A Data Science-Guided Approach for the Development of Nickel-Catalyzed Homo-Diels-Alder Reactions.

The Ni-catalyzed homo-Diels-Alder (hDA) reaction represents a convergent but under-investigated approach to preparing bridged bicyclic ring systems. Using the monophosphine descriptor library, Ni-catalyzed hDA reactions of acyclic and cyclic electron deficient olefins were investigated, and key ligand effects required for reactivity were identified using classification models. This analysis guided the discovery of the monophosphine ()-AntPhos as a chiral ligand for the enantioselective hDA of acyclic dienophiles.

A Promiscuous rSAM Enzyme Enables Diverse Peptide Cross-linking.

Ribosomally produced and post-translationally modified polypeptides (RiPPs) are a diverse group of natural products that are processed by a variety of enzymes to their biologically relevant forms. PapB is a member of the radical -adenosyl-l-methionine (rSAM) superfamily that introduces thioether cross-links between Cys and Asp residues in the PapA RiPP. We report that PapB has high tolerance for variations in the peptide substrate.

Activator-free olefin oligomerization and isomerization reactions catalyzed by an air- and water-tolerant Wacker oxidation intermediate.

A bench-stable, hydroxy-bridged α-diimine-Pd dimer can self-activate to an olefin oligomerization and isomerization catalyst in the presence of substrate. A cationic Pd-hydride is generated principally through a Wacker oxidation of olefin to ketone, and with C(4+) olefins, lesser amounts of allylic C-H activation, β-H transfer, and release of diene products are observed.

Dinitrogen complexes supported by tris(phosphino)silyl ligands.

The tetradentate tris(phosphino)silyl ligand [SiP(iPr)(3)] ([SiP(iPr)(3)] = [Si(o-C(6)H(4)P(i)Pr(2))(3)](-)) has been prepared, and its complexation with iron, cobalt, nickel, and iridium precursors has been explored. Several coordination complexes have been thoroughly characterized and are described. These include, for example, the divalent trigonal bipyramidal metal chlorides [SiP(iPr)(3)]M-Cl (M = Fe, Co, Ni), as well as the monovalent dinitrogen adducts [SiP(iPr)(3)]M-N(2) (M = Fe, Co, Ir), which are compared with related [SiP(Ph)(3)]M-Cl and [SiP(Ph)(3)]M-N(2) species (M = Fe, Co).