Chapter 15: Alcohols, Diols and Thiols |
Reactions of RLi and
RMgX with Esters
(review of Chapter 14)
Reaction usually in Et2O followed by H3O+
work-up
Reaction type: Nucleophilic Acyl Substitution then Nucleophilic Addition
Summary:
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Step 1: The nucleophilic C in the organometallic reagent adds to the electrophilic C in the polar carbonyl group of the ester. Electrons from the C=O move to the electronegative O creating an intermediate metal alkoxide complex. |
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Step 2:
The tetrahedral intermediate collapses and displaces the alcohol portion of the ester as a leaving group, this produces an aldehyde as an intermediate. |
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Step 3:
The nucleophilic C in the organometallic reagent adds to the electrophilic C in the polar carbonyl group of the ketone. Electrons from the C=O move to the electronegative O creating an intermediate metal alkoxide complex. |
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Step 4:
This is the work-up step, a simple acid/base reaction. Protonation of the alkoxide oxygen creates the alcohol product from the intermediate complex.
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© Dr. Ian Hunt, Department of Chemistry |