Site-Selective Nitration of Aryl Germanes at Room Temperature.

We report a site-selective ipso-nitration of aryl germanes in the presence of boronic esters, silanes, halogens, and additional functionalities. The protocol is characterized by operational simplicity, proceeds at room temperature, and is enabled by [Ru(bpy)3](PF6)2/blue light photocatalysis. Owing to the exquisite robustness of the [Ge] functionality, nitrations of alternative functional handles in the presence of the germane are also feasible, as showcased herein.

Orthogonal C-O Bond Construction with Organogermanes.

We report a fully orthogonal C-O bond formation strategy, which involves the selective coupling of arylgermanes with alkyl alcohols (primary, secondary and tertiary) as well as carboxylic acids, tolerating otherwise widely employed coupling handles, such as aromatic (pseudo)halogens (C-I, C-Br, C-Cl, C-F, C-OTf, C-OFs), silanes and boronic acid derivatives. This unprecedented [Ge]-based C-O bond construction is rapid (15 min to few hours reaction time), air-tolerant, operationally simple and mild, as it is base-free and proceeds at room temperature.

Domino Construction of Benzoxazole-Derived Sulfonamides via Metal-Free Denitrogenation of 5-Iodo-1,2,3-triazoles in the Presence of SO2 and Amines.

A straightforward domino approach to assemble benzoxazole-derived sulfonamides has been developed. The method is based on annulation-induced in situ generation of diazo compounds from readily available 2-(5-iodo-1,2,3-triazolyl)phenols, followed by metal-free denitrogenative transformation upon the action of 1,4-diazabicyclo[2.2.2]octane bis(sulfur dioxide) (DABSO) and amines. The protocol is operationally simple and features a broad substrate scope, furnishing a library of target compounds in generally good yields.

Germylation of Arenes via Pd(I) Dimer Enabled Sulfonium Salt Functionalization.

While aryl germanes have recently found usage as coupling partners in powerful catalytic applications, the synthetic access to this promising functionality is currently limited. This report details the straightforward synthesis of functionalized aryl triethylgermanes via formal C-H functionalization. Building on the concept of directing-group-free and site-selective C-H functionalization of arenes to thianthrenium salt intermediates, we showcase their efficient couplings with triethylgermane (Et3Ge-H) at room temperature, which was enabled by the air- and moisture-stable Pd(I) dimer, [Pd(µ-I)(PtBu3)]2. The method tolerates numerous functional groups, including valuable (pseudo)halides.

Modular and Selective Arylation of Aryl Germanes (C-GeEt3 ) over C-Bpin, C-SiR3 and Halogens Enabled by Light-Activated Gold Catalysis.

Selective C sp 2 -C sp 2 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.