Chiral Ru(II) Schiff base complex-catalysed enantioselective epoxidation of styrene derivatives using iodosyl benzene as oxidant. II

Six-coordinated chiral Ru(II) Schiff base complexes of the type [RuLX(Y)(2) ] where L = terdentate chiral Schiff bases derived from L-tyrosine, L-pheny lalanine with salicylaldehyde, 3-tertiary-butyl-, 3,5-di-tertiary-butyl-, 3 ,5-dichloro- and 3,5-dinitrosalicylaldehyde, X = PPh3 and Y = H2O have been investigated as catalysts for enantioselective epoxidation of styrene, 4-c hloro-, 4-nitro- and 4-methylstyrene in fluorobenzene in order to explore t he efficiency of catalytic system by varying the substituents on the ligand moiety of the catalysts as well as on the substrates using iodosyl benzene as terminal oxidant. Much better results were obtained with catalyst 5 and 10 with 4-nitrostyrene. The enantiomeric excess of the resulting epoxide w as evaluated by chiral capillary column. (C) 1999 Elsevier Science B.V. All rights reserved.