3-Nitro-2-(trihalomethyl)-2H-chromenes in reactions with sodium azide: synthesis of 4-(trihalomethyl)-2,4-dihydrochromeno[3,4-d][1,2,3]triazoles

A method was developed for the synthesis of 4-(trihalomethyl)-2,4-dihydrochromeno[3,4-d][1-3]triazoles, based on the reaction of 3-nitro-2-(trifluoro(trichloro)methyl)- and 3-nitro-2-(trifluoromethyl)-2-phenyl-2H-chromenes with sodium azide in DMSO or DMF in the presence of p-toluenesulfonic acid.