Wang F, Chen C, Meng Q. Comprehensive Theoretical Study of Cp*Ir
III-Catalyzed Intermolecular Enantioselective Allylic C-H Amidation: Reaction Mechanism, Electronic Processes, and Regioselectivity.
J Org Chem 2023;
88:2493-2504. [PMID:
36716217 DOI:
10.1021/acs.joc.2c02951]
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Abstract
Density functional theory was used to elucidate the reaction mechanism of Cp*IrIII-catalyzed intermolecular regioselective C(sp3)-H amidation of alkenes with methyl dioxazolones. All substrates, intermediates, and transition states were fully optimized at the ωB97XD/6-31G(d,p) level (LANL2DZ(f) for Ir). The computational results revealed that this amidation occurred through the IrIII/IrV catalytic cycle, involving four important elementary steps: C-H bond activation, oxidative addition of methyl dioxazolone, reductive elimination, and proto-demetalation, and the first was the rate-determining step. The C-H bond activation showed good α- and branch-regioselectivity, decided by the distortion energy of 2-pentene and the interaction energy of the transition state, respectively. The oxidative addition of dioxazolone occurred in one elementary step with CO2 disassociation. The reductive elimination showed good branch-regioselectivity determined by the distorted energy of the allyl group. In the proto-demetalation, hydrogen directly transferred from the oxygen atom to the nitrogen atom. Moreover, to clarify the effect of the substituted groups, selected 12 substrates were also discussed in this text.
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