核苷

-

\usepackage{chemfig}
\begin{document}

\chemfig{
	(-[3,0.25])
	(<:[,0.7]base)
	-[5.5,0.5]
		(<:[7,0.7]OH)
	-[3.8,0.5]
		(<:[5,0.7]HO)
	-[2.2,0.5]
		(-[0.5,0.5]O)
		(<[3.5,0.7]-[4.5,0.7]HO)
}

\end{document}