Visible-light-induced meta-selective sulfonylation of pyridine via an EDA complex

Pyridine is a versatile structural unit found in a broad spectrum of pharmaceuticals, agrochemicals, and materials. Achieving selective meta-functionalization under mild conditions remains challenging due to its inherent electronic properties. In this work, we accomplished a photoinduced method for meta-selective sulfonylation of pyridines, facilitated by an electron donor-acceptor (EDA) complex between iodide ions and sulfonyl chlorides. The reaction proceeds via an oxazino-pyridine intermediate, with sulfonyl chloride acting as the sulfonyl radical precursor. This protocol stands out for its mild, photocatalyst-free conditions, high C5-selectivity, and good scalability, offering a promising approach for the synthesis of meta-sulfonylated pyridines.