Synthesis of 3-hetaryl-4,5,6,7-tetrahydrobenzo[b]thiophenes

A novel efficient synthesis of 3-hetaryl-4,5,6,7-tetrahydrobenzob]thiophenes was achieved by the cyclocondensation of ethyl 2-amino-4,5,6,7-tetrahydrobenzo6]thiophene-3-carboxylate with selected o-substituted aromatic amines or with alifatic, aromatic and heterocyclic acid hydrazides in the presence of polyphosphoric acid.