$Hex - 3 - ynal\xrightarrow[\begin{subarray}{l} (ii)\,PB{r_3} \\ (i)\,Mg/ether \\ (i)\,C{O_2}/{H_3}{O^ + } \end{subarray} ]{{(i)\,NaB{H_4}}}\,?$
${C_6}{H_5} - COO - C{H_3}\mathop {\xrightarrow{{1.\,LiAl{H_4}}}}\limits_{2.\,{H_2}O} $