Modular and Selective Arylation of Aryl Germanes (C−GeEt(3)) over C−Bpin, C−SiR(3) and Halogens Enabled by Light‐Activated Gold Catalysis

Selective C [Formula: see text] –C [Formula: see text] couplings are powerful strategies for the rapid and programmable construction of bi‐ or multiaryls. To this end, the next frontier of synthetic modularity will likely arise from harnessing the coupling space that is orthogonal to the powerful Pd‐catalyzed coupling regime. This report details the realization of this concept and presents the fully selective arylation of aryl germanes (which are inert under Pd(0)/Pd(II) catalysis) in the presence of the valuable functionalities C−BPin, C−SiMe(3), C−I, C−Br, C−Cl, which in turn offer versatile opportunities for diversification. The protocol makes use of visible light activation combined with gold catalysis, which facilitates the selective coupling of C−Ge with aryl diazonium salts. Contrary to previous light‐/gold‐catalyzed couplings of Ar–N(2) (+), which were specialized in Ar–N(2) (+) scope, we present conditions to efficiently couple electron‐rich, electron‐poor, heterocyclic and sterically hindered aryl diazonium salts. Our computational data suggest that while electron‐poor Ar–N(2) (+) salts are readily activated by gold under blue‐light irradiation, there is a competing dissociative deactivation pathway for excited electron‐rich Ar–N(2) (+), which requires an alternative photo‐redox approach to enable productive couplings.