REGIOSELECTIVE CONVERSION OF LACTAM TO CORRESPONDING THIOLACTAM IN ETRAHYDROPYRROLO[1,2-A]THIENO[3,2-E][1,3]DIAZEPINE

Starting from the etrahydropyrrolo[1,2-a]thieno[3,2-e][1,3]diazepine ( 2a) we obtained thio-and dithiolactam 3a and 4a by action of one or tw o equivalents of Lawesson's reagent. Dithiolactam 4a treated with merc uric chloride in boiling water led to the monolactam ja. This latter w as also synthesized with good yields using another pathway in which th e thionation reaction was performed on N-(thien-2'-ylmethyl)-5-oxoprol ine methyl ester precursor (la) before the cyclization step.