Direct Regiospecific and Highly Enantioselective Intermolecular α-Allylic Alkylation of Aldehydes by a Combination of Transition-Metal and Chiral Amine Catalysts
The first direct intermolecular regiospecific and highlyenantioselective α‐allylic alkylation of linear aldehydes by a combination of achiral bench‐stable Pd0 complexes and simple chiralamines as co‐catalysts is disclosed. The co‐catalytic asymmetric chemoselective and regiospecific α‐allylic alkylation reaction is linked in tandem with in situ reduction to give the corresponding 2‐alkyl alcohols
首次公开了通过非手性稳固的Pd 0配合物和简单的手性胺作为助催化剂的组合,线性醛类的第一个直接的分子间区域特异性和高对映选择性的α-烯丙基烷基化反应。将共催化的不对称化学选择性和区域特异性α-烯丙基烷基化反应与原位还原串联在一起,得到相应的2-烷基醇,其对映体比率很高(er高达98:2; er =对映体比率)。它也是有价值的2-烷基取代的半缩醛,2-烷基-丁烷-1,4-二醇和胺的快速入口。公开了具有生物活性的天然产物(例如,Arundic酸)的简明共催化不对称全合成。
Diastereoselective Anti Aldol Reactions of Chiral Ethyl Ketones. Enantioselective Processes for the Synthesis of Polypropionate Natural Products.
作者:David A. Evans、Howard P. Ng、J.Stephen Clark、Dale L. Rieger
DOI:10.1016/s0040-4020(01)88879-7
日期:1992.1
aldol reactions of the β-keto imide 3a, the related ethyl ketone 20b, and its diastereomer 22b have been studied. In these aldol reactions, the chiral ethyl ketones 3a and 20b were found to exhibit the opposite sense of asymmetric induction in the analogous anti aldol bond constructions from the derived (E) boron enolates. The relevance of this study to the synthesis of polypropionate natural products
Catalytic Asymmetric Claisen Rearrangement of Unactivated Allyl Vinyl Ethers
作者:Maryll E. Geherty、Robert D. Dura、Scott G. Nelson
DOI:10.1021/ja1039314
日期:2010.9.1
original discovery, catalyzed enantioselective variants of the venerable Claisenrearrangement remain relatively rare. We have discovered a cooperative transition metal-Lewis acid cocatalyst system that affects highly enantio- and diastereoselective examples of archetypical Claisenrearrangements. The catalyzed rearrangements proceed using an easily prepared enantioenriched transition metal catalyst
Studies directed toward the synthesis of the rutamycins. Assemblage of the polypropionate region of rutamycin B
作者:David A. Evans、Howard P. Ng
DOI:10.1016/s0040-4039(00)77580-0
日期:1993.4
the asymmetric synthesis of the polypropionate segment of rutamycin B is reported. In this convergent synthesis the construction of the C1-C8 and C9-C17 subunits and their union through a doublestereodifferentiatingaldol fragment coupling are described. The stereoselectivity of this coupling reaction critically depends on both the configuration and choice of protecting group for the C9 oxygen.