Suggest a reagent and a reactant that could be used to form the following molecules by conjugate addition of a cuprate. There can be multiple possibilities.
(a)

Verified step by step guidance

1. Identify the target molecule as an ester with a conjugated system, specifically a β-keto ester.
2. Recognize that conjugate addition (1,4-addition) involves adding a nucleophile to the β-position of an α,β-unsaturated carbonyl compound.
3. Determine the structure of the α,β-unsaturated carbonyl compound needed. In this case, it would be an α,β-unsaturated ester with the same carbon skeleton minus the group added by the cuprate.
4. Select a suitable cuprate reagent. Cuprates are organocopper compounds, typically of the form R2CuLi, where R is an alkyl or aryl group. Choose a cuprate that will add the desired alkyl group to the β-position.
5. Combine the α,β-unsaturated ester with the chosen cuprate reagent under appropriate conditions to achieve the conjugate addition, forming the target molecule.

Key Concepts

Conjugate Addition

Conjugate addition refers to the nucleophilic addition of a reagent to an α,β-unsaturated carbonyl compound. This reaction typically involves the addition of a nucleophile to the β-carbon of the double bond, resulting in the formation of a new carbon-carbon bond. Understanding this mechanism is crucial for predicting the products of reactions involving cuprates and unsaturated systems.

Cuprates

Cuprates are organometallic compounds containing copper, often used as nucleophiles in organic synthesis. They are typically derived from lithium diorganocopper reagents, which can effectively add to electrophilic centers in conjugate addition reactions. Recognizing the reactivity and selectivity of cuprates is essential for designing reactions that yield specific products.

Electrophiles

Electrophiles are species that accept electron pairs from nucleophiles during chemical reactions. In the context of conjugate addition, the α,β-unsaturated carbonyl compounds act as electrophiles, where the carbonyl carbon is particularly susceptible to nucleophilic attack. Identifying suitable electrophiles is key to successfully predicting and executing conjugate addition reactions.