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Search for "C–C bond cleavage" in Full Text gives 30 result(s) in Beilstein Journal of Organic Chemistry.
Organobase-catalyzed three-component reactions for the synthesis of 4H-2-aminopyrans, condensed pyrans and polysubstituted benzenes
- Moustafa Sherief Moustafa,
- Saleh Mohammed Al-Mousawi,
- Maghraby Ali Selim,
- Ahmed Mohamed Mosallam and
- Mohamed Hilmy Elnagdi
Beilstein J. Org. Chem. 2014, 10, 141–149, doi:10.3762/bjoc.10.11
- propiolate (4a) in the presence of L-proline to produce the penta-substituted benzene derivative 13b in 60% yield (Scheme 4). In order to explain this unusual finding, we proposed that malononitrile, perhaps formed under the reaction conditions by C–C bond cleavage promoted fragmentation of 8, adds to 9 to
Graphical Abstract
Scheme 1: Reaction of active methylenenitriles with α,β-unsaturated ketones 1.
Scheme 2: Synthesis of 2-amino-4-phenyl-3-cyanopyridines 2.
Scheme 3: Synthesis of polysubstituted benzenes 3.
Scheme 4: Syntheses of compound 9 and compounds 13a,b.
Figure 1: X-ray crystal structure of 9.
Figure 2: X-ray crystal structure of 13a.
Figure 3: X-ray crystal structure of 18.
Scheme 5: Syntheses of compounds 18 and 21.
Figure 4: X-ray crystal structure of 21.
Figure 5: X-ray crystal structure of 26.
Scheme 6: Syntheses of compound 26.
Figure 6: X-ray crystal structure of 27a.
Scheme 7: Syntheses of compound 28a,b.
Figure 7: X-ray crystal structure of 28b.
Figure 8: X-ray crystal structure of 31a.
Figure 9: X-ray crystal structure of 31b.
Scheme 8: Syntheses of compound 31a,b.
Scheme 9: Syntheses of compound 33a,b.
Figure 10: X-ray crystal structure of 33a.
Scheme 10: Syntheses of compound 37a–c.
Figure 11: X-ray crystal structure of 37a.
Figure 12: X-ray crystal structure of 37b.
Scheme 11: Syntheses of compounds 38–40.
Figure 13: X-ray crystal structure of 39.
The chemistry of amine radical cations produced by visible light photoredox catalysis
- Jie Hu,
- Jiang Wang,
- Theresa H. Nguyen and
- Nan Zheng
Beilstein J. Org. Chem. 2013, 9, 1977–2001, doi:10.3762/bjoc.9.234
- azodicarboxylates. α-Arylation of amines. Plausible mechanism for α-arylation of amines. Photoinduced C–C bond cleavage of tertiary amines. Photoredox cleavage of C–C bonds of 1,2-diamines. Proposed mechanism photoredox cleavage of C–C bonds. Intermolecular [3 + 2] annulation of cyclopropylamines with olefins
Graphical Abstract
Scheme 1: Amine radical cations’ mode of reactivity.
Scheme 2: Reductive quenching of photoexcited Ru complexes by Et3N.
Scheme 3: Photoredox aza-Henry reaction.
Scheme 4: Formation of iminium ions using BrCCl3 as stoichiometric oxidant.
Scheme 5: Oxidative functionalization of N-aryltetrahydroisoquinolines using Eosin Y.
Scheme 6: Synthetic and mechanistic studies of Eosin Y-catalyzed aza-Henry reaction.
Scheme 7: Oxidative functionalization of N-aryltetrahydroisoquinolines using RB and GO.
Scheme 8: Merging Ru-based photoredox catalysis and Lewis base catalysis for the Mannich reaction.
Scheme 9: Merging Au-based photoredox catalysis and Lewis base catalysis for the Mannich reaction.
Scheme 10: Merging Ru-based photoredox catalysis and Cu-catalyzed alkynylation reaction.
Scheme 11: Merging Ru-based photoredox catalysis and NHC catalysis.
Scheme 12: 1,3-Dipolar cycloaddition of photogenically formed azomethine ylides.
Scheme 13: Plausible mechanism for photoredox 1,3-dipolar cycloaddition.
Scheme 14: Photoredox-catalyzed cascade reaction for the synthesis of fused isoxazolidines.
Scheme 15: Plausible mechanism for the photoredox-catalyzed cascade reaction.
Scheme 16: Photoredox-catalyzed α-arylation of glycine derivatives.
Scheme 17: Photoredox-catalyzed α-arylation of amides.
Scheme 18: Intramolecular interception of iminium ions by sulfonamides.
Scheme 19: Intramolecular interception of iminium ions by alcohols and sulfonamides.
Scheme 20: Intermolecular interception of iminium ions by phosphites.
Scheme 21: Photoredox-catalyzed oxidative phosphonylation by Eosin Y.
Scheme 22: Conjugated addition of α-amino radicals to Michael acceptors.
Scheme 23: Conjugated addition of α-amino radicals to Michael acceptors assisted by a Brønsted acid.
Scheme 24: Conjugated addition of α-amino radicals derived from anilines to Michael acceptors.
Scheme 25: Oxygen switch between two pathways involving α-amino radicals.
Scheme 26: Interception of α-amino radicals by azodicarboxylates.
Scheme 27: α-Arylation of amines.
Scheme 28: Plausible mechanism for α-arylation of amines.
Scheme 29: Photoinduced C–C bond cleavage of tertiary amines.
Scheme 30: Photoredox cleavage of C–C bonds of 1,2-diamines.
Scheme 31: Proposed mechanism photoredox cleavage of C–C bonds.
Scheme 32: Intermolecular [3 + 2] annulation of cyclopropylamines with olefins.
Scheme 33: Proposed mechanism for intermolecular [3 + 2] annulation.
Scheme 34: Photoinduced clevage of N–N bonds of aromatic hydrazines and hydrazides.
Recent developments in gold-catalyzed cycloaddition reactions
- Fernando López and
- José L. Mascareñas
Beilstein J. Org. Chem. 2011, 7, 1075–1094, doi:10.3762/bjoc.7.124
- authors proposed an initial nucleophilic attack of the carbonyl oxygen on the gold(I)-activated alkyne to form a vinyl–gold intermediate XII, analogous to that previously shown in Scheme 5 (IX). Aromatization of this intermediate through C–C bond cleavage of the oxirane unit, followed by addition of the
Graphical Abstract
Scheme 1: AuCl3-catalyzed benzannulations reported by Yamamoto.
Scheme 2: Synthesis of 9-oxabicyclo[3.3.1]nona-4,7-dienes from 1-oxo-4-oxy-5-ynes [40].
Scheme 3: Stereocontrolled oxacyclization/(4 + 2)-cycloaddition cascade of ketone–allene substrates [43].
Scheme 4: Gold-catalyzed synthesis of polycyclic, fully substituted furans from 1-(1-alkynyl)cyclopropyl keto...
Scheme 5: Gold-catalyzed 1,3-dipolar cycloaddition of 2-(1-alkynyl)-2-alken-1-ones with nitrones [47].
Scheme 6: Enantioselective 1,3-dipolar cycloaddition of 2-(1-alkynyl)-2-alken-1-ones with nitrones [48].
Scheme 7: Gold-catalyzed 1,3-dipolar cycloaddition of 2-(1-alkynyl)-2-alken-1-ones with α,β-unsaturated imine...
Scheme 8: Gold-catalyzed (4 + 3) cycloadditions of 1-(1-alkynyl)oxiranyl ketones [50].
Scheme 9: (3 + 2) Cycloaddition of gold-containing azomethine ylides [52].
Scheme 10: Gold-catalyzed generation and reaction of azomethine ylides [53].
Scheme 11: Gold-catalyzed intramolecular (4 + 2) cycloadditions of unactivated alkynes and dienes [55].
Scheme 12: Gold-catalyzed preparation of bicyclo[4.3.0]nonane derivatives from dienol silyl ethers [59].
Scheme 13: Gold(I)-catalyzed intramolecular (4 + 2) cycloadditions of arylalkynes or 1,3-enynes with alkenes [60].
Scheme 14: Gold(I)-catalyzed intermolecular (2 + 2) cycloaddition of alkynes with alkenes [62].
Scheme 15: Metal-catalyzed cycloaddition of alkynes tethered to cycloheptatriene [65].
Scheme 16: Gold-catalyzed cycloaddition of functionalized ketoenynes: Synthesis of (+)-orientalol F [68].
Scheme 17: Gold-catalyzed intermolecular cyclopropanation of enynes with alkenes [70].
Scheme 18: Gold-catalyzed intermolecular hetero-dehydro Diels–Alder cycloaddition [72].
Figure 1: Gold-catalyzed 1,2- or 1,3-acyloxy migrations of propargyl esters.
Scheme 19: Gold(I)-catalyzed stereoselective olefin cyclopropanation [74].
Scheme 20: Reaction of propargylic benzoates with α,β-unsaturated imines to give azepine cycloadducts [77].
Scheme 21: Gold-catalyzed (3 + 3) annulation of azomethine imines with propargyl esters [81].
Scheme 22: Gold(I)-catalyzed isomerization of 5-en-2-yn-1-yl acetates [83].
Scheme 23: (3 + 2) and (2 + 2) cycloadditions of indole-3-acetates 41 [85,86].
Scheme 24: Gold(I)-catalyzed (2 + 2) cycloaddition of allenenes [87].
Scheme 25: Formal (3 + 2) cycloaddition of allenyl MOM ethers and alkenes [90].
Scheme 26: (4 + 3) Cycloadditions of allenedienes [97,98].
Scheme 27: Gold-catalyzed transannular (4 + 3) cycloaddition reactions [101].
Scheme 28: Gold(I)-catalyzed (4 + 2) cycloadditions of allenedienes [102].
Scheme 29: Enantioselective gold(I)-catalyzed (4 + 2) cycloadditions of allenedienes [88,102,104].
Scheme 30: (3 + 2) versus (2 + 2) Cycloadditions of allenenes [87,99].
Figure 2: NHC ligands with different π-acceptor properties [106].
Scheme 31: (3 + 2) versus (2 + 2) Cycloadditions of allenenes [106].
Scheme 32: Gold(I)-catalyzed intermolecular (4 + 2) cycloaddition of allenamides and acyclic dienes [109].
Synthetic applications of gold-catalyzed ring expansions
- David Garayalde and
- Cristina Nevado
Beilstein J. Org. Chem. 2011, 7, 767–780, doi:10.3762/bjoc.7.87
- activation of the cyclopropene, cation 55 is formed. C–C bond cleavage of the cyclopropyl ring followed by a Friedel–Crafts reaction affords, after recovery of aromaticity, the observed products [47]. 4 Ring expansions involving annulation reactions Diels–Alder, [1,3]-dipolar-, [2 + 2]- and [4 + 3
Graphical Abstract
Scheme 1: Transition metal promoted rearrangements of bicyclo[1.1.0]butanes.
Scheme 2: Gold-catalyzed rearrangements of strained rings.
Scheme 3: Gold-catalyzed ring expansions of cyclopropanols and cyclobutanols.
Scheme 4: Mechanism of the cycloisomerization of alkynyl cyclopropanols and cyclobutanols.
Scheme 5: Proposed mechanism for the Au-catalyzed isomerization of alkynyl cyclobutanols.
Scheme 6: Gold-catalyzed cycloisomerization of 1-allenylcyclopropanols.
Scheme 7: Gold-catalyzed cycloisomerization of cyclopropylmethanols.
Scheme 8: Gold-catalyzed cycloisomerization of aryl alkyl epoxides.
Scheme 9: Gold-catalyzed synthesis of furans.
Scheme 10: Transformations of alkynyl oxiranes.
Scheme 11: Transformations of alkynyl oxiranes into ketals.
Scheme 12: Gold-catalyzed cycloisomerization of cyclopropyl alkynes.
Scheme 13: Gold-catalyzed synthesis of substituted furans.
Scheme 14: Proposed mechanism for the isomerization of alkynyl cyclopropyl ketones.
Scheme 15: Cycloisomerization of cyclobutylazides.
Scheme 16: Cycloisomerization of alkynyl aziridines.
Scheme 17: Gold-catalyzed synthesis of disubstituted cyclohexadienes.
Scheme 18: Gold-catalyzed synthesis of indenes.
Scheme 19: Gold-catalyzed [n + m] annulation processes.
Scheme 20: Gold-catalyzed generation of 1,4-dipoles.
Scheme 21: Gold-catalyzed synthesis of repraesentin F.
Scheme 22: Gold-catalyzed ring expansion of cyclopropyl 1,6-enynes.
Scheme 23: Gold-catalyzed synthesis of ventricos-7(13)-ene.
Scheme 24: 1,2- vs 1,3-Carboxylate migration.
Scheme 25: Gold-catalyzed cycloisomerization of vinyl alkynyl cyclopropanes.
Scheme 26: Proposed mechanism for the cycloisomerization of vinyl alkynyl cyclopropanes.
Scheme 27: Gold-catalyzed 1,2-acyloxy rearrangement/cyclopropanation/cycloisomerization cascades.
Scheme 28: Formal total synthesis of frondosin A.
Scheme 29: Gold-catalyzed rearrangement/cycloisomerization of cyclopropyl propargyl acetates.
Photosonochemical catalytic ring opening of α-epoxyketones
- Hamid R. Memarian and
- Ali Saffar-Teluri
Beilstein J. Org. Chem. 2007, 3, No. 2, doi:10.1186/1860-5397-3-2
- electron transfer reactions by dicyanoanthracene (DCA), [32][33] tetracyanoethylene (TCNE) [34][35] and 2,4,6-triphenylpyrilium tetrafluoroborate. [36][37][38][39][40] In the case of C-C bond cleavage, the generated intermediates from epoxide radical cations have been trapped by molecular oxygen to form
Graphical Abstract
Scheme 1: Ultrasound-assisted photocatalytic ring opening of α-epoxyketones.
Scheme 2: Possible intermediates involved in the ring opening of α-epoxyketones.
Scheme 3: Possible formation of a complex involved in reaction in acetone.
Scheme 4: Interaction of oxygen lone pair of carbonyl group with carbocation center.
Figure 1: The semi-empirical PM3 calculations for interaction of 1a with NBTPT.
