Trifluoroacetic acid → (s)-n-[1-(4-Chlorophenyl)ethylidene]-n-[4-(2-methyl-6-nitro-2,3-dihydroimidazo[2,1-b]oxazol-2-ylmethyl)piperazin-1-yl]amine

Participants

Reaction Steps

A mixture of tert-butyl (S)-[4-(2-methyl-6-nitro-2,3-dihydroimidazo[2,1-b]oxazol-2-ylmethyl)-piperazin-1-yl]carbamate prepared in Example 503 (200 mg, 0.52 mmol), trifluoroacetic acid (2 ml) and methylene chloride (4 ml) was stirred at room temperature for 30 minutes. The reaction mixture was concentrated under reduced pressure, and the residue was dissolved in methylene chloride (4 ml) and then neutralized with triethylamine (4 ml, 28.7 mmol). To the neutralized solution, a solution of 4-chloroacetophenone (97 mg, 0.63 mmol) in ethanol (4 ml) was added followed by stirring under reflux for 4 hours. The reaction mixture was allowed to return to room temperature and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (n-hexane/acetone=3/1) to afford (S)-N-[1-(4-chlorophenyl)ethylidene]-N-[4-(2-methyl-6-nitro-2,3-dihydroimidazo[2,1-b]oxazol-2-ylmethyl)piperazin-1-yl]amine (39 mg, yield 18%) as a light yellow powder.

Provenance & Evidence