Allyltrimethoxysilane Addition to<i>N</i>-Acylhydrazones: Two Catalytic Methods Employing CuCl and Fluoride
作者:Gregory K. Friestad、Hui Ding
DOI:10.1055/s-2004-829190
日期:——
Two alternative reaction conditions developed for allyltrimethoxysilane addition to N-benzoylhydrazones enable efficient and versatile access to homoallylic α-branched amines. Aldehyde hydrazones, both aromatic and aliphatic, and ketone hydrazones all give good yields. One set of conditions employs catalytic amounts of CuCl and tetrabutylammonium triphenyldifluorosilicate (TBAT); improved yields and reaction times are obtained at 80 °C in the presence of bis(diphenylphosphino)ethane (dppe) and t-BuOH as additives. The second set of conditions employs 20 mol% TBAT as a fluoride source in a metal-free catalytic system; here t-BuOH offers only modest improvement, and ambient temperatures are optimal. For example, under this second set of conditions, the N-benzoylhydrazone from ethyl pyruvate affords the homoallylic tert-alkyl amine adduct in 78% yield.
针对烯丙基三甲氧基硅烷与 N-苯甲酰肼的加成反应开发出了两种替代反应条件,从而能够高效、多用途地获得均烯丙基δ-±-支链胺。芳香族和脂肪族的醛肼以及酮肼都有很好的产率。其中一套条件使用了催化量的 CuCl 和四丁基三苯基二氟硅酸铵 (TBAT);在 80 °C 温度下,以双(二苯基膦)乙烷 (dppe) 和 t-BuOH 作为添加剂,可提高产率并缩短反应时间。第二套条件是在无金属催化体系中使用 20 mol% 的 TBAT 作为氟源;t-BuOH 在此条件下只能起到适度的改善作用,而环境温度则是最佳条件。例如,在第二套条件下,丙酮酸乙酯中的 N-苯甲酰基腙可生成均烯丙基叔烷基胺加合物,收率为 78%。