\documentclass[12pt,border=3pt,tikz,class=scrartcl,multi=false]{standalone}
\usepackage{times}
\usepackage[T1]{fontenc}
\usepackage[latin1]{inputenc}
\usepackage{mathtools,amssymb,gensymb}
\usepackage{pgfplots}
\pgfplotsset{compat=1.12}
\usetikzlibrary{positioning,calc,arrows,fit,backgrounds,decorations.text,shapes}
\usepackage{chemfig,chemmacros}
\renewcommand*{\familydefault}{\sfdefault}
\renewcommand*\printatom[1]{\ensuremath{\mathsf{#1} } }
\setatomsep{2.5em}
\setdoublesep{.6ex}
\setarrowdefault{,1,ultra thick}
\setbondstyle{very thick,cap=but}
\definesubmol\nobond{-[0,.6,,,draw=none]}
\usepackage[american]{circuitikz}
\pagestyle{empty}
\thispagestyle{empty}
\begin{document}
\renewcommand{\baselinestretch}{1}
\begin{tikzpicture}[thick, >=latex']
\node (n1) {
\schemestart[][west]
\chemfig{-(=[:-60]O)-[:60](-[::-60])-[::60]}
\arrow{->[\parbox{3.5cm}{\small\chemfig{NaCN\,NH_4Cl\,MgSO_4}\\\chemfig{NH_3\,/\,MeOH}\\$30^\circ$C/$4$hrs}]
[\parbox{3.5cm}{\small2. L-tartaric acid\\MeOH, rt, 72hrs}]}[,2.5]
\chemfig{H_2N-[:30](<:[3])(-[:-30]C~[::0]N)<[1](-[::-60])-[::60]}
\arrow{0}[,0]\+
\chemfig{HOOC-[:30](<[2]OH)-[:-30](<[6]OH)-[:30]COOH}
\arrow{->[][*{0}\parbox{3cm}{\small\chemfig{NaOH,\,CH_2Cl_2}\\then \chemfig{H_2SO_4} (aq)}]}[-90]
\chemleft[\subscheme{
\chemfig{N^{\scriptstyle+}(-[3]H)(-[:190]H)(-[6]H)-[:30](<:[3])(-[:-30]C~[::0]N)<[1](-[::-60])-[::60]}
\arrow{0}[-90,0.1]
\chemfig{HSO_4^\ominus}
}\chemright]
\arrow{->[*{0.south}\parbox{2.7cm}{\small1. 100\degree C, 20hrs\\2. \chemfig{NaOH}\\3. \chemfig{EtOCOCl} }]
[*{0.north}\parbox{2.7cm}{\small4. \chemfig{HCl}\\5. \chemfig{DCH} }]}[180,1.95]
\chemfig{H-N^{\scriptstyle+}(-[:-30]H)
(-[1]*6(------) )
-[6]*6(------)
}
\chemfig{EtO-[:30](=[2]O)-[:-30]N(-[6,0.3,,,draw=none]H)-[:30](<:[3])(-[:-30](=[::60]O)-[::-60]O^\ominus)
<[1](-[::60])-[::-60]}
\schemestop
};
\end{tikzpicture}
\end{document}