DMTSF-mediated electrophilic cyclization for the synthesis of 3-thiomethyl-substituted benzo[]furan derivatives.

Benzofuran is an important backbone for molecules that make up several pharmaceuticals, herbicides/pesticides, and organo-electronics. An environmentally benign dimethyl(methylthio)sulfonium tetrafluoroborate salt was used as an electrophile to induce cyclization of -alkynyl anisoles to form 2,3-disubstituted benzofurans. The cyclization is performed at ambient reaction conditions, only takes 12 hours to get excellent yields, and shows a high tolerance for various substituted alkynes.

A one-pot successive cyclization-alkylation strategy for the synthesis of 2,3-disubstituted benzo[]thiophenes.

In this study, a new environmentally benign iodine-mediated one-pot iodocyclization/alkylation strategy for the synthesis of benzo[b]thiophene derivatives starting from 2-alkynylthioanisoles was developed. The synthesis of a diverse population of 2,3-disubstituted benzo[b]thiophenes was achieved in high yields by employing moderate reaction conditions using 1,3-dicarbonyl substrates as the nucleophile and various substituted propargyl alcohols as both the cyclization precursor and the alkylating agent. This method resulted in the formation of a series of complex structures obtained in a single step.