Highly Efficient, Regio- and Stereoselective Ring Opening of Epoxides and Thiiranes with Ce(OTf)₄

Abstract

Ceric triflate, Ce(OTf)₄ is used as an efficient catalyst for ring opening of epoxides in the presence of alcohols, water, and acetic acid. The reactions proceed with high regio and stereoselectivity and in excellent yields. The reaction of R(+) styrene oxide with methanol occurs with excellent optical purity. Ring opening of thiiranes in alcohols, water and acetic acid followed by dimerisation to the corresponding disulfides occur efficiently in the presence of this reagent. A mild method for the preparation of dithianes from thiiranes and Ce(OTf)₄ is also described.