MacNeil CS, Mendelsohn LN, Zhong H, Pabst TP, Chirik PJ. Synthesis and Reactivity of Organometallic Intermediates Relevant to Cobalt-Catalyzed Hydroformylation.
Angew Chem Int Ed Engl 2020;
59:8912-8916. [PMID:
32182395 DOI:
10.1002/anie.202001677]
[Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2020] [Indexed: 01/28/2023]
Abstract
Intermediates relevant to cobalt-catalyzed alkene hydroformylation have been isolated and evaluated in fundamental organometallic transformations relevant to aldehyde formation. The 18-electron (R,R)-(iPr DuPhos)Co(CO)2 H has been structurally characterized, and it promotes exclusive hydrogenation of styrene in the presence of 50 bar of H2 /CO gas (1:1) at 100 °C. Deuterium-labeling studies established reversible 2,1-insertion of styrene into the Co-D bond of (R,R)-(iPr DuPhos)Co(CO)2 D. Whereas rapid β-hydrogen elimination from cobalt alkyls occurred under an N2 atmosphere, alkylation of (R,R)-(iPr DuPhos)Co(CO)2 Cl in the presence of CO enabled the interception of (R,R)-(iPr DuPhos)Co(CO)2 C(O)CH2 CH2 Ph, which upon hydrogenolysis under 4 atm H2 produced the corresponding aldehyde and cobalt hydride, demonstrating the feasibility of elementary steps in hydroformylation. Both the hydride and chloride derivatives, (X=H- , Cl- ), underwent exchange with free 13 CO. Under reduced pressure, (R,R)-(iPr DuPhos)Co(CO)2 Cl underwent CO dissociation to form (R,R)-(iPr DuPhos)Co(CO)Cl.
Collapse