Process for preparing 7-oxo cephalosporins and 6-oxo penicillins

A process for preparing a compound of the formula:

• ##STR3## R.sup.1 is hydrogen or an easily removable conventional penicillin or cephalosporin ester protecting group;
• and
• R.sup.2 is hydrogen, acetoxy or SHet where Het is a five or six membered heterocyclic ring containing carbon and one to four atoms selected from the group consisting of N, O and S, each such ring being unsubstituted or substituted with one or two groups selected from alkyl, alkoxyalkyl and trifluoromethyl, each alkyl or alkoxy group having from one to four carbon atoms,
• comprising reacting, in the presence of a non-hydroxylic solvent, a 7-amino cephalosporin or 6-amino penicillin of the formula:
• ##STR4## in which A, R.sup.1 and R.sup.2 are defined as above, with a carbonyl containing oxidizing agent selected from the group consisting of:
• mesitylglyoxal,
• 3-nitromesitylglyoxal,
• 3,5-dinitromesitylglyoxal,
• benzothiazole-2-carboxaldehyde,
• 6-nitrobenzothiazole-2-carboxaldehyde,
• 3,5-di-i-propyl-1,2-benzoquinone,
• 3-methyl-5-i-propyl-1,2-benzoquinone,
• tetrachloro-1,2-benzoquinone
• tetrabromo-1,2-benzoquinone,
• 2,6-di-t-butyl-1,4-benzoquinone and
• 3,5-di-t-butyl-1,2-benzoquinone,
• said reaction being carried out with removal of water.