The chameleon-like behaviour of 3-amino-1,2,4-triazole in the Biginelli reaction: unexpected formation of a novel spiroheterocyclic system

A novel Biginelli-like assembly of 3-amino-1,2,4-triazole with methyl acetoacetate and salicylaldehyde has been developed to enable easy access to spiro{[1]benzopyran-2,7′-[1,2,4]triazolo[1,5-a]pyrimidine} compounds as representatives of a new class of spiro-fused heterocycles. A three-component condensation mechanism is proposed and discussed.