Water → 3-Methyl-7-[2-phenyl-2-(4-ethyl-2,3-dioxopiperazine-1-carboxamido)acetamido]ceph-3-em-4-carboxylic acid

Beteiligte Stoffe

Reaktionsschritte

Cephalexin (696 mg., 2 mmoles) was dissolved in 10 ml. of water at 5° C. by the action of potassium carbonate (304 mg., 2.2 mmoles). Ethyl acetate (5 ml.) was added and then 4-ethyl-2,3-dioxopiperazine-1-carbonyl chloride (450 mg., 2.2 mole) was added over a period of 15 minutes at 0°-5° C. After addition was complete, the reaction mixture was stirred for an additional 30 minutes, at which time the ethyl acetate layer was separated and the aqueous phase washed with an additional portion of ethyl acetate. The aqueous phase was adjusted to 2.5 and the product extracted into several portions of fresh ethyl acetate. The acidic ethyl acetate extracts were combined, back-washed with water, washed with brine, dried over anhydrous magnesium sulfate, evaporated to dryness in vacuo, and the residue crystallized from methylene chloride to yield 3-methyl-7-[2-phenyl-2-(4-ethyl-2,3-dioxopiperazine-1-carboxamido)acetamido]ceph-3-em-4-carboxylic acid (568 mg., m.p. 199°-200° C.).

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