58 環状アリルスルホニウムイリドのシグマトロピー転位とその天然物合成への応用(ポスター発表の部)

概要

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The [2,3]sigmatropic rearrangement of cyclic allylsulfonium ylides(B), generated from the diazo malonate of Z-phenylthio-3-butenol derivatives(8a-8d) with catalytic amount of rhodium acetate in refluxing benzene, afforded γ,δ-unsaturated seven-membered lactones (9a-9d) in moderate yield. In a similar fashion, treatment of a diazo malonate,readily prepared from homologous alcohol(7e), with rhodium acetate provided eight-membered lactone(9e), albeit in low yield. On the other hand, this methodology was applied to the synthesis of six-membered spirolactones: treatment of α-diazo allylsulfides containing cyclopentene, cyclohexene or cycloheptene ring(16a-16c), which were prepared from corresponding cycloalkanone by a 9 step sequence, with rhodium acetate afforded the desired six-membered spirolactones(17a-17c) in excellent yields. An application of this rearrangement to the stereoselective synthesis of natural vernolepin(18) will also be discussed.
天然有機化合物討論会の論文
1990-09-25