Asymmetric Bioreductions of β-Nitro Acrylates as a Route to Chiral β2-Amino Acids
摘要:
Reductions of beta-nitroacrylates by Saccharomyces carlsbergensis old yellow enzyme is the key step in a concise route to optically active beta(2)-amino acids. The enzymatic reductions occur with 87 - 96% ee, with larger substrates providing greater stereoselectivities. This work extends enantioselective enzymatic alkene reductions to include acyclic systems with weakly coordinating substituents.
已经开发出一种新的手性N,N'-二氧化物-Cu I催化剂用于不对称的亨利(硝基醛)反应。该方法得益于手性空间的轻松修改。作为高效的N-氧化物配体,已将1d用于与芳香族和杂芳香族醛的亨利反应。以良好的收率获得了相应的硝基醇产物,对映体过量高达98%。此外,α-酮酸酯也被该催化剂催化,以产生有吸引力的旋光性α-羟基β-硝基酯,其包含手性季碳中心(ee高达99%)。基于多种技术的结合,其中包括1通过1 H NMR,ESI-HRMS和MM2计算,提出了所提出的机理以解释反应性和不对称电感性的起源。
Enantioselective Nitroaldol Reaction of α-Ketoesters Catalyzed by Cinchona Alkaloids
作者:Hongming Li、Baomin Wang、Li Deng
DOI:10.1021/ja057237l
日期:2006.1.1
The development of highly enantioselective and general catalytic nitroaldol (Henry) reactions with ketones is a challenging yet desirable task in organic synthesis. In this communication, we report an asymmetric nitroaldol reaction with alpha-ketoesters catalyzed by a new C6'-OH cinchonaalkaloid catalyst. This is the first highly efficient organocatalytic asymmetric Henry reaction with ketones. This
Asymmetric aldol additions using bifunctional cinchona-alkaloid-based catalysts
申请人:Deng Li
公开号:US20070112199A1
公开(公告)日:2007-05-17
One aspect of the present invention relates to asymmetric catalytic nitroaldol (Henry) reactions with ketones as the electrophilic component. In one embodiment, the present invention relates to asymmetric nitroaldol reactions with α-keto esters catalyzed by a new C6′-OH cinchona alkaloid catalyst. In certain embodiments, this reaction is operationally simple and affords high enantioselectivity as well as good to excellent yield for an exceptionally broad range of α-keto esters.