Regioselective synthesis and oxidation of a new series of 6-nitro-4,5,6,7-tetrahydro-1,2,4-triazolo[1,5-a]pyrimidines

A method was developed for the synthesis of compounds of a new series of 5,7-diaryl-6-nitro-4,5,6,7-tetrahydroazolo[1,5-a]pyrimidines under the conditions of the Michael reaction between the corresponding triazole-containing Schiff bases and β-nitrostyrene derivative followed by additional heterocyclization. The oxidation of the resulting tetrahydro derivatives with manganese(iv) oxide made it possible to prepare previously unknown functional derivatives of 2-substituted 5,7-bis(4-methoxyphenyl)-6-nitro-1,2,4-triazolo-[1,5-a]pyrimidines, whose structures were determined using NMR correlation spectroscopy (¹H—¹H NOESY, ¹H—¹³C HMBC).