Reaction of 3,4,4,5-tetrachloro-4H-1,2,6-thiadiazine with benzyltriethylammonium chloride.

Graphical abstract Highlights • 3,4,4,5-Tetrachloro-4 H -1,2,6-thiadiazine reacts with cat. BnEt 3 NCl to give a mixture of mono- and polycyclic heterocycles. • Single crystal X-ray studies support the structures of four minor products. • Independent synthesis for 8-bromo-4-chloropyrrolo[2′,1′:2,3]imidazo[4,5- c ][1,2,6]thiadiazine-6,7-dicarbonitrile. Abstract 3,4,4,5-Tetrachloro-4 H -1,2,6-thiadiazine was reacted with BnEt 3 NCl (10 mol%) to give perchloro-9-thia-1,5,8,10-tetraazaspiro[5.5]undeca-1,4,7,10-tetraene (up to 18% yield), 4,5,6-trichloropyrimidine-2-carbonitrile (up to 44% yield) and four minor side products: 2,7-dichlorothiazolo[5,4- d ]pyrimidine-5-carbonitrile, 2-(4-chloro-6 H -thiazolo[5,4- c ][1,2,6]thia-diazin-6-ylidene)malononitrile, 4,8-dichloropyrrolo[2′,1′:2,3]imidazo[4,5- c ][1,2,6]thiadiazine-6,7-dicarbonitrile and 4,7-dichloro-[1,2,6]thiadiazino[3,4- b ]thiazolo[5,4- e ][1,4]diazepin-9(10 H)-one. Single crystal X-ray studies support the structures of the minor products. Tentative rationale for the formation of these minor products and the synthesis of 8-bromo-4-chloropyrrolo[2′,1′:2,3]imidazo[4,5- c ][1,2,6]thiadiazine-6,7-dicarbonitrile are presented. [ABSTRACT FROM AUTHOR]