The regioselective conversion of C-H bonds into C-Si bonds is extremely important owing to the natural abundance and non-toxicity of silicon. Classical silylation reactions often suffer from poor functional group compatibility, low atom economy, and insufficient regioselectivity. Herein, we disclose a template-assisted method for the regioselective para silylation of toluene derivatives. A new template was designed, and the origin of selectivity was analyzed experimentally and computationally. An interesting substrate-solvent hydrogen-bonding interaction was observed. Kinetic, spectroscopic, and computational studies shed light on the reaction mechanism. The synthetic significance of this strategy was highlighted by the generation of a precursor of a potential lipophilic bioisostere of γ-aminobutyric acid (GABA), various late-stage diversifications, and by mimicking enzymatic transformations.

This report describes the chemoselective coupling of polyfluoroarenes with aryl germanes in the presence of aromatic C–I, C–Br, C–Cl, C–OTf, and C–SiMe3 groups, as well as demonstrates the further downstream diversification to give richly functionalized and highly fluorinated polyarenes. The strategy relies on an in situ Umpolung of the F n ArH, followed by selective Au(I)/Au(III)-catalyzed coupling with electron-poor or -rich aryl germanes, even in the presence of challenging ortho-substituents, and widens the currently available coupling space in oxidative gold catalysis to previously inaccessible electron-poor/electron-poor biaryls.

The development of orthogonal Csp2–Csp2 coupling regimes to the omnipresent Pd-catalysis class would enable an additional dimension of modularity in the construction of densely functionalized biaryl motifs. In this context, the identification of potent functional groups for selective transformations is in high demand. Although organogermanium compounds are generally believed to be of low reactivity in homogenous catalysis, this report discloses the highly efficient and orthogonal reactivity of aryl germanes with arenes under gold catalysis. The method is characterized by mildness, the employment of an air- and moisture-stable gold catalyst, and robustness. Our mechanistic studies show that aryl germanes are highly reactive with Au(I) and Au(III). Our computational data suggest that the origin of this reactivity primarily lies in the relatively low bond dissociation energy and as such low distortion energy to reach the key bond activating transition state.

Selective Csp2 –Csp2 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 Pd0/PdII catalysis) in the presence of the valuable functionalities C−BPin, C−SiMe3, 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–N2+, which were specialized in Ar–N2+ 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–N2+ salts are readily activated by gold under blue‐light irradiation, there is a competing dissociative deactivation pathway for excited electron‐rich Ar–N2+, which requires an alternative photo‐redox approach to enable productive couplings.

While alkynyl silanes are ubiquitously employed in synthetic handles, especially in the build-up of more complex alkynes, such as alkyne-based polyaromatic materials, the identification of a similar robust functionality with ideally orthogonal reactivity space would greatly expand the modularity and scope in the construction of functional alkynes. We herein disclose the efficient, mild, and modular arylation of alkynylgermanes, which is enabled by blue light-assisted gold catalysis and allows for the chemoselective arylation of the alkynylgermane moiety at room temperature in 2 h over alkynyl silanes, aryl halides, aryl BPin, and various other functional groups. Conversely, the alkynylgermane proved to be uniquely stable toward typical alkynyl silane deprotection conditions as well as Sonogashira cross-coupling conditions, which underlines its orthogonal reactivity space and significant potential as a complementary robust alkyne handle.