Ethyl Acetate → Racemic 1,1-dimethylethyl 7-[2-(2-tritylaminothiazol-4-yl)-2-methoxyimino-acetamido]-3-(ethoxycarbonylmethylthio)-8-oxo-4-thia-1-azabicyclo[4,2,0]oct-2-ene-2-carboxylate

Participants

Reaction Steps

1.55 g of the product of Step A dissolved in 30 ml of pyridine and 1.4 g of diphosphorus tetraiodide were stirred under an inert atmosphere for 30 minutes and after a further 0.76 g of diphosphorus tetraiodide were added, the mixture was stirred for 1 hour. 100 ml of ethyl acetate were added followed by filtering and concentrating to dryness under reduced pressure at a temperature below 30° C. The residue was dissolved in ethyl acetate and the solution was filtered, washed first with 0.1N hydrochloric acid, then with a solution of sodium bicarbonate, and then with a sodium chloride solution, after which it was dried and concentrated to dryness. The residue was chromatographed on silica and eluted with a mixture of methylene chloride and acetone (10-0.75). After crystallization from ether, 675 mg of racemic 1,1-dimethylethyl 7-[2-(2-tritylaminothiazol-4-yl)-2-methoxyimino-acetamido]-3-(ethoxycarbonylmethylthio)-8-oxo-4-thia-1-azabicyclo[4,2,0]oct-2-ene-2-carboxylate melting at 212°-214° C. (decomposes) were obtained.

Provenance & Evidence