Photoactivated Pyridine Directed Fluorination through Hydrogen Atom Transfer

J Org Chem. 2023 Dec 15;88(24):17538-17543. doi: 10.1021/acs.joc.3c02146. Epub 2023 Nov 30.

Abstract

We have established hydrogen atom transfer (HAT) as the key player in a directed, photopromoted fluorination of pyridylic groups. The Lewis basic pyridyl nitrogen directs amine radical dication propagated HAT and Selectfluor fluorination of various ortho substituents in a highly regioselective manner with little to no side product formation. A variety of pyridines and quinolines were employed to showcase the directing capability of the nitrogen atom. Additionally, both experimental and computational data are provided that illuminate how this mechanism differs from and complements prior work in the area.