Cyclic meso-ionic heterocycles. Part 24. The reaction of 1,2-dithiolium-4-olates with aniline. The formationof 11-phenylbenz[b]indeno[2,1-e]-1,4-thiazine

Abstract Reaction of the type B meso-ionic heterocycle 3,5-diphenyl-1,2-dithiolium-4-olate ( 1 ) with aniline yields N -phenyl-(3-phenyl-1-phenylimino-inden-2-yl)-amine ( 10 ) and 11-phenylbenz[ b indeno[2,1- e ]-1,4-thiazine ( 12 ). Mechanistic investigations establish that the 3-phenylindenylamine ( 10 ) is an intermediate in the formation of the tetracyclic 1,4-thiazine ( 12 ).