An efficient route to N-alkylated 3,4-dihydroisoquinolinones with substituents at the 3-position.

A facile synthetic procedure for the production of N-alkylated 3,4-dihydroisoquinolinone derivatives is described. The desired products were obtained by N-alkylation of 3,3'-dimethyl-3,4-dihydroisoquinoline derivatives followed by oxidation of the resulting iminium salts. Reaction conditions for both steps were very mild and the desired cyclization products could be obtained in good yield. This strategy allows the generation of N-substituted 3,4-dihydroisoquinolinone derivatives with substituents at the 3-position.

The dual role of ruthenium and alkali base catalysts in enabling a conceptually new shortcut to N-unsubstituted pyrroles through unmasked α-amino aldehydes.

A virtually salt-free and straightforward bimolecular assembly giving N-unsubstituted pyrroles through fully unmasked α-amino aldehydes, which was enabled by the dual effects of a catalytic ruthenium complex and an alkali metal base, is reported. Either solvent-free or acceptorless dehydrogenation facilitates high atom, step, and pot economy, which are otherwise difficult to achieve in multistep operations involving protection/deprotection.