Chapter 11.12, Problem 18P

Dicarbonyl compounds such as quinones are reactive dienophiles.

(a) $\text{1,4-Benzoquinone}$ reacts with $\text{2-chloro-1,3-butadiene}$ to give a single product ${\text{C}}_{10}{\text{H}}_9{\text{ClO}}_2$ in $95\%$ yield. Write a structural formula forthis product.

(b) $\text{2-Cyano-1,4-benzoquinone}$ undergoes a Diels–Alder reactionwith $\text{1,3-butadiene}$ to give a single product ${\text{C}}_{11}{\text{CH}}_9{\text{NO}}_2$ in $84\%$ yield.What is its structure?