Cyclocondensation Reactions of 3-Amino-2-hydrazino-4(3H)-pyrimidones. Formation of 1,2,4-Triazolopyrimidines and Pyrimidotetrazines

Article abstract of DOI:10.1021/jo00387a021

3-amino-2hydrazino-4(3H)-pyrimidinones 1, derived from diaminoguanidine and β-keto esters, react readily with ortho esters in hot acetic acid or butanol to give 1,2,4-triazolo<4,3-a>pyrimidin-7(8H)-ones 2.In acetic acid at room temperature, 1 reacts with ortho esters, dimethylformamide dimethyl acetal, and diethoxymethyl acetate to form 2 and 6H-pyrimido<1,2-b><1,2,4,5>tetrazin-6-ones 3.The latter ring system undergoes a thermal, acid catalyzed, rearrangement to 2.