${C_2}{H_5}I\xrightarrow{{alc. KOH}}X\xrightarrow[{CC{l_4}}]{{B{r_2}}}Y\,\xrightarrow{{KCN}}Z\xrightarrow{{{H_3}{O^ + }}}A$
$\begin{matrix}
O\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \\
||\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \\
C{{F}_{3}}\,C\,OH+C{{H}_{3}}\,CH\,C{{H}_{3}} \\
\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,| \\
\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,OH \\
\end{matrix}\xrightarrow{{{H}_{2}}S{{O}_{4}}}\begin{matrix}
O\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \\
||\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \\
C{{F}_{3}}\,C\,OCH\,C{{H}_{3}}+{{H}_{2}}O \\
|\,\,\,\,\,\,\,\,\,\,\,\, \,\,\,\, \\
C{{H}_{3}}\,\,\,\,\,\,\,\,\,\,\, \\
\end{matrix}$