Tandem pericyclic reactions in a new FeCl3-promoted synthesis of catechol analogues of restrytisol C
作者:N.F Thomas、K.C Lee、Thomas Paraidathathu、J.F.F Weber、K Awang、D Rondeau、P Richomme
DOI:10.1016/s0040-4020(02)00798-6
日期:2002.9
The uncommon stilbene, 3,4-dimethoxy-12-acetoxy stilbene, has been synthesised by Heck coupling methodology in three steps. Treatment of this stilbene with ferric chloride in dichloromethane (room temperature) gave the unnatural stilbenoid dimers; 8,8-(12,12'-bisacetoxyphenyl)-7'-(3',4'-dimethoxyphenyl)-3,4-dimethoxy-7',8'-dihydro-naphthalene and 8-(12-acetoxyphenyl)-8'-(12'-hydroxyphenyl)-7'-(3',4'-diinethoxyphenyl)-3,4-dimethoxy-7',8'-dihydro-naphthalene. The structures of both stilbene dimers were unambiguously confirmed by 1D (H-1, C-13 and 2D NMR experiments (COSY, HMQC, HMBC and NOESY). This is the first report of a FeCl3-promoted sequential pericyclic pathway leading to a highly oxygenated oligostilbenoid dimer (incorporating two asymmetric centres). The NMR spectroscopic evidence and a mechanistic interpretation consistent with these structures are discussed. (C) 2002 Elsevier Science Ltd. All rights reserved.