Synthetic Organic Chemistry Laboratory, Advanced Science Institute, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-10198, Japan.
Chem Asian J. 2011 Feb 1;6(2):658-68. doi: 10.1002/asia.201000740. Epub 2010 Dec 16.
The tandem aza-Michael reaction/enantioselective protonation of α-substituted α,β-unsaturated carbonyl compounds is described in detail. The key to success is the combined use of a Brønsted basic palladium-μ-hydroxo complex and amine salts, which allows for the controlled generation of active catalyst and nucleophilic free amines. This catalytic system was applicable to various acceptors and aromatic amines, and the desired β-amino acid derivatives with a chiral center at the α position were produced in good yield with excellent enantioselectivity (up to 98% ee). For electron-deficient amines, the introduction of free amine as an additive was effective in promoting the reaction. The results of mechanistic studies, including determination of the absolute configuration of the product, are discussed.
详细描述了α-取代的α,β-不饱和羰基化合物的串联氮杂迈克尔反应/对映选择性质子化反应。成功的关键是联合使用布朗斯特碱性钯-μ-羟基金属配合物和胺盐，这允许活性催化剂和亲核游离胺的受控生成。该催化体系适用于各种受体和芳基胺，并且具有手性中心的所需的β-氨基酸衍生物在α位置以良好的产率和优异的对映选择性（高达 98%ee）生成。对于缺电子的胺，引入游离胺作为添加剂可以有效地促进反应。讨论了包括确定产物的绝对构型的机理研究结果。
