Asymmetric oxidation of sulfides catalyzed by chiral (salen)Mn(III) complexes with a pyrrolidine backbone

✍ Scribed by Aiping Gao; Mei Wang; Jicheng Shi; Dongping Wang; Wei Tian; Mei Wang; Licheng Sun

• Publisher: John Wiley and Sons
• Year: 2006
• Tongue: English
• Weight: 117 KB
• Volume: 20
• Category: Article
• ISSN: 0268-2605
• DOI: 10.1002/aoc.1121

✦ Synopsis

Abstract

Catalytic properties of a series of chiral (pyrrolidine salen)Mn(III) complexes for asymmetric oxidation of aryl methyl sulfides were evaluated. Moderate activity, good chemical selectivity and low enantioselectivity were attained with iodosylbenzene as a terminal oxidant. Enantioselectivity of sulfide oxidation was affected slightly by polar solvent and the sulfoxidation carried out in THF for thioanisole and in CH~3~CO~2~Et for electron‐deficient sulfides gave better enatioselctivities. The addition of the donor ligand PPNO (4‐phenylpyridine N‐oxide) or MNO (trimethylamine N‐oxide) only has a minor positive effect on the enantioselectivity. Also explored was the steric effect of the N~aza~‐substituent in the backbone of (pyrrolidine salen)Mn(III) complexes on the enantioselectivity of sulfide oxidation. The sulfides' access pathway is discussed based on the catalytic results. Copyright © 2006 John Wiley & Sons, Ltd.