Substituent-Control of Two Modes of Intramolecular Reactions of Allyloxy-Silyllithiums and Propargyloxy-Silyllithiums
作者:Atsushi Kawachi、Hirofumi Maeda、Kohei Tamao
DOI:10.1246/bcsj.78.1520
日期:2005.8
Intramolecular reactions of the [(allyloxy)silyl]lithiums and the [(propargyloxy)silyl]lithiums have been investigated. The [(allyloxy)silyl]lithiums proceed in two reaction modes depending on the electronic effect of the substituents at the terminus of the olefin. The [(allyloxy)silyl]lithiums bearing hydrogen, n-C6H13, or trimethylsilyl substituent undergo the [2,3]-sila-Wittig rearrangement to afford the lithium allylsilanolates, while those bearing the phenyl, thienyl, or triphenylsilyl substituent experience the 4-exo-trig cyclization and subsequent 1,3-cycloelimination to give the lithium cyclopropylsilanolates. On the other hand, the [(propargyloxy)silyl]lithiums preferentially undergo the 4-exo-dig cyclization over the [2,3]-sila-Wittig rearrangement in all cases.
已对[(烯丙氧基)硅基]锂盐和[(炔丙氧基)硅基]锂盐的分子内反应进行了研究。[(烯丙氧基)硅基]锂盐根据烯烃末端取代基的电子效应,呈现出两种反应模式。具有氢、n-C6H13或三甲基硅基取代基的[(烯丙氧基)硅基]锂盐经历[2,3]-硅-维蒂格重排,生成锂烯丙基硅醇盐,而具有苯基、噻吩基或三苯基硅基取代基的则经历4-exo-trig环化和随后的1,3-环消除,生成锂环丙基硅醇盐。另一方面,在所有情况下,[(炔丙氧基)硅基]锂盐优先经历4-exo-dig环化,而不是[2,3]-硅-维蒂格重排。