Mechanism of the rearrangement of 2-thioacylmethylene-1,3-dithioles to 1,6,6a-trithiapentalenes (6a-thiathiophthens)

Abstract

The rearrangement of 2-thioacylmethylene-1,3-dithioles to 1,6,6a-trithiapentalenes is catalysed by sulphur and a mechanism involving the formation and decomposition of a spiro compound is proposed; the rearrangement, and an alternative source of the spiran from a thioacylcarbene are considered to be responsible for the formation of trithiapentalenes from 1,2-dithiole-3-thiones and arylacetylenes.