5-Cyano-7-(2-hydroxyphenyl)-4-[(2-hydroxyphenyl)amino]pyrrolo[2,3-c][1,2,6]thiadiazin-6(7H)-iminium Chloride Hydrate

Reaction of 2-(3,5-dichloro-4H-1,2,6-thiadiazin-4-ylidene)malononitrile with sodium 2-aminophenolate (1.5 equiv.) in anhydrous THF at ca. 0–20 °C afforded the known 4-chlorobenzo[5,6][1,4]oxazino[2,3-c][1,2,6]thiadiazine in 76% yield. In contrast, treatment of the same substrate with 2-aminophenol (3 equiv.) in acetonitrile at ca. 20 °C gave 5-cyano-7-(2-hydroxyphenyl)-4-[(2-hydroxyphenyl)amino]pyrrolo[2,3-c][1,2,6]thiadiazin-6(7H)-iminium chloride hydrate in 93% yield. This compound was characterized by 1H and 13C NMR, IR and UV-vis and mass spectrometry, together with melting point and elemental analysis, and its structure was supported by single-crystal X-ray crystallography.