Photoinduced Ge(II)-Catalyzed Divergent Functionalization of Pyridyl Halides via Electron Donor–Acceptor Complexes

We report a photoinduced Ge(II)-catalyzed strategy for divergent functionalization of pyridyl halides that leverages in situ electron donor-acceptor (EDA) complex formation to catalytically generate pyridyl radicals, enabling aryl, alkynyl, and alkenyl couplings under mild, protic conditions without an external photocatalyst. Notably, the protocol exhibits excellent chemoselectivity for pyridyl C-X bonds, leaving other aryl halides, including those bearing electron-withdrawing substituents, intact. The protocol further enables unique transformations, including complete C8-selective coupling with 7-aminoquinoline and the modular assembly of benzo[f]isoquinolines from alkenyl boron reagents. Mechanistic studies support an EDA-mediated radical pathway. This work provides a sustainable platform for the divergent functionalization of pyridyl halides and expands the application of main-group elements in catalytic EDA chemistry.