The pyridylsuccinates (1) and pyridylglutarates (2), with various substituents on the pyridine ring, were cyclized in Dowtherm A at 250 °C. The succinates cyclized in two competing reaction routes, giving rise to pyrido[1,2-a]-pyrimidines (route A) and N-pyridylpyrrolinones (route B). The ratio of the two products varied with the nature of the substituent and its position. The N-pyridylpyrrolinones proved to be mixtures of the desmotropes (5) and (6) which were separated. The pyridylglutarates (2) gave only the pyrido[1,2-a]pyrimidines (4). The 6-substituted pyrido[1,2-a]pyrimidines underwent a ring-transformation reaction at or above 250 °C, forming the corresponding 1,8-naphthyridines (8) and (9).
|Number of pages||6|
|Journal||Journal of the Chemical Society, Perkin Transactions 1|
|Publication status||Published - Jan 1 1980|
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