Hydrochloric Acid → (R)-2-methyl-6-nitro-2,3-dihydroimidazo[2,1-b]oxazol-2-ylmethyl bis(4-chlorophenyl)carbamate

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Reaction Steps

Pyridine (0.37 ml, 4.5 mmol) and triphosgene (0.16 g, 0.5 mmol) were added to a suspension of (R)-2-hydroxymethyl-2-methyl-6-nitro-2,3-dihydroimidazo[2,1-b]oxazole prepared in Example 37 (0.30 g, 1.5 mmol) in methylene chloride (15 ml) with cooling on ice-bath followed by stirring at room temperature for 2.5 hours. To the reaction mixture, bis(4-chlorophenyl)amine (0.39 g, 1.6 mmol) was added, and the resulting mixture was stirred at room temperature for 20 hours. The reaction mixture was cooled on ice-bath and added 10% hydrochloric acid. The resulting mixture was extracted with methylene chloride, and the extract was dried over magnesium sulfate and then concentrated under reduced pressure. The residue was purified by silicagel column chromatography (methylene chloride/ethyl acetate=19/1) and recrystallized from isopropanol to afford (R)-2-methyl-6-nitro-2,3-dihydroimidazo[2,1-b]oxazol-2-ylmethyl bis(4-chlorophenyl)carbamate (82 mg, yield 12%) as a white solid.

Provenance & Evidence