Trifluoroacetic acid → HCID 69481769, compound

Participants

Reaction Steps

Tert-butyl (S)-4-[2-(N-methyl-2-methyl-6-nitro-2,3-dihydroimidazo[2,1-b]oxazol-2-ylmethylamino)-ethyl]piperazine-1-carboxylate prepared in Example 173 (400 mg, 0.94 mmol) was dissolved in methylene chloride (5 ml). To the solution, trifluoroacetic acid (5 ml) was added followed by stirring at room temperature for 5 hours. The reaction mixture was concentrated under reduced pressure and added methylene chloride (2 ml) and triethylamine (2 ml). After stirring for 5 minutes at room temperature, the solution was concentrated under reduced pressure. The residue was dissolved in methanol (10 ml). To the solution, 4-(trifluoromethyl)benzaldehyde (0.4 ml, 2.83 mmol), sodium cyanotrihydroborate (178 mg, 2.83 mmol) and acetic acid (0.2 ml) were added followed by stirring at room temperature for 30 minutes. To the solution, a saturated sodium hydrogencarbonate solution and methylene chloride were added followed by stirring, and the mixture was extracted with methylene chloride. The organic phase was dried over magnesium sulfate. After filtration, the resulting filtrate was concentrated under reduced pressure. The residue was purified by silica gel column chromatography (methylene chloride/methanol=200/1) and crystallized from methylene chloride-isopropyl ether to afford (S)-N-methyl-N-(2-methyl-6-nitro-2,3-dihydroimidazo[2,1-b]oxazol-2-ylmethyl)-2-[4-(4-trifluoromethylbenzyl)piperazin-1-yl]ethylamine (307 mg, yield 68%) as a white powder.

Provenance & Evidence