Generation of thioaldehydes by base-catalysed cleavage of N-(alkoxycarbonylmethylthio)phthalimides

Abstract

N-(Methoxycarbonylmethylthio)- and N-(ethoxycarbonylmethylthio)-phthalimide react at room temperature with triethylamine to generate the corresponding alkyl thioxoacetates, which have been trapped, in situ, by cycloaddition to conjugated dienes; the endo- and exo-adducts of cyclopentadiene and ethyl thioxoacetate dissociate at 111 °C thereby allowing transfer of the thioaldehyde to other conjugated dienes.