Imine-enamine tautomerization of dihydroazolopyrimidines 4. Synthesis and tautomerization of 5-(2-hydroxyphenyl)-dihydro-1,2,4-triazolo[1,5-a]pyrimidines

The condensation of 3-amino-1,2,4-triazole with 2-hydroxychalcones gives 7-aryl-5-(2-hydroxyphenyl)-4,7(6,7)-dihydro-1,2,4-triazolo1,5-a]pyrimidines. Both tautomeric forms were isolated for a number of these compounds. PMR spectroscopy was used to show that the enamine form is predominant in DMSO in contrast to the case in CHCl₃.For Communication 3, see 1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1353–1356, October, 1993.