\documentclass[a4paper,12pt]{report}
\usepackage{chemtex}
\begin{document}

\initial

\begin{figure}[h]\centering
\parbox{.3\textwidth}{\ethene{H}{H$_3$C}{CH$_3$}{Br}}
\hfil
\parbox{.3\textwidth}{\cbranch{H}{S}{H}{S}{C}{S}{}{S}{H}
  \xi=-200 \cright{}{Q}{C}{D}{O}{S}{OH}}
\hfil
\parbox{.3\textwidth}{\hetisix{Q}{Q}{Q}{Q}{Q}{Q}{O}{Q}{O}
  \xi=-171 \fuseup{Q}{Q}{Q}{Q}{D}{Q}{D}{Q}{D}}
\caption{Chemie mit {\tt CHEMTEX}\label{a1}}
\end{figure}

\end{document}