Ž . Journal of Molecular Catalysis A: Chemical 121 1997 25–31 Synthesis, physicochemical studies and aerobic enantioselective ž / epoxidation of non functionalized olefins catalyzed by new Co II chiral salen complexes R.I. Kureshy ) , N.H. Khan, S.H.R. Abdi, A.K. Bhatt, P. Iyer Central Salt and Marine Chemicals Research Institute, BhaÕnagar - 364 002, India Received 11 September 1996; accepted 20 November 1996 Abstract Ž . Ž . Co II chiral salen complexes 1 – 3 derived from a-naphthyl salicylaldehyde with 1 S,2 S q diaminocyclohexane, Ž . Ž . 1 R,2 R y diaminodiphenylethane and S q 1,2-diaminopropane have been prepared. The characterization of the complexes was done by microanalysis, magnetic moment, IR-, UVrVis-, CD spectral studies, optical rotation, conductance measurements and cyclic voltammetry. Epoxidation of non-functionalized prochiral olefins viz. styrene, trans 3-nonene and trans 4-octene was achieved by the combined use of an atmospheric pressure of molecular oxygen and sacrificial reductant Ž . isobutyraldehyde catalyzed by the above synthesized Co II chiral salen complexes with and without pyridine N-oxide as cooxidant. Good yields of the desired epoxide were obtained with the substrate trans 3-nonene and trans 4-octene by GLC. 1 Ž . Enantiomeric excess of the epoxide were evaluated by H NMR using chiral shift reagent Eu hfc and by chiral capillary 3 column. Keywords: Aerobic epoxidation; Enantioselective; Non-functionalized olefins; Cobalt; Chiral Schiff base 1. Introduction Enantioselective epoxidation of prochiral olefins is one of the most challenging area in w x organic synthesis 1–3 because the epoxide formed are very useful synthetic intermediates for complexed chiral bioactive molecules or as end product which also have biological activity wx such as gypsy moth insect pheromones 4 . Much attention has been paid towards the develop- ) Corresponding author. Fax: q91-278-426970; e-mail: gen- eral@cscsmcri.ren.nic.in. ment of direct and selective epoxidation of olefins by use of molecular oxygen and a suit- able reductant which can accept one oxygen atom from molecular oxygen to perform the w x reaction 1–3,5–9 . Several reports have been published about the utility of primary alcohol w x wx wx 10 , aldehydes 6 or cyclic ketones 3 as effi- cient reductant in the aerobic oxidation of olefins w x catalyzed by transition metal complexes 11–13 . In continuation of our earlier work on enan- tioselective epoxidation of non functionalized Ž . Ž . Ž . olefins using Ru II , Ru III and Mn III chiral w x Schiff base complexes 14–16 and to explore 1381-1169r97r$17.00 Copyright q 1997 Elsevier Science B.V. All rights reserved. Ž . PII S1381-1169 96 00452-9