Abstract: The present invention provides a method by which a 6-hydroxyethyl penam compound represented by General Formula (2) below can be produced with a high selectivity: wherein R represents a hydrogen atom or a protective group for carboxylic acid and X2 represents a halogen atom; the method including the steps of reacting a Grignard reagent with a halogeno penam compound represented by General Formula (1) below: wherein R and X2 are the same as above, and X1 represents a halogen atom; reacting the generated compound with an amine compound; and further reacting the generated compound with acetaldehyde.

Abstract: The present invention provides a method by which a 6-hydroxyethyl penam compound represented by General Formula (2) below can be produced with a high selectivity: wherein R represents a hydrogen atom or a protective group for carboxylic acid and X2 represents a halogen atom; the method including the steps of reacting a Grignard reagent with a halogeno penam compound represented by General Formula (1) below: wherein R and X2 are the same as above, and X1 represents a halogen atom; reacting the generated compound with an amine compound; and further reacting the generated compound with acetaldehyde.

Abstract: A process for preparing a 3-cephem compound represented by the formula (3), the process comprising the steps of reacting a &bgr;-lactam compound represented by the formula (1) with a phosphorus halide compound in the presence of an organic base to give an imino-&bgr;-lactam compound represented by the formula (2), adding a phenol to the same reaction system to cause decomposition due to reaction with an alcohol and simultaneously to remove the protection of carboxylic acid ester, giving a 3-cephem compound represented by the formula (3) or a salt thereof where R1, R2, R3 and X are as defined above.

Abstract: The present invention provides a cephem compound having a high antimicrobial activity against various pathogenic bacteria.The cephem compound of the invention is represented by the formula ##STR1## wherein Q represents CH or N, R.sup.1 represents a carboxylate or the like, R.sup.2 represents a hydrogen atom, and R represents ##STR2## wherein R.sup.3 represents a group --(CH.sub.2).sub.m --Y (wherein m is an integer of 1 to 5, and Y represents a quaternary ammonium group) or the like, n is an integer of 0 to 4, B.sup.- represents an anion, f is 0 or 1 when R.sup.1 represents a carboxylate, and 2 when R.sup.1 represents a carboxyl group, and the ring C represents a 5-membered heterocyclic group of not more than 4 nitrogen atoms, which may be substituted by a lower alkyl group.