Question

How could each of the following compounds be prepared from a ketone and an organohalide?

a.

b.

Short answer

a.

b.

Step-by-step solution

Step-by-Step SolutionStep 1: Alkylating the α-carbon

The process of alkylation is carried out by removing protons present on the $\mathbf{\alpha }$-carbon using a strong base (LDA). An enolate ion is formed, and then the addition of alkyl halide to the enolate ion occurs.

Preparation of compound (a) from symmetrical ketone and organohalide

a) The starting materials needed to prepare the given compound are 2-propanone (ketone) and 3-iodoprop-1-ene (organohalide). A strong base LDA is used to form an enolate ion, and then alkyl halide is added. The alkyl group of organohalide is put on the $\mathrm{\alpha }$-carbon of the ketone compound.

Preparation of compound (a)

Preparation of compound (b) from symmetrical ketone and organohalide

(b)The starting materials for preparing the given compound are 3-pentanone (ketone) and benzyl bromide (organohalide). A strong base LDA/THF is used to form an enolate ion, and then alkyl halide is added. The alkyl group of benzyl bromide is put on the $\mathrm{\alpha }$-carbon of the 3-pentanone.

Preparation of compound (b)