(figure) $\xrightarrow[CC{{l}_{4}}]{B{{r}_{2}}}(A)\xrightarrow[(ii)\,NaN{{H}_{2}}]{(i)\,alc.\,KOH}(B)\xrightarrow[(ii)\,C{{H}_{3}}-Cl]{(i)\,NaN{{H}_{2}}}(C)$