A novel, facile, and highly enantioselective Brønsted acid-catalyzed alpha-hydroxylation of beta-dicarbonyl compounds with up to 99:1 er using nitroso compounds as the oxygen source has been developed. The results disclosed herein considerably extend the substrate scope for the alpha-aminoxylation, allowing expeditious, straightforward, and efficient access to valuable alpha-hydroxy-beta-dicarbonyl compounds with the highest levels of enantiocontrol.

Knowledge about bonding in diiminepyridine (L) halide, alkyl, and dinitrogen complexes of the metals iron, cobalt, and nickel is summarized, and two new examples are added to the set: L(1)Ni(Me) and L(1)Ni(N(2)). Reactivity of these types of complexes is discussed in terms of organic radical chemistry. New C-C couplings with L(2)CoAr complexes are described and proposed to involve halide abstraction and radical coupling. Calculations support the high tendency of the diiminepyridine ligand to accept an electron coming from a metal-carbon bond and so facilitate loss of a radical.

The iterative polyketide synthases from the biosynthetic pathways of three enediyne natural products were examined. The results established the all-trans conjugated pentadecaheptanene as the only major product shared by the PKSs. The experiments further revealed some intrinsic differences among the PKSs by demonstrating the formation of different by-products.

Reaction of LCoCH2SiMe3 (L = 2,6-bis[2,6-dimethylphenyliminoethyl]pyridine) with H2 produces LCo(N2), presumably via intermediate LCoH. Reaction of LCo(N2) (prepared in this way or via reaction of LCoCl2 with Na/Hg) with aryl halides ArX (X = Cl, Br, I) produces LCoAr and LCoX in a ratio depending on the nature of Ar and X. For X = Cl, the reaction is slowest but also produces the largest amount of LCoAr. Electron-withdrawing substituents both accelerate the reaction and improve the yield of LCoAr. Computational studies support a radical mechanism for this reaction, involving displacement of N2 to give LCo(XAr) followed by loss of the Ar radical, which then binds to a second Co(0) moiety.

The coupling of HSiEt3 and related silanes to β‐diiminate ligands is achieved through a series of SiH, CH, and SiC bond‐breaking and bond‐forming reactions. Complex 1 (see scheme) loses an Et(Si) group as ethane and couples the remaining SiEt2H fragment to a benzylic methyl group of the ligand skeleton. According to DFT calculations, the reaction involves silylene intermediates.