26305-75-9Relevant articles and documents
Hydrodimerization of Methyl Acrylate Catalyzed by Halogenotris(triphenylphosphine)cobalt
Kanai, Hiroyoshi,Ishii, Keiji
, p. 1015 - 1018 (1981)
Methyl acrylate was hydrodimerized in a methanolic solution by CoX(PPh3)3 (X = halogen) into dimethyl adipate.The in situ prepared cobalt complexes from cobalt halides, triphenylphosphine, and zinc gave higher yields of the hydrodimer in the presence of alkali halides.A mechanism is proposed which involves the protonation of Co(I)-methyl acrylate ?-complex to give (2-methoxycarbonylethyl)cobalt complex, followed by a further addition of methyl acrylate.
Olefin Hydroarylation Catalyzed by a Single-Component Cobalt(-I) Complex
Suslick, Benjamin A.,Tilley, T. Don
supporting information, p. 1495 - 1499 (2021/03/03)
A single-component Co(-I) catalyst, [(PPh3)3Co(N2)]Li(THF)3, has been developed for olefin hydroarylations with (N-aryl)aryl imine substrates. More than 40 examples were examined under mild reaction conditions to afford the desired alkyl-arene product in good to excellent yields. Catalysis occurs in a regioselective manner to afford exclusively branched products with styrene-derived substrates or linear products for aliphatic olefins. Electron-withdrawing functional groups (e.g., -F, -CF3, and -CO2Me) were tolerated under the reaction conditions.
Mechanistic Interrogation of Alkyne Hydroarylations Catalyzed by Highly Reduced, Single-Component Cobalt Complexes
Suslick, Benjamin A.,Tilley, T. Don
supporting information, p. 11203 - 11218 (2020/07/08)
Highly reactive catalysts for ortho-hydroarylations of alkynes have previously been reported to result from activation of CoBr2 by Grignard reagents, but the operative mechanism and identity of the active cobalt species have been undefined. A mechanistic analysis of a related system, involving hydroarylations of a (N-aryl)aryl ethanimine with diphenylacetylene, was performed using isolable reduced Co complexes. Studies of the stoichiometric reaction of Co(I) or Co(II) precursors with CyMgCl implicated catalyst initiation via a β-H elimination/deprotonation pathway. The resulting single-component Co(-I) complex is proposed as the direct pre-catalyst. Michaelis-Menten enzyme kinetic studies provide mechanistic details regarding the catalytic dependence on substrate. The (N-aryl)aryl ethanimine substrate exhibited saturation-like behavior, whereas alkyne demonstrated a complex dependency; rate inhibition and promotion depend on the relative concentration of alkyne to imine. Activation of the aryl C-H bond occurred only in the presence of coordinated alkyne, which suggests operation of a concerted metalation-deprotonation (CMD) mechanism. Small primary isotope effects are consistent with a rate-determining C-H cleavage. Off-cycle olefin isomerization catalyzed by the same Co(-I) active species appears to be responsible for the observed Z-selectivity.
