Collection of Czechoslovak Chemical Communications - digital archive 

Abstract

Substituted allylic alcohols (2-buten-1-ol, 1-buten-3-ol, cinnamyl alcohol and 3-methyl-2-buten-1-ol) react with acyl isothiocyanates (4-chlorobenzoyl, 2,6-difluorobenzoyl, 3-phenylpropenoyl, 2-thienocarbonyl, 3-chloro-2-thienocarbonyl and 3-chloro-2-benzo[b]thienocarbonyl isothiocyanate) with the formation of highly reactive O-substituted allyl N-acylmonothiocarbamates, which either spontaneously or by heating in boiling benzene undergo [3,3]-sigmatropic rearrangement to S-substituted allyl N-acylmonothiocarbamates. The structure of S-esters with isomerized allylic group affords the unequivocal evidence of the [3,3]-sigmatropic route of studied rearrangement. Further heating of [3,3]-rearranged N-(4-chlorobenzoyl)monothiocarbamates results in the [1,3]-sigmatropic shift of monothiocarbamate group. Using arylalkyl alcohols with the allylic double bond inserted into an aromatic system the obtained O-esters either do not undergo any rearrangement (benzyl alcohol) or undergo [1,3]-sigmatropic rearrangement (2- and 3-furylmethanol and 1-(2-furyl)ethanol) to the corresponding S-esters. For explanation of this reaction the tandem of [3,3]- and [1,3]-sigmatropic rearrangements is suggested.