The methoxycarbonylcarbene insertion into 1,3-dithiolane and 1,3-oxathiolane rings

Abstract

Treatment of substituted 1,3-dithiolanes and 1,3-oxathiolanes with methyl diazoacetate in the presence of Rh-2(OAC)(4) effects ring expansion to the corresponding substituted 1,4-dithiane-2-carboxylates and 1,4-oxathiane-3-carboxylates. The sulfur ylides initially generated in these reactions undergo Stevens rearrangement in competition with both [2,3]-C-C-sigmatropic rearrangement and intramolecular fraomentation. In the case of 2-styryl-substituted 1,3-oxathiolane and 1,3-dithiolane, fing expansion on one-, three- and fourcarbons subsequently takes place. (c) 2006 Elsevier Ltd. All fights reserved.