Syntheses of 5-(2-arylazenyl)-1,2,4-triazoles and 2-amino-5-aryl-1,3,4-oxadiazoles

Efficient Synthesis of Polysubstituted Acylguanidines and Guanylureas

“…The benzotriazole moiety in compounds 5a − f was displaced by the action of amines 6a − n in refluxing tetrahydrofuran (THF) (Scheme , Table ) to form the desired N -acyl polysubstituted guanidines 7a − o ; the benzotriazole formed as a byproduct was removed from reaction mixtures by washing with a 10% aqueous solution of sodium hydroxide. We previously described reactions of acylated benzotriazolylcarboximidamides 5 with hydrazines for the preparation of 1,2,4-triazole ring systems 26a. In some cases, the concurrent displacement of benzotriazole or the amino functionality was observed and 5-amino-1,2,4-triazoles or 5-benzotriazol-1-yl-1,2,4-triazoles or both were obtained.…”

“…We 24a-c and others 24d have previously reported (benzotriazole-1-yl)carboximidamides 3 to be efficient reagents for the synthesis of polysubstituted guanidines in solution and on solid support . Acyl(benzotriazolyl)carboximidamides 5 are also versatile intermediates for the synthesis of five- and six-membered ,24b heterocycles. We now report the utilization of 5 and synthesis and utilization of 11 in the efficient preparation of polysubstituted acylguanidines and guanylureas, respectively.…”

Synthesis and Antimicrobial Activity of 3-(1,3,4-Oxadiazol-2-yl)quinazolin-4(3H)-ones

“…Yield: 70%, mp: 243–245°C, lit. 231–233°C [ 32 ]. IR (KBr), v, cm −1 : 745 (C-Cl), 1277, 1043 (C-O-C), 1662 (C=N), 3480, 3396 (NH 2 ).…”

Synthesis of Heterocycles Mediated by Benzotriazole. 1. Monocyclic Systems

“…However, for R = aryl, a reaction of 482 with the second molecule of hydrazine takes place first to form intermediate 484 before cyclocondensation to 5-hydrazino-1,2,4-triazole 485 . Spontaneous oxidation of hydrazines 485 with atmospheric oxygen furnishes orange- to red-colored azo derivatives 486 , which are isolated in 78−86% yields (Scheme ) …”