One-pot synthesis of 4-substituted isoquinolinium zwitterionic salts by metal-free C-H bond activation.

The unprecedented isoquinolinium zwitterionic salts with an unusual C-4 substitution pattern were efficiently prepared via the multicomponent reaction of in situ formed N-benzylisoquinolinium bromide with aromatic aldehydes and cyclic 1,3-dicarbonyl compounds.