HU Juan, WANG Daoyong, ZHENG Zhuo*, HU Xiangping*
(Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China)
Abstract: A series of phosphine-phosphoramidite ligands derived from commercially available, inexpensive chiral 1-phenylethylamine were employed in the Rh-catalyzed asymmetric hydrogenation of various a-enol ester phosphonates. The results indicated that the ligand (Sc,Sa)-2b bearing a Me-group on amino moiety exhibited similar enantioselectivity but superior catalytic activity to (Rc,Ra)-THNAPhos. Excellent enantioselectivities (up to >99% ee) and high catalytic activity (S/C up to 5000) have been achieved in the hydrogenation of various b-alkyl and b-aryl substituted substrates, demonstrating the high potential of this phosphine-phosphoramidite ligand in the preparation of optically active a-hydroxyphosphonates.
Key words: asymmetric catalysis; rhodium; phosphine-phosphoramidite ligand; a-enol ester phosphonate; hydrogenation
Journal of Molecular Catalysis, Vol. 26, Issue 6, 2012, 487-492