Reactions of 1,4-dihydro-3-(2H)benzoisoquinolinones with aldehydes in the presence of a strong base. Condensation and aromatization as competing reactions

In reactions of 1-phenyl-1,4-dihydro-3-(2H)benzoisoquinolinones with benzaldehyde in the presence of a strong base, the final result can be ring substitution with aromatization or only aromatization of the starting isoquinolinone, depending on the position of the ring junction ([f] or [h]), in the 5-methyl derivative the latter process becomes predominating. In the system sodium hydride-dimethylformamide, containing no aromatic aldehyde, methylation at site 4 occurs. Using compounds labelled with deuterium, it has been established that the 4-benzyl or 4-methyl derivatives with aromatic structures are formed through hydride ion migrations.