Sodium hydride → tert-butyl (R)-4-(2-methyl-6-nitro-2,3-dihydroimidazo[2,1-b]oxazol-2-ylmethyl)piperazin-1-carboxylate

Participants

Reaction Steps

Tert-butyl (R)-4-[3-(2-chloro-4-nitroimidazol-1-yl)-2-hydroxy-2-methylpropyl]-piperazine-1-carboxylate prepared in Example 368 (376 mg, 0.93 mmol) was dissolved in 1,4-dioxane (10 ml). To the solution, sodium hydride (45 mg, 1.12 mmol) was added with cooling on ice-bath, and the resulting solution was stirred at room temperature for 30 minutes and then stirred under reflux for 24 hours. The reaction mixture was allowed to return to room temperature and concentrated under reduced pressure. To the residue, water was added slowly, and the solution was extracted with ethyl acetate twice. The organic phase was dried over sodium sulfate and then filtered. The filtrate was concentrated under reduced pressure. The residue was purified by silica gel column chromatography (n-hexane/acetone=3/1) to afford tert-butyl (R)-4-(2-methyl-6-nitro-2,3-dihydroimidazo[2,1-b]oxazol-2-ylmethyl)piperazin-1-carboxylate (239 mg, yield 70%) as a white powder.

Provenance & Evidence