Trifluoroacetic acid → [4-(2-Methyl-6-nitro-2,3-dihydroimidazo[2,1-b]oxazol-2-ylmethyl)piperazin-1-yl]phenylmethanone

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Reaction Steps

A mixture of 2-(4-tert-butoxycarbonylpiperazin-1-yl)methyl-2-methyl-6-nitro-2,3-dihydroimidazo[2,1-b]oxazole prepared in Example 306 (142 mg, 0.39 mmol), trifluoroacetic acid (1 ml) and methylene chloride (1 ml) was stirred at room temperature for 1 hour. The reaction mixture was concentrated under reduced pressure, and the residue was dissolved in methylene chloride (2 ml). To the mixture, triethylamine (2 ml, 14.35 mmol) was added. To the solution, benzoyl chloride (54 μl, 0.46 mmol) was added with cooling on ice-bath followed by stirring at room temperature for 1 hour. The reaction mixture was diluted with methylene chloride, washed with a saturated sodium hydrogencarbonate solution, water and a saturated saline solution in this order, dried over sodium sulfate and then filtered. The filtrate was concentrated under reduced pressure, and the residue was treated with diethyl ether to afford [4-(2-methyl-6-nitro-2,3-dihydroimidazo[2,1-b]oxazol-2-ylmethyl)piperazin-1-yl]phenylmethanone (72 mg, yield 50%) as a yellow powder.

Provenance & Evidence