Amines such as 1,2,3,4-tetrahydroisoquinoline undergo redox-neutral annulations with
ortho-(nitromethyl)benzaldehyde. Benzoic acid acts as a promoter in these reactions, which
involve concurrent amine α-C–H bond and N–H bond functionalization. Subsequent removal
of the nitro group provides access to tetrahydroprotoberberines not accessible via
typical redox-annulations. Also reported are decarboxylative annulations of ortho-(nitromethyl)benzaldehyde with proline and pipecolic acid.
Key words
C–H bond functionalization - redox-neutral - redox-annulation - denitration - decarboxylative
annulation