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Room temperature olefination of methane with titanium–carbon multiple bonds

C–H activation of methane followed by dehydrocoupling at room temperature led ultimately to the formation of the olefin H(2)C[double bond, length as m-dash]CH(t)Bu via the addition of redox-active ligands (L) such as thioxanthone or 2,2′-bipyridine (bipy) to (PNP)Ti[double bond, length as m-dash]CH(...

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Autores principales: Kurogi, Takashi, Won, Joonghee, Park, Bohyun, Trofymchuk, Oleksandra S., Carroll, Patrick J., Baik, Mu-Hyun, Mindiola, Daniel J.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Royal Society of Chemistry 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5933228/
https://www.ncbi.nlm.nih.gov/pubmed/29780468
http://dx.doi.org/10.1039/c7sc05238c
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author Kurogi, Takashi
Won, Joonghee
Park, Bohyun
Trofymchuk, Oleksandra S.
Carroll, Patrick J.
Baik, Mu-Hyun
Mindiola, Daniel J.
author_facet Kurogi, Takashi
Won, Joonghee
Park, Bohyun
Trofymchuk, Oleksandra S.
Carroll, Patrick J.
Baik, Mu-Hyun
Mindiola, Daniel J.
author_sort Kurogi, Takashi
collection PubMed
description C–H activation of methane followed by dehydrocoupling at room temperature led ultimately to the formation of the olefin H(2)C[double bond, length as m-dash]CH(t)Bu via the addition of redox-active ligands (L) such as thioxanthone or 2,2′-bipyridine (bipy) to (PNP)Ti[double bond, length as m-dash]CH(t)Bu(CH(3)) (1). Using both of these exogenous ligand systems, we could trap the titanium fragment via an insertion reaction with these two substrates to afford species of the type (PNP)Ti(L)(LH). A combination of computational and isotopic labeling studies reveals that the L ligand promotes the C–C bond forming step by migration of the methyl moiety in 1 to the α-alkylidene carbon by producing a Ti(iii) species (PNP)Ti{CH(CH(3))(t)Bu}(L). In the case of L = thioxanthone, β-hydrogen abstraction gives an olefin, whereas with 2,2′-bipyridine β-hydride elimination and migratory insertion lead to (PNP)Ti(L)(LH). These redox-active ligands play two important roles: (i) they accept an electron from the Ti-alkylidene fragment to allow the methyl to approach the alkylidene and (ii) they serve as traps of a hydrogen atom resulting from olefin elimination. These systems represent the first homogeneous models that can activate methane and selectively dehydrocouple it with a carbene to produce an olefin at room temperature.
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spelling pubmed-59332282018-05-18 Room temperature olefination of methane with titanium–carbon multiple bonds Kurogi, Takashi Won, Joonghee Park, Bohyun Trofymchuk, Oleksandra S. Carroll, Patrick J. Baik, Mu-Hyun Mindiola, Daniel J. Chem Sci Chemistry C–H activation of methane followed by dehydrocoupling at room temperature led ultimately to the formation of the olefin H(2)C[double bond, length as m-dash]CH(t)Bu via the addition of redox-active ligands (L) such as thioxanthone or 2,2′-bipyridine (bipy) to (PNP)Ti[double bond, length as m-dash]CH(t)Bu(CH(3)) (1). Using both of these exogenous ligand systems, we could trap the titanium fragment via an insertion reaction with these two substrates to afford species of the type (PNP)Ti(L)(LH). A combination of computational and isotopic labeling studies reveals that the L ligand promotes the C–C bond forming step by migration of the methyl moiety in 1 to the α-alkylidene carbon by producing a Ti(iii) species (PNP)Ti{CH(CH(3))(t)Bu}(L). In the case of L = thioxanthone, β-hydrogen abstraction gives an olefin, whereas with 2,2′-bipyridine β-hydride elimination and migratory insertion lead to (PNP)Ti(L)(LH). These redox-active ligands play two important roles: (i) they accept an electron from the Ti-alkylidene fragment to allow the methyl to approach the alkylidene and (ii) they serve as traps of a hydrogen atom resulting from olefin elimination. These systems represent the first homogeneous models that can activate methane and selectively dehydrocouple it with a carbene to produce an olefin at room temperature. Royal Society of Chemistry 2018-02-13 /pmc/articles/PMC5933228/ /pubmed/29780468 http://dx.doi.org/10.1039/c7sc05238c Text en This journal is © The Royal Society of Chemistry 2018 https://creativecommons.org/licenses/by/3.0/This article is freely available. This article is licensed under a Creative Commons Attribution 3.0 Unported Licence (CC BY 3.0)
spellingShingle Chemistry
Kurogi, Takashi
Won, Joonghee
Park, Bohyun
Trofymchuk, Oleksandra S.
Carroll, Patrick J.
Baik, Mu-Hyun
Mindiola, Daniel J.
Room temperature olefination of methane with titanium–carbon multiple bonds
title Room temperature olefination of methane with titanium–carbon multiple bonds
title_full Room temperature olefination of methane with titanium–carbon multiple bonds
title_fullStr Room temperature olefination of methane with titanium–carbon multiple bonds
title_full_unstemmed Room temperature olefination of methane with titanium–carbon multiple bonds
title_short Room temperature olefination of methane with titanium–carbon multiple bonds
title_sort room temperature olefination of methane with titanium–carbon multiple bonds
topic Chemistry
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5933228/
https://www.ncbi.nlm.nih.gov/pubmed/29780468
http://dx.doi.org/10.1039/c7sc05238c
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