The first asymmetrichydrogenation of β,β-diaryl unsaturated phosphonates has been realized for synthesis of β,β-diaryl chiralphosphonates with excellent enantioselectivities (up to 99.9% ee) catalyzed by the Rh-(R,R)-f-spiroPhos complex. Furthermore, this catalyst also exhibits comparably excellent performance for β-aryl-β-alkyl unsaturated phosphonates providing the corresponding chiral phosphonates
首次实现了β,β-二芳基不饱和膦酸酯的不对称氢化,用于在Rh-( R , R )-f-spiroPhos 络合物催化下合成具有优异对映选择性(高达99.9% ee)的β,β-二芳基手性膦酸酯. 此外,该催化剂对 β-芳基-β-烷基不饱和膦酸酯也表现出相当优异的性能,提供相应的手性膦酸酯,其 ee 值高达 99.9%。这种方法为不对称合成手性膦酸盐提供了一种直接的途径。
Enantioselective synthesis of optically active alkylphosphonates via Rh-catalyzed asymmetric hydrogenation of β-substituted α,β-unsaturated phosphonates
The Rh-catalyzed asymmetric hydrogenation of beta-substituted alpha,beta-unsaturated phosphonates using (S-c,S-p)-WalPhos as the chiral ligand is reported, in which a wide range of optically active beta-substituted alkylphosphonates were obtained in good yields and with good to excellent enantioselectivities (86-98% ee). In contrast to the Rh/(R-c,S-a)-FAPhos system previously reported by us, the present catalytic system shows a wider substrate scope, and can perform the hydrogenation under milder reaction conditions. Crown Copyright (C) 2012 Published by Elsevier Ltd. All rights reserved.
Rhodium-Catalyzed Enantioselective Hydrogenation of Unsaturated Phosphonates by ClickFerrophos Ligands
Newly developed ClickFerrophos II ligands were applied in the hydrogenation of alpha,beta-unsaturated phosphonates. The use of a rhodium/ClickFerrophos II catalyst was examined in the hydrogenation of fimctionalized alpha,beta-unsaturated phosphonates and was revealed to be effective for beta-alkyl-beta-aryl or beta-dialkyl phosphonates, (Z)-beta-enolester phosphonates, and alpha-phenylethenyl phosphonates, producing the corresponding chiral phosphonates in good yields with high enantioselectivities (up to 96% ee).