Heating-induced decarboxylative cyclization for the synthesis of 5-trifluoromethyl-1,2,4-triazoles from trifluoroacetimidohydrazides andα-oxocarboxylic acids

A simple metal and additive-free approach for the assembly of 5-trifluoromethyl-1,2,4-triazoles via only heatinginduced decarboxylative cyclization of readily available trifluoroacetimidohydrazides andα-oxocarboxylic acids has been developed.In this protocol,the rarely reported tetrahedral carboxylic acids intermediate could be in-situ generated and undergo subsequent decarboxylation to afford the target heterocycle products.

Elemental Sulfur and Dimethyl Sulfoxide-Promoted Oxidative Cyclization of Trifluoroacetimidohydrazides with Methylheta-renes for the Synthesis of 3-Hetaryl-5-trifluoromethyl-1,2,4-triazoles

A metal-free approach for the synthesis of 3-hetaryl-5-trifluoromethyl-1,2,4-triazoles via sulfur/dimethyl sulfoxide-promoted oxidative cyclization of readily available trifluoroacetimidohydrazides with methylhetarenes has been developed.This transformation proceeds in cascade sulfur-mediated generation of thioaldehyde,condensation,intramolecular cyclization and oxidative aromatization sequence.

Metal-free synthesis of 3-trifluoromethyl-1,2,4-triazoles via oxidative cyclization of trifluoroacetimidohydrazides with N,N-dimethylformamide as carbon synthons

A metal-free approach for the synthesis of 3-trifluoromethyl-1,2,4-triazoles via I2-mediated oxidative cyclization of readily accessible trifluoroacetimidohydrazides with N,N-dimethylformamide(DMF)has been disclosed.In this transformation,the commonly used organic solvent DMF is applied as a C1 synthon and the methine unit of the 1,2,4-triazole products is independently from N-methyl and N-acyl of DMF.The application potential of the developed method has been demonstrated by the synthesis of the key skeleton of factor IXa inhibitors.