| 摘要 |
<p>Intermediates of the formula (III): (III) wherein R1 is amino or a protected amino and X1 is carbonyl or a group of the formula: in which R2 is hydrogen, acyl, aryl which may be substituted with suitable substituent(s), lower alkyl substituted with suitable substituent(s), lower alkenyl, lower alkynyl, cycloalkyl which may be substituted with suitable substituent(s), cyclo(lower)-alkenyl, or S or O containing 5-membered heterocyclic group substituted with oxo group(s), or a salt thereof are useful in the preparation of 7-substituted-3-cephem and cepham-4-carboxylic acids which exhibit antimicrobial activities against a wide variety of pathogenic microorganisms including Gram negative and Gram positive bacteria.</p> |
