Question

What reagents should be used to prepare the following compounds?

1. 
2. 
3. 

Short answer

The alkylation of ß -carbon is done via two reactions: the Michael reaction, and the second is via Enamine.Both these reactions form 1,5-dicarbonyl compounds. In these reactions, nucleophiles are added to the ß -carbon of the α, ß -unsaturated carbonyl compounds.

1. 
2. 
3. 

Step-by-step solution

Alkylating the ß -carbon

The alkylation of ß -carbon is done via two reactions: the Michael reaction, and the second is via Enamine.Both these reactions form 1,5-dicarbonyl compounds. In these reactions, nucleophiles are added to the ß -carbon of the α, ß -unsaturated carbonyl compounds.

The reagents used to prepare compound (a)

The given product is formed by alkylating the ß -carbon via a Michael reaction. The enolate ion of ß -diketone is added to the -carbon of the ,ß -unsaturated ketone. The reagents used for the product formation are ,ß -unsaturated ketone and ß -diketone. The reaction is as follows,

Michael reaction (a)

The reagents used to prepare compound (b)

b. The product formation is done by alkylating the ß -carbon via a Michael reaction. The reaction starts with removing a proton from the α -carbon of ß -diester. The enolate ion of ß -diester is added to the α , ß -carbon of the,ß -unsaturated ketone. The reagents used for the product formation are α , ß -unsaturated ketone and ß -diester. The reaction is as follows,

Michael reaction (b)

The reagents used to prepare compound (c)

c. The given product is formed by alkylating the ß -carbon via an Enamine. The Enamine attaches the α -carbon of ketone to the ß -carbon of an α , ß -unsaturated carbonyl compound. A 1,5-dicarbonyl compound is formed in this reaction and is shown as follows,

Alkylating the -carbon via an Enamine (c)