New collaboration article by the Hopmann/Bayer and Skrydstrup groups

Abstract
We have developed a carbonylative approach to the synthesis of diversely substituted 2-aroylbenzoate esters featuring a new protocol for the carbonylative coupling of aryl bromides with boronic acids and a new strategy to favour carbonylative over non-carbonylative reactions. Two different synthetic pathways – (i) the alkoxycarbonylation of 2-bromo benzophenones and (ii) the carbonylative Suzuki–Miyaura coupling of 2-bromobenzoate esters – were evaluated. The latter approach provided a broader substrate tolerance, and thus was the preferred pathway. We observed that 2-substituted aryl bromides were challenging substrates for carbonylative chemistry favouring the non-carbonylative pathway. However, we found that carbonylative Suzuki–Miyaura couplings can be improved by slow addition of the boronic acid, suppressing the unwanted direct Suzuki coupling and, thus increasing the yield of the carbonylative reaction.

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New research article from the Skrydstrup group

Abstract
Electrocatalysis is a promising tool for utilizing carbon dioxide as a feedstock in the chemical industry. However, controlling the selectivity for different CO2 reduction products remains a major challenge. We report a series of manganese carbonyl complexes with elaborated bipyridine or phenanthroline ligands that can reduce CO2 to either formic acid, if the ligand structure contains strategically positioned tertiary amines, or CO, if the amine groups are absent in the ligand or are placed far from the metal center. The amine-modified complexes are benchmarked to be among the most active catalysts for reducing CO2 to formic acid, with a maximum turnover frequency of up to 5500 s–1 at an overpotential of 630 mV. The conversion even works at overpotentials as low as 300 mV, although through an alternative mechanism. Mechanistically, the formation of a Mn–hydride species aided by in situ protonated amine groups was determined to be a key intermediate by cyclic voltammetry, 1H NMR, DFT calculations, and infrared spectroelectrochemistry.

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New research article by the Hopmann/Bayer group

Abstract
A formal C‐H carboxylation of unactivated arenes using CO2 in green solvents is described. The present strategy combines a sterically controlled Ir‐catalyzed C‐H borylation followed by a Cu‐catalyzed carboxylation of the in situ generated organoboronates. The reaction is highly regioselective for the C‐H carboxylation of 1,3‐disubstituted and 1,2,3‐trisubstituted benzenes, 1,2‐ or 1,4‐symmetrically substituted benzenes, fluorinated benzenes and different heterocycles. The developed methodology was applied to the late‐stage C‐H carboxylation of commercial drugs and ligands.

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New communication from the Skrydstrup group

Abstract
An extensive range of functionalized aliphatic ketones with good functional‐group tolerance has been prepared by a NiI‐promoted coupling of either primary or secondary alkyl iodides with NN2 pincer NiII‐acyl complexes. The latter were easily accessed from the corresponding NiII‐alkyl complexes with stoichiometric CO. This Ni‐mediated carbonylative coupling is adaptable to late‐stage carbon isotope labeling, as illustrated by the preparation of isotopically labelled pharmaceuticals. Preliminary investigations suggest the intermediacy of carbon‐centered radicals.

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