Synthesis of a new chiral bisphosphine ligand, MOCBP, and its use in rhodium(I)-catalyzed asymmetric hydrogenation of a cyclic enamide

Abstract

A new chiral bisphosphine ligand ( 6) bearing a cyclobutane framework was readily prepared by using diastereoselective [2+2] cycloaddition. Its rhodium(I) complex was found to be an efficient catalyst for the asymmetric hydrogenation of a cyclic enamide, N-acetyl-1-methylene-1,2,3,4-tetrahydroisoquinoline ( 9), affording ( R)-(−)- N-acetylsalsodine ( 10) in up to 80.6% ee.