Discovery of long-acting N-(cyanomethyl)-N-alkyl-l-prolinamide inhibitors of dipeptidyl peptidase IV Original Research Article

Details of structure–activity relationships (SAR) for P2 moiety of a P1 2-cyanopyrrolidine dipeptidyl peptidase IV (DPP-IV) inhibitor 4a including stereochemistry are presented. Based on this information, a series of P1 (N-alkyl)aminoacetonitrile analogs 9–20 possessing optimal P2 structure were synthesized and evaluated as inhibitors of DPP-IV. Among them, a representative compound 11, N-(cyanomethyl)-N-ethyl-l-prolinamide, was further evaluated to determine its effect on the plasma glucose level. Also 4a, 10, and 11 were evaluated for their isozyme selectivity to predict their safety problems.