A new, high-yield synthesis of 3-aryl-1,2,4-triazoles

作者：Guirado Antonio^*; Lopez Caracena Libertad; Lopez Sanchez Jose I; Sandoval Jose; Vera Maria; Bautista Delia; Galvez Jesus^*

来源：Tetrahedron, 2016, 72(49): 8055-8060.

DOI：10.1016/j.tet.2016.10.045

• Triazoles
• Chloral
• Chloralamides
• Benzimidoyl chlorides
• Hydrazine

A convenient new synthetic approach to 3-aryl-1,2,4-triazoles has been developed. Chloralamides were obtained by high yield reactions between benzamides and chloral hydrate. These reacted with a phosphorus pentachloride/phosphorus oxychloride mixture undergoing a near quantitative conversion to N-(1,2,2,2-tetrachloroethyl)benzimidoyl chlorides, which were treated with hydrazine hydrate to directly give 3-aryl-1,2,4-triazoles in high to quantitative yields. The formation of these products involves a double condensation process followed by a spontaneous (beta-elimination of chloroform. The molecular structure of 1-(4-chlorobenzoyI)-3-(4-methoxypheny1)-1,2,4-triazole was determined by X-ray crystallography. Theoretical computational studies on aromatization of 3-aryl-5-trichloromethyl-1,2,4-triazolines via chloroform elimination and to determine relative stabilities of 3-phenyl-1,2,4-triazole tautomers were performed using ab initio, density functional (B3LYP), Moller-Plesset (MP2), and the thermochemical recipe T1.

• 出版日期2016-12-8