Pyridinium ylids 4 were generated as reaction intermediates from the decarboxylation of pyridinium bctaincs 3, which were preparcd from the reactions of x-amino acid ester hydrochlorides with 2, 4,6-triphenylpyrylium tetrafluoroborate. Protonation, addition and substitution reactions of 4 with electrophiles werc studied in this paper.