Abstract A mild N-alkylation method has been developed for the synthesis of N-alkylated pyridiniumcarboxylic acids, using Ag 2 OH 2 O catalysis to enhance the low-reactivity of pyridinecarboxylic acids. Two approaches were undertaken for the synthesis of a series of GnRH antagonists containing pyridinium moieties at the side chain:(1) incorporation of Npy- alkylated D-pyridylalanine during solid phase peptide chain assembly, and (2) coupling of ...