Ligand-Dependent Catalytic Cycle and Role of Styrene in
Nickel-Catalyzed Anhydride Cross-Coupling: Evidence for
Turnover-Limiting Reductive Elimination
Jeffrey B. Johnson
Eric A. Bercot
John M. Rowley
Geoffrey W. Coates
Tomislav Rovis
10.1021/ja067845g.s001
https://acs.figshare.com/articles/journal_contribution/Ligand_Dependent_Catalytic_Cycle_and_Role_of_Styrene_in_Nickel_Catalyzed_Anhydride_Cross_Coupling_Evidence_for_Turnover_Limiting_Reductive_Elimination/3020119
Results from a mechanistic study on the Ni(COD)<sub>2</sub>−bipy-catalyzed alkylation of anhydrides are
consistent with turnover-limiting reductive elimination at high Et<sub>2</sub>Zn concentrations. While the presence of
styrene does not affect the initial rate of alkylation, it appears to inhibit catalyst decomposition and provides
higher product yield at long reaction times. In contrast, Ni(COD)<sub>2</sub>−<i><sup>i</sup></i><sup></sup>PrPHOX-catalyzed anhydride alkylation
proceeds through two competing catalytic cycles differentiated by the presence of styrene. The presence
of styrene in this system appears to accelerate rate-limiting oxidative addition and promotes the cycle
which proceeds 4 times more rapidly and with much higher enantioselectivity than its styrene-lacking
counterpart.
2007-03-07 00:00:00
Ni
presence
styrene
proceeds 4 times
Et 2Zn concentrations
alkylation
anhydride
reaction times
catalyst decomposition