Strategy for cyclopentenone annulation of olefins: A general protocol for bicyclo [n.3.0] enone synthesis
作者:Goverdhan Mehta、K.Srinivas Rao
DOI:10.1016/s0040-4039(01)90055-3
日期:——
Several bicyclic α-chloro enones obtained through Greene annulation of cyclic olefins are shown to undergo efficient, two step, enone transposition via Luche reduction and aq. formic acid treatment. Application of this methodology to the formal synthesis of exaltone® and (±)-muscone is described.
which was isomerized to the above product. The cyclization of 4-(4-alkyl)cyclohexylidene-2-(trimethylsilylmethyl)but-2-enal proceeded stereoselectively. While, (E)-3-(cyclohex-1-en-1-yl)-2-(trimethylsilylmethyl)prop-2-en-1-al cyclized immediately affording 8-methylenebicyclo[4.3.0]non-9-en-7-ol. The corresponding (Z)-isomer gave several cyclization products as a complex mixture.
Synthesis and structure of ansa-metallocene complexes (M=ZrCl2, TiCl2, YCl, and LuCl) containing the bis(2-methyl-4,5,6,7-tetrahydroinden-yl)dimethylsilane ligand
作者:Ronald L Halterman、Herbert Schumann、Frank Dübner
DOI:10.1016/s0022-328x(00)00177-7
日期:2000.6
The three step synthesis of 2-methyl-4,5,6,7-tetrahydro-1H-indene from cyclohexyl methacrylate is described [(a) PPA cyclization: (b) LiAlH4 reduction. (c) HCl dehydration]. This annelated trisubstituted cyclopentadiene was bridged selectively to form ethylene- or dimethylsilyl-bridged bis(2-methyl-4,5,6,7-tetrahydro-1H-inden-1-yl) ligands. Metal complexes (M = ZrCl2, TiCl2 YCl, and LuCl) of the bis(2-methyl-4,5,6,7-tetrahydroinden-1-yl)dimethylsilane ligand were formed as meso/dl stereoisomeric mixtures in ratios from 1:1 to 2:1 dl:meso. (C) 2000 Published by Elsevier Science S.A. All rights reserved.
Three-carbon annelations. Regiocontrolled reactivity of trimethylsilyl- and ethoxyethyl-protected cyanohydrins. Versatile homoenolate and acyl anion equivalents
作者:Richard M. Jacobson、George P. Lahm、John W. Clader
DOI:10.1021/jo01291a005
日期:1980.2
Three carbon annelation reagents: unsaturated alpha aminonitriles as homoenolate equivalents