Sergey A. Komykhov

Partially hydrogenated aromatic substituted tetrazolo[1,5-a]pyrimidines

By treating 5-aminotetrazole with aromatic α,β-unsaturated ketones or with Mannich base hydrochlorides there have been synthesized aromatic substituted 4,7-dihydrotetrazolo[1,5-a]-pyrimidines. They can be reduced to the corresponding 4,5,6,7-tetrahydro derivatives by the action of NaBH4. The high thermodynamic stability of the 4,7-dihydrotetrazolo[1,5-a]pyrimidines when compared with the 4,5-dihydro isomers has been revealed. Reaction of 5-aminotetrazole both with cyclohexanone as well as with 2-cyclohexylidenecyclohexanone leads to formation of 9,9-pentamethylene-4,5,6,7,8,9-hexahydrotetrazolo[5,1-b]quinazoline, the structure of which was demonstrated using X-ray crystallography.

Synthesis and structure of 3,7-dihydro-2h-1,2,4-triazolo-[1′,5′-a′]tripyrimido[4,5-d]benzo[bpyrans

The condensation of 5-(2-hydroxyphenyl)-6, 7-dihydro-1, 2, 4-triazolo[l, 5-a]pyrimidines with aldehydes yields derivatives of a new heterocyclic system, namely, 3,7-dihydro-2H-1,2,4-triazolo[1′,5′-a′]pyrimido[4,5-d]-benzo[b]pyran, including the 9-methyl-2,3-diphenyl derivative, whose structure was established by x-ray diffraction structural analysis.

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-triazolo[1,5-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.

(5S,7R)-5-Aryl-7-methyl-4,5,6,7-tetrahydro-[1, 2, 4]triazolo[1,5-a]pyrimidin-7-ols as products of three-component condensation

(5S,7R)-5-Aryl-7-methyl-4,5,6,7-tetrahydro[1, 2, 4]triazolo[1,5-a]pyrimidin-7-ols were synthesized by three-component reactions of 1H-1,2,4-triazol-3-amine with aromatic aldehydes and acetone in the presence of TsOH. Antimicrobial and antifungal activities of these new substances were investigated in vitro.