Return to Contents Chapter 15: Alcohols, Diols and Thiols Ch 15 contents

Reactions of RLi and RMgX with Esters
(review of Chapter 14)

reaction of RLi or RMgX with esters
Reaction usually in Et2O followed by H3O+ work-up

Reaction type:  Nucleophilic Acyl Substitution then Nucleophilic Addition

Summary:

Related Reactions
REACTION OF RLi or RMgX WITH AN ESTER

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.
addition of Grignard reagent to an ester
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.
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.
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.

 


previous page
next page
© Dr. Ian Hunt, Department of Chemistry, University of Calgary