A mixture of (S)-2-methyl-6-nitro-2-(piperazin-1-ylmethyl)-2,3-dihydroimidazo[2,1-b]oxazole dihydrochloride prepared in Example 408 (401 mg, 1.5 mmol), DMF (8 ml) and potassium carbonate (750 mg, 5.4 mmol) was stirred at room temperature for 10 minutes. To the reaction mixture, a solution of 4-(4-chlorophenyl)-1,2,3,6-tetrahydropyridine-1-carbonylchloride (400 mg, 1.56 mmol) in DMF (3 ml) was added slowly with cooling on ice-bath followed by stirring at room temperature overnight. To the reaction mixture, water was added, and the solution was extracted with ethyl acetate. The organic phase was washed with water three times and a saturated saline solution, dried over sodium sulfate and then filtered. The filtrate was concentrated under reduced pressure, and the residue was recrystallized from ethanol to afford (S)-[4-(4-chlorophenyl)-1,2,3,6-tetrahydropyridin-1-yl]-[4-(2-methyl-6-nitro-2,3-dihydroimidazo[2,1-b]oxazol-2-ylmethyl)piperazin-1-yl]methanone (380 mg, yield 53%) as a light yellow powder.
