Mechanistic Insight into the Rh(III)-Catalyzed CH Activation of 2‑Acetyl-1-Arythydrazines in Water
journal contributionposted on 09.02.2017, 00:00 authored by Weirong Wu, Tao Liu, Caiyun Huang, Jing Zhang, Xiaoping Man
A mechanistic study of the Cp*RhIII-catalyzed CH functionalization of 2-acetyl-1-arythydrazines with diazo compounds in water was carried out by using density functional theory calculations. The results reveal that the acetyl-bonded NH deprotonation is prior to the phenyl CH activation. The mechanisms from protonation by acetic acid disagree with the proposal by the Wang group. Different from the Rh(III)-catalyzed CH activation reported by experimental literature, the rate-determining step of the whole catalytic cycle with an overall barrier of 31.7 kcal mol–1 (IV → TS12-P′) is the protonation process of hydroxy O rather than the CH bond cleavage step. The present theoretical study rationalizes the experimental observation at the molecular level.
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Differentmolcleavagetheory calculations-1-ArythydrazineRhstudy rationalizesdensityActivationTSmechanismAcetylhydroxy OfunctionalizationproposalIII12-Pbarrieractivationphenyldeprotonation2- acetyl -1-arythydrazinesacetyl-bondedWang groupIVacetic acidprotonation process31.7kcalrate-determining stepMechanistic InsightCpdiazo compoundsbond