Lecture on Conjugate Addition Reactions

These flashcards cover key concepts of conjugate addition reactions, Michael addition, and the Stork enamine synthesis based on the lecture notes.

What is a Michael addition reaction?

A reaction where a nucleophile attacks the beta position of an alpha-beta unsaturated aldehyde or ketone, resulting in the formation of a new bond.

What role does the beta position play in alpha-beta unsaturated compounds during conjugate addition?

The beta position acts as an electrophilic center that can be attacked by nucleophiles.

What happens to the β-position during a conjugate addition?

A nucleophile attacks the β-position, followed by protonation to give an enol, which tautomerizes to a carbonyl.

What are Michael donors and Michael acceptors?

A Michael donor is a doubly stabilized enolate that acts as a nucleophile, while a Michael acceptor is an alpha-beta unsaturated aldehyde or ketone that can be attacked.

Define the Stork enamine synthesis.

A three-step process that involves the formation of an enamine, a Michael addition, and hydrolysis.

Why are regular enolates not effective Michael donors?

Regular enolates are not stable enough to function as Michael donors due to lack of sufficient stabilization.

What is the significance of the double bond between the alpha and beta positions in a conjugated system?

It creates a reactive site for nucleophilic attack during conjugate addition reactions.

What does 'one-four addition' refer to in a Michael addition?

Addition of nucleophiles at the one (alpha) and four (beta) positions in an alpha-beta unsaturated system.

How can you convert a ketone to an enamine?

By treating it with a secondary amine and acid.

What reagent would you use to add a methyl group to the beta position of an alpha-beta unsaturated ketone?

Lithium dimethylcuprate (Li2Cu(CH3)2) can be used to add a methyl group at the beta position.