Return to Contents  Chapter 22: Amines  Ch 22 contents

Reduction of Amides

reduction of amides using LiAlH4
Reactions usually in Et2O or THF followed by H3O+ work-ups
Reaction type:  Nucleophilic Acyl Substitution then Nucleophilic Addition

Summary

hydride reductions of different types of amides
Related reactions
 
REACTION OF LiAlH4 WITH AN AMIDE
Step 1:
The nucleophilic H from the hydride 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.
reduction of an amide using hydride
Step 2:
The tetrahedral intermediate collapses and displaces the O as part of a metal alkoxide leaving group, this produces a highly reactive iminium ion an intermediate.
Step 3: 
Rapid reduction by the nucleophilic H from the hydride reagent as it adds to the electrophilic C in the iminium system. π electrons from the C=N move to the cationic N neutralising the charge creating the amine product.
 

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Dr. Ian Hunt, Department of Chemistry, University of Calgary