Reactivity of 1-aryl-4-dimethylamino-2-phenyl-1,3-diaza-1,3-butadienes towards dienophiles, 1,3-dipoles and carbanions

The reactivity of 1-aryl-4-dimethylamino-2-phenyl-1,3-diaza-1,3-butadienes (1) towards dienophiles, 1,3-dipoles and C-nucleophiles was investigated. N-Phenylmethylene-benzenesulfonamide (2), phenylisocyanate (6), C,N-diphenylnitrone (9) and acylacetates (10) reacted with 1 giving quinazoline or pyrimidine derivatives. The possible mechanisms involved in products formation are discussed.