Insertion of Fischer carbene complexes into the carboncarbon bond. Ring expansion of a sulfur heterocycle from five- to six-membered

The reaction of 4-X-5-alkylthio-3H-1,2-dithiole-3-thione (1) with Fischer carbene complexes (2) gives, as a main product, cyclohexa dithiine derivatives due to insertion of the carbene ligand into the C3C4 bond of the heterocycle. The reaction takes place with 1 where the alkyl substituents in position 5 are ethyl, butyl, benzyl and dodecyl and the substituents in position 4 are H, O-Me, Ph and Cl. Complexes with Cr and W as metallic center were used, the Cr complexes were more reactive than the W derivatives.