Unsymmetrical ferrocenylethylamine-derived monophosphoramidites: highly efficient chiral ligands for Rh-catalyzed enantioselective hydrogenation of enamides and alpha-dehydroamino acid derivatives.
[reaction: see text] A new family of unsymmetrical ferrocenylethylamine-derived monophosphoramidites were synthesized and successfully applied in the Rh-catalyzed enantioselective hydrogenation of a range of enamides and alpha-dehydroamino acid esters, and ee values of up to 99.5% were obtained for both types of substrate. These results suggest that unsymmetrical amine-derived monophosphoramidites can also exhibit excellent enantioselectivity for a broad range of substrates, comparable to or higher than those of the most efficient symmetrical amine-derived monophosphoramidites reported thus far.
Zeng
Qing-Heng
QH
Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, China.
Hu
Xiang-Ping
XP
Duan
Zheng-Chao
ZC
Liang
Xin-Miao
XM
Zheng
Zhuo
Z