10.1002/chem.201801262
Chemistry - A European Journal
COMMUNICATION
Based on the above results and combination w ith previous
literatures,[4,7] a plausible mechanism w as then proposed as
show n in Scheme 3. For the alkynes and alkenes, the same
high active species B w as genarated from the NFSI and
CuCl. This N radical attacked the phenylacetylene and
styrene to give the azirinium C and azidinium E, w hich
further trapped Cl anion from the CuCl2 w hich w as
accompanied w ith a single electron transfer to produce the
target compounds 3a and 5a w ith the release of CuCl,
respectively.
In summary, w e have established a simple and rapid
methodology for the aminochlorination of unactivated alkynes
and alkenes, and thus for the construction of functionalized
chloroenamines and chloroamines in good to high yields,
respectively. The reaction displays some advantages, such as
the mild reaction conditions, simple and rapid, no ligand and
w ide broad substrates application. The azirinium and azidinium
intermediates w ere involved in the aminochlorination reactions
of alkynes and alkenes. Our ongoing studies focus on more
diverse transformations of chloroenamines and chloroamines as
well as functionalized alkynes and alkenes.
Experimental Section
To a Schlenk tube was added NFSI (95 mg, 0.3 mmol, 1.5 equiv.),CuCl
(2 mg, 0.02 mmol, 0.1 equiv.) and CuCl2 (27 mg, 0.2 mmol, 1.0 equiv.)
under N2 atmosphere. Then alkynes 1 (0.2 mmol, 1.0 equiv.) and CH3CN
(1.0 mL) were sequentially added into a Schlenk tube. The reaction
mixture was stirred at 60 oC for about 0.5 h until complete disappearance
of 1 (monitored by TLC). The mixture was passed through a short
kieselguhr column by using CH2Cl2 as elution and concentrated in vacuo,
purified by flash chromatography on silica gel (gradient elution of EtOAc
/petroleum ether, PE : EA = 10 : 1).
Scheme 3. The possible aminochlorination reaction mechanism of
alkynes and alkenes.
Acknowledgements
The
gram
scale
and
transformation
of
the
aminochlorination of alkynes and alkenes w ere further
investigated (Scheme 4). It w as observed that the
corresponding chloroenamine 3a and chloroamine 5a could
be produced in 70% and 86% yields in the 10 mmol scale of
starting materials, respectively (Scheme 4, eq. 1 and eq.2).
Treating the chloroenamine 3a w ith the NaOH in EtOH at 50
oC, the N-(1,2-diethoxy-2-phenylethyl) benzenesulfonamide
11 w as obtained, w hereas for the chloroamine 5a, the N-(2-
ethoxy-2-phenylethyl) benzene sulfonamide 12 w as
generated as a major product under the similar reaction
conditions accompanied by the small amount of 13 (eq.3
and eq.4).
We are grateful for financial support from the National Key
Research
and
Development
Program
of
China
(2017YFD0201404) for this w ork and Natural Science
Foundation of Tianjin City (17JCZDJC37300). And w e also
thank the support from the Collaborative Innovation Center of
Chemical Science and Engineering (Tianjin).
Keywords: aminochlorination • alkynes • alkenes• NFSI •
chloroenamine
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Scheme 4. The gram scale of the aminochlorination of alkynes or alkenes
and transformations of chloroenamine 3a and chloroamine 5a.
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