Solvent and substituent effects on conjugated eliminations in propargylic systems
作者:Frédéric Le Strat、Jacques Maddaluno
DOI:10.1016/s0040-4039(00)00856-x
日期:2000.7
The deprotonation of 4-methoxy-but-2-ynal diethyl acetal by n-butyllithium induces an acetylenic–allenic isomerization (in diethylether) or a conjugated elimination reaction (in THF), providing the corresponding 1,4-dialkoxycumulene. An allenyllithium, that has been trapped as an allenylstannane, is proposed to be a common intermediate to both pathways. Also, the deprotonation of 4-dialkylamino-but-2-ynal
正丁基锂对4-甲氧基-丁-2-炔基二乙基乙缩醛进行去质子反应可诱导炔属-烯烃异构化(在乙醚中)或共轭消除反应(在THF中),从而提供相应的1,4-二烷氧基枯烯。有人提出,以烯丙基锡烷的形式被捕获的烯丙基锂是这两种途径的共同中间产物。同样,在相同条件下4-二烷基氨基-丁-2-炔基二乙基乙缩醛的去质子化反应得到(E)和(Z)氨基巴豆酸酯的混合物,其形成可以通过化学选择性除去乙缩醛质子生成中间体来解释。均被甲锡烷基化俘获的烯丙基锂。