Unexpected rearrangements in the synthesis of arylidene- or alkylidene-2-thiophthalides

Article abstract of DOI:10.1016/0040-4020(96)00678-3

Mechanistic studies concerning the reaction by which poly(isothianaphthene) (PITN) is synthesized in one step from commercially available monomers by reacting them with phosphorus pentasulphide (P₄S₁₀), have led to the idea of synthesizing a chain-stopper molecule which should give rise to suitable quinoid model compounds for PITN. Within this context benzylidenedithiophthalide and pentylidenedithiophthalide were chosen as target molecules. The unexpected rearrangements and the control of these rearrangements in the synthesis of benzylidenedithiophthalide and pentylidenedithiophthalide are reported.