Trifluoroacetic acid → (s)-4-(2-Methyl-6-nitro-2,3-dihydroimidazo[2,1-b]oxazol-2-ylmethyl)piperazine-1-carboxylic acid[3-(4-trifluoromethylphenyl)-2-propenyl]amide

Participants

Reaction Steps

A mixture of tert-butyl (S)-4-(2-methyl-6-nitro-2,3-dihydroimidazo[2,1-b]oxazol-2-ylmethyl)piperazine-1-carboxylate prepared in Example 393 (926 mg, 2.52 mmol), trifluoroacetic acid (10 ml) and methylene chloride (3 ml) was stirred at room temperature for 5 hours. The reaction mixture was concentrated under reduced pressure, and the residue was dissolved in DMF (3 ml) and neutralized with triethylamine (2 ml, 14.35 mmol). To the solution, a mixture of 3-(4-trifluoromethylphenyl)-2-propenylamine (761 mg, 3.78 mmol), 1,1′-carbonyldiimidazole (613 mg, 3.78 mmol) and DMF (3 ml) stirred at room temperature overnight was added followed by stirring at room temperature overnight. To the reaction mixture, water was added followed by extraction with ethyl acetate. The extract was washed with water three times and a saturated saline solution, dried over magnesium sulfate and then filtered. The filtrate was concentrated under reduced pressure, and the residue was purified by silica gel column chromatography (methylene chloride/methanol=20/1) to afford (S)-4-(2-methyl-6-nitro-2,3-dihydroimidazo[2,1-b]oxazol-2-ylmethyl)piperazine-1-carboxylic acid[3-(4-trifluoromethylphenyl)-2-propenyl]amide (1.2 g, yield 96%) as a light yellow powder.

Provenance & Evidence