Visible-Light-Induced C4-Selective Functionalization of Pyridinium Salts with Cyclopropanols

Abstract

The site-selective C-H functionalization of heteroarenes is of considerable importance for streamlining the rapid modification of bioactive molecules. Herein, we report a general strategy for visible-light-induced beta-carbonyl alkylation at the C4 position of pyridines with high site selectivity using various cyclopropanols and N-amidopyridinium salts. In this process, hydrogen-atom transfer between the generated sulfonamidyl radicals and O-H bonds of cyclopropanols generates beta-carbonyl radicals, providing efficient access to synthetically valuable beta-pyridylated (aryl)ketones, aldehydes, and esters with broad functional-group tolerance. In addition, the mild method serves as an effective tool for the site-selective late-stage functionalization of complex and medicinally relevant molecules.