OXA-SPIRODIPHOSPHINE LIGAND AND METHOD FOR ASYMMETRIC HYDROGENATION OF alpha, beta-UNSATURATED CARBOXYLIC ACIDS

摘要

The present invention provides an oxa-spirodiphosphine ligand having a structure of general Formula (I) below:; ;wherein in general Formula (I), R1, R2, R3 and R4 are the same, and are alkyl, alkoxy, aryl, aryloxy, or hydrogen, in which R1, R2, R3 and R4 may or may not form a ring, any two of them may form a ring, or a polycyclic ring may be formed between two pairs of them; R5 and R6 is alkyl, aryl, or hydrogen; and R7 and R8 is alkyl, benzyl, or aryl. The present invention also provides a method for asymmetric hydrogenation of α,β-unsaturated carboxylic acids. A complex of the oxa-spirodiphosphine ligand with ruthenium shows excellent activity and enantioselectivity in the asymmetric hydrogenation of various α,β-unsaturated carboxylic acids, with which a chiral carboxylic acid product can be obtained with an enantioselectivity up to 99%.