Question

(a) Add curved arrows for each step to show how A is converted to the epoxy ketone C. (b) Classify the conversion of A to C as a substitution, elimination, or addition. (c) Draw one additional resonance structure for B.

Short answer

(a)

Conversion of A to C(b) The reaction from step A to step B is an electrophilic addition reaction.

The reaction from step B to step C is a nucleophilic substitution reaction.

(c)Resonance structure of B

Step-by-step solution

Step-by-Step SolutionStep 1: Attack of the nucleophile

The nucleophile ${}_{}{}^{-}\mathrm{O}-\mathrm{OH}$ attacks the electrophilic center on the $\mathrm{\alpha },\mathrm{\beta }$-unsaturated alkene.

Dehydroxylation

The ${}_{}{}^{-}\mathrm{OH}$ group bonded to the oxygen atom departs as the oxygen atom forms a bond with the nearby carbanionic center to form an epoxy ketone.

Determining the products of the given reaction

(a) The curved arrows to show the conversion of A to B are shown hereunder:

Conversion of A to C

(b) The reaction from step A to step B is an electrophilic addition reaction.

The reaction from step B to step C is a nucleophilic substitution reaction.

(c) The resonance structure for B is given hereunder.

Resonance structure of B