Hydrochloric Acid → HCID 23081451, compound

Participants

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 (130 mg, 0.35 mmol), trifluoroacetic acid (3 ml) and methylene chloride (5 ml) was stirred at room temperature for 1 hour. The reaction mixture was concentrated under reduced pressure. The residue was dissolved in methylene chloride (5 ml) and added triethylamine (107.5 mg, 1.06 mmol). To the solution, benzyl chloroformate (120 mg, 0.71 mmol) was added with cooling on ice-bath followed by stirring at room temperature for 1 hour. The reaction mixture was washed with water, a saturated sodium hydrogencarbonate solution and a saturated saline solution in this order, dried over sodium sulfate and then filtered. The filtrate was concentrated under reduced pressure. The residue was purified by silica gel column chromatography (methylene chloride/methanol=20/1) to afford a yellow oil. The oil was dissolved in ethyl acetate (5 ml). To the solution, a saturated hydrochloride solution in ethyl acetate was added, and the precipitates were filtered off to afford benzyl 4-(2-methyl-6-nitro-2,3-dihydroimidazo[2,1-b]oxazol-2-ylmethyl)piperazin-1-carboxylate hydrochloride (46.8 mg, yield 30%) as a white powder.

Provenance & Evidence