5-氨基-4-羧基咪唑核苷酸（CAIR）

3D结构

C1=NC(=C(N1[C@H]2[C@@H]([C@@H]([C@H](O2)COP(=O)(O)O)O)O)N)C(=O)O

-

\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)(-[3,0.7](=[2,0.7]O)(-[4.7,0.7]HO)(-[6,0.25]6))
	-[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)(-[3,0.7]C(=[2,0.7]O)(-[6,0.25]6))
	(
		-[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}