1-(2-Fluoro-4-nitrophenyl)-3-methyl-4-(difluoromethyl)-1H-1,2,4-triazol-5(4H)-one → 1-(2-Fluoro-4-aminophenyl)-3-methyl-4-(difluoromethyl)-1H-1,2,4-triazol-5(4H)-one

Participants

Reaction Steps

A mixture of 24.5 g (0.085 mole) of 1-(2-fluoro-4-nitrophenyl)-4-difluoromethyl-4,5-dihydro-3-methyl-1,2,4-triazol-5(1H)-one and 0.30 g of platinum oxide in 250 mL of absolute ethanol was hydrogenated in a Parr hydrogenation apparatus. The calculated amount of hydrogen required was taken up in 45 minutes. The reaction mixture was filtered through a Buchner funnel, and the filtrate was evaporated under reduced pressure, leaving a dark brown solid residue. This residue was placed on a silica gel column and eluted with methylene chloride/ethyl acetate (75/25). After the product-containing fractions were combined, evaporation of the solvents under reduced pressure yielded 20.1 g of 1-(2-fluoro-4-aminophenyl)-4-difluoromethyl-4,5-dihydro-3-methyl-1,2,4-triazol-5(1H)-one. The NMR spectrum was consistent with the proposed structure.

Provenance & Evidence