Visible-Light-Driven C4-Selective Alkylation of Pyridinium Derivatives with Alkyl Bromides

Reported herein is a general strategy
for the photochemical cross-coupling
between N-amido­pyridinium salts and various
alkyl bromides under photocatalyst-free conditions, granting facile
access to various C4-alkylated pyridines. This approach exploits the
intriguing photochemical activity of electron donor–acceptor
(EDA) complexes between N-amido­pyridinium salts
and bromide, which provides a photoactive handle capable of generating
silyl radicals and driving the alkylation process. The robustness
of this protocol was further demonstrated by the late-stage functionalization
of complex compounds under mild and metal-free conditions.