Sodium hydride → Tert-butyl(r)-4-[4-(2-methyl-6-nitro-2,3-dihydroimidazo[2,1-b]oxazol-2-ylmethoxy)benzoyl]piperazine-1-carboxylate

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Reaction Conditions

Reaction Steps

Tert-butyl 4-(4-hydroxybenzoyl)piperazine-1-carboxylate (6.6 g, 21.5 mmol) was dissolved in DMF (50 ml). To the solution, sodium hydride (991 mg, 24.8 mmol) was added at room temperature, and the solution was stirred for 20 minutes at 80° C. To the solution, (R)-2-chloro-1-(2-methyloxiran-2-ylmethyl)-4-nitroimidazole prepared in Example 12 (5.16 mg, 23.7 mmol) was added with cooling on ice-bath, and the solution was stirred for further 20 minutes at 80° C. To the reaction mixture, ice-water was added, and the solution was stirred vigorously. The precipitates were filtered off, washed with water, dissolved in methylene chloride. The organic phase was washed with a saturated saline solution, dried over magnesium sulfate and then filtered. The resulting filtrate was concentrated under reduced pressure. The residue was purified by silica gel column chromatography (methylene chloride/methanol=100/1) and then crystallized from methylene chloride-diisopropyl ether to afford tert-butyl (R)-4-[4-(2-methyl-6-nitro-2,3-dihydroimidazo[2,1-b]oxazol-2-ylmethoxy)benzoyl]piperazine-1-carboxylate (7.35 g, yield 70%) as a white powder.

Provenance & Evidence