Organometallic Compounds

Report
Fall 2011
Dr. Halligan
CHM 236
Chapter 11
• Organometallic Compounds
Ch. 11 Overview
• Organolithium and Grignard Reagents
• Coupling reactions with Gilman reagents
• Palladium-Catalyzed Coupling reactions
including the Suzuki and Heck
• Alkene Metathesis: Reactions with Grubb’s
and Schrock’s catalysts
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Organometallic Compounds
An organic compound containing a carbon–metal bond
Organolithium compounds and organomagnesium
compounds are two of the most common organometallic
compounds
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Preparation of Organolithium
Compounds
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Preparation of Organomagnesium
Compounds
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Alkyl halides, vinyl halides, and aryl halides can all be
used to form organolithium and organomagnesium
compounds
However, these organometallic compounds cannot be
prepared from compounds containing acidic groups
(OH, NH2, NHR, SH, C=CH, CO2H)
Let’s draw a reaction to show how this happens:
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Coupling Reactions
Preparation of the Gilman reagent:
Example of carbon–carbon formation using the
Gilman reaction:
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Gilman reagents can be used to prepare compounds
that cannot be prepared by using nucleophilic
substitution reactions:
Why can’t these compounds be prepared by SN1 or
SN2 reactions?
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Gilman reagents can replace halogens in compounds
containing other functional groups:
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The Heck Reaction
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The Stille Reaction
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The Suzuki Coupling
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Mechanism of the Suzuki Coupling
Reaction
Oxidative addition: Pd (0) to Pd (II):
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Hydroxide exchange:
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Transmetallation:
Reductive elimination:
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Mechanism of the Heck Coupling
Reaction
Oxidative addition: Pd (0) to Pd (II):
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 Complex formation:
 complex
Insertion:
 complex
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Elimination:
Trans
stereochemistry
Regeneration of the catalyst:
Undergoes oxidative
addition to bromobenzene
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