Acetic Acid → HCID 69481564, compound

Participants

Reaction Steps

A mixture of tert-butyl (S)-4-(6-nitro-2,3-dihydroimidazo[2,1-b]oxazol-2-ylmethyl)piperazine-1-carboxylate prepared in Example 394 (100 mg, 0.27 mmol) and trifluoroacetic acid (2 ml) was stirred at room temperature for 3 hours. The reaction mixture was concentrated under reduced pressure. The residue was dissolved in methylene chloride (5 ml) and neutralized with triethylamine (1 ml, 7.17 mmol), and then the solution was concentrated under reduced pressure. The residue was dissolved in methanol (5 ml), and the solution was added 4-trifluoromethylbenzaldehyde (148 mg, 0.85 mmol), sodium cyanotrihydroborate (53 mg, 0.85 mmol), and acetic acid (49 μl, 0.85 mmol) in this order followed by stirring at room temperature for 18 hours. The reaction mixture was concentrated under reduced pressure. To the residue, a saturated sodium hydrogencarbonate solution was added, and the solution was extracted with methylene chloride twice. The organic phases were combined, washed with a saturated sodium hydrogencarbonate solution and a saturated saline solution in this order, dried over magnesium sulfate and then filtered. The filtrate was concentrated under reduced pressure, and the residue was purified by silica gel column chromatography (methylene chloride/ethyl acetate=1/1) to afford (S)-6-nitro-2-[4-(4-trifluoromethylbenzyl)piperazin-1-ylmethyl]-2,3-dihydroimidazo[2,1-b]oxazole (53 mg, yield 46%) as a light yellow powder.

Provenance & Evidence