9.7: Enolate alkylation
- Page ID
- 225814
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Example 1: Alpha Alkylation |
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Mechanism
1) Enolate formation. The B– represents a strong base such as NaNH2 or LDA:

2) Sn2 attack

Alkylation of Unsymmetrical Ketones
Unsymmetrical ketones can be regioselctively alkylated to form one major product depending on the reagents.
Treatment with LDA in THF at -78oC tends to form the less substituted kinetic enolate.

Using sodium ethoxide in ethanol at room temperature forms the more substituted thermodynamic enolate, though yields of alkylation product are likely to be poorer because of the side reactions mentioned above.

Problems
1) Please write the structure of the product for the following reactions.

Answers
1)

Contributors
- William Reusch, Professor Emeritus (Michigan State U.), Virtual Textbook of Organic Chemistry
- Prof. Steven Farmer (Sonoma State University)
- 23.8: Direct Enolate Alkylation. Authored by: William Reusch, Prof. Steven Farmer. Located at: https://chem.libretexts.org/Textbook_Maps/Organic_Chemistry/Map%3A_Organic_Chemistry_(Smith)/Chapter_23%3A_Substitution_Reactions_of_Carbonyl_Compounds_at_the_Alpha_Carbon/23.8%3A_Direct_Enolate_Alkylation. Project: Chemistry LibreTexts. License: CC BY-NC-SA: Attribution-NonCommercial-ShareAlike