\definesubmol{acetyl}{(=[::60]O)-[::-60]H_3C}
\definesubmol{benzoate}{*6(-=-=-(-(=[::60]O)-[::-60]OH)=)}%

\chemfig{
   {\color{red}O}            % the oxygen in the middle
        (-[:210]!{acetyl})   % treat one submol as a branch,
   -[:-30]!{benzoate}%        % the other one as the main chain
}