A catalytic system comprised of a cobalt-diphosphine complex and a Lewis acid (LA) such as AlMe3 has been found to promote hydrocarbofunctionalization reactions of alkynes with Lewis basic and electron-deficient substrates such as formamides, pyridones, pyridines, and azole derivatives through site-selective C-H activation. Compared with known Ni/LA catalytic system for analogous transformations, the present catalytic system not only feature convenient set up using inexpensive and bench-stable precatalyst and ligand such as Co(acac)3 and 1,3-bis(diphenylphosphino)propane (dppp), but also display distinct site-selectivity toward C-H activation of pyridone and pyridine derivatives. In particular, a completely C4-selective alkenylation of pyridine has been achieved for the first time. Mechanistic stidies including DFT calculations on the Co/Al-catalyzed addition of formamide to alkyne have suggested that the reaction involves cleavage of the carbamoyl C-H bond as the rate-limiting step, which proceeds through a ligand-to-ligand hydrogen transfer (LLHT) mechanism leading to an alkyl(carbamoyl)cobalt intermediate. File list (3) download file view on ChemRxiv WCS_CoLA_manuscript.pdf (0.96 MiB) download file view on ChemRxiv WCS_CoLA_SI.pdf (20.25 MiB) download file view on ChemRxiv 11ck.cif (0.99 MiB)

Four chiral phosphapalladacycle complexes functionalized with the malonate moiety at the chiral carbon have been synthesized via a consecutive asymmetric hydrophosphination and cyclometallation protocol. High conversions were achieved in the P-H addition reaction, which was itself catalyzed by a phosphapalladacycle. Moderate to good enantioselectivities, were obtained for this step depending on the nature of the [a] 4386 Scheme 2. Synthesis of (S [P] )-8 from racemic phosphine ligands.