Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, PR China.
Org Biomol Chem. 2012 Aug 14;10(30):5971-8. doi: 10.1039/c2ob25206f. Epub 2012 May 10.
A range of enethioate derivatives of 1,3-diones underwent reductive aldol cyclizations catalyzed by a chiral copper hydride generated in situ from 5 mol% TaniaPhos (SL-T001-1), 5 mol% Cu(OAc)(2)·H(2)O, 5 mol% bipyridine and 2.0 equiv. of PhSiH(3), to furnish polycyclic β-hydroxythioester products bearing three newly established contiguous stereocenters, with >98:2 dr and in up to 94% yield and 98% ee. The use of an amine such as bipyridine or 2,6-lutidine as additive results in an increase of the overall reaction rate. The major bicyclic aldol product has all substituents cis and can be rationalized by a reductively generated (Z)-enolate reacting with the dione via a cyclic transition state.
一系列乙硫磷的 1,3-二酮衍生物在由 5 mol% TaniaPhos (SL-T001-1)、5 mol% Cu(OAc)(2)·H(2)O、5 mol% 联吡啶和 2.0 当量的 PhSiH(3)原位生成的手性铜氢化物催化下发生还原羟醛缩合反应，生成多环β-羟硫酯产物，产物中含有三个新建立的连续立体中心，具有>98:2 的 dr 值，收率高达 94%，对映选择性为 98%。使用诸如联吡啶或 2,6- 二甲基吡啶等胺作为添加剂会提高整体反应速率。主要的二环羟醛缩合产物的所有取代基均为顺式，可以通过还原生成的（Z）-烯醇盐与二酮通过环状过渡态反应来解释。
