Bromhydrol → 2,2,2-Trichloroethyl 2-methyl-7-(2-phenylacetamido)-3-cephem-4-carboxylate

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Reaction Steps

A solution of 2,2,2-trichloroethyl 2-methyl-2,3-methylene-6-(2-phenylacetamido)penam-3-carboxylate (0.92 g.) in dried dichloromethane (5 ml.) was dropwise added at -10° C. over about 5 minutes to a solution of aluminum bromide (0.8 g.) in dried dichloromethane (10 ml.) and the mixture was stirred for 2 hours at room temperature. After the reaction was completed, the reaction mixture was washed in turn with 2% hydrochloric acid, a sodium bicarbonate aqueous solution and a saturated sodium chloride aqueous solution and then dried over magnesium sulfate, after which the solvent was distilled off under reduced pressure. The residual crystals were washed with ether and dried to give 2,2,2-trichloroethyl 2-methyl-7-(2-phenylacetamido)3-cephem-4-carboxylate (0.74 g.), mp 175° to 178° C. And the residue obtained by concentrating the ether washing was purified by column chromatography on silica gel to give 2,2,2-trichloroethyl 2-methyl-7-(2-phenylacetamido)-3-cephem-4-carboxylate (0.05 g.), mp 118° to 120° C., which is a stereoisomer at 2 position of the above obtained 2,2,2-trichloroethyl 2-methyl-7-(2-phenylacetamido)-3-cephem-4-carboxylate, mp 175° to 178° C., and 2,2,2-trichloroethyl 2-methyl-7-(2-phenylacetamido)-2-cephem-4-carboxylate (0.05 g.), mp 136° to 137° C. The above obtained 2,2,2-trichloroethyl 2-methyl-7-(2-phenylacetamido)-3-cephem-4-carboxylate, mp 118° to 120° C., was recrystallized from benzene to give crystals, mp 120° to 123° C.

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