One-step conversion of 2-amino-N'-arylbenzamidines into 3-aryl-4-imino-3,4-dihydroquinazoline-2-carbonitriles using 4,5-dichloro-1,2,3-dithiazolium chloride.

2-Amino-N'-arylbenzamidines react with 4,5-dichloro-1,2,3-dithiazolium chloride (Appel salt) in the presence of Hünig's base (2 equiv) to give in one step 3-aryl-4-imino-3,4-dihydroquinazoline-2-carbonitriles in 53-81% yields. Nine examples are presented along with the single-crystal X-ray structure of 4-imino-3-phenyl-3,4-dihydroquinazoline-2-carbonitrile. Furthermore, the behavior of the latter toward both acid and base hydrolysis is investigated. All new compounds are fully characterized, and a mechanistic rationale for the formation of the iminoquinazolines is provided.