Synthesis of the New Triheterocyclic System C 3 N-C 4 N-C 6 N. 3-Aryl-2,5,5-trimethyl-9a-methylsulfanyl-9-phenoxy-4,5,6,8,9,9a-hexahydr o-3H-azeto[1,2-a]pyrrolo[3,2-c]azepin-8-ones. -The first members [cf.(VII), 6 examples] of the new triheterocyclic system are prepared in a regio-and stereoselective manner by a four-step sequence from the oximes (I). -(MAR-