Photoredox-catalysed formal [3+2] cycloaddition of N-aryl α-amino acids with isoquinoline N-oxides.

A formal [3+2] cycloaddition of N-aryl α-amino acids with isoquinoline N-oxides via visible light-driven photoredox catalysis is reported. Under transition metal-free conditions using a dicyanopyrazine-derived chromophore (DPZ) as the photoredox catalyst, the transformation was efficient and led to a series of important diazabicyclo[3.2.1]octane-based N-heterocyclic compounds. This work demonstrates the synthetic utility of N-aryl α-amino acids as 1,2-synthons and provides a new strategy for the dearomatization of isoquinolines.