Thionation of N-Methyl- and N-Unsubstituted Thiazolidine Enaminones

Abstract

The potential of the directional non-bonded 1,5-type S···O interactions to initiate an incipient stage of an in situ rearrangement of N-unsubstituted thiazolidine enaminones to the functionalized 1,2-dithioles has been demonstrated. Spectral characteristics, as well as an X-ray structural analysis of the selected rearranged product, indicate that a dynamic interconversion occurs in a solution between the 1,2-dithiole and 3,3aλ⁴,4-trithia-1-azapentalene bicylic form. The lack of the rearrangement in the case of the N-methyl substituted enaminone precursor is attributed to an unfavorable methyl migration in the last reaction step