Intramolecular oxidative cyclization of N-(2,2,2-trifluoro-1-(phenylimino)ethyl)benzimidamide

Abstract

A fast and convenient method for synthesis of 1,3-diaryl-5-(trifluoromethyl)-1H-1,2,4-triazole compounds has been described via intramolecular oxidative cyclization of the N-(2,2,2-trifluoro-1-(arylimino)ethyl)benzimidamide intermediates by I 2 /KI in excellent yields without any purification. N-(2,2,2-Trifluoro-1-(arylimino)ethyl)benzimidamide intermediates which are used in this project have been synthesized from the reaction of N-aryl-2,2,2-trifluoroacetimidoyl chlorides and benzamide hydrochloride derivatives at room temperature for the first time.

Construction of trifluoromethyl-containing heterocycles from trifluoroacetimidoyl chlorides and derivatives

“…The coupling of trifluoroacetimidoyl chlorides and benzamide hydrochlorides in the presence of K 2 CO 3 could afford benzimidamide intermediates, which was developed by Darehkordi and co-workers (Scheme 5). 16 Then, I 2 /KI-mediated intramolecular oxidative cyclization of the resulting benzimidamide intermediates occurred to furnish the trifuoromethylated-1,2,4-triazoles in excellent yields via intramolecular N–N bond formation. High efficiency and easy work-up of this reaction were observed.…”

Regioselective Synthesis of 5-Trifluoromethyl 1,2,4-Triazoles via [3 + 2]-Cycloaddition of Nitrile Imines with CF3CN

“…Wu and co-workers subsequently developed a metal-free oxidative cyclization and a copper-catalyzed intramolecular decarbonylative cyclization reaction of trifluoroacetimidohydrazides with methylhetarenes or isatins for the synthesis of 5-trifluoromethyl-1,2,4-triazoles [ 31 , 32 , 33 ] and 2-(5-trifluoromethyl-1,2,4-triazol-3-yl)aniline derivatives [ 34 ], respectively. Darehkordi and co-workers described the synthesis of 1,3-diaryl-5-(trifluoromethyl)-1 H -1,2,4-triazoles via the iodine-mediated intramolecular oxidative cyclization of N -(2,2,2-trifluoro-1-(arylimino)ethyl)benzimidamide intermediates, synthesized from the reaction of N -aryl-2,2,2-trifluoroacetimidoyl chlorides and benzamide hydrochloride derivatives ( Scheme 1 c) [ 35 ]. More recently, the Ma research group developed a copper-catalyzed three-component reaction of aryldiazonium salts with fluorinated diazo reagents and nitriles, leading to two regiomers of trifluoromethylated N 1 -aryl-1,2,4-triazoles ( Scheme 1 d) [ 36 ].…”