Synthesis of Unprecedented Benzofused [1,2,4]-Triazoloquinazolines via Benzyne Diels-Alder Reaction with 7-Vinyl-[1,2,4]triazolo[1,5-c]pyrimidines as Dienes

The benzyne Diels-Alder reaction with 7-vinyl-[1,2,4]triazolo[1,5-c]pyrimidines as a kind of unusual acyclic dienes has been investigated. The transformation proceeded smoothly in the presence of CsF to afford the unprecedented partially hydrogenated benzo[f][1,2,4]triazolo[1,5-c]quinazolines in good yields. Treatment of benzo[f][1,2,4]triazolo[1,5-c]quinazolines with DDQ provided the respective dehydroaromatization products.