\documentclass{ppex}
\nonstopmode
\AtBeginDocument {\setlength \unitlength {0.09pt}}
\usepackage {carom}
\pagestyle{empty}
\setlength\textwidth{207.0pt}
\begin{document}
\ResetPreambleCommands
\ReadyForTheFray
\usepackage {carom}
\steroid[dim]
 {3D==O;%
 {{13}B}==\lmoiety{H$_3$C};%
 {{17}SB}==HO;%
 {{17}SA}==COCH$_3$}
\end{document}