$\,{H_3}C\, - \,\,\mathop C\limits^{\mathop {||}\limits^O } \,\, - \,\,\mathop C\limits^{\mathop |\limits^{OH} } H\,\, - \,\,\mathop C\limits^{\mathop |\limits^{N{O_2}} } H\,\, - \,\,C{O_2}H$
$\begin{array}{*{20}{c}}
{O = CH - C{H_2} - CH - CHO} \\
{\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,|} \\
{\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,H - C = O\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,}
\end{array}$