Abstract: A novel cephalosporin derivative of the formula: ##STR1## [wherein X is hydrogen, hydroxyl, acyloxy, alkoxy, carbamoyloxy, quaternary ammonium or a group of the formula --SR.sup.1 (where R.sup.1 is a nitrogen-containing heterocyclic group)] or a pharmaceutically acceptable salt or ester thereof is found to have potent antibiotic activity against various bacteria, particularly against gram-negative bacteria such as Escherichia coli, Klebsiella pneumoniae, Proteus vulgaris, Proteus mirabilis, Proteus morganii, Proteus rettgeri and Citrobacter freundii.

Abstract: Novel 3-acyloxymethyl-cephem compounds of the formula: ##STR1## wherein R.sup.1 is hydrogen or an acyl group; X is a divalent group consisting of a carbon chain having 2 to 3 carbon atoms and a carbonyl or sulfonyl group at one terminal end thereof, said divalent group being either substituted or unsubstituted on the carbon chain; and Z is an organic acid residue, and salts thereof were found to be useful as starting materials for preparing cephalosporins of the formula: ##STR2## wherein R.sup.2 stands for a residue of a nucleophilic compound and R.sup.1 has the same meaning as above.

Abstract: A compound of the formula: ##STR1## wherein R.sup.1 represents hydrogen or an alkyl group, X represents oxygen or sulfur or a group of formula --NR.sup.2 (where R.sup.2 is hydrogen or an alkyl group and in the case of alkyl, it may form a ring jointed with R.sup.1), and Y represents acetoxy group or a group of formula --SR.sup.3 (where R.sup.3 is a nitrogen-containing heterocyclic group), or a pharmaceutically acceptable salt thereof, is found to have a broad antimicrobial spectrum and, in particular, effective against gram-negative bacteria including Escherichia coli, Klebsiella pneumoniae, Proteus vulgaris, Proteus morganii, as well as gram positive ones. Thus, these compounds may be used for antimicrobial agents in therapeutical purposes.

Abstract: Novel cephalosporin compounds of the formula ##STR1## wherein R.sup.1 is an acyl group and R.sup.2 is an alkylene group which may be substituted with a lower alkoxyl group, or pharmaceutically acceptable salt thereof, have strong inhibitory actions on broad spectra of gram-positive and gram-negative bacteria and, particularly against Esherichia coli and Klebsiella pneumoniae. Thus, the compounds are useful as therapeutic agent for various bacterial infections of animals including human beings.

Abstract: A 3-hydroxymethylcephalosporin which is not protected at the carboxyl group can be directly oxidized with a hexavalent chromium compound to give in good yield a lactol type cephalosporin represented by the general formula: ##SPC1##Wherein R.sup.1 is hydrogen or an alkoxy group and R.sup.2 is an acylamino, or imido group. The resulting compounds are very useful and important as intermediates for preparing, e.g. 3-alkoxyiminomethyl cephalosporins.