Computational Investigation of the 1,4-Rh Shift in the [(Ph2PCH2CH2PPh2)Rh]-Catalyzed Alkyne Arylation Reaction

摘要: Computations (density functional theory) of the post-transmetallation stages (carborhodation, 1,4-shift consisting C–H oxidative addition/C–H reductive elimination, and hydrolysis) in catalytic cycle for arylation 2-butyne with phenylboronic acid mediated by [(dppe)RhI] catalyst [dppe = 1,2-bis(diphenylphosphanyl)ethane] shows that (1) carborhodation is facile (ΔG‡ ≈ 10 kcal mol–1); (2) barriers hydrolysis are approximately equal 19–24 (3) 1,4-Rh shift product ca. 5 kcal mol–1 more stable than non-rearranged product, good agreement experimental results. Analogous computations (Z)-2-butene as a model substrate show much slower 19 sp3 → sp2 faster sp2 → sp2 1,4-shift; Rh–C σ bonds depends on steric environment hybridization C atom; (4) β-hydride elimination most likely reaction after carborhodation.