Sodium hydride → 2-Methyl-6-nitro-2,3-dihydroimidazo[2,1-b]oxazol-2-ylmethyl 4-(4-trifluoromethylphenyl)-1,2,3,6-tetrahydropyridine-1-carboxylate

Sodium hydride (11 mg, 0.28 mmol) was added to a solution of 3-(2-chloro-4-nitroimidazol-1-yl)-2-hydroxy-2-methylpropyl 4-(4-trifluoromethylphenyl)-1,2,3,6-tetrahydropyridine-1-carboxylate prepared in Example 85 (0.11 g, 0.23 mmol) in DMF (1 ml) followed by stirring for 1 hour with cooling on ice-bath. Ice-water was added to the reaction mixture, the resulting mixture was extracted with ethyl acetate. The extract was washed with water, dried over magnesium sulfate and then concentrated under reduced pressure. The residue was purified by silica gel column chromatography (methylene chloride/ethyl acetate=4/1) and then washed with diisopropyl ether to afford 2-methyl-6-nitro-2,3-dihydroimidazo[2,1-b]oxazol-2-ylmethyl 4-(4-trifluoromethylphenyl)-1,2,3,6-tetrahydropyridine-1-carboxylate (0.04 g, yield 39%) as a white solid.