gem-Dialkylthio vinylallenes: alkylthio-regulated reactivity and application in the divergent synthesis of pyrroles and thiophenes.

gem-Dialkylthio vinylallenes were obtained for the first time and applied to the divergent synthesis of fully-substituted pyrroles and thiophenes by domino cyclizations. These two cyclization pathways were regulated by alkylthio groups. Plausible reaction mechanisms were presented and supported by DFT calculations. An unprecedented metal-free carbothiolation was discovered in the formation of thiophenes.