Compound $U$ is prepared using the Michael reaction as shown below:

i$)$ NaOH $($cat$)$

ii$)$

iii$)H_3{O}^{+}$

$C_{10}{H}_{14}{O}_3$

T

U

$($i$)$ Draw the chemical structure of compound $U.$

$($ii$)$ Draw and briefly discuss the reaction mechanism for the formation of compound U$.$ Explain the chemoselectivity observed in this reaction.