Catalytic methoxylation of aryl halides using 13C- and 14C-labeled CO2.

The functionalization of carbon dioxide (CO2) into high-value building blocks is a relevant topic in carbon isotope labeling, where CO2 is the primary carbon source. A catalytic methoxylation of aryl halides directly from [13C] and [14C]CO2 is reported. Relying on the intermediacy of the methoxyborane BBN-OCH3, as a new secondary nucleophilic labeled source, this strategy allowed labeling of a series of substrates, including challenging pharmaceuticals containing tertiary alkyl amine substituents.

Photocatalytic deoxygenation of N-O bonds with rhenium complexes: from the reduction of nitrous oxide to pyridine N-oxides.

The accumulation of nitrogen oxides in the environment calls for new pathways to interconvert the various oxidation states of nitrogen, and especially their reduction. However, the large spectrum of reduction potentials covered by nitrogen oxides makes it difficult to find general systems capable of efficiently reducing various N-oxides. Here, photocatalysis unlocks high energy species able both to circumvent the inherent low reactivity of the greenhouse gas and oxidant N2O (E 0(N2O/N2) = +1.77 V vs. SHE), and to reduce pyridine N-oxides (E 1/2(pyridine N-oxide/pyridine) = -1.04 V vs. SHE). The rhenium complex [Re(4,4'-tBu-bpy)(CO)3Cl] proved to be efficient in performing both reactions under ambient conditions, enabling the deoxygenation of N2O as well as synthetically relevant and functionalized pyridine N-oxides.

"(Diphosphine)Nickel"-catalyzed negishi cross-coupling: an experimental and theoretical study.

The use of a strongly donating "(bis-dialkylphosphine)Ni" fragment promotes the catalytic coupling of a large range of ArCl and ArZnCl derivatives under mild conditions. Stoichiometric mechanistic investigations and DFT calculations prove that a Ni(0) /Ni(II) cycle is operative in this system.