Low-temperature oxyanion-accelerated vinylcyclopropane-cyclopentene rearrangement. Reaction of 2-(2-(trimethylsilyl)ethenyl)cyclopropyl acetates with methyl lithium

[摘要] Reactions of four diastereomeric 2-(2-(trimethylsilyl)ethenyl)cyclopropyl acetates 7, derived from enol silyl ether 4 and Fischer carbene complex 6, with 2.2 equiv of MeLi at -80 degrees to -30 degrees C afforded cyclopentenol 8 as a single diastereomer and acyclic enol silyl ethers 9 via the corresponding cyclopropanolates in ratios depending on the vinylsilane geometry. Predominant formation of 8 over 9 from (Z)-7 irrespective of the stereochemistry at C-1 was observed. This is the first example of oxyanion-accelerated vinylcyclopropane-cyclopentene rearrangement which proceeds at unprecedentedly low temperatures. (C) 1997 Elsevier Science Ltd.

[发布日期] 1997-05-05