Synthesis of a Benzo[5,6]cyclohepta[1,2-b]thiophene and Thieno[3,2-c]benzazepine Derivatives

A new series of 2-methyl-4-(4-methylpiperazin-1-yl)-10H-benzo[5,6]cyclohepta[1,2-b]thiophene (5) and 2-methyl-4-(4-methylpiperazin-1-yl)thieno[3,2-c][1]benzazepine derivatives 6b-f have been synthesized from 2-methylthiophene and phthalic anhydride. Preparation of the key intermediate 2-methyl-4,5-dihydro-10H-benzo[5,6]cyclohepta[1,2-b]thiophene-4-one (12) and 2-methylthieno[3,2-c][1]benzazepine-4(5H),10-dione (16) were carried out by intramolecular dehydration of the phenylacetic acid 11 and Lewis acid associated cyclization of the isocyanate 14, respectively.