1983 Volume 56 Issue 12 Pages 3667-3671
2-(Dimethylcarbamoyl)quinolines are converted into 2-(methylaminoacetyl)quinolines (2) and 2-methyl-1H-pyrrolo[3,4-b]quinolin-3(2H)-ones (3) by irradiation in a nitrogen atmosphere. The reaction was quite efficient in acetonitrile but inefficient in hydrocarbon solvents and ethanol. The introduction of a chlorine atom to the 4-position of a quinoline nucleus caused an increase of the yield of 3 in company with a decrease of the yield of 2. On the other hand, irradiation in an oxygen atmosphere afforded 2-(methylcarbamoyl)quinolines as a main product but 2 and 3 were minor products. The results of quenching and sensitization experiments confirmed that the triplet π,π* state was responsible for the formation of those products. It is suggested that the reaction involves zwitterionic intermediates formed via Type II hydrogen abstraction by the ring nitrogen from the N-methyl group.
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