Chemistry An Asian Journal 2010-02-01

An efficient and convenient synthesis of ethyl 1-(4-methoxyphenyl)-5-phenyl-1H-1,2,3-triazole-4-carboxylate.

Jung-Hsuan Chen, Shuan-Ru Liu, Kwunmin Chen

Index: Chem. Asian J. 5(2) , 328-33, (2010)

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Abstract

The "click chemistry" of using organic azides and terminal alkynes is arguably the most efficient and straightforward route to the synthesis of 1,2,3-triazoles. In this paper, an alternative and direct access to ethyl 1-(4-methoxyphenyl)-5-phenyl-1H-1,2,3-triazole-4-carboxylate is described. Treatment of ethyl diazoacetate with 4-methoxyaniline derived aryl imines in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene provided fully substituted 1,2,3-triazoles in good to high chemical yields. The base-mediated reaction tolerates various substituted phenyl imines as well as ethyl diazoacetate or the more bulky diazoacetamide. A reasonable mechanism is proposed that involves the addition of an imine nitrogen atom to the terminal nitrogen atom of the diazo compound, followed by aromatization to give the 1,2,3-triazole. The presence of the 4-carboxy group is advantageous as it can be easily transformed into other functional groups.