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- Title
Computational Investigation of the 1,4-Rh Shift in the [(Ph<sub>2</sub>PCH<sub>2</sub>CH<sub>2</sub>PPh<sub>2</sub>)Rh]-Catalyzed Alkyne Arylation Reaction.
- Authors
Kantchev, Eric Assen B.; Zhou, Feng; Pangestu, Surya R.; Sullivan, Michael B.; Su, Haibin
- Abstract
Computations (density functional theory) of the post-transmetallation stages (carborhodation, 1,4-shift consisting of C-H oxidative addition/C-H reductive elimination, and hydrolysis) in the catalytic cycle for the arylation of 2-butyne with phenylboronic acid mediated by [(dppe)RhI] catalyst [dppe = 1,2-bis(diphenylphosphanyl)ethane] shows that (1) carborhodation is facile (Δ G‡ ≈ 10 kcal mol-1); (2) the barriers of the 1,4-shift and hydrolysis are approximately equal (Δ G‡ ≈ 19-24 kcal mol-1); (3) the 1,4-Rh shift product is ca. 5 kcal mol-1 more stable than the non-rearranged product, in good agreement with the experimental results. Analogous computations for ( Z)-2-butene as a model substrate show that (1) carborhodation is much slower (Δ G‡ ≈ 19 kcal mol-1); (2) the sp3 → sp2 1,4-shift is faster than the sp2 → sp2 1,4-shift; (3) the hydrolysis of Rh-C σ bonds depends more on the steric environment than the hybridization of the C atom; and (4) β-hydride elimination is the most likely reaction after carborhodation.
- Subjects
ALKYNE synthesis; DENSITY functional theory; ARYLATION; CARBON-hydrogen bonds; OXIDATIVE addition
- Publication
European Journal of Organic Chemistry, 2015, Vol 2015, Issue 32, p7114
- ISSN
1434-193X
- Publication type
Article
- DOI
10.1002/ejoc.201501098