Chapter 17, Problem 48P

Compound Y $\left(C_8{H}_4{O}_3\right)$ dissolves slowly when warmed with aqueous sodium bicarbonate. The IR spectrum of Y has strong peaks at 1779 and at 1854 $c{m}^{-1}$. The broadband proton-decoupled ${}^{13}C$ spectrum of Y exhibits signals at $\delta$ $125\left(CH\right)$, $130\left(C\right)$, $136\left(CH\right),and162\left(C\right)$. Acidification of the bicarbonate solution of Y gave compound Z. The proton-decoupled ${}^{13}C$ NMR spectrum of Z showed four signals. When Y was warmed in ethanol, compound AA was produced. The ${}^{13}C$ NMR spectrum of AA displayed 10 signals. Propose structures for Y, Z, and AA.