Evidence for heterolytic cleavage of a cyclic oxonium ylide: implications for the mechanism of the Stevens [1,2]-shift

2017 ◽  
Vol 53 (94) ◽  
pp. 12654-12656 ◽  
Author(s):  
Seyedeh Nargess Hosseini ◽  
Jeffrey R. Johnston ◽  
F. G. West
Keyword(s):  
Heterolytic Cleavage ◽  
Oxonium Ylide ◽  
Zwitterionic Intermediate

In contrast to prior evidence for a homolytic mechanism, a cyclopropylcarbinyl-substituted oxonium ylide furnished cleavage products consistent with a zwitterionic intermediate.

scholarly journals Dirhodium Carboxylate Catalysts from 2‐Fenchyloxy or 2‐Menthyloxy Arylacetic Acids: Enantioselective C−H Insertion, Aromatic Addition and Oxonium Ylide Formation/Rearrangement

ChemCatChem ◽  
2021 ◽  
Author(s):  
Aoife M. Buckley ◽  
Daniel C. Crowley ◽  
Thomas A. Brouder ◽  
Alan Ford ◽  
U. B. Rao Khandavilli ◽  
...  
Keyword(s):  
Arylacetic Acids ◽  
Oxonium Ylide

ChemInform Abstract: Trapping of Oxonium Ylide with Isatins: Efficient and Stereoselective Construction of Adjacent Quaternary Carbon Centers.

ChemInform ◽  
2008 ◽  
Vol 39 (12) ◽  
Author(s):  
Xin Guo ◽  
Haoxi Huang ◽  
Liping Yang ◽  
Wenhao Hu
Keyword(s):  
Quaternary Carbon ◽  
Carbon Centers ◽  
Oxonium Ylide

scholarly journals Frustration across the periodic table: heterolytic cleavage of dihydrogen by metal complexes

2017 ◽  
Vol 375 (2101) ◽  
pp. 20170002 ◽  
Author(s):  
R. Morris Bullock ◽  
Geoffrey M. Chambers
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Molecular Complexes ◽  
Main Group ◽  
Lewis Base ◽  
Metal Compounds ◽  
Metal Catalysis ◽  
Heterolytic Cleavage ◽  
Lewis Pairs

This perspective examines frustrated Lewis pairs (FLPs) in the context of heterolytic cleavage of H 2 by transition metal complexes, with an emphasis on molecular complexes bearing an intramolecular Lewis base. FLPs have traditionally been associated with main group compounds, yet many reactions of transition metal complexes support a broader classification of FLPs that includes certain types of transition metal complexes with reactivity resembling main group-based FLPs. This article surveys transition metal complexes that heterolytically cleave H 2 , which vary in the degree that the Lewis pairs within these systems interact. Many of the examples include complexes bearing a pendant amine functioning as the base with the metal functioning as the hydride acceptor. Consideration of transition metal compounds in the context of FLPs can inspire new innovations and improvements in transition metal catalysis. This article is part of the themed issue ‘Frustrated Lewis pair chemistry’.

scholarly journals Control of Chemoselectivity in Dirhodium(II)-Catalyzed Reaction of 5,6-Dioxygenated 2-Diazo-3-oxohexanoates: C-H Insertion Reaction versus Oxonium Ylide Formation.

1998 ◽  
Vol 46 (7) ◽  
pp. 1182-1183 ◽  
Author(s):  
Takayuki YAKURA ◽  
Akiharu UEKI ◽  
Yukiko MORIOKA ◽  
Toyoshige KURATA ◽  
Kenji TANAKA ◽  
...  
Keyword(s):  
Insertion Reaction ◽  
Oxonium Ylide

Concerted Rearrangement versus Heterolytic Cleavage in Anionic [2,3]- and [3,3]-Sigmatropic Shifts. A DFT Study of Relationships among Anion Stabilities, Mechanisms, and Rates

2003 ◽  
Vol 68 (6) ◽  
pp. 2310-2316 ◽  
Author(s):  
Fredrik Haeffner ◽  
K. N. Houk ◽  
Suzanne M. Schulze ◽  
Jeehiun K. Lee
Keyword(s):  
Dft Study ◽  
Heterolytic Cleavage

Iterative Approach to Polycyclic Ethers Based on Stereoselective Oxonium Ylide [2,3]-Shifts

2001 ◽  
Vol 123 (21) ◽  
pp. 5144-5145 ◽  
Author(s):  
Fredrik P. Marmsäter ◽  
F. G. West
Keyword(s):  
Iterative Approach ◽  
Oxonium Ylide ◽  
Polycyclic Ethers

Trapping of Oxonium Ylide with Isatins:  Efficient and Stereoselective Construction of Adjacent Quaternary Carbon Centers

2007 ◽  
Vol 9 (23) ◽  
pp. 4721-4723 ◽  
Author(s):  
Xin Guo ◽  
Haoxi Huang ◽  
Liping Yang ◽  
Wenhao Hu
Keyword(s):  
Quaternary Carbon ◽  
Carbon Centers ◽  
Oxonium Ylide

scholarly journals Computational Investigation of the Role of Active Site Heterogeneity for a Supported Organovanadium(III) Hydrogenation Catalyst

2021 ◽  
Author(s):  
Prajay Patel ◽  
Robert Wells ◽  
David Kaphan ◽  
Massimiliano Delferro ◽  
Rex T. Skodje ◽  
...  
Keyword(s):  
Active Site ◽  
Active Sites ◽  
Density Functional ◽  
Computational Models ◽  
Surface Heterogeneity ◽  
Reaction Pathways ◽  
Spectroscopic Techniques ◽  
Organometallic Catalysts ◽  
Heterolytic Cleavage ◽  
Styrene Hydrogenation

<div> <div> <p></p><p><a>A crucial consideration for supported heterogeneous catalysts is the non-uniformity of the active sites, particularly for Supported Organometallic Catalysts (SOMCs). Standard spectroscopic techniques, such as X-ray absorption spectroscopy (XAS), reflect the nature of the most populated sites, which are often intrinsically structurally distinct from the most catalytically active sites. With computational models, often only a few representative structures are used to depict catalytic active sites on a surface, even though there are numerous observable factors of surface heterogeneity that contribute to the kinetically favorable active species. A previously reported study on the mechanism of a surface organovanadium(III) catalyst [(SiO)V<sup>III</sup>(Mes)(THF)] for styrene hydrogenation yielded two possible mechanisms: heterolytic cleavage and redox cycling. These two mechanistic scenarios are challenging to differentiate experimentally based on the kinetic readouts of the catalyst are identical. To showcase the importance of modeling surface heterogeneity and its effect on catalytic activity, density functional theory (DFT) computational models of a series of potential active sites of [(SiO)V<sup>III</sup>(Mes)(THF)] for the reaction pathways are applied in combination with kinetic Monte Carlo (kMC) simulations. Computed results were t then compared to the previously reported experimental kinetic study</a><a>.: 1) DFT free energy reaction pathways indicated the likely active site and pathway for styrene hydrogenation; a heterolytic cleavage pathway requiring a bare tripodal vanadium site. 2) From the kMC simulations, a mixture of the different bond lengths from the support oxygen to the metal center was required to qualitatively describe the experimentally observed kinetic aspects of a supported organovanadium(III) catalyst for olefin hydrogenation. </a>This work underscores the importance of modeling surface heterogeneity in computational catalysis.</p><p></p></div></div>

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