Acetic Acid → benzyl (2R)-2-[4-[4-(2,2,3,3-tetrafluoropropoxy)phenyl]-4,5-dihydro-5-oxo-1H-1,2,4-triazol-1-yl]propionate

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Reaction Steps

4-[4-(2,2,3,3-Tetrafluoropropoxy)phenyl]-3(2H,4H)-1,2,4-triazolone (18 g) was dissolved in 180 ml of dimethylformamide, to which 60% sodium hydride in oil (2.52 g) was added. The mixture was vigorously stirred at room temperature for 40 minutes. The reaction solution was added to a solution of 20 g of benzyl (2S)-2-trifluoromethanesulfonyloxypropionate prepared in Example 3 in 240 ml of tetrahydrofuran under nitrogen atmosphere at -40° to -30° C. over the period of ca. 40 minutes. The mixture was stirred at -40° to -20° C. for 40 minutes, to which 10 ml of acetic acid was added. Then, the reaction solution was diluted with a mixture of 100 ml of ethyl acetate and 500 ml of diisopropyl ether, washed with 250 ml of water, 2N-hydrochloric acid (250 ml×2) and 250 ml of an aqueous solution of sodium chloride successively. After dring over magnesium sulfate, the solvent was distilled off under reduced pressure. The residue was purified by silica gel chromatography (silica gel: 250 g, eluent; hexane:ethyl acetate=2:1) to give 24 g of benzyl (2R)-2-[4-[4-(2,2,3,3-tetrafluoropropoxy)phenyl]-4,5-dihydro-5-oxo-1H-1,2,4-triazol-1-yl]propionate (yield: 82%) as a colorless oil.

Provenance & Evidence