Organocalcium-mediated nucleophilic alkylation of benzene

The electrophilic aromatic substitution of a C–H bond of benzene is one of the archetypal transformations of organic chemistry. In contrast, the electron-rich π-system of benzene is highly resistant to reactions with electron-rich and negatively charged organic nucleophiles. Here, we report that thi...

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Bibliographic Details
Published in:Science (American Association for the Advancement of Science) 2017-12, Vol.358 (6367), p.1168-1171
Main Authors: Wilson, Andrew S. S., Hill, Michael S., Mahon, Mary F., Dinoi, Chiara, Maron, Laurent
Format: Article
Language:English
Subjects:
Alkylation
Benzene
Calcium
Carbon compounds
Chemical Sciences
Chemical synthesis
Density functional theory
Ethene
Ethylene
Hydrocarbons
Hydrogen bonds
Lithium
Magnesium
Mineralogy
Nucleophiles
Organic chemistry
Physics
Regeneration
Substitution reactions
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Summary:The electrophilic aromatic substitution of a C–H bond of benzene is one of the archetypal transformations of organic chemistry. In contrast, the electron-rich π-system of benzene is highly resistant to reactions with electron-rich and negatively charged organic nucleophiles. Here, we report that this previously insurmountable electronic repulsion may be overcome through the use of sufficiently potent organocalcium nucleophiles. Calcium n-alkyl derivatives—synthesized by reaction of ethene, but-1-ene, and hex-1-ene with a dimeric calcium hydride—react with protio and deutero benzene at 60°C through nucleophilic substitution of an aromatic C–D/H bond. These reactions produce the n-alkyl benzenes with regeneration of the calcium hydride. Density functional theory calculations implicate an unstabilized Meisenheimer complex in the C–H activation transition state.
ISSN:0036-8075
1095-9203
DOI:10.1126/science.aao5923