-
\usepackage{chemfig}
\begin{document}
\chemfig{
\fbox{R}-[2,0.8]N(-[2,0.25]9)
-[3.5,0.6](-[3.3,0.25]4)(-[4.5,0.7]N(-[2,0.25]3)(-[4,0.3]H_2))
=[2,0.8](-[4.8,0.25]5)
-[0.5,0.8]N(-[5.5,0.25]7)(-[,0.3]H)
=[6.55,0.8]
(-[4,0.2]8)
-[5.25,0.6]
}
\end{document}-
\usepackage{chemfig}
\begin{document}
\chemfig{
(-[3.3,0.25]4)(-[4.5,0.7]N-[3,0.25]3)
=[2,0.8](-[4.8,0.25]5)
(
-[0.5,0.8]N(-[5.5,0.25]7)
=[6.55,0.8](-[4,0.25]8)
-[5.25,0.8]N(-[2,0.25]9)(-[6,0.8]\fbox{R})
-[3.5,0.6]
)
}
\end{document}