Fragmentation of 1-methyl-1,2,3,4-tetrahydroquinoline-2,3-dicarboxylic acid derivatives upon electron ionization

The electron ionization-inducted fragmentation patterns of cis-3a,4,9,9a-tetrahydro-4-methyl-2-phenyl-1H-pyrrolo[3,4-b]quinoline-1,3(2H)-dione derivatives have been studied. It was found that fragmentation starts at N-phenylsuccinimide ring and its pattern depends on the type and position of the substituents at carbon atoms 5-8. Peaks, which can be assigned to the products of the retro Diels-Alder opening of the nitrogen atom containing tetrahydroquinoline ring, were observed.