The reaction of 2, 4, 5-triphenyl-3H-pyrrol-3-one I-oxide with dimethyl acetylenedicarboxylate gave pyridine 9a, 4 (3H)-pyridone loa, isoxazolidine 11, and traces of pyridone 13. Pyridone 10a is not an intermediate in the formation of 9a, yet on photolysis or pyrolysis above its melting point, loa yielded pyridine 9a. Possible reaction mechanisms that rationalize the formation of these products are discussed.
