Showing papers on "Annulation published in 1987"
165 citations
TL;DR: In this article, a new furan annelation by the palladium-catalyzed reaction of 2-alkynyl carbonates with β-keto esters is described.
109 citations
TL;DR: Pentalenic acid, 5, and pentalenene, 4, and their C-9 epimers 5a and 4a, respectively, were synthesized using [4+1] and [2+3] cyclopentene annulation methodology as discussed by the authors.
49 citations
TL;DR: In this paper, the authors showed that carbonyl carbene complexes bearing either heteroatoms or CC bonds in a carbene γ-position are susceptible towards facile decarbonylation.
49 citations
TL;DR: Preparation en huit etapes du pentalenenes et de l'epipentalenene a partir de la dimethyl-7,7 bicyclo [3.3.0] octene-1one-3
Abstract: Preparation en huit etapes du pentalenene et de l'epipentalenene a partir de la dimethyl-7,7 bicyclo [3.3.0] octene-1one-3
47 citations
TL;DR: Manganese(III)-promoted addition of various 1,3-dicarbonyl compounds to enol ethers or terminal enol esters, followed by hydrolysis of the resulting adducts and base catalyzed aldol cyclization provides an effective process for the synthesis of a wide range of fused and spiro 2-cyclopentenones.
46 citations
TL;DR: In this article, the same authors showed that γ-and δ-dicarbonyles avec SnF 2 and l'iodomethyl-2 allyl trimethyl silane can be found to have obtention d'oxa-8bicyclo [3.2.1] octanes and d'oxya-9bicycleclo[3.3] nonanes.
Abstract: Reactions de composes γ- et δ-dicarbonyles avec SnF 2 et l'iodomethyl-2 allyl trimethyl silane: obtention d'oxa-8bicyclo [3.2.1] octanes et d'oxa-9bicyclo [3.3.1] nonanes
40 citations
TL;DR: An efficient and highly diastereo and enantioselective annulation of cyclic 1.3-diketones to tetrahydro-quinolinediones of type 4 and 5 in good overall yields is described in this article.
35 citations
TL;DR: In this article, the homolytic cyclization of some alkenyl β-lactams afforded carbapenams, by exo addition, when a vicinally disubstituted double double double bond was involved.
31 citations
TL;DR: In this paper, the total synthesis of racemic 14-epiupial (3) is described, and the preparation of 3 is achieved in 23 steps starting from 8.
31 citations
TL;DR: Enol ethers, β-dicarbonyl compounds and the Mn(III) reagent Mn3O(OAc)7 react under mild conditions to form 1-alkoxy-1.2-dihydrofurans in good (70-98%) yields.
Abstract: Enol ethers, β-dicarbonyl compounds and the Mn(III) reagent Mn3O(OAc)7 react under mild conditions to form 1-alkoxy-1.2-dihydrofurans in good (70–98%) yields. The latter are readily converted to furans by acid-catalyzed elimination of ROH.
TL;DR: In this article, a partir de dimethyl-4,4 cyclopentene-2one via le dimethyl7,7 ethoxycarbonyl-2 phenylthio-4 bicyclo [3.3.0] octene-4acetate-1 de t-butyle prepare par action du tetrafluoroborate de phenylthyio-1 vinyl triphenyl phosphonium sur ledimethyl-3,3 ethoxy carbonyl -7 trimethylsiloxy-6 bicyclo[3.1.0
Abstract: Synthese a partir de dimethyl-4,4 cyclopentene-2one via le dimethyl-7,7 ethoxycarbonyl-2 phenylthio-4 bicyclo [3.3.0] octene-4acetate-1 de t-butyle prepare par action du tetrafluoroborate de phenylthio-1 vinyl triphenyl phosphonium sur le dimethyl-3,3 ethoxycarbonyl-7 trimethylsiloxy-6 bicyclo [3.1.0] hexaneacetate-1 de t-butyle
TL;DR: In this paper, the carbanion of chloromethyl aryl sulfone reacts with 1-cyanonaphthalene to form a bis-annulated product and 1-nitronaphthene vicarious nucleophilic substitution of hydrogen takes place.
Abstract: The carbanion of chloromethyl aryl sulfone reacts with 1-cyanonaphthalene to form a bis-annulated product whereas with 1-nitronaphthalene vicarious nucleophilic substitution of hydrogen takes place. This result and the bis-annulation of quinoxalines and naphthyridines which was reported earlier are rationalized in terms of the negative charge delocalization in the intermediate σ-adducts.
TL;DR: In this paper, a three-step 4-methyl furan annulation sequence was described via the radical cyclisation of bromoacetal 3 to 2-alkoxy-4-methylene tetrahydrofuran 4.
TL;DR: In this paper, the construction through an A-ring annulation strategy of a fully B-ring methylated saturated tricyclic taxane model and the demonstration of its preference for trans BC ring junction stereochemistry are described.
TL;DR: Vinylaziridine 2 underwent alkylative ring opening with trimethylsilyl iodide to furnish supinidine ethyl ester 4 from which isoretronecanol 7 and trachelanthamidine 9 were synthesized stereoselectively.
TL;DR: In this paper, the Titanium tetrachloride-catalyzed conjugate addition of 3-methyl-1,1-bis(trimethylsiloxy)-1-butene to 16 gave (93%) a 3:2 mixture of the keto acids 20 and 21, which were separated.
TL;DR: In this paper, Butyl 2-benzylidene-1-carbapenam-3-carboxylate was obtained through homolytic cyclization of a suitably substituted nonfused β-lactam.
TL;DR: Vinylcyclopropanes of type 2 were converted to either annulated cyclopentenes of type 3 or bicyclo [3.2.1] octene of type 4 through carefully controlled rearrangement pathways as mentioned in this paper.
TL;DR: In this article, α-oxoketene dithioacetals derived from various cyclic and acyclic ketones are shown to be useful intermediates for the synthesis of substituted and fused quinolizinium derivatives by reaction with 2-picolyllithium followed by cyclization in the presence of borontrifluoride etherate.
TL;DR: In this paper, a new synthetic approach to paniculide A based on annulation of 2-formylpropionate with α-phenylthio-β-vinylbutenolide 4 is described.
TL;DR: In this paper, the reaction of the dilithio derivative of dimethyl cis -4-cyclohexen-1,2-dicarboxylate with 3-substituted propiolic acid phenyl esters proceeds via an unusual mechanistic path to generate fused bicyclic 2-cyclopentenones in a single step.
TL;DR: A novel aromatic annelation leading to fused thioresorcinol dimethylethers has been developed by reacting cyclic ∝-oxoketene dithioacetals with propargylmagnesium bromide followed by treatment of the resulting carbinolacetal with borontrifluoride etherate in methanol as mentioned in this paper.
TL;DR: In this article, the chemospecific production and intramolecular aromatic electrophilic substitution (annulation) of bis(phenylthio)carbocations (bisphenylthionium ions) has been studied using appropriate model compounds.
TL;DR: In this paper, the pyranose ring was used as the tetrahydrocoumalate skeleton to synthesize methyl 2,3-anhydro-α-D-lyxopyranoside by cyclopentane annulation.
Abstract: 1-α-O-Methyl-loganin (1) was synthesised from methyl 2,3-anhydro-α-D-lyxopyranoside by cyclopentane annulation using the pyranose ring as the tetrahydrocoumalate skeleton.