The reaction of 2-(substituted amino) pyridine with reactive malonic acid derivatives
provided an extremely facile synthesis of the mesoionic compound 4-oxo-4H-pyrido [1, 2-a]
pyrimidin-1-ium-2-olates. N, N′-Disubstituted amidine reacted with diethyl malonate to
afford 4-quinolone in a one-pot cyclization and rearrangement (type A/I) of 4-
oxopyridiniumolate 6. The latter compound was isolated via a reaction of acyclic amidine
with AME's. A cycloaddition reaction of the mesoionic pyrimidine 6 with maleic anhydride ...