\documentclass[10pt]{article}

\usepackage{fullpage}
\usepackage{setspace}
\usepackage{parskip}
\usepackage{titlesec}
\usepackage[section]{placeins}
\usepackage{xcolor}
\usepackage{breakcites}
\usepackage{lineno}
\usepackage{hyphenat}





\PassOptionsToPackage{hyphens}{url}
\usepackage[colorlinks = true,
            linkcolor = blue,
            urlcolor  = blue,
            citecolor = blue,
            anchorcolor = blue]{hyperref}
\usepackage{etoolbox}
\makeatletter
\patchcmd\@combinedblfloats{\box\@outputbox}{\unvbox\@outputbox}{}{%
  \errmessage{\noexpand\@combinedblfloats could not be patched}%
}%
\makeatother


\usepackage{natbib}




\renewenvironment{abstract}
  {{\bfseries\noindent{\abstractname}\par\nobreak}\footnotesize}
  {\bigskip}

\titlespacing{\section}{0pt}{*3}{*1}
\titlespacing{\subsection}{0pt}{*2}{*0.5}
\titlespacing{\subsubsection}{0pt}{*1.5}{0pt}


\usepackage{authblk}


\usepackage{graphicx}
\usepackage[space]{grffile}
\usepackage{latexsym}
\usepackage{textcomp}
\usepackage{longtable}
\usepackage{tabulary}
\usepackage{booktabs,array,multirow}
\usepackage{amsfonts,amsmath,amssymb}
\providecommand\citet{\cite}
\providecommand\citep{\cite}
\providecommand\citealt{\cite}
% You can conditionalize code for latexml or normal latex using this.
\newif\iflatexml\latexmlfalse
\providecommand{\tightlist}{\setlength{\itemsep}{0pt}\setlength{\parskip}{0pt}}%

\AtBeginDocument{\DeclareGraphicsExtensions{.pdf,.PDF,.eps,.EPS,.png,.PNG,.tif,.TIF,.jpg,.JPG,.jpeg,.JPEG}}

\usepackage[utf8]{inputenc}
\usepackage[ngerman,greek,english]{babel}



\usepackage{float}








\begin{document}

\title{Feasible Synthesis of N, O-Bidentate Difluoroboron Chromo-phores through
Direct Functionalization of Quinoxalin-2(1H)-ones with Ketones in One
Shot}



\author[1]{Shuaichen Zhang}%
\author[1]{Jing Zhang}%
\author[2]{Xiang Ling}%
\author[1]{Yifa Zhao}%
\author[1]{Yue Ma}%
\author[1]{Peng Sun}%
\affil[1]{China Academy of Chinese Medical Sciences Institute of Chinese Materia Medica}%
\affil[2]{China Pharmaceutical University School of Pharmacy}%


\vspace{-1em}



  
  \date{May 27, 2024}


\begingroup
\let\center\flushleft
\let\endcenter\endflushleft
\maketitle
\endgroup





\selectlanguage{english}
\begin{abstract}
Organic difluoroboron complexes is a kind of potential platforms for a
wide range of applications owing to their excellent photo-physical
properties. Herein, we have explored a simple and direct synthesis
methodologies for a library of N,O-Bidentate difluoroboron complexes
from quinoxalin-2(1H)-ones and ketones in one shot. The photophysical
properties of the generated com-plexes were evaluated and the
application potential of these compound on subcellular was also
explored.%
\end{abstract}%



\sloppy


\textbf{Cite this paper:}\emph{Chin. J. Chem.} \textbf{2023} , \emph{41}
, XXX---XXX. \textbf{DOI: 10.1002/cjoc.202300XXX}

Feasible Synthesis of N, O-Bidentate Difluoroboron Chromophores through
Direct Functionalization of Quinoxalin-2(1H)-ones with Ketones in One
Shot

Shuaichen Zhang,\textsuperscript{\#a} Jing
Zhang,\textsuperscript{\#a}Xiang Ling,\textsuperscript{b} Yifan
Zhao,\textsuperscript{a} Yue Ma,\textsuperscript{a} and Peng
Sun*\textsuperscript{a}

\textsuperscript{a} State Key Laboratory for Quality Ensurance and
Sustainable Use of Dao-di Herbs; Artemisinin Research Center and
Institute of Chinese Materia Medica, China Academy of Chinese Medical
Sciences, Beijing 100700, People's Republic of China.\textsuperscript{b}
Department of Pharmaceutics, School of Pharmacy, China Pharmaceutical
University, State Key Laboratory of Natural Medicines, Nanjing 210009,
People's Republic of China.\selectlanguage{english}
\begin{longtable}[]{@{}l@{}}
\toprule
\textbf{Keywords}\tabularnewline
\midrule
\endhead
N, O-Bidentate Difluoroboron \textbar{} Chromophores \textbar{}
Quinoxalin-2(1H)-ones \textbar{} Ketones \textbar{} Green Chemistry
\textbar{}\tabularnewline
\textbf{Comprehensive Summary}\tabularnewline
Organic difluoroboron complexes is a kind of potential platforms for a
wide range of applications owing to their excellent photophysical
properties. Herein, we have explored a simple and direct synthesis
methodologies for a library of N,O-Bidentate difluoroboron complexes
from quinoxalin-2(1H)-ones and ketones in one shot. The photophysical
properties of the generated complexes were evaluated and the application
potential of these compound on subcellular was also
explored.\tabularnewline
\bottomrule
\end{longtable}

\section*{}

{\label{section}}

Background and Originality Content

Green chemistry is a pressing concern for chemists, as the increasing
pollution and waste generated during chemical processes have become a
major environmental issue. The demand for environmentally-friendly
processes in organic synthesis has spurred interest in developing
efficient and sustainable reactions for the synthesis of valuable
organic compounds. Since the discovery of boron dipyrromethenates
(BODIPYs) in 1968,\textsuperscript{{[}1{]}} organic difluoroboron
complexes have occupied an increasingly important position in organic
chemistry and material science owing to their superior photophysical
properties, such as high fluorescent quantum yield, tunable structure
and emission, as well as robust photo- and chemical
stability.\textsuperscript{{[}2-5{]}} Especially in the last decade, a
large number of difluoroboron complexes have been explored and applied
in fluorescent sensing, laser dyes, organic light-emitting devices,
bioconjugates components, bio-imaging,\textsuperscript{{[}6-10{]}} and
even singlet-oxygen generators for photodynamic
therapy.\textsuperscript{{[}11, 12{]}} According to the difference of
the ligands, organic difluoroboron complexes can be categorized into
three types: N,N-bidentate type, O,O-bidentate type, and N,O-bidentate
type. BODIPYs,\textsuperscript{{[}3, 13, 14{]}} including
azo-BODIPYs,\textsuperscript{{[}15{]}} and 1,3-dioxa-2-borine have been
well studied with plenty of publications,\textsuperscript{{[}16{]}}which
could be regarded as the typical representatives of the prior two types
of organic difluoroboron complexes compounds. Whereas, the research on
N,O-bidentate organic difluoroboron complexes is relatively lagging
behind.\textsuperscript{{[}17, 18{]}} The scope and function of
N,O-bidentate organic difluoroboron complexes are still rarely involved
but promising region worthy further exploration.

Compared to the significant progresses in the expansion of the structure
and application for organic difluoroboron complexes, the innovation in
the synthetic strategy for these compounds is few and far between.
Generally, the process to prepare an organic difluoroboron complex can
be divided into two stages: 1) synthesis of corresponding organic
bidentate ligand; 2) complexation with boron sources, in most cases is
boron trifluoride diethyl etherate (Scheme
1a).\textsuperscript{{[}19-26{]}} Despite of the drawbacks of tedious
synthetic steps and low efficiency,\textsuperscript{{[}23-26{]}} the
structural diversity of the organic difluoroboron complexes is also
limited by the deficiency in effective synthetic methods with broad
functional groups tolerance. Recently, as the prosperity of
transition-metal-catalyzed C-H bond activation reactions, Glorius group
developed two pioneering samples to construct the organic ligands and
difluoroboron complexes in one shot via copper-mediated C-H bond
activation strategy (Scheme 1b).\textsuperscript{{[}27, 28{]}} These
protocols not only provided efficient and rapid assemble solution for
organic difluoroboron complexes, but also enriched the inventory of
N,O-bidentate products. Apart from the copper tetrafluoroborate
(Cu(BF\textsubscript{4})\textsubscript{2}\selectlanguage{ngerman}·6H\textsubscript{2}O) employed
as catalyst and boron source, stoichiometric silver salts were also
necessary as oxidant, which impaired the green chemical scores of these
protocols in some extent. With the attention to expand the scope and
function of N, O-bidentate organic difluoroboron complexes further, and
also from the perspective of green chemistry and sustainable
development, novel efficient synthetic method is always of continuing
interest.\textsuperscript{{[}29-31{]}} In this paper, we have
established a straightforward synthesis of N,O-bidentate organic
difluoroboron chromophores from quinoxalin-2(1H)-ones and readily
available ketones (Scheme 1c). The reaction showcases excellent step and
atom economy, broad functional group tolerance and operational
convenience. A vast array of N, O-bidentate organic difluoroboron
complexes are synthesized via our protocol. Furthermore, the
photophysical properties and application of these compounds in
bio-imaging are also explored in several dimensions.

\textbf{Scheme 1} Progress in the synthesis of organic difluoroboron
complexes.

Results and Discussion

At first, the reaction was conducted between
1-methylquinoxalin-2(1H)-one (\textbf{1a} ) and acetophenone
(\textbf{2a} ) as shown in Table 1. The desired product
\textbf{3aa}could be obtain with 0.5 equiv of
Cu(BF\textsubscript{4})\textsubscript{2}·6H\textsubscript{2}O as
catalyst and BF\textsubscript{2} source (Table 1, Entry 1). The yield
could be increased to 65\% with 2.0 equiv of
Cu(BF\textsubscript{4})\textsubscript{2}·6H\textsubscript{2}O (Table 1,
Entry 2-3). When we increased the amount of
Cu(BF\textsubscript{4})\textsubscript{2}·6H\textsubscript{2}O to 2.5
equiv, no better outcomes was obtained (Table 1, Entry 4). Next, we turn
to examine the combination of
Cu(BF\textsubscript{4})\textsubscript{2}·6H\textsubscript{2}O and other
BF\textsubscript{2} sources, and 82\% product was generated with 0.5
equiv of Cu(BF\textsubscript{4})\textsubscript{2}·6H\textsubscript{2}O
and 2 equiv of HBF\textsubscript{4} (Table 1, Entry 5-7). A series of
solvents were also tested and the results indicated that DCE is the
proper choice (Table 1, Entry 8-15). When we conducted the reaction at
lower temperature, the yield was reduced to 59\% (Table 1, Entry 16). To
our delight, even 58\% of product could be generated without the use of
Cu(BF\textsubscript{4})\textsubscript{2}·6H\textsubscript{2}O. The
amount of HBF\textsubscript{4} and the reaction temperature were
screened in the absence of Cu salt, and the highest yield was obtained
with 2 equiv. of HBF\textsubscript{4} at 80 \textsuperscript{o}C (Table
1, Entry 19-23).

\textbf{Table 1} Optimization of the reaction
conditions\textsuperscript{a}\selectlanguage{english}
\begin{longtable}[]{@{}lllll@{}}
\toprule
\begin{minipage}[b]{0.19\columnwidth}\raggedright\strut
Entry\strut
\end{minipage} & \begin{minipage}[b]{0.19\columnwidth}\raggedright\strut
Catalyst (0.5 equiv)\strut
\end{minipage} & \begin{minipage}[b]{0.19\columnwidth}\raggedright\strut
BF\textsubscript{2} source (2.0 equiv)\strut
\end{minipage} & \begin{minipage}[b]{0.19\columnwidth}\raggedright\strut
Solvent\strut
\end{minipage} & \begin{minipage}[b]{0.19\columnwidth}\raggedright\strut
Yield\textsuperscript{b}\strut
\end{minipage}\tabularnewline
\midrule
\endhead
\begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
1\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
Cu(BF\textsubscript{4})\textsubscript{2}\selectlanguage{ngerman}·6H\textsubscript{2}O\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
/\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
DCE\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
43\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
2\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
Cu(BF\textsubscript{4})\textsubscript{2}\selectlanguage{ngerman}·6H\textsubscript{2}O (1
equiv)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
/\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
DCE\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
62\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
3\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
Cu(BF\textsubscript{4})\textsubscript{2}\selectlanguage{ngerman}·6H\textsubscript{2}O (2
equiv)\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
/\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
DCE\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
65\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
4\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
Cu(BF\textsubscript{4})\textsubscript{2}\selectlanguage{ngerman}·6H\textsubscript{2}O (2.5
equiv)\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
/\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
DCE\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
65\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
5\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
Cu(OAc)\textsubscript{2}\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
BF\textsubscript{3}\selectlanguage{ngerman}·Et\textsubscript{2}O\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
DCE\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
39\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
6\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
Cu(BF\textsubscript{4})\textsubscript{2}\selectlanguage{ngerman}·6H\textsubscript{2}O\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
BF\textsubscript{3}\selectlanguage{ngerman}·Et\textsubscript{2}O\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
DCE\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
46\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
7\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
Cu(BF\textsubscript{4})\textsubscript{2}\selectlanguage{ngerman}·6H\textsubscript{2}O\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
B(OH)\textsubscript{3}\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
DCE\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
78\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
8\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
Cu(BF\textsubscript{4})\textsubscript{2}\selectlanguage{ngerman}·6H\textsubscript{2}O\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
HBF\textsubscript{4}\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
DCE\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
\textbf{82}\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
9\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
Cu(BF\textsubscript{4})\textsubscript{2}\selectlanguage{ngerman}·6H\textsubscript{2}O\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
HBF\textsubscript{4}\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
H\textsubscript{2}O\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
Trace\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
10\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
Cu(BF\textsubscript{4})\textsubscript{2}\selectlanguage{ngerman}·6H\textsubscript{2}O\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
HBF\textsubscript{4}\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
Toluene\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
48\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
11\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
Cu(BF\textsubscript{4})\textsubscript{2}\selectlanguage{ngerman}·6H\textsubscript{2}O\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
HBF\textsubscript{4}\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
MeCN\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
27\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
12\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
Cu(BF\textsubscript{4})\textsubscript{2}\selectlanguage{ngerman}·6H\textsubscript{2}O\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
HBF\textsubscript{4}\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
DCM\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
56\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
13\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
Cu(BF\textsubscript{4})\textsubscript{2}\selectlanguage{ngerman}·6H\textsubscript{2}O\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
HBF\textsubscript{4}\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
DMF\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
Trace\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
14\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
Cu(BF\textsubscript{4})\textsubscript{2}\selectlanguage{ngerman}·6H\textsubscript{2}O\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
HBF\textsubscript{4}\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
DMSO\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
Trace\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
15\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
Cu(BF\textsubscript{4})\textsubscript{2}\selectlanguage{ngerman}·6H\textsubscript{2}O\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
HBF\textsubscript{4}\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
THF\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
31\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
16\textsuperscript{c}\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
Cu(BF\textsubscript{4})\textsubscript{2}\selectlanguage{ngerman}·6H\textsubscript{2}O\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
HBF\textsubscript{4}\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
DCE\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
59\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
17\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
Cu(BF\textsubscript{4})\textsubscript{2}\selectlanguage{ngerman}·6H\textsubscript{2}O\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
HBF\textsubscript{4} (1.2 equiv)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
DCE\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
72\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
18\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
Cu(BF\textsubscript{4})\textsubscript{2}\selectlanguage{ngerman}·6H\textsubscript{2}O\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
HBF\textsubscript{4} (1.5 equiv)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
DCE\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
78\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
19\textsuperscript{c}\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
/\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
HBF\textsubscript{4}\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
DCE\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
\textbf{58}\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
20\textsuperscript{c}\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
/\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
HBF\textsubscript{4} (2.5 equiv)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
DCE\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
59\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
21\textsuperscript{c}\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
/\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
HBF\textsubscript{4} (1.5 equiv)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
DCE\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
46\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
22\textsuperscript{c}\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
/\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
HBF\textsubscript{4} (1.2 equiv)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
DCE\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
35\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
23\textsuperscript{d}\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
/\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
HBF\textsubscript{4}\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
DCE\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
48\strut
\end{minipage}\tabularnewline
\bottomrule
\end{longtable}

\textsuperscript{\emph{a}} Reaction conditions: \textbf{1a} (0.20 mmol,
1 equiv), \textbf{2a} (0.4 mmol, 2 equiv), catalyst (0.5 euqiv),
BF\textsubscript{2} source (2 equiv), solvent (3 mL),
110\textsuperscript{o}C; \textsuperscript{\emph{b}} Isolated
yields;\textsuperscript{\emph{c}} The reaction was performed at
80\textsuperscript{o}C; \textsuperscript{\emph{c}} The reaction was
performed at 60 \textsuperscript{o}C

With the optimized reaction conditions established, we explored the
scope and generality of the present process (Table 2). At the outset, a
series of ketones including aryl and alkyl ketones were examined. The
electromeric effect of the substituents at the C4-position of the phenyl
ring of acetophenone has negligible influence on the yield of the
reaction, substrates with simple electron-donating groups substituents
(eg., -Me, -OMe, -NH\textsubscript{2)} and electron-withdrawing groups
(eg., -Br, -I) offer corresponding products (\textbf{3ab} -\textbf{3ag}
) in the yield of about 68\%. When the substitutant was changed to
bigger morpholine, the product was also synthesized in 62\%
(\textbf{3ah} ) yield respectively. Next, acetophenone with substituent
at other position and multi-substituted samples were tested, and the
products were obtained in the yields of 57\% to 69\% (\textbf{3ai}
-\textbf{3al} ). When the phenyl group of \textbf{2} was changed with
naphthyl, anthryl, and N-protected car-

\textbf{Table 2} Scope of the reaction. \textsuperscript{a, b}

\textsuperscript{a} Standard conditions \textbf{A} :
substrates\textbf{1} (0.2 mmol), substrates \textbf{2} (0.4 mmol, 2.0
equiv.), Cu(BF\textsubscript{4})\selectlanguage{ngerman}·6H\textsubscript{2}O (0.1 mmol, 50
mol\%), and HBF\textsubscript{4} (0.4 mmol, 2.0 equiv.) in DCE (3.0 mL),
at 110\textsuperscript{o}C for 48 h. Standard conditions \textbf{B}
:\textbf{1} (0.2 mmol), \textbf{2} (0.4 mmol, 2.0 equiv.), and
HBF\textsubscript{4} (0.4 mmol, 2.0 equiv.) in DCE (3.0 mL), at
80\textsuperscript{o}C for 48 h. \textsuperscript{b} Isolated yields,
the yields of the relevant products obtained under Condition \textbf{B}
are marked in blue. \textsuperscript{c} Absorption maxima of the
complexes in DCM (2×10\textsuperscript{-5} M). \textsuperscript{d}
Emssion maxima of the complexes in DCM (10\textsuperscript{-7} M).

bazole, the desired products (\textbf{3am} -\textbf{3ao} ) were prepared
in59\%-65\% yields. Except for these aromatic ketones, acetone can also
react smoothly to give \textbf{3ap} in 53\% yield. Next, we sought to
examine the limitation of quinoxalin-2(1H)-ones. In the beginning,
N-benzyl and N-acetate group were compatible with the standard
conditions, offering the desired products (\textbf{3ea} , \textbf{3fa} )
in 76\% and 70\% respectively. Next, the N-protecting group were
displaced with a range of aryl groups, the products were synthesized in
59\% to 72\% yields (\textbf{3ba} -\textbf{3da} ). To our delight, when
the N-protecting group was removed, the reaction performed smoothly
offering corresponding product in over 50\% yields (\textbf{3ga}
-\textbf{3ha} ). To demonstrate the efficiency of this procedure
further, the reaction was carried out at 10 mmol scale, and\textbf{3aa}
was prepared in 65\% yield at the gram scale. In consideration of the
cost and environment factors, the reactions were also evaluated under
conditions \textbf{B} without
Cu(BF\textsubscript{4})\textsubscript{2}·6H\textsubscript{2}O, and the
yields of the products were provided in the Table 2 marked in blue.

Just as documented, organic difluoroboron complexes display marvelous
photoluminescence. When the synthesized products were put under UV light
irradiation (365 nm), bright fluorescence emission from green to red
were observed not only in solution but also in solid state (Figure
1a\textbf{,} b). Next, a series of studies were carried out to get more
understanding about the photophysical properties of these compounds.
According to the Uv-vis and fluorescence spectra of \textbf{3aa} in
multiple solvents (Figure 2c), the dichloromethane solution
of\textbf{3aa} exhibit the highest quantum yield of up to 0.548 (using
naphthacene {[}\selectlanguage{greek}Φ\selectlanguage{english}F = 0.6 (\selectlanguage{greek}λ\selectlanguage{english}ex = 443 nm){]} as the standard).\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/image7/image7}

\end{center}
\end{figure}

\textbf{Figure 1} Fluorescence photographs and spectra of the generated
organic difluoroboron complexes. \textsuperscript{a} Fluorescence
photographs of solid powder of representative difluoroboron complexes
under UV light irradiation (365 nm). \textsuperscript{b} Fluorescence
photographs of representative complexes in DCM (2\selectlanguage{ngerman}×10\textsuperscript{-5}
M) under UV light irradiation (365 nm). \textsuperscript{c} Absorption
(2×10\textsuperscript{-5} M) and emission (10\textsuperscript{-7} M)
spectra of 3aa in different solvents.

Next, the absorption and emission spectra of these products in
dichloromethane were investigated sufficiently, the absorption and
emission maxima of these solution vary from 403 nm to 504 nm, and 463 nm
to 598 nm with strong substituent-dependency (Table S1). The Stokes
shift is a fatal parameter for fluorophorre associated closely with
their applicational potential. Fluorophores with large Stokes shifts,
which possess few spectral overlaps between the absorption and the
emission, are desirable for bio-imaging and bio-Sensing due to their
higher sensitivity by eliminating of self-absorption. Herein, the
largest Stokes shifts of these synthesized complexes was evaluated to
reach up to 184 nm (\textbf{3an} ), which provide promising potential
fluorescent probe for bio-sensing. The extraordinary Stokes shifts
of\textbf{3an} may be attributed to its high degree of charge separation
caused by the electron donating, and accepting effect between the
electron-deficient difluoroboron motif and the electron-rich naphthalene
group. Since the solid state has a significantly difference luminescence
performance from the solution state influenced by the aggregation state
of the molecules, \textbf{3ak} and \textbf{3ba} were selected for the
solid-state fluorescence test, and the emission maxima of these
complexes vary from 580 nm to 600 nm, and the quantum yield
of\textbf{3ba} is as high as 61.3\% (Table S2). These results elucidate
the dual-phase emission properties of the complexes. Moreover, to
explore the application of the compounds in cell
bio-imaging,\textbf{3ad} was selected based on the structure of the
complex for lysosome-targeting experiments (for details, see
Supplementary Materials Figure S1).

Conclusions

We have developed a straightforward and sustainable synthetic
methodology to construct N,O-Bidentate difluoroboron complexes from
quinoxalin-2(1H)-ones and ketones without transition-metal-catalyst.
This approach benefits from easily available starting materials,
excellent step and atom economy, and good functional group
compatibility. In addition, most of these complexes have broad and
intense absorption and emission bands, and display bright and intensive
fluorescence in dual-phase. The results of colocalization experiments of
the selected product also demonstrated the specificity for lysosomes
targeting, indicating potential applications for cell tracking related
to lysosomes function. Ongoing research including further mechanistic
details and applicational exploration are currently underway.

Experimental

Reaction condition \textbf{A} : Quinoxalin-2(1H)-ones \textbf{1} (0.2
mmol, 1.0 equiv), methyl ketone\textbf{2} (0.4 mmol 2 equiv),
Cu(BF\textsubscript{4})\textsubscript{2}·6H\textsubscript{2}O (0.5
equiv), HBF\textsubscript{4} (2.0 equiv) and DCE (3.0 mL) were added to
a 35.0 mL sealed tube. The reaction mixture was heated to
110\textsuperscript{o}C for 48 hours. When the reaction was finished, 20
mL saturated ammonium chloride solution was added and the residue was
extracted with DCM (3×5.0 mL). The pure product was obtained by flash
chromatography on Aluminum oxide using petroleum ether and
Dichloromethane as the eluent (PE/DCM = 5:1 to 1:3).

Reaction condition \textbf{B} : Quinoxalin-2(1H)-ones \textbf{1} (0.2
mmol, 1.0 equiv), methyl ketones \textbf{2} (0.4 mmol 2 equiv),
HBF\textsubscript{4} (2.0 equiv) and DCE (3.0 mL) were added to a 35.0
mL sealed tube. The reaction mixture was heated to
80\textsuperscript{o}C for 48 hours. When the reaction was finished, 20
mL saturated ammonium chloride solution was added and the residue was
extracted with DCM (3×5.0 mL). The pure product was obtained by flash
chromatography on Aluminum oxide using petroleum ether and
Dichloromethane as the eluent (PE/DCM = 5:1 to 1:3).

Supporting Information

The supporting information for this article is available on the WWW
under https://doi.org/10.1002/cjoc.2023xxxxx.

Acknowledgement (optional)

The author thanks the generous financial support from the Scientifc and
Technological Innovation Project of China Academy of Chinese Medical
Sciences CI2021A05102, the National Natural Science Foundation of China
(21702235, 82141001), the Fundamental Research Funds for the Central
Public Welfare Research Institutes (ZZ13-YQ-098, ZZ14-FL-010,
ZZ15-ND-10).

References\selectlanguage{english}
\begin{longtable}[]{@{}l@{}}
\toprule
\vtop{\hbox{\strut {[}1{]} Treibs, A.; Kreuzer, F.H.
Difluorboryl-komplexe von di-und tripyrrylmethenen. Justus. Liebigs.
Annalen. Der. Chemie. 1968, 718, 208-223.}\hbox{\strut {[}2{]} Bumagina,
N.A.; Antina, E.V.; Ksenofontov, A.A.; Antina, L.A.; Kalyagin, A.A.;
Berezin, M.B. Basic structural modifications for improving the practical
properties of BODIPY. \emph{Coordin. Chem. Rev.} \textbf{2022},
\emph{469}, 214684.}\hbox{\strut {[}3{]} Kothavale, S.S.; Lee, J.Y.
Three-and four-coordinate, boron-based, thermally activated delayed
fluorescent emitters. \emph{Adv. Opt. Mater.} \textbf{2020}, \emph{8},
2000922.}\hbox{\strut {[}4{]} Li, J.; Li, X.; Wang, G.; Wang, X.; Wu,
M.; Liu, J.; Zhang, K. A direct observation of up-converted
room-temperature phosphorescence in an anti-Kasha dopant-matrix system.
\emph{Nat. Commun.} \textbf{2023}, \emph{14}, 1987.}\hbox{\strut {[}5{]}
Murali, A.C.; Nayak, P.; Nayak, S.; Das, S.; Senanayak, S.P.;
Venkatasubbaiah, K. Boron-Thioketonates: A New Class of S, O-Chelated
Boranes as Acceptors in Optoelectronic Devices. \emph{Angewandte Chemie}
\textbf{2023}, \emph{135}, e202216871.}\hbox{\strut {[}6{]} Estergreen,
L.; Mencke, A.R.; Cotton, D.E.; Korovina, N.V.; Michl, J.; Roberts,
S.T.; Thompson, M.E., Bradforth, S.E. Controlling Symmetry Breaking
Charge Transfer in BODIPY Pairs. \emph{Acc. Chem. Res.} \textbf{2022},
\emph{55}, 1561-1572.}\hbox{\strut {[}7{]} Gong, Q.; Zhang, X.; Li, W.;
Guo, X.; Wu, Q.; Yu, C.; Jiao, L.; Xiao, Y.; Hao, E. Long-Wavelength
Photoconvertible Dimeric BODIPYs for Super-Resolution Single-Molecule
Localization Imaging in Near-Infrared Emission. \emph{J. Am. Chem. Soc.}
\textbf{2022}, \emph{144}, 21992-21999.}\hbox{\strut {[}8{]} Schäfer,
C.; Hultmark, S.; Yang, Y.; Müller, C., Börjesson, K. Room Temperature
Dye Glasses: A Guideline Toward the Fabrication of Amorphous Dye Films
with Monomeric Absorption and Emission. \emph{Chem. Mater.}
\textbf{2022}, \emph{34}, 9294-9302.}\hbox{\strut {[}9{]} Shonde, T.B.;
Mondal, A.; Liu, H.; Chaaban, M.; Ben-Akacha, A.; Lee, S.; Knorr, E.S.,
Ma, B. Dramatically Enhanced X-ray Scintillation of BODIPY via
Sensitization by an Organic Metal Halide. \emph{ACS Mater. s Lett.}
\textbf{2022}, \emph{4}, 271-276.}\hbox{\strut {[}10{]} Zheng, X.;
Zhang, L.; Ju, M.; Liu, L.; Ma, C.; Huang, Y.; Wang, B.; Ding, W.; Luan,
X., Shen, B. Rational Modulation of BODIPY Photosensitizers to Design
Metal--Organic Framework-Based NIR Nanocomposites for High-Efficiency
Photodynamic Therapy in a Hypoxic Environment. \emph{ACS Appl. Mater.
Inter.} \textbf{2022}, \emph{14}, 46262-46272.}\hbox{\strut {[}11{]}
Zhao, P.; Wang, Z.; Wang, Y.; Wu, Z.; Guo, Y.; Wang, C.; Fang, X.; Qu,
Z.; Wang, H., Zhao, G. A novel heavy-atom-free lysosome-targeted BODIPY
as triplet photosensitizer based on SOCT-ISC mechanism for photodynamic
therapy. \emph{Dyes. Pigments} \textbf{2023}, \emph{214},
111214.}\hbox{\strut {[}12{]} Agazzi, M.L.; Ballatore, M.B.; Durantini,
A.M.; Durantini, E.N., Tomé, A.C. BODIPYs in antitumoral and
antimicrobial photodynamic therapy: An integrating review. \emph{J.
Photoch. Photobio. C.} \textbf{2019}, \emph{40},
21-48.}\hbox{\strut {[}13{]} Franke, J.M.; Raliski, B.K.; Boggess, S.C.;
Natesan, D.V.; Koretsky, E.T.; Zhang, P.; Kulkarni, R.U.; Deal, P.E.,
Miller, E.W. BODIPY fluorophores for membrane potential imaging.
\emph{J. Am. Chem. Soc.} \textbf{2019}, \emph{141},
12824-12831.}\hbox{\strut {[}14{]} Mellerup, S.K.; Wang, S. Boron-based
stimuli responsive materials. \emph{Chem. Soc. Rev.} \textbf{2019}, 48,
3537-3549.}\hbox{\strut {[}15{]} Song, X.; Bai, S.; He, N.; Wang, R.;
Xing, Y.; Lv, C., Yu, F. Real-time evaluation of hydrogen peroxide
injuries in pulmonary fibrosis mice models with a mitochondria-targeted
near-infrared fluorescent probe. \emph{ACS sensors} \textbf{2021},
\emph{6}, 1228-1239.}\hbox{\strut {[}16{]} Chen, P.Z.; Zhang, H.; Niu,
L.Y.; Zhang, Y.; Chen, Y.Z.; Fu, H.B.; Yang, Q.Z. A solid-state
fluorescent material based on carbazole-containing difluoroboron
β-diketonate: multiple chromisms, the self-assembly behavior, and
optical waveguides. \emph{Adv. Funct. Mater.} \textbf{2017}, \emph{27},
1700332.}\hbox{\strut {[}17{]} Chen, Y.; Ouyang, Q.; Li, Y.; Zeng, Q.;
Dai, B.; Liang, Y.; Chen, B.; Tan, H.; Cui, M. Evaluation of N,
O-Benzamide difluoroboron derivatives as near-infrared fluorescent
probes to detect β-amyloid and tau tangles. \emph{Eur. J. Med. Chem.}
\textbf{2022}, \emph{227}, 113968.}\hbox{\strut {[}18{]} Chen, Y.; Yuan,
C.; Xie, T.; Li, Y.; Dai, B.; Zhou, K.; Liang, Y.; Dai, J.; Tan, H.;
Cui, M. N, O-Benzamide difluoroboron complexes as near-infrared probes
for the detection of β-amyloid and tau fibrils. \emph{Chem. Commun.}
\textbf{2020}, \emph{56}, 7269-7272.}\hbox{\strut {[}19{]} Kubota, Y.;
Tanaka, S.; Funabiki, K.; Matsui, M. Synthesis and Fluorescence
Properties of Thiazole--Boron Complexes Bearing a β-Ketoiminate Ligand.
\emph{Org. Lett.} \textbf{2012}, \emph{14},
4682-4685.}\hbox{\strut {[}20{]} Li, S.; Fu, L.; Xiao, X.; Geng, H.;
Liao, Q.; Liao, Y.; Fu, H. Regulation of Thermally Activated Delayed
Fluorescence to Room-Temperature Phosphorescent Emission Channels by
Controlling the Excited-States Dynamics via J- and H-Aggregation.
\emph{Angew Chem. Int. Ed. Engl.} \textbf{2021}, \emph{60},
18059-18064.}\hbox{\strut {[}21{]} Nosova, E.V.; Moshkina, T.N.;
Lipunova, G.N.; Baklanova, I.V.; Slepukhin, P.A., Charushin, V.N.
Synthesis, structure and photoluminescent properties of BF2 and BPh2
complexes with N,O-benzazine ligands. \emph{J. Fluorine Chem.}
\textbf{2015}, \emph{175}, 145-151.}\hbox{\strut {[}22{]} Xia, M.; Wu,
B.; Xiang, G. Synthesis, structure and spectral study of two types of
novel fluorescent BF\textsubscript{2} complexes with heterocyclic
1,3-enaminoketone ligands. \emph{J. Fluorine Chem.} \textbf{2008},
\emph{129}, 402-408.}\hbox{\strut {[}23{]} Cai, Y.-H.; Chih, H.-Y.; Lee,
G.-H.; Lai, C.K. Aggregation-induced emissions in the mesogenic
BF\textsubscript{2} complexes of aroylhydrazines. \emph{New J Chem.}
\textbf{2021}, \emph{45}, 12557-12568.}\hbox{\strut {[}24{]} Hu, Y.;
Nan, J.; Gong, X.; Zhang, J.; Yin, J.; Ma, Y. Zinc-catalyzed C--H
alkenylation of quinoline N-oxides with ynones: a new strategy towards
quinoline-enol scaffolds. \emph{Chem. Commun.} \textbf{2021}, \emph{57},
4930-4933.}\hbox{\strut {[}25{]} Yang, D.; Liu, P.; Bai, T.; Kong, J.
N,N-Dimethyl-Substituted Boron Ketoiminates for Multicolor Fluorescent
Initiators and Polymers. \emph{Macromolecules} \textbf{2020}, \emph{53},
3339-3348.}\hbox{\strut {[}26{]} Yao, Q.-C.; Wu, D.-E.; Ma, R.-Z.; Xia,
M. Study on the structure--property relationship in a series of novel
BF\textsubscript{2} chelates with multicolor fluorescence. \emph{J.
Organometallic. Chem.} \textbf{2013}, \emph{743},
1-9.}\hbox{\strut {[}27{]} Tan, G.; Maisuls, I.; Strieth-Kalthoff, F.;
Zhang, X.; Daniliuc, C.; Strassert, C.A.; Glorius, F. AIE-Active
Difluoroboron Complexes with N,O-Bidentate Ligands: Rapid Construction
by Copper-Catalyzed C-H Activation. \emph{Adv. Sci.} \textbf{2021}, 8,
2101814.}\hbox{\strut {[}28{]} Tan, G.; Schrader, M.L.; Daniliuc, C.;
Strieth-Kalthoff, F.; Glorius, F. C-H Activation Based Copper-Catalyzed
One-Shot Synthesis of N,O-Bidentate Organic Difluoroboron Complexes.
\emph{Angew. Chem. Int. Ed. Engl.} \textbf{2020}, \emph{59},
21541-21545.}\hbox{\strut {[}29{]} Duan, C.; Zhou, Y.; Shan, G.-G.;
Chen, Y.; Zhao, W.; Yuan, D.; Zeng, L.; Huang, X.; Niu, G. Bright
solid-state red-emissive BODIPYs: facile synthesis and their
high-contrast mechanochromic properties. \emph{J. Mater. Chem.}
\textbf{2019}, \emph{7}, 3471-3478.}\hbox{\strut {[}30{]} Pérez-Venegas,
M.; Villanueva-Hernández, M.N.; Peña-Cabrera, E.; Juaristi, E.
Mechanochemically Activated Liebeskind--Srogl (LS) Cross-Coupling
Reaction: Green Synthesis of meso-Substituted BODIPYs.
\emph{Organometallics.} \textbf{2020}, \emph{39},
2561-2564.}\hbox{\strut {[}31{]} He, G.; Lu, Q.; Xu, F.; Zhang, D.; Li,
Y.; Xia, J. Facile synthesis of poly (BODIPY) s via solid state
polymerization and application in temperature sensor. \emph{Polymer.}
\textbf{2022}, \emph{241}, 124514.}}\selectlanguage{ngerman}\tabularnewline
\midrule
\endhead
Manuscript received: XXXX, 2023 Manuscript revised: XXXX, 2023
Manuscript accepted: XXXX, 2023 Accepted manuscript online: XXXX, 2023
Version of record online: XXXX, 2023\tabularnewline
\bottomrule
\end{longtable}\selectlanguage{ngerman}

The Authors\selectlanguage{english}
\begin{longtable}[]{@{}lll@{}}
\toprule
& After acceptance, please insert a group photo of the authors taken
recently. &\tabularnewline
& \textbf{Left to Right:} Authors Names &\tabularnewline
\bottomrule
\end{longtable}

\textbf{Entry for the Table of Contents}\selectlanguage{english}
\begin{longtable}[]{@{}l@{}}
\toprule
\textbf{Feasible Synthesis of N, O-Bidentate Difluoroboron Chromophores
through Direct Functionalization of Quinoxalin-2(1H)-ones with Ketones
in One Shot} Shuaichen Zhang,\# Jing Zhang,\# Xiang Ling, Yifan Zhao,
Yue Ma, and Peng Sun* \emph{Chin. J. Chem.} \textbf{2023}, \emph{41},
XXX---XXX. \textbf{DOI: 10.1002/cjoc.202300XXX}\tabularnewline
\midrule
\endhead
A rapid and green synthetic protocol for N,O-bidentate difluoroboron
chromophores was achieved via cascade C-H functionalization and
difluoroboronation reaction from readily accessible feedstock chemicals
in one shot.\tabularnewline
\bottomrule
\end{longtable}

\selectlanguage{english}
\FloatBarrier
\end{document}

