Process for preparing cephalosporin compounds

A process for preparing an amide compound, which comprises reacting a 7-aminocephalosporanic acid with a carboxylic acid in the presence of a dehydration condensing agent and at least a 0.1 equal molar amount of an acid or an acid complex, wherein said 7-aminocephalosporanic acid is represented by the formula ##STR9## said carboxylic acid is represented by the formula:

• ##STR10## and said amide compound is a 7-substituted amino-3-substituted methylcephem-carboxylic acid represented by the formula:
• ##STR11## wherein W represents a hydrogen atom, ethenyl, 2-carboxyethenyl, chlorine, methoxy, or a group represented by --CH.sub.2 Y, wherein Y represents a hydrogen atom or a nucleophilic compound residue, Z represents a hydrogen atom, a metal atom, or an alkyl group having 1 to 5 carbon atoms, an aryl group having 6 to 10 carbon atoms, a cycloalkyl group having 6 to 10 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms;
• and A represents .dbd.CH-- or .dbd.N--, E represents --S-- or --O--;
• Q represents .dbd.O or a functional group represented by .dbd.N.about.R.sup.4, wherein R.sup.4 represents a hydroxy group or an alkoxy group and .about. in .dbd.N.about.R.sup.4 represents syn- or anti-form, wherein said dehydration condensing agent is a carbodiimide represented by formula:
• R.sup.1 --N.dbd.C.dbd.N--R.sup.2
• wherein R.sup.1 and R.sup.2, which may be the same or different, each represents an alkyl group having 1 to 5 carbon atoms, an aryl group having 6 to 10 carbon atoms, a cycloalkyl group having 6 to 10 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms, and wherein said acid or acid complex is a sulfonic acid represented by R.sup.3 SO.sub.3 H, a hydrohalogen acid represented by HX, a Lewis acid, or a Lewis acid complex;
• wherein R.sup.3 represents a hydroxy group, an alkyl group having 1 to 5 carbon atoms, an aryl group having 6 to 10 carbon atoms, a cycloalkyl group having 6 to 10 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms;
• and X represents a halogen atom.