Phosgene → 2-Tert-butoxycarbonyloxyimino-1-phenylbutane-1,3-dione

Participants

Reaction Steps

A solution of 2-hydroxyimino-1-phenylbutane-1,3-dione (3.82 g.) and pyridine (1.62 ml.) in benzene (30 ml.) was added dropwise to a solution of phosgene (1.98 g.) in benzene (25 ml.) for 40 minutes at 5° to 9° C. After stirring for 1 hour at the same temperature, the mixture was allowed to stand overnight. A solution of tert-butyl alcohol (2.96 g.) and pyridine (3.16 g.) in benzene (30 ml.) was added dropwise for 30 minutes at 5° C. to the resultant solution containing 2-chlorocarbonyloxyimino-1-phenylbutane-1,3-dione. After stirring for 1 hour at the same temperature, the mixture was stirred for 6 hours at room temperature, after which the mixture was allowed to stand overnight. Cooled water (100 ml.) was added to the reaction mixture and the organic layer was then washed with water, a 0.5M citric acid aqueous solution (20 ml.) (4 times) and a 5% sodium carbonate aqueous solution (20 ml.) (4 times) until the aqueous layer became almost colorless. The organic layer was further washed with a sodium chloride aqueous solution and then dried over magnesium sulfate. After drying, the solution was treated with activated charcoal and the solvent was distilled off to give an oil (3.48 g.). The oil was partly crystallized by allowing it to stand and ether was then added to the mixture to precipitate crystals. The precipitates were collected by filtration and recrystallized from a mixed solvent of carbon tetrachloride and petroleum ether to give 2-tert-butoxycarbonyloxyimino-1-phenylbutane-1,3-dione (350 mg.), mp 90° to 103° C (dec.).

Provenance & Evidence