Alkylation of Ketones and Enamines

The video tutorial explains the reaction of cyclopentanone with LDA and methyl bromide, detailing the mechanism and the formation of enolate ions. It covers practice problems, the difference between kinetic and thermodynamic products, and alternative alkylation methods using enamine intermediates. The tutorial also explores reactions with acid chloride, emphasizing the role of different bases and conditions in determining the major product.

What is the primary role of LDA in the reaction with cyclopentanone?

• To act as a nucleophile

• To add a methyl group

• To remove the alpha hydrogen

• To stabilize the ketone

What is the major product when cyclopentanone is reacted with LDA followed by methyl bromide?

• A cyclohexanone

• A ketone with an added methyl group

• A cyclopentanol

• A ketone with an added ethyl group

Which condition favors the formation of the kinetic product in unsymmetrical ketones?

• High temperature and LDA

• Low temperature and LDA

• Room temperature and sodium hydride

• High temperature and sodium hydride

What is the role of sodium hydride in the reaction with ketones?

• To add a methyl group

• To act as an electrophile

• To remove the alpha hydrogen

• To stabilize the enolate ion

Which base is used to form the thermodynamic product in ketone alkylation?

• Sodium hydride at room temperature

• LDA at high temperature

• LDA at low temperature

• Sodium hydride at low temperature

What is the advantage of using an enamine intermediate for alkylation?

• It is faster than other methods

• It requires a strong base

• It avoids the use of strong bases like LDA

• It allows for polyalkylation

What is the first step in forming an enamine from a ketone?

• Reacting with a primary amine

• Reacting with a secondary amine

• Reacting with an acid chloride

• Reacting with water

Which electrophile can be used with an enamine to form a diketone?

• An alpha-beta unsaturated aldehyde

• A primary amine

• An alkyl halide

• An acid chloride

What happens to the nitrogen group in the final step of enamine reactions?

• It forms a double bond

• It is converted to a ketone

• It is expelled as a gas

• It remains unchanged

What is the final product when an enamine reacts with an acid chloride?

• An enol

• A monoalkylated ketone

• A primary amine

• A diketone