PROCESS FOR THE PREPARATION OF A 4-HALO-2-HYDROXYIMINO-ACETOACETIC ACID ESTER

摘要

A process for the preparation of a 4-halo-2-hydroxyiminoacetoacetic acid ester which comprises reacting a 4-halo-acetoacetic acid ester with an alkyl nitrite under acidic conditions. The 4-halo-2-hydroxyiminoacetoacetic acid ester may be reacted, if desired without isolation, with thiourea to give a syn 2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetic acid ester in high yield. The process may form part of a reaction sequence for the preparation of beta -lactam antibiotics having a syn 2-(2-aminothiazol-4-yl)-2-(substituted oxyimino)acetamido side chain.