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 derivative of 6-aminopenicillanic acid or 7-aminocephalosporanic acid is produced by a process which comprises chlorinating or brominating a 6-thioacylaminopenicillanic acid or 7-thioacylaminocephalosporanic acid compound to obtain a corresponding iminothiohalide compound, and then solvolyzing the iminothiohalide compound. The process is novel and industrially feasible for producing the amino compound, which is not accompanied by "reconversion reaction".

Abstract: A derivative of 6-aminopenicillanic acid or 7-aminocephalosporanic acid is produced by a process which comprises disulfidizing a 6-thioacylaminopenicillanic acid or 7-thioacylaminocephalosporanic acid compound to obtain a corresponding disulfide compound, and then solvolyzing the disulfide compound. The process is novel and industrially feasible for producing the amino compound, which is not accompanied by "reconversion reaction".