Chapter 16, Problem 16.65P

The treatment of isoprene $\left[{\text{CH}}_{\text{2}}=\text{C}\left({\text{CH}}_{\text{3}}\right)\text{CH}={\text{CH}}_{\text{2}}\right]$ with one equivalent of mCPBA forms A as the major product. A gives a molecular ion at $84$ in its mass spectrum, and peaks at $2850–3150{\text{cm}}^{-1}$ in its IR spectrum. The 1H NMR spectrum of A is given below. What is the structure of A?