10.1021/jo00387a021
This research explores the cyclocondensation reactions of 3-amino-2-hydrazino-4(3H)-pyrimidinones to form 1,2,4-triazolo[4,3-a]pyrimidin-7(8H)-ones and 6H-pyrimido[1,2-b][1,2,4,5]tetrazin-6-ones. The study aims to develop a synthetic strategy for creating ring-fused systems containing nitrogen at the ring-junction, utilizing the adjacent amino and hydrazino functional groups in a heterocyclic system. The researchers reacted 3-amino-2-hydrazino-4(3H)-pyrimidinones with ortho esters, dimethylformamide dimethyl acetal, and diethoxymethyl acetate in various solvents and conditions, yielding products with substituents. Key findings include the preferential reactivity of the primary amino function of the hydrazino substituent and the isomerization of the ring-fused tetrazine derivative to a ring-fused 1,2,4-triazole.