A FACILE SYNTHESIS OF SUBSTITUTED 1,4-BENZOTHIAZEPIN-5(4H)-ONES AND PYRIDO[3,2-F][1,4]THIAZEPIN-5(4H)-ONES - CRYSTAL AND MOLECULAR-STRUCTURE OF 4H)-OXOPYRIDO[3,2-F][1,4]THIAZEPINE-3-CARBONITRILE

A new synthesis of pyrido[3,2-f][1,4]thiazepine derivatives 3 starting with 2-chloronicotinic acid (1), methylaminoacetonitrile hydrochlorid e and carbon disulfide is described. As proved by a crystal structure determination, a boat conformation with approximated mirror symmetry c an be assigned to the 1,4-thiazepine ring in 3b. 2-Chloro-N-cyanomethy l-N-methyl-5-nitrobenzamide (5) reacts with carbon disulfide in presen ce of a strong base in DMF or DMSO depending on the temperature to eit her the benzothiopyran compound 6 or by intramolecular aromatic nucleo philic substitution to a seven-membered ring system as thiolate anion which can be alkylated to give the 1,4-benzothiazepine derivative 7, o r to an open-chain amido ketene dithioacetal 8.