Iron-ligand coordination in tandem radical cyclizations: Synthesis of benzo[b]thiophenes by a one-pot reaction of iron 1,3-diketone complexes with 2-thiosalicylic acids

摘要

Iron-the mediator: 1,3-Diketone ligands coordinated to iron undergo unprecedented tandem reactions with 2-thiosalicylic acids to give 2-substituted 3-hydroxylbenzo[b]thiophenes in up to 98 % yield. A similar reaction with 2-mercaptonicotinic acid gave a thieno[2,3-b]pyridine derivative in 72 % yield (see scheme). A mechanism involving redox transformation and tandem radical cyclization of the coordinated ligands is proposed.