NMR Problem. Extra Credit:

CLUE $-$ Dienophile contains an alkynel

$A$

$C_7{H}_{10}O$

${?}^{1}H-NMR$

$3\mathrm{.}15(s,1H)$

$2\mathrm{.}34(d,2H)$

$1\mathrm{.}91(m,1H)$

$0\mathrm{.}86(d,6H)$

B

$C_{13}{H}_{20}{O}_3$

${?}^{1}H-NMR$

$6\mathrm{.}83(t,1H)$

$3\mathrm{.}77(s,3H)$

$3\mathrm{.}74(s,3H)$

$3\mathrm{.}12(d,2H)$

$3\mathrm{.}04(s,2H)$

$2\mathrm{.}31(d,2H)$

$1\mathrm{.}91(m1H)$

$0\mathrm{.}86(d,6H)$