Triethylamine → (S)-2-{4-[3-(4-chlorophenyl)propane-1-sulfonyl]piperazin-1-ylmethyl}-2-methyl-6-nitro-2,3-dihydroimidazo[2,1-b]oxazole

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 (300 mg, 0.82 mmol) and trifluoroacetic acid (10 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 (10 ml). To the solution, triethylamine (3 ml, 21.52 mmol) was added followed by stirring at room temperature for 10 minutes, and then 3-(4-chlorophenyl)propane-1-sulfonyl chloride (300 mg, 1.19 mmol) was added followed by stirring at room temperature for 3 days. The reaction mixture was washed with water and a saturated saline solution, 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=50/1) to afford (S)-2-{4-[3-(4-chlorophenyl)propane-1-sulfonyl]piperazin-1-ylmethyl}-2-methyl-6-nitro-2,3-dihydroimidazo[2,1-b]oxazole (330 mg, yield 84%) as a white powder.

Provenance & Evidence