A Metal-Free Visible-Light Photoredox Construction and Direct C–H Functionalization of Pyridines: Green Synthesis of Polysubstituted Picolinaldehydes

The
development of a novel environmental benign and sustainable
synthetic method for highly efficient construction and direct C–H
functionalization of N-heterocycles remains a pivotal central research
topic for organic and medicinal chemistry. Herein, a novel visible-light-enabled
biomimetic aza-6π electrocyclization for efficient assembly
of diverse pyridines and further tandem Minisci-type reaction were
developed. A broad spectrum of polysubstituted picolinaldehydes were
readily constructed with high efficacy and good functional group tolerance
under metal- and oxidant-free conditions.