Selectivity of penicillin G acylase towards phenylacetic acid derivatives in amide bond synthesis in toluene

Penicillin G acylase (PGA) accepts in toluene several analogues of phenylac etic acid as acyl donors. The 4-hydroxyphenyl-acetic group is preferentiall y accepted, and steric factors, such as the substitution at the aromatic ri ng or at the methylene group, cause a remarkable reduction in the initial r ates. Results indicate that the selectivity follows a similar trend both in toluene and in aqueous media and that the synthetic potential of PGA can b e fully exploited also in non-aqueous media with the consequent advantages, such as the absence of competitive hydrolytic reactions, higher solubility of phenylacetic derivatives and the possibility of working with equimolar amounts of reactants. (C) 2001 Elsevier Science B.V. All rights reserved.