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Search for "C–C bond cleavage" in Full Text gives 34 result(s) in Beilstein Journal of Organic Chemistry.
Recent highlights in biosynthesis research using stable isotopes
- Jan Rinkel and
- Jeroen S. Dickschat
Beilstein J. Org. Chem. 2015, 11, 2493–2508, doi:10.3762/bjoc.11.271
- incorporation of labeled Gly into the methyl group was rationalized by glycine degradation, directing the labeling via tetrahydrofolate and SAM into aspirochlorine biosynthesis. The conversion of the Phe residue to Gly may proceed through either oxidative C–C bond cleavage or a retro-aldol reaction in 18, in
Graphical Abstract
Figure 1: Structures of lovastatin (1), aflatoxin B1 (2) and amphotericin B (3).
Scheme 1: a) Structure of rhizoxin (4). b) Two possible mechanisms of chain branching catalysed by a branchin...
Scheme 2: Structure of coelimycin P1 (8) and proposed biosynthetic formation from the putative PKS produced a...
Scheme 3: Structure of trioxacarcin A (9) with highlighted carbon origins of the polyketide core from acetate...
Scheme 4: Proposed biosynthetic assembly of clostrubin A (12). Bold bonds show intact acetate units.
Figure 2: Structure of forazoline A (13).
Figure 3: Structures of tyrocidine A (14) and teixobactin (15).
Figure 4: Top: Structure of the NRPS product kollosin A (16) with the sequence N-formyl-D-Leu-L-Ala-D-Leu-L-V...
Scheme 5: Proposed biosynthesis of aspirochlorine (20) via 18 and 19.
Scheme 6: Two different macrocyclization mechanisms in the biosynthesis of pyrrocidine A (24).
Figure 5: Structure of thiomarinol A (27). Bold bonds indicate carbon atoms derived from 4-hydroxybutyrate.
Figure 6: Structures of artemisinin (28), ingenol (29) and paclitaxel (30).
Figure 7: The revised (31) and the previously suggested (32) structure of hypodoratoxide and the structure of...
Figure 8: Structure of the two interconvertible conformers of (1(10)E,4E)-germacradien-6-ol (34) studied with...
Scheme 7: Proposed cyclization mechanism of corvol ethers A (42) and B (43) with the investigated reprotonati...
Scheme 8: Predicted (top) and observed (bottom) 13C-labeling pattern in cyclooctatin (45) after feeding of [U-...
Scheme 9: Proposed mechanism of the cyclooctat-9-en-7-ol (52) biosynthesis catalysed by CotB2. Annotated hydr...
Scheme 10: Cyclization mechanism of sesterfisherol (59). Bold lines indicate acetate units; black circles repr...
Scheme 11: Cyclization mechanisms to pentalenene (65) and protoillud-6-ene (67).
Scheme 12: Reactions of chorismate catalyzed by three different enzyme subfamilies. Oxygen atoms originating f...
Scheme 13: Incorporation of sulfur into tropodithietic acid (72) via cysteine.
Scheme 14: Biosynthetic proposal for the starter unit of antimycin biosynthesis. The hydrogens at positions R1...
Recent advances in copper-catalyzed C–H bond amidation
- Jie-Ping Wan and
- Yanfeng Jing
Beilstein J. Org. Chem. 2015, 11, 2209–2222, doi:10.3762/bjoc.11.240
- ] reported the copper-catalyzed, tert-butyl hydroperoxide (TBHP)-assisted C–H amidation of tertiary amines 1. By heating at 80 °C, the C–H bond in dimethylaniline underwent direct amidation to provide products 3 in the presence of amides 2. On the other hand, the dephenylation transformation via C–C bond
- cleavage took place as the main route when N-phenyl-N-methylaniline was employed as the alternative reactant, which led to the production of 3 as the main products, while corresponding products 4 via C–H bond amidation occurred as the minor ones. Notably, this kind of C–H amidation strategy could be
Graphical Abstract
Scheme 1: Copper-catalyzed C–H amidation of tertiary amines.
Scheme 2: Copper-catalyzed C–H amidation and sulfonamidation of tertiary amines.
Scheme 3: Copper-catalyzed sulfonamidation of allylic C–H bonds.
Scheme 4: Copper-catalyzed sulfonamidation of benzylic C–H bonds.
Scheme 5: Copper-catalyzed sulfonamidation of C–H bonds adjacent to oxygen.
Scheme 6: Copper-catalyzed amidation and sulfonamidation of inactivated alkyl C–H bonds.
Scheme 7: Copper-catalyzed amidation and sulfonamidation of inactivated alkanes.
Scheme 8: Copper-catalyzed intramolecular C–H amidation for lactam synthesis.
Scheme 9: Copper-catalyzed intramolecular C–H amidation for lactam synthesis.
Scheme 10: Copper-catalyzed amidation/sulfonamidation of aryl C–H bonds.
Scheme 11: C–H amidation of pyridinylbenzenes and indoles.
Scheme 12: Mechanism of the Cu-catalyzed C2-amidation of indoles.
Scheme 13: Copper-catalyzed, 2-phenyl oxazole-assisted C–H amidation of benzamides.
Scheme 14: DG-assisted amidation/imidation of indole and benzene C–H bonds.
Scheme 15: Copper-catalyzed C–H amination/amidation of quinoline N-oxides.
Scheme 16: Copper-catalyzed aldehyde formyl C–H amidation.
Scheme 17: Copper-catalyzed formamide C–H amidation.
Scheme 18: Copper-catalyzed sulfonamidation of vinyl C–H bonds.
Scheme 19: CuCl2-catalyzed amidation/sulfonamidation of alkynyl C–H bonds.
Scheme 20: Cu(OH)2-catalyzed amidation/sulfonamidation of alkynyl C–H bonds.
Scheme 21: Sulfonamidation-based cascade reaction for the synthesis of tetrahydrotriazines.
Scheme 22: Copper-catalyzed cascade reaction for the synthesis of quinazolinones.
Scheme 23: Copper-catalyzed cascade reactions for the synthesis of fused quinazolinones.
Scheme 24: Copper-catalyzed synthesis of quinazolinones via methyl C–H bond amidation.
Scheme 25: Dicumyl peroxide-based cascade synthesis of quinazolinones.
Scheme 26: Copper-catalyzed cascade reactions for the synthesis of indolinones.
Copper-catalyzed aerobic radical C–C bond cleavage of N–H ketimines
- Ya Lin Tnay,
- Gim Yean Ang and
- Shunsuke Chiba
Beilstein J. Org. Chem. 2015, 11, 1933–1943, doi:10.3762/bjoc.11.209
- cleavage of N–H ketimines. Treatment of N–H ketimines having an α-sp3 hybridized carbon under Cu-catalyzed aerobic reaction conditions resulted in a radical fragmentation with C–C bond cleavage to give the corresponding carbonitrile and carbon radical intermediate. This radical process has been applied for
- the construction of oxaspirocyclohexadienones as well as in the electrophilic cyanation of Grignard reagents with pivalonitrile as a CN source. Keywords: C–C bond cleavage; copper; ketimines; molecular oxygen; radical; Introduction Alkylideneaminyl radicals (iminyl radicals) have been utilized for
- formation of the desired 6-membered azaspirocycle 3a’ was observed, while oxaspirocyclohexadienone 3a, biaryl alkene 4a, and p-tolunitrile (5a) were isolated in 29%, 32%, and 86% yields, respectively (Scheme 4). Oxaspirocyclohexadienone 3a was formed through C–C bond cleavage from N–H ketimine intermediate
Graphical Abstract
Scheme 1: Generation of iminyl radicals from oxime derivatives.
Scheme 2: Oxidative generation of iminyl radicals from N–H ketimines.
Scheme 3: Copper-catalyzed aerobic reactions of in situ generated biaryl N–H ketimines.
Scheme 4: Copper-catalyzed aerobic C–C bond cleavage reactions of N–H ketimines.
Scheme 5: Proposed reaction mechanisms for the formation of 3a, 4a and 5a, and the reaction of hydroperoxide 6...
Scheme 6: Formation of bromoketone 6e.
Scheme 7: Electrophilic cyanation of Grignard reagents with pivalonitrile (1f).
Scheme 8: Electrophilic cyanation with pivalonitrile (1e).
Recent applications of ring-rearrangement metathesis in organic synthesis
- Sambasivarao Kotha,
- Milind Meshram,
- Priti Khedkar,
- Shaibal Banerjee and
- Deepak Deodhar
Beilstein J. Org. Chem. 2015, 11, 1833–1864, doi:10.3762/bjoc.11.199
- syntheses of virgidivarine and virgiboidine by employing an intramolecular ene–ene–yne domino RRM protocol in combination with an oxidative C–C bond cleavage. This protocol opens-up new opportunities for the construction of intricate dipiperidine-based targets in a stereoselective manner (Scheme 12). Lee
Graphical Abstract
Figure 1: Ruthenium alkylidene catalysts used in RRM processes.
Figure 2: General representation of various RRM processes.
Figure 3: A general mechanism for RRM process.
Scheme 1: RRM of cyclopropene systems.
Scheme 2: RRM of cyclopropene with catalyst 2. (i) catalyst 2 (2.5 mol %), ethylene (24, 1 atm), (ii) toluene...
Scheme 3: RRM of various cyclopropene derivatives with catalyst 2. (i) catalyst 2 (2.5 mol %), CH2Cl2 (c = 0....
Scheme 4: RRM of substituted cyclopropene system with catalyst 2.
Scheme 5: RRM of cyclobutene system with catalyst 2.
Scheme 6: RRM approach to various bicyclic compounds.
Scheme 7: RRM approach to erythrina alkaloid framework.
Scheme 8: ROM–RCM sequence to lactone derivatives.
Scheme 9: RRM protocol towards the synthesis of lactone derivative 58.
Scheme 10: RRM protocol towards the asymmetric synthesis of asteriscunolide D (61).
Scheme 11: RRM strategy towards the synthesis of various macrolide rings.
Scheme 12: RRM protocol to dipiperidine system.
Scheme 13: RRM of cyclopentene system to generate the cyclohexene systems.
Scheme 14: RRM of cyclopentene system 74.
Scheme 15: RRM approach to compound 79.
Scheme 16: RRM approach to spirocycles.
Scheme 17: RRM approach to bicyclic dihydropyrans.
Scheme 18: RCM–ROM–RCM cascade using non strained alkenyl heterocycles.
Scheme 19: First ROM–RCM–ROM–RCM cascade for the synthesis of trisaccharide 97.
Scheme 20: RRM of cyclohexene system.
Scheme 21: RRM approach to tricyclic spirosystem.
Scheme 22: RRM approach to bicyclic building block 108a.
Scheme 23: ROM–RCM protocol for the synthesis of the bicyclo[3.3.0]octene system.
Scheme 24: RRM protocol to bicyclic enone.
Scheme 25: RRM protocol toward the synthesis of the tricyclic system 118.
Scheme 26: RRM approach toward the synthesis of the tricyclic enones 122a and 122b.
Scheme 27: Synthesis of tricyclic and tetracyclic systems via RRM protocol.
Scheme 28: RRM protocol towards the synthesis of tetracyclic systems.
Scheme 29: RRM of the propargylamino[2.2.1] system.
Scheme 30: RRM of highly decorated bicyclo[2.2.1] systems.
Scheme 31: RRM protocol towards fused tricyclic compounds.
Scheme 32: RRM protocol to functionalized tricyclic systems.
Scheme 33: RRM approach to functionalized polycyclic systems.
Scheme 34: Sequential RRM approach to functionalized tricyclic ring system 166.
Scheme 35: RRM protocol to functionalized CDE tricyclic ring system of schintrilactones A and B.
Scheme 36: Sequential RRM approach to 7/5 fused bicyclic systems.
Scheme 37: Sequential ROM-RCM protocol for the synthesis of bicyclic sugar derivatives.
Scheme 38: ROM–RCM sequence of the norbornene derivatives 186 and 187.
Scheme 39: RRM approach toward highly functionalized bridge tricyclic system.
Scheme 40: RRM approach toward highly functionalized tricyclic systems.
Scheme 41: Synthesis of hexacyclic compound 203 by RRM approach.
Scheme 42: RRM approach toward C3-symmetric chiral trimethylsumanene 209.
Scheme 43: Triquinane synthesis via IMDA reaction and RRM protocol.
Scheme 44: RRM approach to polycyclic compounds.
Scheme 45: RRM strategy toward cis-fused bicyclo[3.3.0]carbocycles.
Scheme 46: RRM protocol towards the synthesis of bicyclic lactone 230.
Scheme 47: RRM approach to spiro heterocyclic compounds.
Scheme 48: RRM approach to spiro heterocyclic compounds.
Scheme 49: RRM approach to regioselective pyrrolizidine system 240.
Scheme 50: RRM approach to functionalized bicyclic derivatives.
Scheme 51: RRM approach to tricyclic derivatives 249 and 250.
Scheme 52: RRM approach to perhydroindoline derivative and spiro system.
Scheme 53: RRM approach to bicyclic pyran derivatives.
Scheme 54: RRM of various functionalized oxanorbornene systems.
Scheme 55: RRM to assemble the spiro fused-furanone core unit. (i) 129, benzene, 55 °C, 3 days; (ii) Ph3P=CH2B...
Scheme 56: RRM protocol to norbornenyl sultam systems.
Scheme 57: Ugi-RRM protocol for the synthesis of 2-aza-7-oxabicyclo system.
Scheme 58: Synthesis of spiroketal systems via RRM protocol.
Scheme 59: RRM approach to cis-fused heterotricyclic system.
Scheme 60: RRM protocol to functionalized bicyclic systems.
Scheme 61: ROM/RCM/CM cascade to generate bicyclic scaffolds.
Scheme 62: RCM of ROM/CM product.
Scheme 63: RRM protocol to bicyclic isoxazolidine ring system.
Scheme 64: RRM approach toward the total synthesis of (±)-8-epihalosaline (300).
Scheme 65: Sequential RRM approach to decalin 304 and 7/6 fused 305 systems.
Scheme 66: RRM protocol to various fused carbocyclic derivatives.
Scheme 67: RRM to cis-hydrindenol derivatives.
Scheme 68: RRM protocol towards the cis-hydrindenol derivatives.
Scheme 69: RRM approach toward the synthesis of diversed polycyclic lactams.
Scheme 70: RRM approach towards synthesis of hexacyclic compound 324.
Scheme 71: RRM protocol to generate luciduline precursor 327 with catalyst 2.
Scheme 72: RRM protocol to key building block 330.
Scheme 73: RRM approach towards the synthesis of key intermediate 335.
Scheme 74: RRM protocol to highly functionalized spiro-pyran system 339.
Scheme 75: RRM to various bicyclic polyether derivatives.
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.
