 from nitrophenols 409 and chloromethylthiirane (398a).
Scheme 89: Synthesis of N-aryl-N-(thietane-3-yl)cyanamides 412 from N-arylcyanamides 411 and chloromethylthiir...
Scheme 90: Synthesis of 1-(thietane-3-yl)pyrimidin-2,4(1H,3H)-diones 414 from chloromethylthiirane (398a) and ...
Scheme 91: Synthesis of 2,4-diiminothietanes 418 from 2-iminothiiranes 416 and isocyanoalkanes 415.
Scheme 92: Synthesis of 2-vinylthietanes 421 from thiiranes 419 and 3-chloroallyl lithium (420).
Scheme 93: Synthesis of thietanes from thiiranes 419 and trimethyloxosulfonium iodide 424.
Scheme 94: Mechanism for synthesis of thietanes 425 from thiiranes 419 and trimethyloxosulfonium iodide 424.
Scheme 95: Synthesis of functionalized thietanes from thiiranes and dimethylsulfonium acylmethylides.
Scheme 96: Mechanism for the rhodium-catalyzed synthesis of functionalized thietanes 429 from thiiranes 419 an...
Scheme 97: Synthesis of 3-iminothietanes 440 through thermal isomerization from 4,5-dihydro-1,3-oxazole-4-spir...
Scheme 98: Synthesis of thietanes 443 from 3-chloro-2-methylthiolane (441) through ring contraction.
Scheme 99: Synthesis of an optically active thietanose 447 from D-xylose involving a ring contraction.
Scheme 100: Synthesis of optically thietane 447 via the DAST-mediated ring contraction of 448.
Scheme 101: Synthesis of the optically thietane nucleoside 451 via the ring contraction of thiopentose in 450.
Scheme 102: Synthesis of spirothietane 456 from 3,3,5,5-tetramethylthiolane-2,4-dithione (452) and benzyne (453...
Scheme 103: Synthesis of thietanes 461 via photoisomerization of 2H,6H-thiin-3-ones 459.
Scheme 104: Phosphorodithioate-mediated synthesis of 1,4-diarylthietanes 465.
Scheme 105: Mechanism of the phosphorodithioate-mediated synthesis of 1,4-diarylthietanes 465.
Scheme 106: Phosphorodithioate-mediated synthesis of trisubstituted thietanes (±)-470.
Scheme 107: Mechanism on the phosphorodithioate-mediated synthesis of trisubstituted thietanes.
Scheme 108: Phosphorodithioate-mediated synthesis of thietanes (±)-475.
Scheme 109: Phosphorodithioate-mediated synthesis of 1,2-disubstituted thietanes from aldehydes 476 and acrylon...
Scheme 110: Phosphorodithioate-mediated synthesis of 1,2-disubstituted thietanes via a one-pot three-component ...
Scheme 111: Mechanism for the phosphorodithioate-mediated synthesis of 1,2-disubstituted thietanes via three-co...
Scheme 112: Phosphorodithioate-mediated synthesis of substituted 3-nitrothietanes.
Scheme 113: Mechanism on the phosphorodithioate-mediated synthesis of 1,2-disubstituted thietanes (±)-486.
Scheme 114: Asymmetric synthesis of (S)-2-phenylthietane (497).
Scheme 115: Asymmetric synthesis of optically active 2,4-diarylthietanes.
Scheme 116: Synthesis of 3-acetamidothietan-2-one 503 via the intramolecular thioesterification of 3-mercaptoal...
Scheme 117: Synthesis of 4-substituted thietan-2-one via the intramolecular thioesterification of 3-mercaptoalk...
Scheme 118: Synthesis of 4,4-disubstituted thietan-2-one 511 via the intramolecular thioesterification of the 3...
Scheme 119: Synthesis of a spirothietan-2-one 514 via the intramolecular thioesterification of 3-mercaptoalkano...
Scheme 120: Synthesis of thiatetrahydrolipstatin starting from (S)-(−)-epichlorohydrin ((S)-142a).
Scheme 121: Synthesis of 2-phenethyl-4-(propan-2-ylidene)thietane (520) from 5-bromo-6-methyl-1-phenylhept-5-en...
Scheme 122: Synthesis of 2-phenethyl-4-(propan-2-ylidene)thietane (520) directly from S-(5-bromo-6-methyl-1-phe...
Scheme 123: Synthesis of 2-alkylidenethietanes from S-(2-bromoalk-1-en-4-yl)thioacetates.
Scheme 124: Synthesis of 2-alkylidenethietanes from S-(2-bromo/chloroalk-1-en-4-yl)thiols.
Scheme 125: Synthesis of spirothietan-3-ol 548 from enone 545 and ammonium hydrosulfide.
Scheme 126: Asymmetric synthesis of the optically active thietanoside from cis-but-2-ene-1,4-diol (47).
Scheme 127: Synthesis of 2-alkylidenethietan-3-ols 557 via the fluoride-mediated cyclization of thioacylsilanes ...
Scheme 128: Synthesis of 2-iminothietanes via the reaction of propargylbenzene (558) and isothiocyanates 560 in...
Scheme 129: Synthesis of 2-benzylidenethietane 567 via the nickel complex-catalyzed electroreductive cyclizatio...
Scheme 130: Synthesis of 2-iminothietanes 569 via the photo-assisted electrocyclic reaction of N-monosubstitute...
Scheme 131: Synthesis of ethyl 3,4-diiminothietane-2-carboxylates from ethyl thioglycolate (570) and bis(imidoy...
Scheme 132: Synthesis of N-(thietan-3-yl)-α-oxoazaheterocycles from azaheterocyclethiones and chloromethyloxira...
Scheme 133: Synthesis of thietan-3-yl benzoate (590) via the nickel-catalyzed intramolecular reductive thiolati...
Scheme 134: Synthesis of 2,2-bis(trifluoromethyl)thietane from 3,3-bis(trifluoromethyl)-1,2-dithiolane.
Scheme 135: Synthesis of thietanes from enamines and sulfonyl chlorides.
Scheme 136: Synthesis of spirothietane 603 via the [2 + 3] cycloaddition of 2,2,4,4-tetramethylcyclobutane-1,3-...
Scheme 137: Synthesis of thietane (605) from 1-bromo-3-chloropropane and sulfur.
Synthesis of 3-substituted isoxazolidin-4-ols using hydroboration–oxidation reactions of 4,5-unsubstituted 2,3-dihydroisoxazoles
- Lívia Dikošová,
- Júlia Laceková,
- Ondrej Záborský and
- Róbert Fischer
Beilstein J. Org. Chem. 2020, 16, 1313–1319, doi:10.3762/bjoc.16.112
- readily obtained through the reductive cleavage of benzoylated isoxazolidines, employing the Lewis acid-catalyzed SN reaction with triethylsilane as the hydride source (Scheme 1). For this reason, the benzoates 6a and 6b were readily prepared from the corresponding 2,3-dihydroisoxazoles 5a and 5b
Graphical Abstract
Figure 1: 3-Substituted isoxazolidin-4-ols resembling 3-hydroxypyrrolidines.
Scheme 1: Synthetic approach towards isoxazolidin-4-ols via the regioselective reductive cleavage of the C5–O...
Scheme 2: Hydroboration-oxidation of 4,5-unsubstituted 2,3-dihydroisoxazoles.
Figure 2: Selected NOE enhancements observed in the isoxazolidin-4-ol trans-8a. The arrows show the NOESY cor...
Scheme 3: Dess-Martin oxidation of isoxazolidin-4-ols to ketones.
Scheme 4: Inversion of the relative configuration of the isoxazolidine ring.
Figure 3: Selected NOE enhancements observed in the isoxazolidin-4-ol cis-10a. The arrows show the NOESY corr...
Scheme 5: N-debenzylation via N-Troc-protected isoxazolidines.
Synthesis of pyrrolidinedione-fused hexahydropyrrolo[2,1-a]isoquinolines via three-component [3 + 2] cycloaddition followed by one-pot N-allylation and intramolecular Heck reactions
- Xiaoming Ma,
- Suzhi Meng,
- Xiaofeng Zhang,
- Qiang Zhang,
- Shenghu Yan,
- Yue Zhang and
- Wei Zhang
Beilstein J. Org. Chem. 2020, 16, 1225–1233, doi:10.3762/bjoc.16.106
- oxidative addition of the Pd(0) species to alkene intermediate 8a leads to Pd-complex I. Intramolecular coordination of Pd-complex I with the C–C double bond forms complex II which is followed by the syn insertion of alkene to give complex III [50][51]. Subsequent β-hydride elimination of III gives complex
Graphical Abstract
Figure 1: Bioactive pyrrolo[2,1-a]isoquinolines and hexahydropyrrolo[2,1-a]isoquinolines.
Scheme 1: [3 + 2] Cycloaddition with amino esters or amino acids.
Scheme 2: Scaffolds derived from the initial [3 + 2] adducts.
Scheme 3: [3 + 2] Cycloaddition with amino esters or amino acids. Conditions: 1:3:4 (1.2:1:1.1), Et3N (1.5 eq...
Scheme 4: Synthesis of pyrrolo[2,1-a]isoquinolines 9. Reaction conditions: 5 (0.5 mmol, 1 equiv), 7 (3 equiv)...
Scheme 5: Synthesis of pyrrolo[2,1-a]isoquinolines 11. Reaction conditions: 6 (0.5 mmol, 1 equiv), 7 (3 equiv...
Scheme 6: Synthesis of pyrrolo[2,1-a]isoquinolines 12. Reaction conditions: 5 or 6 (0.5 mmol, 1 equiv), cinna...
Scheme 7: Plausible mechanism for the synthesis of 9a.
Synthesis and properties of quinazoline-based versatile exciplex-forming compounds
- Rasa Keruckiene,
- Simona Vekteryte,
- Ervinas Urbonas,
- Matas Guzauskas,
- Eigirdas Skuodis,
- Dmytro Volyniuk and
- Juozas V. Grazulevicius
Beilstein J. Org. Chem. 2020, 16, 1142–1153, doi:10.3762/bjoc.16.101
- procedure reported in literature [27]. OLED fabrication and characterization was carried out according to the procedure reported earlier [28]. Materials 2-Aminobenzophenone, 3,5-difluorobenzaldehyde, ammonium acetate, phenothiazine, sodium hydride, sodium sulfate, tert-butyl chloride, zinc chloride
- compounds 1–3 were synthesized through nucleophilic substitution reactions between quinazoline derivative Q1 and the respective donor compound in the presence of sodium hydride in dry dimethylformamide (DMF). The reaction mixtures were refluxed for 24 h. After completion of the reactions, the reaction
- ): Quinazoline derivative (Q1, 0.25 g, 0.79 mmol), 3,6-di-tert-butylcarbazole (0.48 g, 1.7 mmol) and sodium hydride (0.50 g, 1.6 mmol) in dry dimethylformamide (DMF) were used for the nucleophilic substitution reaction. The title compound was obtained as yellowish crystals in a yield of 0.25 g, 37%; Tm = 181 °C
Graphical Abstract
Scheme 1: Synthesis of quinazoline derivatives 1–3. Conditions: i) ammonium acetate, copper(II) chloride, iso...
Figure 1: DSC (a, b, c) and TGA (d) curves of compounds 1–3. Scan rates were 20 °C/min (TGA) and 10 °C/min (D...
Figure 2: Frontier-orbital distributions and optimized geometries at the ground state of quinazoline-based co...
Figure 3: Cyclic voltammograms of quinazoline-based compounds 1–3.
Figure 4: UV–vis absorption spectra of compounds 1–3. a) Theoretical and b) experimental spectra of compounds ...
Figure 5: Fluorescence spectra (a) of dilute solutions and thin films of compounds 1–3 (λexc = 350 nm and PL ...
Figure 6: Electron and hole NTOs of compounds 1–3 in the S1 excited state (vacuum).
Figure 7: Chemical structures of exciplex-forming materials used, and visualization of white electroluminesce...
Accelerating fragment-based library generation by coupling high-performance photoreactors with benchtop analysis
- Quentin Lefebvre,
- Christophe Salomé and
- Thomas C. Fessard
Beilstein J. Org. Chem. 2020, 16, 982–988, doi:10.3762/bjoc.16.87
- to nickel(0) is believed to occur by β-hydride elimination on a sacrificial amount of amine [10]. The strained character of azaspiro[3,3]heptane might prevent this event. On the other hand, pyramidalization at nitrogen is much more important in azetidines [16][17][18]. This might lower the oxidation
Graphical Abstract
Scheme 1: One-day workflow for fragment-based library generation. QC: Quality control. MPLC: Medium-pressure ...
Figure 1: Top: high-power blue LED photoreactors. Bottom, from left to right: photoreactor OFF, ON, and ON th...
Figure 2: TLC–MS equipment: analysis of 5 reactions in 5 minutes.
Figure 3: Pre-QC validation by 60 MHz benchtop NMR.
Scheme 2: Scope of the fragment-based library generation: BCP-amines and azetidines. See Supporting Information File 1 for experimental de...
Scheme 3: Scope of the fragment-based library generation: pyrrolidines, piperidines and morpholines. See Supporting Information File 1 for...
Combining enyne metathesis with long-established organic transformations: a powerful strategy for the sustainable synthesis of bioactive molecules
- Valerian Dragutan,
- Ileana Dragutan,
- Albert Demonceau and
- Lionel Delaude
Beilstein J. Org. Chem. 2020, 16, 738–755, doi:10.3762/bjoc.16.68
- affording a protected tetracyclic kempane derivative. The latter was further converted into (+)-kempene-2 (14a) in 91% yield by deprotection and acetylation (Scheme 17). A reduction of the intermediate ketone with lithium aluminum hydride followed by an acetylation finally led to (+)-kempene-1 (14b) and
Graphical Abstract
Scheme 1: Intramolecular (A) and intermolecular (B) enyne metathesis reactions.
Scheme 2: Ene–yne and yne–ene mechanisms for intramolecular enyne metathesis reactions.
Scheme 3: Metallacarbene mechanism in intermolecular enyne metathesis.
Scheme 4: The Oguri strategy for accessing artemisinin analogs 1a–c through enyne metathesis.
Scheme 5: Access to the tetracyclic core of nanolobatolide (2) via tandem enyne metathesis followed by an Eu(...
Scheme 6: Synthesis of (−)-amphidinolide E (3) using an intermolecular enyne metathesis as the key step.
Scheme 7: Synthesis of amphidinolide K (4) by an enyne metathesis route.
Scheme 8: Trost synthesis of des-epoxy-amphidinolide N (5) [72].
Scheme 9: Enyne metathesis between the propargylic derivative and the allylic alcohol in the synthesis of the...
Scheme 10: Synthetic route to amphidinolide N (6a).
Scheme 11: Synthesis of the stereoisomeric precursors of amphidinolide V (7a and 7b) through alkyne ring-closi...
Scheme 12: Synthesis of the anthramycin precursor 8 from ʟ-methionine by a tandem enyne metathesis–cross metat...
Scheme 13: Synthesis of (−)‐clavukerin A (9) and (−)‐isoclavukerin A (10) by an enyne metathesis route startin...
Scheme 14: Synthesis of (−)-isoguaiene (11) through an enyne metathesis as the key step.
Scheme 15: Synthesis of erogorgiaene (12) by a tandem enyne metathesis/cross metathesis sequence using the sec...
Scheme 16: Synthesis of (−)-galanthamine (13) from isovanilin by an enyne metathesis.
Scheme 17: Application of enyne metathesis for the synthesis of kempene diterpenes 14a–c.
Scheme 18: Synthesis of the alkaloid (+)-lycoflexine (15) through enyne metathesis.
Scheme 19: Synthesis of the AB subunits of manzamine A (16a) and E (16b) by enyne metathesis.
Scheme 20: Jung's synthesis of rhodexin A (17) by enyne metathesis/cross metathesis reactions.
Scheme 21: Total synthesis of (−)-flueggine A (18) and (+)-virosaine B (19) from Weinreb amide by enyne metath...
Scheme 22: Access to virgidivarine (20) and virgiboidine (21) by an enyne metathesis route.
Scheme 23: Enyne metathesis approach to (−)-zenkequinone B (22).
Scheme 24: Access to C-aryl glycoside 23 by an intermolecular enyne metathesis/Diels–Alder cycloaddition.
Scheme 25: Synthesis of spiro-C-aryl glycoside 24 by a tandem intramolecular enyne metathesis/Diels–Alder reac...
Scheme 26: Pathways to (−)-exiguolide (25) by Trost’s Ru-catalyzed enyne cross-coupling and cross-metathesis [94].
Recent advances in Cu-catalyzed C(sp3)–Si and C(sp3)–B bond formation
- Balaram S. Takale,
- Ruchita R. Thakore,
- Elham Etemadi-Davan and
- Bruce H. Lipshutz
Beilstein J. Org. Chem. 2020, 16, 691–737, doi:10.3762/bjoc.16.67
- arylborylation of α-alkylstyrenes 387 has been investigated, delivering 1,1-adducts 389, 390 in the presence of palladacycle PCy3Pd G3, while 1,2-adducts 391–393 result using APhosPd G3. The former reaction proceeds through a second-stage β-hydride elimination/re-insertion pathway, although for the latter set of
Graphical Abstract
Scheme 1: Pharmaceuticals possessing a silicon or boron atom.
Scheme 2: The first Cu-catalyzed C(sp3)–Si bond formation.
Scheme 3: Conversion of benzylic phosphate 6 to the corresponding silane.
Scheme 4: Conversion of alkyl triflates to alkylsilanes.
Scheme 5: Conversion of secondary alkyl triflates to alkylsilanes.
Scheme 6: Conversion of alkyl iodides to alkylsilanes.
Scheme 7: Trapping of intermediate radical through cascade reaction.
Scheme 8: Radical pathway for conversion of alkyl iodides to alkylsilanes.
Scheme 9: Conversion of alkyl ester of N-hydroxyphthalimide to alkylsilanes.
Scheme 10: Conversion of gem-dibromides to bis-silylalkanes.
Scheme 11: Conversion of imines to α-silylated amines (A) and the reaction pathway (B).
Scheme 12: Conversion of N-tosylimines to α-silylated amines.
Scheme 13: Screening of diamine ligands.
Scheme 14: Conversion of N-tert-butylsulfonylimines to α-silylated amines.
Scheme 15: Conversion of aldimines to nonracemic α-silylated amines.
Scheme 16: Conversion of N-tosylimines to α-silylated amines.
Scheme 17: Reaction pathway [A] and conversion of aldehydes to α-silylated alcohols [B].
Scheme 18: Conversion of aldehydes to benzhydryl silyl ethers.
Scheme 19: Conversion of ketones to 1,2-diols (A) and conversion of imines to 1,2-amino alcohols (B).
Scheme 20: Ligand screening (A) and conversion of aldehydes to α-silylated alcohols (B).
Scheme 21: Conversion of aldehydes to α-silylated alcohols.
Scheme 22: 1,4-Additions to α,β-unsaturated ketones.
Scheme 23: 1,4-Additions to unsaturated ketones to give β-silylated derivatives.
Scheme 24: Additions onto α,β-unsaturated lactones to give β-silylated lactones.
Scheme 25: Conversion of α,β-unsaturated to β-silylated lactams.
Scheme 26: Conversion of N-arylacrylamides to silylated oxindoles.
Scheme 27: Conversion of α,β-unsaturated carbonyl compounds to silylated tert-butylperoxides.
Scheme 28: Catalytic cycle for Cu(I) catalyzed α,β-unsaturated compounds.
Scheme 29: Conversion of p-quinone methides to benzylic silanes.
Scheme 30: Conversion of α,β-unsaturated ketimines to regio- and stereocontrolled allylic silanes.
Scheme 31: Conversion of α,β-unsaturated ketimines to enantioenriched allylic silanes.
Scheme 32: Regioselective conversion of dienedioates to allylic silanes.
Scheme 33: Conversion of alkenyl-substituted azaarenes to β-silylated adducts.
Scheme 34: Conversion of conjugated benzoxazoles to enantioenriched β-silylated adducts.
Scheme 35: Conversion of α,β-unsaturated carbonyl indoles to α-silylated N-alkylated indoles.
Scheme 36: Conversion of β-amidoacrylates to α-aminosilanes.
Scheme 37: Conversion of α,β-unsaturated ketones to enantioenriched β-silylated ketones, nitriles, and nitro d...
Scheme 38: Regio-divergent silacarboxylation of allenes.
Scheme 39: Silylation of diazocarbonyl compounds, (A) asymmetric and (B) racemic.
Scheme 40: Enantioselective hydrosilylation of alkenes.
Scheme 41: Conversion of 3-acylindoles to indolino-silanes.
Scheme 42: Proposed mechanism for the silylation of 3-acylindoles.
Scheme 43: Silyation of N-chlorosulfonamides.
Scheme 44: Conversion of acyl silanes to α-silyl alcohols.
Scheme 45: Conversion of N-tosylaziridines to β-silylated N-tosylamines.
Scheme 46: Conversion of N-tosylaziridines to silylated N-tosylamines.
Scheme 47: Conversion of 3,3-disubstituted cyclopropenes to silylated cyclopropanes.
Scheme 48: Conversion of conjugated enynes to 1,3-bis(silyl)propenes.
Scheme 49: Proposed sequence for the Cu-catalyzed borylation of substituted alkenes.
Scheme 50: Cu-catalyzed synthesis of nonracemic allylic boronates.
Scheme 51: Cu–NHC catalyzed synthesis of α-substituted allylboronates.
Scheme 52: Synthesis of α-chiral (γ-alkoxyallyl)boronates.
Scheme 53: Cu-mediated formation of nonracemic cis- or trans- 2-substituted cyclopropylboronates.
Scheme 54: Cu-catalyzed synthesis of γ,γ-gem-difluoroallylboronates.
Scheme 55: Cu-catalyzed hydrofunctionalization of internal alkenes and vinylarenes.
Scheme 56: Cu-catalyzed Markovnikov and anti-Markovnikov borylation of alkenes.
Scheme 57: Cu-catalyzed borylation/ortho-cyanation/Cope rearrangement.
Scheme 58: Borylfluoromethylation of alkenes.
Scheme 59: Cu-catalyzed synthesis of tertiary nonracemic alcohols.
Scheme 60: Synthesis of densely functionalized and synthetically versatile 1,2- or 4,3-borocyanated 1,3-butadi...
Scheme 61: Cu-catalyzed trifunctionalization of allenes.
Scheme 62: Cu-catalyzed selective arylborylation of arenes.
Scheme 63: Asymmetric borylative coupling between styrenes and imines.
Scheme 64: Regio-divergent aminoboration of unactivated terminal alkenes.
Scheme 65: Cu-catalyzed 1,4-borylation of α,β-unsaturated ketones.
Scheme 66: Cu-catalyzed protodeboronation of α,β-unsaturated ketones.
Scheme 67: Cu-catalyzed β-borylation of α,β-unsaturated imines.
Scheme 68: Cu-catalyzed synthesis of β-trifluoroborato carbonyl compounds.
Scheme 69: Asymmetric 1,4-borylation of α,β-unsaturated carbonyl compounds.
Scheme 70: Cu-catalyzed ACB and ACA reactions of α,β-unsaturated 2-acyl-N-methylimidazoles.
Scheme 71: Cu-catalyzed diborylation of aldehydes.
Scheme 72: Umpolung pathway for chiral, nonracemic tertiary alcohol synthesis (top) and proposed mechanism for...
Scheme 73: Cu-catalyzed synthesis of α-hydroxyboronates.
Scheme 74: Cu-catalyzed borylation of ketones.
Scheme 75: Cu-catalyzed borylation of unactivated alkyl halides.
Scheme 76: Cu-catalyzed borylation of allylic difluorides.
Scheme 77: Cu-catalyzed borylation of cyclic and acyclic alkyl halides.
Scheme 78: Cu-catalyzed borylation of unactivated alkyl chlorides and bromides.
Scheme 79: Cu-catalyzed decarboxylative borylation of carboxylic acids.
Scheme 80: Cu-catalyzed borylation of benzylic, allylic, and propargylic alcohols.
Towards the total synthesis of chondrochloren A: synthesis of the (Z)-enamide fragment
- Jan Geldsetzer and
- Markus Kalesse
Beilstein J. Org. Chem. 2020, 16, 670–673, doi:10.3762/bjoc.16.64
- double bonds into the corresponding (Z)-monohalogenated derivatives using palladium(II) acetate, triphenylphosphine and tributyltin hydride. Following this procedure, we were able to obtain (Z)-bromide 4 in four steps and an overall yield of 39% [21][22][23][24]. Cross coupling of fragments 3 and 4 The
Graphical Abstract
Figure 1: Retrosynthetic analysis of chondrochlorene A (1).
Scheme 1: Synthesis of amide 3 [16-20]. TIPDSCl2 = 1,3-dichloro-1,1,3,3-tetraisopropyldisiloxane, TBSOTf = tert-buty...
Scheme 2: Synthesis of (Z)-bromide 4 using a palladium-catalyzed, stereoselective dehalogenation [21-24]. TBSOTf = t...
Scheme 3: Cross coupling of amide 3 and (Z)-bromide 4 (see Table 1 for conditions).
Rhodium-catalyzed reductive carbonylation of aryl iodides to arylaldehydes with syngas
- Zhenghui Liu,
- Peng Wang,
- Zhenzhong Yan,
- Suqing Chen,
- Dongkun Yu,
- Xinhui Zhao and
- Tiancheng Mu
Beilstein J. Org. Chem. 2020, 16, 645–656, doi:10.3762/bjoc.16.61
- environmentally friendly than other frequently used hydrogen sources like hydrosilanes [17], tributyltin hydride (Bu3SnH) (often used in natural product syntheses) [18][19][20] and hydroboranes [21][22][23], since the only byproduct is water. The production, storage and use of H2 received much attention and
Graphical Abstract
Figure 1: Rhodium-catalyzed reductive carbonylation of iodobenzene with CO and H2 to afford benzaldehyde. a) ...
Scheme 1: Scaled-up experiment of the reductive carbonylation of iodobenzene to benzaldehyde under the optimi...
Scheme 2: Catalytic species participating in the catalytic process.
Scheme 3: Substrate scope for the Rh-catalyzed reductive carbonylation of aryl iodides using CO and H2. React...
Scheme 4: Isotope-labeling experiments.
Scheme 5: Proposed reaction mechanism for the Rh-catalyzed reductive carbonylation of aryl iodides using CO a...
Synthesis of disparlure and monachalure enantiomers from 2,3-butanediacetals
- Adam Drop,
- Hubert Wojtasek and
- Bożena Frąckowiak-Wojtasek
Beilstein J. Org. Chem. 2020, 16, 616–620, doi:10.3762/bjoc.16.57
- 19 instead. This compound was obtained from both aldehyde 15 and its precursor ethyl thioester methyl ester 14, respectively (Scheme 3). Both substrates 14 and 15 were reduced to the corresponding diol 17 with lithium aluminum hydride with 73% or 83% yield, respectively. Next, the selective
Graphical Abstract
Scheme 1: Retrosynthesis of (+)-disparlure (1), (−)-disparlure (3), (+)-monachalure (2), and (−)-monachalure (...
Scheme 2: Isomerization of trans-2,3-butanediacetals 9–11 to cis-2,3-butanediacetals 12–14.
Scheme 3: Synthesis of diol 17 and its subsequent modifications.
Scheme 4: Synthesis of (+)-disparlure (1) and (+)-monachalure (2).
Scheme 5: Synthesis of (−)-disparlure (3) and (−)-monachalure (4).
Copper-catalyzed enantioselective conjugate reduction of α,β-unsaturated esters with chiral phenol–carbene ligands
- Shohei Mimura,
- Sho Mizushima,
- Yohei Shimizu and
- Masaya Sawamura
Beilstein J. Org. Chem. 2020, 16, 537–543, doi:10.3762/bjoc.16.50
- work of Stryker and co-workers on triphenylphosphine-stabilized copper hydride complexes [1][2], copper hydrides have been widely used for conjugate reductions of α,β-unsaturated carbonyl compounds [3]. Especially a chiral copper catalyst combined with a stoichiometric amount of a silane reagent, which
- generated copper hydride in situ, has successfully been utilized for enantioselective reactions with β,β-disubstituted α,β-unsaturated carbonyl compounds [4][5][6][7][8][9][10][11]. The pioneering work of Buchwald and co-workers on the enantioselective conjugate reduction of α,β-unsaturated esters using a
- plays crucial roles in both the catalytic activity and stereoselectivity [19][20][21]. Notably, these catalyst systems were also applicable for three-component coupling reactions using hydrosilanes as hydride reagents [17]. Based on this knowledge, we decided to investigate the effects of the phenol–NHC
Recent advances in photocatalyzed reactions using well-defined copper(I) complexes
- Mingbing Zhong,
- Xavier Pannecoucke,
- Philippe Jubault and
- Thomas Poisson
Beilstein J. Org. Chem. 2020, 16, 451–481, doi:10.3762/bjoc.16.42
- oxidized copper complex oxidized the glycine ester, regenerating the catalyst, furnishing the N-centered radical cation. Then, the latter underwent a 1,2-hydride shift in the presence of the base (or the phthalimide anion) to form the α-amino radical that recombined with the alkyl radical formed in the
Graphical Abstract
Scheme 1: [Cu(I)(dap)2]Cl-catalyzed ATRA reaction under green light irradiation.
Scheme 2: Photocatalytic allylation of α-haloketones.
Scheme 3: [Cu(I)(dap)2]Cl-photocatalyzed chlorosulfonylation and chlorotrifluoromethylation of alkenes.
Scheme 4: Photocatalytic perfluoroalkylchlorination of electron-deficient alkenes using the Sauvage catalyst.
Scheme 5: Photocatalytic synthesis of fluorinated sultones.
Scheme 6: Photocatalyzed haloperfluoroalkylation of alkenes and alkynes.
Scheme 7: Chlorosulfonylation of alkenes catalyzed by [Cu(I)(dap)2]Cl. aNo Na2CO3 was added. b1 equiv of Na2CO...
Scheme 8: Copper-photocatalyzed reductive allylation of diaryliodonium salts.
Scheme 9: Copper-photocatalyzed azidomethoxylation of olefins.
Scheme 10: Benzylic azidation initiated by [Cu(I)(dap)2]Cl.
Scheme 11: Trifluoromethyl methoxylation of styryl derivatives using [Cu(I)(dap)2]PF6. All redox potentials ar...
Scheme 12: Trifluoromethylation of silyl enol ethers.
Scheme 13: Synthesis of annulated heterocycles upon oxidation with the Sauvage catalyst.
Scheme 14: Oxoazidation of styrene derivatives using [Cu(dap)2]Cl as a precatalyst.
Scheme 15: [Cu(I)(dpp)(binc)]PF6-catalyzed ATRA reaction.
Scheme 16: Allylation reaction of α-bromomalonate catalyzed by [Cu(I)(dpp)(binc)]PF6 following an ATRA mechani...
Scheme 17: Bromo/tribromomethylation reaction using [Cu(I)(dmp)(BINAP)]PF6.
Scheme 18: Chlorotrifluoromethylation of alkenes catalyzed by [Cu(I)(N^N)(xantphos)]PF6.
Scheme 19: Chlorosulfonylation of styrene and alkyne derivatives by ATRA reactions.
Scheme 20: Reduction of aryl and alkyl halides with the complex [Cu(I)(bcp)(DPEPhos)]PF6. aIrradiation was car...
Scheme 21: Meerwein arylation of electron-rich aromatic derivatives and 5-exo-trig cyclization catalyzed by th...
Scheme 22: [Cu(I)(bcp)(DPEPhos)]PF6-photocatalyzed synthesis of alkaloids. aYield over two steps (cyclization ...
Scheme 23: Copper-photocatalyzed decarboxylative amination of NHP esters.
Scheme 24: Photocatalytic decarboxylative alkynylation using [Cu(I)(dq)(binap)]BF4.
Scheme 25: Copper-photocatalyzed alkylation of glycine esters.
Scheme 26: Copper-photocatalyzed borylation of organic halides. aUnder continuous flow conditions.
Scheme 27: Copper-photocatalyzed α-functionalization of alcohols with glycine ester derivatives.
Scheme 28: δ-Functionalization of alcohols using [Cu(I)(dmp)(xantphos)]BF4.
Scheme 29: Photocatalytic synthesis of [5]helicene and phenanthrene.
Scheme 30: Oxidative carbazole synthesis using in situ-formed [Cu(I)(dmp)(xantphos)]BF4.
Scheme 31: Copper-photocatalyzed functionalization of N-aryl tetrahydroisoquinolines.
Scheme 32: Bicyclic lactone synthesis using a copper-photocatalyzed PCET reaction.
Scheme 33: Photocatalytic Pinacol coupling reaction catalyzed by [Cu(I)(pypzs)(BINAP)]BF4. The ligands of the ...
Scheme 34: Azide photosensitization using a Cu-based photocatalyst.
Architecture and synthesis of P,N-heterocyclic phosphine ligands
- Wisdom A. Munzeiwa,
- Bernard Omondi and
- Vincent O. Nyamori
Beilstein J. Org. Chem. 2020, 16, 362–383, doi:10.3762/bjoc.16.35
- ] were the phosphine boranes were prepared by reacting phosphines with sodium borohydride. Alternatively, the reduction of phosphine oxide byproducts with lithium tetrahydridoaluminate, calcium aluminum hydride, and hydrosilanes can also be used to regenerate the phosphine ligands. Hydrosilane reagents
- -(diphenylphosphine)ethyl)-4,5-diazafluorene ligand 47 which includes a cyclopropylated intermediate (45, Scheme 8). The ligand was prepared by an initial cyclopropanation of diazafluorene 44. For this, 44 was treated with a dibromomethane solution in THF in the presence of sodium hydride under reflux for four hours
Graphical Abstract
Scheme 1: Synthesis of pyridylphosphine ligands.
Figure 1: Pyridylphosphine ligands.
Scheme 2: Synthesis of piperidyl- and oxazinylphosphine ligands.
Scheme 3: Synthesis of linear multi-chelate pyridylphosphine ligands.
Scheme 4: Synthesis of chiral acetal pyridylphosphine ligands.
Scheme 5: Synthesis of diphenylphosphine-substituted triazine ligands.
Scheme 6: Synthesis of (pyridine-2-ylmethyl)phosphine ligands.
Scheme 7: Synthesis of diphosphine pyrrole ligands.
Scheme 8: Synthesis of 4,5-diazafluorenylphosphine ligands.
Scheme 9: Synthesis of thioether-containing pyridyldiphosphine ligands starting from ethylene sulfide and dip...
Scheme 10: Synthesis of monoterpene-derived phosphine pyridine ligands.
Scheme 11: Synthesis of N-phenylphosphine-substituted imidazole ligands.
Scheme 12: Synthesis of triazol-4-ylphosphine ligands.
Scheme 13: Synthesis of phosphanyltriazolopyridines and product selectivity depending on the substituents’ eff...
Scheme 14: Synthesis of PTA-phosphine ligands.
Scheme 15: Synthesis of isomeric phosphine dipyrazole ligands by varying the reaction temperature.
Scheme 16: Synthesis of N-tethered phosphine imidazolium ligands (route A) and diphosphine imidazolium ligands...
Scheme 17: Synthesis of {1-[2-(pyridin-2-yl)- (R = CH) and {1-[2-(pyrazin-2-yl)quinazolin-4-yl]naphthalen-2-yl...
Scheme 18: Synthesis of oxazolylindolylphosphine ligands 102.
Scheme 19: Synthesis of pyrrolylphosphine ligands.
Scheme 20: Synthesis of phosphine guanidinium ligands.
Scheme 21: Synthesis of a polydentate aminophosphine ligand.
Scheme 22: Synthesis of quinolylphosphine ligands.
Scheme 23: Synthesis of N-(triazolylmethyl)phosphanamine ligands.
Figure 2: Triazolylphosphanamine ligands synthesized by Wassenaar’s method [22].
Scheme 24: Synthesis of oxazaphosphorines.
Scheme 25: Synthesis of paracyclophane pyridylphosphine ligands.
Scheme 26: Synthesis of triazolylphosphine ligands.
Figure 3: Click-phosphine ligands.
Scheme 27: Ferrocenyl pyridylphosphine imine ligands.
Scheme 28: Synthesis of phosphinooxazolines (PHOX).
Scheme 29: Synthesis of ferrocenylphosphine oxazoles.
Recent developments in photoredox-catalyzed remote ortho and para C–H bond functionalizations
- Rafia Siddiqui and
- Rashid Ali
Beilstein J. Org. Chem. 2020, 16, 248–280, doi:10.3762/bjoc.16.26
- 22 upon coordination with the carbonyl oxygen atom of the amide group. The complex 22 then coordinated to the acrylate product 23, which rearranged to 24, and the β-hydride elimination of 24 yielded the desired olefinated product 21. C–H olefination of phenolic ethers: Based on Ackermann and co
Graphical Abstract
Figure 1: List of photoredox catalysts used for C–H bond functionalizations.
Figure 2: List of metal-based photoredox catalysts used in this review article.
Figure 3: Jablonski diagram.
Figure 4: Photoredox catalysis via reductive or oxidative pathways. D = donor, A = acceptor, S = substrate, P...
Figure 5: Schematic representation of the combination of photoredox catalysis and transition metal catalysis.
Scheme 1: Weinreb amide C–H olefination.
Figure 6: Mechanism for the formation of 21 from 19 using photoredox catalyst 11.
Scheme 2: C–H olefination of phenolic ethers.
Scheme 3: Decarboxylative acylation of acetanilides.
Figure 7: Mechanism for the formation of 30 from acetanilide derivatives.
Scheme 4: Synthesis of fluorenone derivatives by intramolecular deoxygenative acylation of biaryl carboxylic ...
Figure 8: Mechanism for the photoredox-catalyzed synthesis of fluorenone derivatives.
Scheme 5: Synthesis of benzothiazoles via aerobic C–H thiolation.
Figure 9: Plausible mechanism for the construction of benzothiazoles from benzothioamides.
Scheme 6: Synthesis of benzothiazoles via oxidant-free C–H thiolation.
Figure 10: Mechanism involved in the synthesis of benzothiazoles via oxidant-free C–H thiolation.
Scheme 7: Synthesis of indoles via C–H cyclization of anilides with alkynes.
Scheme 8: Preparation of 3-trifluoromethylcoumarins via C–H cyclization of arylpropiolate esters.
Figure 11: Mechanistic pathway for the synthesis of coumarin derivatives via C–H cyclization.
Scheme 9: Monobenzoyloxylation without chelation assistance.
Figure 12: Plausible mechanism for the formation of 71 from 70.
Scheme 10: Aryl-substituted arenes prepared by inorganic photoredox catalysis using 12a.
Figure 13: Proposed mechanism for C–H arylations in the presence of 12a and a Pd catalyst.
Scheme 11: Arylation of purines via dual photoredox catalysis.
Scheme 12: Arylation of substituted arenes with an organic photoredox catalyst.
Scheme 13: C–H trifluoromethylation.
Figure 14: Proposed mechanism for the trifluoromethylation of 88.
Scheme 14: Synthesis of benzo-3,4-coumarin derivatives.
Figure 15: Plausible mechanism for the synthesis of substituted coumarins.
Scheme 15: Oxidant-free oxidative phosphonylation.
Figure 16: Mechanism proposed for the phosphonylation reaction of 100.
Scheme 16: Nitration of anilines.
Figure 17: Plausible mechanism for the nitration of aniline derivatives via photoredox catalysis.
Scheme 17: Synthesis of carbazoles via intramolecular amination.
Figure 18: Proposed mechanism for the formation of carbazoles from biaryl derivatives.
Scheme 18: Synthesis of substituted phenols using QuCN.
Figure 19: Mechanism for the synthesis of phenol derivatives with photoredox catalyst 8.
Scheme 19: Synthesis of substituted phenols with DDQ (5).
Figure 20: Possible mechanism for the generation of phenols with the aid of photoredox catalyst 5.
Scheme 20: Aerobic bromination of arenes using an acridinium-based photocatalyst.
Scheme 21: Aerobic bromination of arenes with anthraquinone.
Figure 21: Proposed mechanism for the synthesis of monobrominated compounds.
Scheme 22: Chlorination of benzene derivatives with Mes-Acr-MeClO4 (2).
Figure 22: Mechanism for the synthesis of 131 from 132.
Scheme 23: Chlorination of arenes with 4CzIPN (5a).
Figure 23: Plausible mechanism for the oxidative photocatalytic monochlorination using 5a.
Scheme 24: Monofluorination using QuCN-ClO4 (8).
Scheme 25: Fluorination with fluorine-18.
Scheme 26: Aerobic amination with acridinium catalyst 3a.
Figure 24: Plausible mechanism for the aerobic amination using acridinium catalyst 3a.
Scheme 27: Aerobic aminations with semiconductor photoredox catalyst 18.
Scheme 28: Perfluoroalkylation of arenes.
Scheme 29: Synthesis of benzonitriles in the presence of 3a.
Figure 25: Plausible mechanism for the synthesis of substituted benzonitrile derivatives in the presence of 3a....
The reaction of arylmethyl isocyanides and arylmethylamines with xanthate esters: a facile and unexpected synthesis of carbamothioates
- Narasimhamurthy Rajeev,
- Toreshettahally R. Swaroop,
- Ahmad I. Alrawashdeh,
- Shofiur Rahman,
- Abdullah Alodhayb,
- Seegehalli M. Anil,
- Kuppalli R. Kiran,
- Chandra,
- Paris E. Georghiou,
- Kanchugarakoppal S. Rangappa and
- Maralinganadoddi P. Sadashiva
Beilstein J. Org. Chem. 2020, 16, 159–167, doi:10.3762/bjoc.16.18
- hydride-mediated reaction of arylmethyl isocyanides with xanthate esters in DMF is reported. The products thus obtained were compared with the carbamothioates obtained by the sodium hydride-mediated condensation of the corresponding benzylamines and xanthate esters in DMF. To account for these unexpected
- reactions, a mechanism is proposed in which the key steps are supported by quantum chemical calculations. Keywords: benzylamines; carbamothioates; density functional theory; intrinsic reaction coordinate analysis; isocyanides; sodium hydride; xanthate esters; Introduction Carbamothioates (thiocarbamates
- reported the synthesis of thiazoles from xanthate esters [31]. In continuation of this ongoing work, we planned to synthesize 5-alkoxy-4-arylthiazoles 3 by the sodium hydride/DMF-mediated reaction of arylmethyl isocyanides 2 with S-alkyl xanthate esters 1 or O-aryl/O-alkyl dithiocarbonates. Unexpectedly
Graphical Abstract
Scheme 1: Synthesis of carbamothioates from xanthate esters and benzyl isocyanides.
Figure 1: Substrate scope for the synthesis of carbamothioates. Reaction conditions for methods A and B: sodi...
Figure 2: ORTEP diagram of O-benzyl (4-fluorobenzyl)carbamothioate (4c).
Figure 3: Rotamers of thionocarbamates 4 (top) and computer-minimized structures of 4c (bottom).
Scheme 2: Proposed general reaction mechanism for the formation of carbamothioates (e.g., 4a) from xanthate e...
Figure 4: Optimized geometries of the reactants, transition states, intermediates, and products of the propos...
Figure 5: Relative energies of the reactants, transition states (TS1–TS3), and intermediates (Int1–Int3) of t...
Synthesis of 3-alkenylindoles through regioselective C–H alkenylation of indoles by a ruthenium nanocatalyst
- Abhijit Paul,
- Debnath Chatterjee,
- Srirupa Banerjee and
- Somnath Yadav
Beilstein J. Org. Chem. 2020, 16, 140–148, doi:10.3762/bjoc.16.16
- ones [54][70]. With respect to C–H activation reactions, the presence of surface oxides on our RuNC probably governed its ability to catalyse the C–H alkenylation reaction, in contrast to the role of reduced Ru(0) nanoparticles with hydride/deuteride species on their surface, reported by Pieters et al
Graphical Abstract
Figure 1: Biologically and medicinally important 3-alkenylindoles.
Scheme 1: a) Previous and b) present work related to the synthesis of 3-alkenylindoles.
Scheme 2: Substrate scope for the C–H alkenylation of the indoles 1. Reaction conditions: 1 (1 mmol), 2 (2 mm...
Scheme 3: a) Three-phase test to determine a homogeneous or heterogeneous catalytic mechanism of action for t...
Scheme 4: Probable catalytic mechanism for the transformation of 1a by the RuNC.
Understanding the role of active site residues in CotB2 catalysis using a cluster model
- Keren Raz,
- Ronja Driller,
- Thomas Brück,
- Bernhard Loll and
- Dan T. Major
Beilstein J. Org. Chem. 2020, 16, 50–59, doi:10.3762/bjoc.16.7
- electrophilic cyclizations to generate intermediate A. Intermediate A undergoes a 1,5-hydride shift, forming intermediate B. A subsequent cyclization forms intermediate C. Intermediate C generates intermediate E via one of two possible pathways: either a direct 1,3-hydride shift or an indirect pathway involving
- two 1,2-hydride shifts. Theoretical investigations by Hong and Tantillo suggested that the indirect transformation from intermediate C to E is energetically favored and might be biosynthetically relevant [38]. This finding is in agreement with the report by Sato and co-workers [39], who performed
- isotope labeling experiments combined with QM calculations. Intermediate G forms via a 1,5-hydride shift from C6 to C10 to generate a homoallylic cation, and the formation of intermediate H occurs due to cyclization to yield a cyclopropyl ring. Intermediate I forms due to isomeric formation of a
Graphical Abstract
Scheme 1: Mechanism for formation of cyclooctat-9-en-7-ol, published similarly in [42].
Figure 1: Computed electronic energy profiles (kcal/mol) for the CotB2 cyclase mechanism. The calculations us...
Figure 2: Intermediates A–I in the active site model. Interactions are marked by dashed orange lines, the int...
Figure 3: TS structures TS_A_B–TS_G/H_I in the active site model. Interactions are marked by dashed orange li...
Figure 4: Comparison between gas phase and active site model conformations. A) Intermediate D. B) Intermediat...
Synthesis of C-glycosyl phosphonate derivatives of 4-amino-4-deoxy-α-ʟ-arabinose
- Lukáš Kerner and
- Paul Kosma
Beilstein J. Org. Chem. 2020, 16, 9–14, doi:10.3762/bjoc.16.2
- -arabinopyranoside (1), available in multigram amounts, was benzylated in 79% yield using benzyl bromide and sodium hydride in DMF, followed by hydrolysis of the anomeric aglycon of 2 with 5 M HCl and SrCl2 in acetic acid, which afforded the hemiacetal 3 as a 2:3 α/β anomeric mixture in 60% yield (Scheme 1
Graphical Abstract
Figure 1: Modification of lipid A by ArnT.
Scheme 1: Phosphonate and glycal synthesis.
Scheme 2: Synthesis of methyl phosphonate 11 and octyl phosphonates 16 and 17.
