$C{H_3}COOH\xrightarrow{{SOC{l_2}}}P\xrightarrow[{Anhyd.\,\,AlC{l_3}}]{{Benzene}}\,Q\,\xrightarrow{{HCN}}R\xrightarrow{{HOH}}S$
$Hex - 3 - ynal\xrightarrow[\begin{subarray}{l}
(ii)\,PB{r_3} \\
(i)\,Mg/ether \\
(i)\,C{O_2}/{H_3}{O^ + }
\end{subarray} ]{{(i)\,NaB{H_4}}}\,?$