A general method for the preparation of 5-alkylidene-2-cyclopentenones and their 2-phenylsulfanyl substituted derivatives, involving the intramolecular acylation of cc-sulfinyl carbanions with cyclopentadiene-alpha,beta-unsaturated esters as the key reaction followed by flash vacuum pyrolysis, is described. The reactions start from readily available Diels-Alder adducts, synthons of alpha-carbanions of alpha,beta-unsaturated esters. (c) 2006 Elsevier Ltd. All rights reserved.
Synthesis of α-methylenecyclopentanones via silicon directed nazarov reaction of α-trimethylsilymethyl substituted divinyl ketones.
作者:Kyung-Tae Kang、Soung Sin Kim、Jae Chul Lee、Jong Sun U.
DOI:10.1016/s0040-4039(00)92672-8
日期:1992.6
Reactions of alpha-trimethylsilylmethyl-substituted divinyl ketones with FeCl3 gave alpha-methylenecyclopentanones. Thienyl and N-methylpyrrolyl (alpha-trimethylsilylmethyl)vinyl ketones also underwent cyclization to afford the corresponding alpha-methylenecyclopentanones.
Selective bis-hydride reduction of tosylmethyl-substituted tricyclic enones by lithium aluminium hydride synthesis of α-methylene cyclopentenoids
On treatment with LAH the 4-tosylmethyl substituted exo-10-oxatricyclo[5.2.1.02,6]decadienones 1 and 3 undergo two consecutive, regioselective and stereospecific reductions. The first reduction constitutes an SN2′ displacement of the allylic tosyl group, the second a 1,2-reduction of the resulting exo-cyclic enone to form the α-methylene cyclenols 7 and 8, respectively. These products are smoothly