Silica gel supported bis-cinchona alkaloid: A highly efficient chiral ligand for heterogeneous asymmetric dihydroxylation of olefins

Abstract

Comparable reactivity and enantioselectivity to those in homogeneous solution have been achieved in heterogeneous catalytic asymmetric dihydroxylation (AD) of olefins using a new silica gel supported cinchona alkaloid containing 1,4-bis(9-O-quininyl)phthalazine ((QN)(2)-PHAL). Moreover, the silica supported alkaloid exhibited much greater binding ability for OsO4 than its homogeneous analogue. (C) 1997 Elsevier Science Ltd.