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Synthesis and Reactivity of Organometallic Intermediates Relevant to Cobalt‐Catalyzed Hydroformylation
Author(s) -
MacNeil Connor S.,
Mendelsohn Lauren N.,
Zhong Hongyu,
Pabst Tyler P.,
Chirik Paul J.
Publication year - 2020
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.202001677
Subject(s) - hydroformylation , chemistry , cobalt , medicinal chemistry , hydride , catalysis , hydrogenolysis , alkene , aldehyde , styrene , alkylation , organic chemistry , hydrogen , rhodium , polymer , copolymer
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 H 2 /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 N 2 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)CH 2 CH 2 Ph, which upon hydrogenolysis under 4 atm H 2 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.