Highly Enantioselective Hydrogenation of β-Acyloxy and β-Acylamino α,β-Unsaturated Phosphonates Catalyzed by Rhodium Phosphane-Phosphite Complexes
作者:M. Ángeles Chávez、Sergio Vargas、Andrés Suárez、Eleuterio Álvarez、Antonio Pizzano
DOI:10.1002/adsc.201000611
日期:2011.10
The enantioselective hydrogenation of β-(acyloxy)- and β-(acylamino)vinylphosphonates with rhodium catalysts based on chiral phosphane-phosphite ligands has been studied. In the case of the β-(acyloxy)vinylphosphonates, the reaction also produces an achiral phosphonate resulting from the elimination of the benzoate group. High ligand modularity has led to a highly chemo- and enantioselective catalyst
研究了基于手性膦-亚磷酸酯配体的铑催化剂对β-(酰氧基)-和β-(酰氨基)乙烯基膦酸酯的对映选择性氢化。在β-(酰氧基)乙烯基膦酸酯的情况下,该反应还由于消除了苯甲酸酯基团而产生了非手性膦酸酯。高配体模块性导致对两种类型的底物都具有高度化学和对映选择性的催化剂,从而提供了范围广泛的β-酰氧基-和β-酰氨基膦酸酯,对映选择性在90%到99%ee之间。最有趣的是,氢化产物的构型对于两种类型的底物的还原指示相同的立体化学意义,这与之前对α-(酰氧基)乙烯基膦酸酯所观察到的相反。通过假设在催化循环过程中形成了β-烷基中间体,已经使这一观察变得合理,这也解释了在β-(酰氧基)-乙烯基膦酸酯的氢化中消除产物的形成。