$C{H_3}COOH + PC{l_5} \to A\mathop {\xrightarrow{{{C_6}{H_6}}}}\limits_{anh.\,AlC{l_3}} $ $B\mathop {\xrightarrow{{{C_2}{H_5}MgBr}}}\limits_{ether} C$
$PhCHO + Ph \cdot CHO \xrightarrow[in\,\,{{D}_{2}}O]{NaOD} A + \begin{matrix} O \\ || \\ Ph-C-{{O}^{-}} \\ \end{matrix}$$\left( Ph\right.$ is $\left.- C _{6} H _{5}\right)$
$Hex - 3 - ynal\xrightarrow[\begin{subarray}{l}
(ii)\,PB{r_3} \\
(i)\,Mg/ether \\
(i)\,C{O_2}/{H_3}{O^ + }
\end{subarray} ]{{(i)\,NaB{H_4}}}\,?$