Exciton coupling between the transition dipole moments of ordered dyes in supramolecular assemblies, so-called J/H-aggregates, leads to shifted electronic transitions. This can lower the excited state energy, allowing for emission well into the near-infrared regime. However, as we show here, it is not only the excited state energy modifications that J-aggregates can provide. A bay-alkylated quaterrylene was synthesized, which was found to form J-aggregates in 1,1,2,2-tetrachloroethane. A combination of superradiance and a decreased nonradiative relaxation rate made the J-aggregate four times more emissive than the monomeric counterpart. A reduced nonradiative relaxation rate is a nonintuitive consequence following the 180 nm (3300 cm −1 ) red-shift of the J-aggregate in comparison to the monomeric absorption. However, the energy gap law, which is commonly invoked to rationalize increased nonradiative relaxation rates with increasing emission wavelength, also contains a reorganization energy term. The reorganization energy is highly suppressed in J-aggregates due to exciton delocalization, and the framework of the energy gap law could therefore reproduce our experimental observations. J-Aggregates can thus circumvent the common belief that lowering the excited state energies results in large nonradiative relaxation rates and are thus a pathway toward highly emissive organic dyes in the NIR regime.

Redox-active N-(fluoromethoxy)benzotriazoles were made accessible from fluoroacetic acid and hydroxybenzotriazoles via electrodecarboxylative coupling. After alkylation, they become effective monofluoromethoxylation reagents, enabling the photocatalytic CÀ H functionalization of arenes. Thus, irradiation of 1-(OCH 2 F)-3-Me-6-(CF 3 )benzotriazolium triflate with blue LED light in the presence of [Ru(bpy) 3 (PF 6 ) 2 ] promotes the synthesis of diversely functionalized aryl monofluoromethyl ethers. This method allows the late-stage functionalization of biologically relevant structures without relying on ecologically problematic halofluorocarbons.

2,2′-Biaryldicarboxylates are important functionalities in bioactive compounds, functional materials, and chiral catalysts. These compounds have been found to be conveniently accessible from benzoic acids via Rh-catalyzed electrooxidative C–H/C–H couplings, giving valuable dihydrogen as the byproduct. In an undivided cell with Pt electrodes, RhCl3·3H2O catalyzes the oxidative carboxylate-directed ortho-homocoupling of various aromatic acids with a current efficiency of 67%. The protocol is operationally simple, tolerates a wide variety of functional groups, and does not require the exclusion of air and moisture. Heterodimerizations via cross-dehydrogenative couplings of naphthyl-1-carboxylic acids with acrylic or benzoic acids were also shown to work.

Palladium‐catalyzed couplings of silicon enolates with aryl electrophiles are of great synthetic utility, but often limited to expensive bromide substrates. A comparative experimental study confirmed that none of the established ligand systems allows to couple inexpensive aryl chlorides with α‐trimethylsilyl alkylnitriles. In contrast, ylide functionalized phosphines (YPhos) led to encouraging results. A statistical model was developed that correlates the reaction yields with ligand features. It was employed to predict catalyst structures with superior performance. With this cheminformatics approach, YPhos ligands were tailored specifically to the demands of Hiyama couplings. The newly synthesized ligands displayed record‐setting activities, enabling the elusive coupling of aryl chlorides with α‐trimethylsilyl alkyl nitriles. The preparative utility of the catalyst system was demonstrated by the synthesis of pharmaceutically meaningful α‐aryl alkylnitriles, α‐arylcarbonyls and biaryls.

In the presence of a [Ru(p-cymene)Cl 2 ] 2 /triethylphosphine/lithium carbonate catalyst system, aryl bromides undergo (Z)-selective couplings with unprotected 2-arylacrylic acids to form (Z)-diarylacrylic acids. This vinylic C−H functionalization proceeds in high yields of up to 94% and (Z/ E)-ratios of up to 99:1, tolerating a wide range of functional groups. Mechanistic studies indicate that the vinylic C−H activation proceeds via base-assisted cyclometalation rather than via a Heck-type mechanism, which explains its orthogonal stereoselectivity.

The use of electricity as an inexpensive and waste-free oxidant opens up new opportunities for the development of sustainable C–H functionalization reactions. Herein we summarize recent advances in the synthesis of biaryls through electrooxidative processes involving transition metal catalyzed ortho-directed C−H activation. A particular focus is set on electrooxidative C−H/C−M couplings and dehydrogenative couplings.

Controlling regioselectivity in CÀ H functionalizations is a key challenge in chemical method development. In arenes, functionalizations are most difficult to direct towards the CÀ H group furthest away from a substituent, in its para position. We herein demonstrate how the para-CÀ H arylation of anilines with nonactivated aryl halides, elusive to date, is achieved by a base-assisted "metalla-tautomerism" approach. A proton is abstracted from the aniline substrate and replaced by an arylpalladium species, generated from the aryl halide coupling partner. In this step, the palladium is directed away from the N-to the tautomeric para-CÀ H position by a large phosphine ligand combined with a triphenylmethyl shielding group. The triphenylmethyl group is easily installed and removed, and can be recycled.

The 3d‐metal catalyst Mn(CO)5Br was found to efficiently promote ortho C−H allylations of arenecarboxylates in the presence of neocuproine as the ligand. Despite the simplicity of directing group and catalyst system, the selectivity goes well beyond the state‐of‐the‐art in that mono‐allylated products are obtained exclusively with high selectivities for the least hindered ortho‐position. The directing group can optionally be removed by in situ decarboxylation, opening up a regioselective entry to allyl arenes. The preparative utility of the process and its othogonality to other approaches was demonstrated by 44 products with otherwise hard‐to‐access substitution patterns, including 3‐bromo‐allylbenzene, 3‐allylbenzofuran, or 5‐allyl‐2‐methylnitrobenzene.