Asymmetric epoxidation of unsaturated hydrocarbons catalyzed by ruthenium complexes

Ruthenium complexes of various chiral ligands viz. porphyrins, Schiff-base, polypyridyl, pyridinebisoxazolines and pyridinebisimidazoline are known to perform asymmetric epoxidation of unfunctionalized alkenes with moderate to high enantioselectivity. The advancement of asymmetric epoxidation catalyzed by ruthenium chiral complexes has not been systematically reviewed till date. Hence, the subject of this review comprises the use of chiral complexes as catalysts for performing enantioselective epoxidation of olefins using various precursor oxidants. The catalytic ability and intriguing aspects of the ruthenium based catalyst complexes in asymmetric epoxidation under homogeneous reaction along with the mechanistic details are systematically reviewed in this article. This review highlights most recent investigations on the catalytic systems with chiral ruthenium complexes for olefin epoxidation. (C) 2007 Elsevier B.V. All rights reserved.