Trifluoroacetic acid → (R,Z)-2-amino-N'-(3-(3-(3,5-bis(trifluoromethyl)phenyl)-1H-1,2,4-triazol-1-yl)acryloyl)-3-methylbutanehydrazide 2,2,2-trifluoroacetate

Participants

Reaction Steps

In a 10 mL round-bottom flask, (Z)-3-(3-(3,5-bis(trifluoromethyl)phenyl)-1H-1,2,4-triazol-1-yl)acrylohydrazide (0.05 g, 1.0 eq.) was dissolved in THF (5 mL) and cooled to −60° C. where (R)-2-((tert-butoxycarbonyl)amino)-3-methylbutanoic acid (0.038 g, 1.3 eq.) was introduced dropwise. T3P (50% in EtOAc) (0.16 mL, 2 eq.) was added dropwise followed by DIPEA (0.095 mL, 4 eq.) and the reaction mixture was stirred for 1 h at −60° C. The reaction mixture was concentrated under reduced pressure (25° C., 20 mm Hg) to afford the crude product that was purified by column chromatography (60/120 silica gel) using methanol/dichloromethane gradient (the column was packed in dichloromethane and the desired compound started eluting from 3% methanol/dichloromethane). Fractions containing the desired compounds were combined to afford (R,Z)-tert-butyl (1-(2-(3-(3-(3,5-bis(trifluoromethyl)phenyl)-1H-1,2,4-triazol-1-yl)acryloyl)hydrazinyl)-3-methyl-1-oxobutan-2-yl)carbamate (0.017 g, yield: 26%). In a 10 mL round-bottom flask, (R,Z)-tert-butyl (1-(2-(3-(3-(3,5-bis(trifluoromethyl)phenyl)-1H-1,2,4-triazol-1-yl)acryloyl)hydrazinyl)-3-methyl-1-oxobutan-2-yl)carbamate was then dissolved in dichloromethane (2 mL). TFA (0.2 mL) was added and the reaction mixture was stirred at RT for 5 h. The reaction mixture was concentrated under reduced pressure (25° C., 20 mm Hg) to afford the crude product (0.02 g), which was triturated with petroleum ether and dried under reduced pressure to yield (R,Z)-2-amino-N′-(3-(3-(3,5-bis(trifluoromethyl)phenyl)-1H-1,2,4-triazol-1-yl)acryloyl)-3-methylbutanehydrazide 2,2,2-trifluoroacetate (0.007 g, yield: 35%).

Provenance & Evidence