asymmetric Staudinger/aza-Wittig reaction of 2,2-disubstituted cyclohexane-1,3-diones is reported, enabling the facile access of a broad range of cis-3a-arylhydroindoles in high yields with excellent enantioselectivities. The key to the success of this work relies on the first application of chiral bisphosphine DuanPhos to the asymmetric Staudinger/aza-Wittig reaction. An effective reductive system has
报道了前所未有的手性双膦催化的 2,2-二取代环己烷-1,3-二酮的不对称 Staudinger/aza-Wittig 反应,使得能够以高产率和优异的对映选择性轻松获得各种顺式-3a-芳基氢吲哚。这项工作成功的关键在于手性双膦 DuanPhos 首次应用于不对称 Staudinger/aza-Wittig 反应。已经建立了有效的还原系统来解决与手性双膦催化剂相关的具有挑战性的 P V =O/P III氧化还原循环。此外,还进行了全面的实验和计算研究,以阐明不对称反应的机理。利用新开发的化学方法,包括 (+)-powelline、(+)-buphanamine、(+)-vittatine 和 (+)-crinane 在内的几种 crinine 型石蒜科生物碱的对映选择性全合成已经非常简洁地完成和效率。
Practical P-Chiral Phosphane Ligand for Rh-Catalyzed Asymmetric Hydrogenation
作者:Duan Liu、Xumu Zhang
DOI:10.1002/ejoc.200400690
日期:2005.2
conformationally rigid P-chiral bis(trialkylphospholane) ligand 2 (DuanPhos) has been prepared in both enantiomeric forms through a concise syn-thesis. Rh-2 complex has exhibited remarkably high enantio-selectivities (up to >99% ee) and reactivities (up to 10,000 TON) for the hydrogenation of a wide variety of functionalized prochiral alkenes (5 different types), which provides a very practical catalytic system