Abstract: A process for preparing an azetidinone derivative represented by the formula ##STR1## wherein R.sup.1 is hydrogen, halogen or lower alkoxy, R.sup.2 is hydrogen, halogen, lower alkoxy, amino or a group ##STR2## (in which R.sup.5 is substituted or unsubstituted phenyl, substituted or unsubstituted phenylmethyl, substituted or unsubstituted phenoxymethyl, or substituted or unsubstituted benzoyl), or R.sup.1 and R.sup.2, when taken together, are carbonyl, R.sup.3 is substituted or unsubstituted phenyl, and R.sup.4 is hydrogen, optionally substituted hydrocarbon residue or acyl, silyl, sulfonyl or phosphonyl derived from inorganic acid or organic acid, the process comprising reacting a dithioazetidinone derivative represented by the formula ##STR3## wherein R.sup.1, R.sup.2 and R.sup.4 are as defined above and R.sup.9 is substituted or unsubstituted, nitrogen-containing aromatic heterocyclic residue with a compound represented by the formulaR.sup.3 SO.sub.2 CN (VII)wherein R.sup.3 is defined above.

Abstract: This invention provides a process for preparing a thiosulfonate derivative represented by the formulaR.sup.2 SO.sub.2 SR.sup.1 (III)wherein R.sup.1 is substituted or unsubstituted 2-benzothiazolyl, and R.sup.2 is substituted or unsubstituted phenyl, the process being characterized in that a compound represented by the formulaR.sup.1 SX (I)wherein R.sup.1 is as defined above, and X is hydrogen, alkali metal or SR.sup.1, and a sulfinic acid or a salt thereof represented by the formulaR.sup.2 SO.sub.2 Y (II)wherein R.sup.2 is as defined above, and Y is a hydrogen atom, alkali metal atom, alkaline earth metal atom or quaternary ammonium are subjected to an electrolytic reaction in a mixture of water and an organic solvent in the presence of a halogen salt.

Abstract: This invention provides a process for preparing a 2,2-bishalomethylpenam derivative represented by the formula ##STR1## wherein R.sup.1 represents a lower alkyl group, aryl group, arylmethyl group, arylcarbonyl group or aryloxymethyl group, R.sup.2 represents a carboxyl-protecting group, X.sup.1 and X.sup.2 are the same or different and represent a halogen atom, the process being characterized in that a disulfide represented by the formula ##STR2## wherein R.sup.1, R.sup.2 and X.sup.1 are as defined above and R.sup.3 represents an aryl group or heterocyclic group is subjected to an electrolytic reaction in a solvent in the presence of a halogen acid and/or halogen salt.