Ring transformations involving chloroheterocycles. Part III. Reaction of 4-chloroquinazolines with hydrazines

Abstract

Treatment of 4-chloroquinazolines with hydrazine hydrate at 150 °C in a sealed tube gives 4-amino-3-(2-aminophenyl)-4H-1,2,4-triazoles. With 4-chloroquinazoline itself, a second product, 3-(2-aminophenyl)-4H-1,2,4-triazole, is also isolated. The novel 4-amino-4H-1,2,4-triazoles undergo ring closure with triethyl orthoesters to form 5H-1,2,4-triazolo[4,3-d][1,3,4]benzotriazepines, and with aldehydes and ketones to give 6,7-dihydro-5H-1,2,4-triazolo[4,3-d][1,3,4]benzotriazepines. 4-Amino-3-(2-aminophenyl)-4H-1,2,4-triazole has been shown to yield the 3-(2-azidophenyl)-4H-1,2,4-triazole with one equivalent of nitrous acid and 1,2,4-triazolo-[4,3-c][1,2,3]benzotriazine with two equivalents of nitrous acid. Treatment of 4-chloroquinazoline with substituted hydrazines yields 1,3-disubstituted 1H-1,2,4-triazoles. Mechanisms for these rearrangements are suggested.