<i>α</i>-Alkylation of<i>α</i>,<i>β</i>-Unsaturated Aldehyde Dimethylhydrazones Accompanied with the Double Bond Migration to<i>β</i>,<i>γ</i>
作者:Masakazu Yamashita、Kaoru Matsumiya、Ken-ichi Nakano
DOI:10.1246/bcsj.66.1759
日期:1993.6
Lithiated α,β-unsaturated aldehyde N,N-dimethylhydrazones reacted with alkyl halides accompanied by double bond migration to give α-alkylated β,γ-unsaturated aldehyde N,N-dimethylhydrazones in satisfactory yields. This reaction was found to be caused at the first step by deprotonation from a γ-carbon atom by lithium diisopropylamide. In the case of hydrazones with two kinds of γ-protons, deprotonation from the less hindered γ-carbon occurred selectively. Using this reaction, a novel sesquiterpene, 2,5,9-trimethyl-2-vinyl-4,8-decadienal, which has a vinyl group at the α-position, was synthesized in a good yield.
锂化的α,β-不饱和醛N,N-二甲基脲与烷基卤化物反应,伴随着双键迁移,得到了产率良好的α-烷基化的β,γ-不饱和醛N,N-二甲基脲。首次发现该反应的第一步是由二异丙基氨基锂从γ碳原子上的脱质子作用引起的。对于具有两种γ氢的脲类化合物,选择性地从较少阻碍的γ碳上脱质子。利用这一反应,合成了一种新型倍半萜,2,5,9-三甲基-2-乙烯基-4,8-癸二烯醛,其在α位具有乙烯基,产率良好。