Density functional theory (DFT) calculations were performed to gain an in-depth mechanistic understanding of the Rh(I)-catalyzed transannulation of 1,2,3-thiadiazoles with alkenes, alkynes, and nitriles. Computational results indicate that the denitrogenation...

The construction of C­(sp3)–N bonds via direct radical–radical cross-coupling under benign conditions is a desirable but challenging approach. Herein, the cross-coupling of alkyl and amidyl radicals to build aliphatic C–N bonds in a concise, mild, and oxidant-free manner is implemented by nickel/photoredox dual catalysis. In this protocol, the single electron transfer strategy is successfully employed to generate N- and C-centered radicals from sulfonyl azides/azidoformates and alkyltrifluoroborates, respectively. The photocatalyst-induced triplet–triplet energy-transfer mechanism, however, might not be applicable to this reaction. The oxidative quenching pathway of the excited photocatalyst (RuII/*RuII/RuIII/RuII) combined with a possible NiI/NiII/NiIII/NiI catalytic cycle is proposed to account for the nickel/photoredox dual-catalyzed C­(sp3)–N bond formation based on synergistic experimental and computational studies.

Photosynthesis and the biosynthesis of many important metabolites occur in chloroplasts. In these semi-autonomous organelles, the chloroplast genome encodes approximately 100 proteins. The remaining chloroplast proteins, close to 3000, are encoded by nuclear genes whose products are translated in the cytosol and imported into chloroplasts. However, there is still no consensus on the composition of the protein import machinery including its motor proteins and on how newly imported chloroplast proteins are refolded. In this study, we have examined the function of orf2971, the largest chloroplast gene of Chlamydomonas reinhardtii. Depletion of Orf2971 causes accumulation of protein precursors, partial proteolysis and aggregation of proteins, increased expression of chaperones and proteases, and autophagy. Orf2971 interacts with the TIC complex, catalyzes ATP hydrolysis and associates with chaperones and chaperonins. We propose that Orf2971 is intimately connected to the protein import machinery and plays an important role in chloroplast protein quality control.