| 摘要 |
<p>PURPOSE:To obtain the titled compound directly and readily useful as a synthetic intermediate for antibiotics without removing a protecting group during preparation, by treating a cephalosporin compound with a halogenating agent in the presence of methanol and its alkali metal salt. CONSTITUTION:A 7beta-R1SO3CH2CONH-DELTA<3>-cephem-4-carboxylic acid (R1 is hydrocarbon group )[e.g., a compound shown by the formula (A is an organic residue not taking part in the reaction; -COOW is carboxylic acid or its derivative), etc.] is reacted with an alkali metal salt of methanol in an inert solvent at -95-10 deg.C. The resulting compound is treated with a halogenating agent (e.g., Cl, Br. or N- haloamide) capable of producing a positive halogen in the reaction solution at the same temperature as that of the solution. After the reaction, excess alkali metal salt of methanol is decomposed by a carboxylic acid, e.g., formic acid, etc. to give a 7alpha- methoxy-7beta-R1SO3CH2CONH-DELTA<3>-cephem-4-carboxylic acid.</p> |
