Facile synthesis of [1]benzothieno[3,2-b]benzothiophene from o-dihalostilbenes

A convenient one-pot synthesis of [1]benzothieno[3,2-b]benzothiophene from readily available o-dihalostilbenes using combined reagents of sodium sulfide nonahydrate (Na2S·9H2O) or sodium hydrosulfide hydrate (NaSH·nH2O) and sulfur is described along with plausible reaction paths in this intriguing reaction.