Dienophilie des olefines captodatives : Cycloadditlons de diels-alder de l'α-methylthio-acrylonitrlle et transformation des adduits

Abstract

The cycloaddition reactions of the α-methylthio-acrylonitrile with 1,3-dienes are investigated. The uncatalysed thermal reactions proceed in high yields very stereoselectively with cyclic dienes and especially even at room temperature with cyclopentadiene. In this later case we shown that the stereoselectivity decreases with increasing temperature. With acyclic dienes the reactions are regio and stereoselective. These both selectivities can be enhanced by Lewis acid catalysis. The stereochemical assignments of the adducts are performed on the basis of spectroscopie data. Then, the cycloadducts are transformed to cyclic (or polycyclic) dienic compounds by sequential oxydation and elimination reactions. Thus, the α-methylthio-acrylonitrile can be considered as an efficient cyano-acetylene equivalent for Diels-Alder reactions.