On the α-lithiation-rearrangement of N-toluensulfonyl aziridines: mechanistic and synthetic aspects
作者:Peter O'Brien、Clare M Rosser、Darren Caine
DOI:10.1016/j.tet.2003.09.024
日期:2003.12
can then partition through two pathways: (i) rearrangement to allylic or bicyclic sulfonamides via C–H insertion reactions or (ii) reductive alkylation to alkenes via attack by sec-butyllithium and subsequent elimination of TsNH2. In the (−)-sparteine reactions, the products were generated with 38–66% ee and the sense of asymmetric induction involved lithiation of the S-aziridine stereocentre. This is
进行了详细的研究,使用仲丁基锂(有和没有添加(-)-天冬氨酸和TMEDA等配体)对五个环烯N-甲苯磺酰基(甲苯磺酰基)氮丙啶进行重排。烯丙基磺酰胺是环戊烯和环己烯氮丙啶的主要产物,而双环磺酰胺是从环庚烯和环辛烯氮丙啶获得的。在大多数情况下,对甲苯磺酰胺(TsNH 2)作为副产品生产,并就其形成机理进行了机械解释。据信,这些反应涉及α-锂化为锂化的氮丙啶,然后可以通过两个途径分配:(i)通过CH插入反应重排为烯丙基或双环磺酰胺,或(ii)通过仲丁基锂的攻击而还原为烷基化为烯烃。和随后消除TsNH 2。在(-)-天冬氨酸反应中,生成的产物的ee为38-66%,不对称感应的感觉涉及S-氮丙啶立体中心的锂化。这与用环氧化物观察到的相反。