Abstract: The present invention relates to a process for the preparation of 3?-thiosubstituted cephalosporins by enzymatic condensation of a nucleus with a phenylglycine derivative. Furthermore the present invention relates to a crystalline form of a compound of general formula (1) wherein R2 is OH and X is S and R1 is a radical of formula (2a) with R3 is CH3.

Abstract: The present invention relates to a process for the synthesis of cefaclor, which process comprises reacting 7-amino-3-chloro cephalosporanic acid (7-ACCA) with D-phenylglycine in activated form (PGa) in the presence of an enzyme in a reaction mixture to form cefaclor, wherein at least part of 7-ACCA and/or PGa are added to the reaction mixture during the course of the reaction. The invention also relates to an aqueous mixture comprising an amount of cefaclor of >10 (w/w) %, an amount of 7-amino-3-chloro cephalosporanic acid of <2 (w/w) %, and an amount of D-phenyl glycine of <2 (w/w) % and a process for the recovery of cefaclor from this aqueous mixture. The invention also relates to cefaclor in crystal form having an absorbance at 400 nm (A400) of less than 0.250.

Abstract: The present invention describes a process for preparing cephradine, said process comprising reacting 7-aminodesacetoxy cephalosporanic acid (7-ADCA) with D-dihydrophenylglycine in activated form (DHa) in the presence of an enzyme in a reaction mixture to form cephradine, resulting in a conversion of 7-ADCA into cephradine of at least 70%, wherein the concentration D-dihydrophenylglycine (DH) in the reaction mixture is below 2 wt.%, wherein the conversion of 7-ADCA into cephradine & equals; (nCEF/n7-ADCA)*100%, wherein nCEF=quantity of cephradine formed (in mole); and n7-ADCA=total quantity of 7-ADCA added to reaction mixture (in mole).

Abstract: The invention relates to mutated penicillin acylases having a high synthesis/hydrolysis ratio in comparison with wild-type penicillin acylases and at least 1% of the activity. The invention also relates to a process for the enzymatic preparation of a ?-lactam antibiotic from a ?-lactam nucleus and an activated side chain with the aid of mutated penicillin acylases.