Reactive acyl dipeptides as potential penicillin analogues. Part I. α-(Acylaminosuccinimido)-carboxylic acids

A number of esters of α-(acylaminosuccinimido)-carboxylic acids were prepared from diesters of N-acyl-α-aspartyl- or N-acyl-β-aspartyl-α-amino-acids; cyclisation occurred either spontaneously or on heating with triethylamine in ethanol. α-(Acylaminosuccinimido)-carboxylic acids were prepared by catalytic hydrogenation of the benzyl esters or, in less pure form, by heating a dry mixture of the appropriate N-acyl aspartic anhydride and α-amino-acid in vacuo. Like penicillin, the α-(acylaminosuccinimido)-carboxylic acids could be regarded as acyl dipeptides containing a reactive peptide bond, but they displayed little or no antibacterial activity.