Copper‐Catalyzed Decarbonylative Cyclization of Isatins and Trifluoroacetimidohydrazides for the Synthesis of 2‐(5‐Trifluoromethyl‐1,2,4‐triazol‐3‐yl)anilines

Abstract

A copper-catalyzed intramolecular decarbonylative cyclization reaction of isatins and trifluoroacetimidohydrazides for the synthesis of 2-(5trifluoromethyl-1,2,4-triazol-3-yl)aniline derivatives has been developed. This transformation proceeds through a cascade condensation, hydrolysis, decarboxylation, and intramolecular CÀ N bond formation sequence. The obtained 1,2,4-triazole products bearing a free amino group can be readily converted into other useful compounds.

Radical selenylative cyclization of trifluoromethyl propargyl imines for the synthesis of trifluoromethyl- and seleno-azaspiro[4,5]-tetraenones and quinolines

“…12 Likhar and co-workers prepared a series of 2-perfluoroalkyl-3-iodoquinolines and azaspiro compounds through iodocyclization of perfluoroalkyl propargyl imines or amines with I 2 . 13 In order to enrich the molecular diversity of the two kinds of heterocycles and due to our continued interest in the facile construction of functionalized N-heterocycles, 14 we herein communicate our recent findings on Oxone-promoted radical selenylative cyclization of trifluoromethyl propargyl imines and diselenides for the regioselective synthesis of CF 3 - and Se-decorated azaspiro[4,5]-tetraenones and quinolines (Scheme 1). The notable features of this transformation include easily accessible starting materials, broad substrate scope, good regioselectivity, and scalability, providing a straightforward access to multi-functionalized N-heterocycles.…”

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

“…Wu and co-workers reported a iodine-mediated annulation and a FeCl 3 -mediated cascade annulation of trifluoroacetimidoyl chlorides and hydrazones or hydrazides for the synthesis of 5-trifluoromethyl-1,2,4-triazoles ( Scheme 1 a) [ 29 , 30 ]. 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 ].…”

Metal-free synthesis of 3-trifluoromethyl-1,2,4-triazoles via multi-component reaction of trifluoroacetimidoyl chlorides, hydrazine hydrate and benzene-1,3,5-triyl triformate

“…Recent years have witnessed considerable achievements about the construction of trifluoromethyl-substituted 1,2,4-triazoles ( Zhang, et al, 2019 ), which include transition metal-catalyzed three-component reaction of aryldiazonium salts with fluorinated diazo reagents and nitriles ( Peng, et al, 2020 ). Our groups also developed a series of convenient approaches for the assembly of this kind of important five-membered N -heterocycle by using trifluoroacetimidoyl chlorides ( Hu, et al, 2019 ; Du, et al, 2020 ) and trifluoroacetimidohydrazides ( Zhang, et al, 2021a ; Zhang, et al, 2021b ; Zhang, et al, 2021c ; Lu, et al, 2022a ; Zhang, et al, 2022 ) as versatile trifluoromethyl synthons. Compared with the in-depth study toward the synthesis of 5-trifluoromethyl-1,2,4-triazoles, the relevant reports regarding the formation of the more specific 3-trifluoromethyl-1,2,4-triazoles have been rare but still of great significance.…”