$Hex - 3 - ynal\xrightarrow[\begin{subarray}{l}
(ii)\,PB{r_3} \\
(i)\,Mg/ether \\
(i)\,C{O_2}/{H_3}{O^ + }
\end{subarray} ]{{(i)\,NaB{H_4}}}\,?$
${C_2}{H_5}I\xrightarrow{{alc. KOH}}X\xrightarrow[{CC{l_4}}]{{B{r_2}}}Y\,\xrightarrow{{KCN}}Z\xrightarrow{{{H_3}{O^ + }}}A$