A [2++ 4] polar cycloaddition of α-thiocarbocations with 1,3-dienes: synthesis and thermal reaction of 1-acyl-1-methylthio-2-vinylcyclopropanes

Abstract

Treatment of methyl 2-chloro-2-(methylthio)acetate, 1-chloro-1-(methylthio)propan-2-one, chloro-(methylthio)methyl phenyl ketone, or 2-chloro-2-(methylthio)acetonitrile with 1,3-dienes in the presence of stannic chloride followed by addition of triethylamine gave 1-acyl- or 1-cyano-1-(methylthio)-2-vinylcyclopropanes. A mechanistic interpretation of this reaction is presented. Thermal behaviour of the vinylcyclopropanes is also described.