SYNTHESIS OF SOME SUBSTITUTED 1,2,4-TRIAZOLO [1,5-a] PYRIMIDINES OF POTENTIAL BIOLOGICAL ACTIVITY

Abstract

The present investigation is concerned with the synthesis of some substituted 1,2,4-triazolo[ 1,5-a]pyrimidines as potential antibacterial agents as analogue to purine in biochemical reaction. The key intermediates, 5-amino-1 H-3-(pyridy) 1,2,4-triazoles were prepared by fusion of pyridine carboxylic acids with aminoguanidine sulfate at 210 °c for 2 hours, or reaction of pyridine carboxylie acid hydrazides with S-methyl isothiourea sulfate at room temperature in presence of sodium hydroxide for 20 hours to give pyridinoyl aminoguanidine, further cyclization to 5-amino-1H-3-(pyridy)1,2,4-triazoles, whereas the a, [ unsaturated ketones (chalchone derivatives) were prepared by reaction of aromatic aldehydes with acetophenone derivatives in presence of sodium hydroxid at 0 C for 2 hours. Substituted 1,2,4-triazolo[ 1,5-a]pyrimidines were prepared by reflux the aminotriazoles derivatives with chalchone derivatives in ethylene glycol at 210C for 3-hours, or by fusion at 260.C for 0.5 hour to afford the target compounds of 1,2,4-triazolo[ 1,5-a]pyrimidines. Fusion of 5-amino-lH-3-(3-pyridyl)-l,2,4-triazole with chalchone derivatives for 3 minutes; gave the intermediate (4, 7-dihydro derivatives) Vllla and Vlllb which were separated. The following intermediate derivatives were prepared • Pyridine 2-carboxylic acid ethyl ester. • Pyridine 3-carboxylic acid ethyl ester. • Pyridine 4-carboxylic acid ethyl ester.