STEPWISE SYNTHESIS OF TRI SUBSTITUTED 1, 2, 4-TRIAZOLES BY OXIDATIVE AROMATIZATION VIA CASCADE FUNCTIONALIZATION

In this work, we described the two-step synthesis of Tri-substitutedtriazoles using microwave irradiation technique with ferric chloride as catalyst. The acid catalyzed reaction between hydrazine 1 with various aromatic aldehydes (2a-d) in ethanol as a solvent gave desired hydrazones (3a-3d followed by elimination process by losing water in the first step. In the second step, conventional and microwave synthesis of 1,2,4-triazoles proceeds through a cascade C−H functionalization, C−N double bond formation, and oxidative aromatization sequence. Hydrazones (3a-3d) underwent cyclization with aliphatic amines (4e & 4f) in CH3CN in the presence of a catalyst I2 and mild oxidizing agent t-butyl hydro peroxide/ H2O2 and the reaction mixture was stirred at 900 °C for 4 hr or under microwave irradiation using silica gel supported by ferric chloride (SiO2-FeCl3) to afford pure 1,2,4-triazole derivatives 5ea-5ed & 5fa-5fd shown in Scheme 1and Table 1.