Electrochemically Enabled Selenium Catalytic Synthesis of 2,1-Benzoxazoles fromo-Nitrophenylacetylenes

Article abstract of DOI:10.1021/acs.joc.1c00012

The study reported an electrochemically mediated method for the preparation of 2,1-benzoxazoles fromo-nitrophenylacetylenes. Different from the traditional electrochemical reduction of nitro to nitroso, the nitro group directly underwent a cyclization rea

Full text of DOI:10.1021/acs.joc.1c00012

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Electrochemically Enabled Selenium Catalytic Synthesis of 2,1-
Benzoxazoles from o‑Nitrophenylacetylenes
Lin-Wei Wang, Yu-Feng Feng, Hong-Min Lin, Hai-Tao Tang,* and Ying-Ming Pan*
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ABSTRACT: The study reported an electrochemically mediated
method for the preparation of 2,1-benzoxazoles from o-nitro-
phenylacetylenes. Different from the traditional electrochemical
reduction of nitro to nitroso, the nitro group directly underwent a
cyclization reaction with the alkyne activated by selenium cation
generated by the anodic oxidation of diphenyl diselenide and finally
produced the desired products.
increased reaction costs, unfavorable environmental effects,
rganocatalysis has become the third major catalytic
Omethod after metal and enzyme catalysis due to its and formation of byproducts.
The development of electrochemistry provides an efficient,
advantages of simple steps, low cost, and good compatibility of
functional groups.1 A series of organocatalysts, such as N-
heterocyclic carbenes,2 secondary amines,3 and phosphine
catalysts,4 has been developed in the past few decades. After
Sharpless initially reported the chlorination of alkenes
catalyzed by an organoselenium catalyst in 1979,5 selenium-
catalyzed reactions have attracted extensive concern with
continuous research on potential catalysts in organic syn-
thesis.6 Among them, diselenide combined with oxidants, such
as PEROX,7 high-valent iodine reagents,8 N−F reagents,9 and
others,10 for catalysis, has been widely reported in different
reactions (Figure 1a). However, the use of these external
oxidants usually suffers from substantial drawbacks such as
mild, and controllable method for organic synthesis.11 The
electron transfer on the electrode surface could achieve redox
reactions; thus, traditional oxidants could be avoided. In
addition, the controllability of the current and potential
indicates that the oxidation or reduction ability of the reaction
system is operable. Therefore, electrochemically enabled
organocatalysis is a promising metal- and oxidant-free catalytic
method.12 At the anode, the oxidation of organic catalysts
could give intermediates with oxidizing properties. Then, the
reactive intermediates react with the substrate to form the final
product (Figure 1b). For example, Zeng’s group reported a
series of organic reactions with halogen catalysts under
electrochemical conditions.13 Xu’s group utilized electrochemi-
cally enabled nitrogen-containing compounds (TEMPO or
NAr3) as catalysts to synthesize structurally diverse hetero-
cycles compounds.14 The authors of the present study also
reported a series of cross dehydrogenation coupling reactions
catalyzed by halogen.15 However, one shortcoming of the
above-mentioned selenium catalysis is the use of excessive
oxidants. The combination of organic electrosynthesis and
selenium catalysis effectively avoids this shortcoming (Figure
1c). In 1981, Bannou reported a one-step preparation of allylic
derivatives through electrochemical selenium catalysis of
Special Issue: Electrochemistry in Synthetic Organic
Chemistry
Received: January 4, 2021
Figure 1. General catalytic modes.
https://dx.doi.org/10.1021/acs.joc.1c00012
© XXXX American Chemical Society
J. Org. Chem. XXXX, XXX, XXX−XXX
A

The Journal of Organic Chemistry
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Note
isoprenoids.6d Recently, Wirth and others also did some
studies.6e,f To try more reactions in this area, this strategy was
used with o-nitrophenylacetylenes as the substrate template,
and the results obtained nucleophilic cyclization products of o-
nitrophenylacetylenes catalyzed by diphenyl diselenide under
the condition of constant potential in an undivided cell.
The reaction conditions were screened, as shown in Table 1,
and the specific information on the other conditions is
a
Table 1. Optimization of Reaction Conditions
b
entry
variation from the standard reaction conditions
yield (%)
1
none
78
2
3
4
no electricity
no PhSeSePh
reaction at 40 °C
NR
NR
59
5
reaction at 0 °C
36
6
7
8
DMF as a solvent
DMSO as a solvent
trace
trace
trace
30
nBu4NI (2.0 equiv) as an electrolyte
nBu4NBF6 (2.0 equiv) as an electrolyte
constant potential: 1.3 V vs Ag/AgCl
constant potential: 2.1 V vs Ag/AgCl
constant current: 5 mA
9
Figure 2. Substrate scope of nitroalkynes. Reaction conditions:
graphite rod cathode (Φ 6 mm), Pt plate anode (1 cm × 1 cm),
undivided cell, constant potential = 1.6 V vs Ag/AgCl, 1 (0.3 mmol),
Et4NPF6 (0.5 equiv), PhSeSePh (10 mol %), CH3CN = 10 mL, rt.
Isolated yields.
10
11
12
NR
63
72
c
a
Reaction conditions: graphite rod cathode (Φ 6 mm), Pt plate anode
(1 cm × 1 cm), undivided cell, constant potential = 1.6 V vs Ag/AgCl,
1a (0.3 mmol), Et4NPF6 (0.5 equiv), catalyst (10 mol %), CH3CN =
ortho- or meta-position on the aryl ring of R1 (2j, 2k). A
notable detail is that 2k had a longer reaction time but an
improved yield than that of the other products. In addition,
when R1 was a fused ring or the heteroaryl group was tolerated,
the corresponding product was isolated in 65% and 80% yields,
respectively. Substrates bearing alkyl groups (R1 = propyl,
cyclopropyl) were also suitable for this transformation.
Excitingly, 1p could also achieve the target product 2p with
a yield of 33%. However, the corresponding products of
unsubstituted terminal alkyne and TMS-substituted alkyne
were not detected because the reaction of these two substrates
would generate lots of byproducts. Next, the tolerance of R2 on
the benzene ring attached to the nitro group was explored.
Among them, the electronic effect of R2 demonstrated a little
effect on the reaction, and both showed medium to good yields
(2s−2x, 56%−89%). The yield of the electron-withdrawing
groups was higher than that of the electron-donating groups.
Moreover, 2-nitro-3-(phenylethynyl)pyridine obtained the
target product in good yield (2y, 86%).
Several control experiments were performed to further
clarify the reaction mechanism, as shown in Figure 3. When
the reaction was carried out in the presence of 1,1-
diphenylethene, a known free radical scavenger, 2a, was
obtained with an isolated yield of 68% under standard
conditions (Figure 4a). This finding illustrated that the
reaction was not carried out in a radical manner. Further
experiments showed that 1a could produce the target product
in the presence of PhSeCl without electricity (Figure 4b).
Meanwhile, the reaction could occur under anhydrous and
oxygen-free conditions, and a good yield was obtained (Figure
4c). In addition, cyclic voltammetry (CV) experiments were
conducted to further study the reaction mechanism (Figure
b
c
10 mL, rt. Isolated yields. 0.4 F mol−1. NR = no reaction
provided in Table S1. The optimal yield of product 2a
obtained a yield of 78% when the reaction was conducted in
CH3CN as a solvent at a constant potential of 1.6 V vs Ag/
AgCl in the presence of Et4NPF6 (0.5 equiv) with diphenyl
diselenide (PhSeSePh) as the catalyst (entry 1). Moreover, the
necessity of electricity and PhSeSePh were verified through
experiments. No desired product 2a was detected under the
conditions without electricity (entry 2) or PhSeSePh (entry 3).
Reactions at 0 °C (entry 4) or 40 °C (entry 5) led to a
decrease in yield. In comparison, only a trace yield of 2a was
obtained when DMF (entry 6) or DMSO (entry 7) were used
as the solvent. When nBu4NI or nBu4NBF6 was used instead of
Et4NPF6 as the electrolyte, a decline in yield was obtained
(entries 8 and 9). Exploration of the influence of voltage on the
reaction showed that, when the voltage was reduced to 1.3 V
(entry 10), the reaction did not occur. When the voltage was
increased to 2.1 V (entry 11), the yield of 2a decreased. The
change in yield was also tested under constant current
conditions, and the results showed that the reaction at a
constant current of 5 mA (entry 12) would lead to a decrease
in the yield of 2a.
The tolerance of the substrate functional group was explored
under the optimal conditions, and the results are shown in
Figure 2. Various nitroalkynes with different aromatic groups
containing electron-withdrawing (F, Cl, Br, CF3, and CN) and
electron-donating (Me, OMe, and t-Bu) groups reacted well,
obtaining desired products 2b−2i in moderate to medium
yields (51%−78%). The desirable yields of 2,1-benzoxazoles
also were obtained for the nitroalkynes containing Cl at its
B
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Note
experiment, part of the released selenium cation continued to
participate in catalysis (Figure S2).
CONCLUSIONS
■
In summary, an electrochemical selenium catalytic system for
nitroalkynes generation intramolecular nucleophilic cyclization
was developed to construct 2,1-benzoxazoles in undivided
cells. This strategy has a good reaction efficiency and a
widened substrate range. In the reaction process, constant
pressure is used to replace the external oxidant, thus avoiding
the use of traditional oxidants and transition metals.
EXPERIMENTAL SECTION
■
Experimental Procedure. Without special instructions, all
reagents and solvents were commercially available and were not
further purified. Column chromatography was carried out using silica
gel (300−400 mesh). NMR spectroscopy was performed on Bruker
Figure 3. Control experiments.
1
AV-400 or Bruker AV-600 instruments. Chemical shifts for H NMR
spectra are reported as δ in units of parts per million (ppm) downfield
from TMS (δ 0.00) and relative to the signal of chloroform-d (δ 7.26,
singlet) or DMSO-d6 (δ 2.50, multiplet). 13C NMR spectra were
relative to the signal of CDCl3 (77.0 ppm) or DMSO-d6 (39.5 ppm).
The abbreviations used to explain the multiplicities were as follows: s,
singlet; d, doublet; t, triplet; m, multiplet; brs, broad singlet; J,
coupling constant in Hz. 13C NMR spectra are reported as δ in units
of parts per million (ppm) downfield from TMS (δ 0.00) and relative
to the signal of chloroform-d (δ 77.00, triplet). The HRMS spectrum
was measured by a micromass QTOF2 Quadrupole/Time of Flight
Tandem mass spectrometer with electron spray ionization. Cyclic
voltammograms were recorded on a CHI 660E potentiostat. Crystal
measurement by XtaLAB Synergy-DS.
Synthesis of Starting Materials.18 To a solution of 1-nitro-2-
iodobenzene (3.0 mmol) in triethylamine (10 mL) at room
temperature was added PdCl2(PPh3)2 (0.0421 g, 0.06 mmol). The
resultant suspension was stirred for 10 min, followed by the addition
of alkynes (3.6 mmol) and then CuI (0.0114 g, 0.06 mmol). This
mixture was then stirred for 6 h. The reaction mixture was washed
with NH4Cl (aq sat.) and brine and dry over Na2SO4. The solvent
was removed, and the residue was subjected to silica gel column
chromatography.
Procedures for the Electrolysis. A 25 mL three-necked round-
bottomed flask was charged with nitroalkynes 1 (0.3 mmol, 1.0
equiv), diphenyl diselenide (0.03 mmol, 10 mol %), and Et4NPF6
(0.15 mmol, 0.5 equiv). The flask was equipped with a graphite rod
(Φ 6 mm) cathode and a platinum plate (1 cm × 1 cm) anode. A Ag/
AgCl electrode was used as the reference electrode. CH3CN (10 mL)
was added. Electrolysis was carried out at room temperature, which
used a constant potential of 1.6 V vs Ag/AgCl until the substrate was
completely consumed (monitored by TLC). After the reaction was
completed, the solvent was concentrated under reduced pressure.
Purification with silica gel column chromatography using petroleum
ether/ethyl acetate to afford the desired products 2.
Figure 4. Proposed reaction mechanism.
S3). Obvious oxidation peaks of 1a and 2a could be observed
at 2.00 V (curve b and curve e). Meanwhile, oxidation peaks of
PhSeSePh were 1.25 and 1.45 V (curve c). These two
oxidation peaks represent the oxidation activation of
PhSeSePh, and phenyl selenium radical B generates selenium
cation A by single electron transfer on the anode.16 Therefore,
our reaction condition was 1.6 V. CV curve d shows that the
oxidation peak of 1a disappeared, and the reduction peak
appeared at 0.39 V. In accordance with the reported
literature,16 the former could be due to the combination of
substrate 1a with selenium cations produced by PhSeSePh, and
the latter indicated that selenium cations were reduced at the
cathode.
In accordance with the above control experiments and the
reported literature,16a,17 a possible mechanism for the electro-
chemical cyclization is proposed in Figure 4. The reaction
starts with the formation of selenium cation A and phenyl
selenium radical B by the activation of diphenyl diselenide in
anodization. Phenyl selenium radical B could also generate
selenium cation A by single electron transfer on the anode.
The addition of A to substrate 1a produces intermediate C.
Then the oxygen on the nitro group of intermediate C
undergoes an intramolecular nucleophilic cyclization to attack
the alkyne activated by selenium cation to obtain intermediate
D. The cleavage of the N−O bond generates intermediate E,
which releases a selenium cation after the cyclization reaction
to obtain the final target product 2a. According to the switch
To demonstrate our method’s potential for application, we
performed the reaction at a gram scale level in a beaker-type cell
with the same electrode at room temperature for 12 h to afford
corresponding products with satisfactory yields.
Crystal Preparation for 2f. A glass tube (Φ 8 mm) was charged
with 2f (30.1 mg). DMSO (1 mL) was added. Then 0.3 mL of H2O
was slowly added along the wall. Parafilm was used to seal the glass
tube and make holes; then the tube was kept in a cool place for 3
days. Crystals precipitated in the glass tube.
C
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Note
Benzo[c]isoxazol-3-yl(phenyl)methanone (2a): yellow solid; 78%
yield, 52.2 mg; mp 91−92 °C; petroleum ether/ethyl acetate =
100:1−60:1 (v/v) as an eluent for column chromatography; 1H NMR
(400 MHz, CDCl3) δ 8.32−8.27 (m, 2H), 8.16−8.10 (m, 1H), 7.78−
7.73 (m, 1H), 7.71−7.64 (m, 1H), 7.61−7.54 (m, 2H), 7.45−7.39
(m, 1H), 7.32−7.26 (m, 1H); 13C{1H} NMR (101 MHz, CDCl3) δ
181.5, 160.4, 157.3, 136.0, 133.8, 131.4, 130.1, 128.7, 128.5, 121.7,
121.6, 115.9; HR-MS (ESI) m/z calcd for C14H10NO2 [M + H]+
224.0706, found 224.0707.
1H), 1.38 (s, 9H); 13C{1H} NMR (101 MHz, CDCl3) δ 181.0, 160.6,
157.8, 157.2, 133.4, 131.3, 130.1, 128.3, 125.8, 121.8, 121.5, 115.8,
35.2, 31.0; HR-MS (ESI) m/z calcd for C18H18NO2 [M + H]+
280.1332, found 280.1333.
4-(Benzo[c]isoxazole-3-carbonyl)benzonitrile (2i): yellow solid;
56% yield, 41.7 mg; mp 155−156 °C; petroleum ether/ethyl acetate =
1
70:1−20:1 (v/v) as an eluent for column chromatography; H NMR
(400 MHz, CDCl3) δ 8.41−8.36 (m, 2H), 8.15−8.11 (m, 1H), 7.89−
7.86 (m, 2H), 7.80−7.75 (m, 1H), 7.49−7.43 (m, 1H), 7.38−7.31
(m, 1H); 13C{1H} NMR (101 MHz, CDCl3) δ 179.7, 159.4, 157.3,
139.0, 132.5, 131.6, 130.4, 129.4, 122.1, 121.3, 117.7, 116.8, 116.1;
HR-MS (ESI) m/z calcd for C15H8N2NaO2 [M + Na]+ 271.0478,
found 271.0477.
Benzo[c]isoxazol-3-yl(p-tolyl)methanone (2b): yellow solid; 74%
yield, 52.6 mg; mp 100−101 °C; petroleum ether/ethyl acetate =
1
80:1−50:1 (v/v) as an eluent for column chromatography; H NMR
(400 MHz, CDCl3) δ 8.14−8.09 (m, 2H), 8.05−8.00 (m, 1H), 7.67−
7.62 (m, 1H), 7.34−7.25 (m, 3H), 7.20−7.14 (m, 1H), 2.37 (s, 3H);
13C{1H} NMR (101 MHz, CDCl3) δ 181.0, 160.6, 157.2, 144.9,
133.4, 131.3, 130.2, 129.4, 128.2, 121.7, 121.5, 115.8, 21.8; HR-MS
(ESI) m/z calcd for C15H12NO2 [M + H]+ 238.0863, found 238.0859.
Benzo[c]isoxazol-3-yl(4-methoxyphenyl)methanone (2c): yellow
solid; 77% yield, 58.5 mg; mp 122−123 °C; petroleum ether/ethyl
acetate = 80:1−40:1 (v/v) as an eluent for column chromatography;
1H NMR (400 MHz, CDCl3) δ 8.34−8.30 (m, 2H), 8.13−8.09 (m,
1H), 7.73−7.69 (m, 1H), 7.41−7.35 (m, 1H), 7.27−7.21 (m, 1H),
7.04−7.00 (m, 2H), 3.89 (s, 3H); 13C{1H} NMR (101 MHz, CDCl3)
δ 179.6, 164.2, 160.8, 157.1, 132.6, 131.2, 128.7, 128.0, 121.8, 121.4,
115.6, 114.0, 55.5; HR-MS (ESI) m/z calcd for C15H12NO3 [M + H]+
254.0812, found 254.0829.
Benzo[c]isoxazol-3-yl(3-chlorophenyl)methanone (2j): yellow
solid; 75% yield, 57.8 mg; mp 89−90 °C; petroleum ether/ethyl
acetate = 100:1−60:1 (v/v) as an eluent for column chromatography;
1H NMR (600 MHz, DMSO-d6) δ 8.12−8.08 (m, 2H), 7.99−7.95
(m, 1H), 7.92−7.88 (m, 1H), 7.84−7.81 (m, 1H), 7.71−7.66 (m,
1H), 7.60−7.55 (m, 1H), 7.45−7.41 (m, 1H); 13C{1H} NMR (151
MHz, DMSO-d6) δ 179.9, 159.5, 156.8, 137.6, 133.6, 133.5, 132.2,
130.9, 129.4, 129.2, 128.4, 120.9, 120.7, 115.8; HR-MS (ESI) m/z
calcd for C14H9ClNO2 [M + H]+ 258.0316, found 258.0306.
Benzo[c]isoxazol-3-yl(2-chlorophenyl)methanone (2k): yellow
solid; 89% yield, 68.6 mg; mp 54−55 °C; petroleum ether/ethyl
acetate = 100:1−50:1 (v/v) as an eluent for column chromatography;
1H NMR (400 MHz, DMSO-d6) δ 7.93−7.88 (m, 1H), 7.84−7.80
(m, 1H), 7.72−7.66 (m, 2H), 7.67−7.63 (m, 1H), 7.63−7.54 (m,
2H), 7.46−7.40 (m, 1H); 13C{1H} NMR (101 MHz, DMSO-d6) δ
181.4, 158.8, 157.2, 136.3, 133.2, 132.1, 130.4, 130.2, 130.0, 129.9,
127.7, 119.9, 119.8, 116.0; HR-MS (ESI) m/z calcd for C14H9ClNO2
[M + H]+ 258.0316, found 258.0310.
Benzo[c]isoxazol-3-yl(naphthalen-2-yl)methanone (2l): yellow
solid; 65% yield, 53.2 mg; mp 114−115 °C; petroleum ether/ethyl
acetate = 80:1−50:1 (v/v) as an eluent for column chromatography;
1H NMR (400 MHz, DMSO-d6) δ 8.85−8.82 (m, 1H), 8.19−8.15
(m, 1H), 8.12−8.09 (m, 2H), 8.06−8.01 (m, 1H), 8.00−7.95 (m,
1H), 7.91−7.86 (m, 1H), 7.74−7.68 (m, 1H), 7.67−7.61 (m, 1H),
7.58−7.53 (m, 1H), 7.42−7.37 (m, 1H); 13C{1H} NMR (101 MHz,
DMSO-d6) δ 181.0, 160.1, 156.8, 135.3, 133.1, 132.1, 132.1, 131.9,
129.9, 129.3, 129.1, 128.7, 127.8, 127.3, 124.7, 121.0, 120.6, 115.7;
HR-MS (ESI) m/z calcd for C18H12NO2 [M + H]+ 274.0863, found
274.0860.
Benzo[c]isoxazol-3-yl(4-fluorophenyl)methanone (2d): yellow
solid; 66% yield, 47.7 mg; mp 83−84 °C; petroleum ether/ethyl
acetate = 100:1−60:1 (v/v) as an eluent for column chromatography;
1H NMR (400 MHz, CDCl3) δ 8.43−8.36 (m, 2H), 8.19−8.13 (m,
1H), 7.81−7.75 (m, 1H), 7.49−7.42 (m, 1H), 7.35−7.26 (m, 3H);
1
13C{1H} NMR (101 MHz, CDCl3) δ 179.7, 166.1 (C−F, JC−F
=
3
255.2 Hz), 160.2, 157.2, 132.9 (C−F, JC−F = 9.4 Hz), 132.3 (C−F,
4JC−F = 3.1 Hz), 131.4, 128.6, 121.7, 121.6, 116.0 (C−F, 2JC−F = 21.9
Hz); 19F NMR (376 MHz, CDCl3) δ −103.2; HR-MS (ESI) m/z
calcd for C14H9FNO2 [M + H]+ 242.0612, found 242.0611.
Benzo[c]isoxazol-3-yl(4-chlorophenyl)methanone (2e): yellow
solid; 71% yield, 54.7 mg; mp125−126 °C; petroleum ether/ethyl
acetate = 120:1−70:1 (v/v) as an eluent for column chromatography;
1H NMR (400 MHz, CDCl3) δ 8.29−8.22 (m, 2H), 8.14−8.05 (m,
1H), 7.79−7.70 (m, 1H), 7.58−7.49 (m, 2H), 7.45−7.37 (m, 1H),
7.32−7.24 (m, 1H); 13C{1H} NMR (101 MHz, CDCl3) δ 179.9,
160.0, 157.2, 140.4, 134.2, 131.5, 131.4, 129.1, 128.7, 121.8, 121.6,
115.9; HR-MS (ESI) m/z calcd for C14H9ClNO2 [M + H]+ 258.0316,
found 258.0316.
Benzo[c]isoxazol-3-yl(thiophen-2-yl)methanone (2m): orange
solid; 80% yield, 55.0 mg; mp 173−174 °C; petroleum ether/ethyl
acetate = 100:1−60:1 (v/v) as an eluent for column chromatography;
1H NMR (600 MHz, CDCl3) δ 8.56−8.53 (m, 1H), 8.17−8.13 (m,
1H), 7.85−7.82 (m, 1H), 7.75−7.71 (m, 1H), 7.43−7.39 (m, 1H),
7.30−7.26 (m, 2H); 13C{1H} NMR (151 MHz, CDCl3) δ 172.7,
159.5, 157.2, 142.0, 135.9, 135.5, 131.5, 128.9, 128.5, 121.6, 121.3,
115.8; HR-MS (ESI) m/z calcd for C12H8NO2S [M + H]+ 230.0270,
found 230.0269.
Benzo[c]isoxazol-3-yl(4-bromophenyl)methanone (2f): yellow
solid; 75% yield, 67.5 mg; mp 139−140 °C; petroleum ether/ethyl
acetate = 100:1−50:1 (v/v) as an eluent for column chromatography;
1H NMR (400 MHz, CDCl3) δ 8.10−8.04 (m, 2H), 8.02−7.97 (m,
1H), 7.67−7.57 (m, 3H), 7.34−7.28 (m, 1H), 7.21−7.16 (m, 1H);
13C{1H} NMR (101 MHz, CDCl3) δ 180.0, 159.9, 157.2, 134.5,
1-(Benzo[c]isoxazol-3-yl)butan-1-one (2n): colorless oil; 40%
yield, 22.7 mg; petroleum ether/ethyl acetate = 120:1−70:1 (v/v)
as an eluent for column chromatography; 1H NMR (600 MHz,
CDCl3) δ 8.07−8.03 (m, 1H), 7.74−7.70 (m, 1H), 7.42−7.37 (m,
1H), 7.28−7.25 (m, 1H), 3.16 (t, J = 7.3 Hz, 2H), 1.90−1.82 (m,
2H), 1.06 (t, J = 7.4 Hz, 3H); 13C{1H} NMR (101 MHz, CDCl3) δ
190.3, 159.7, 157.5, 131.3, 128.4, 121.3, 119.1, 115.9, 42.0, 17.1, 13.7;
HR-MS (ESI) m/z calcd for C11H12NO2 [M + H]+ 190.0863, found
190.0862.
Benzo[c]isoxazol-3-yl(cyclopropyl)methanone (2o): white solid;
78% yield, 43.8 mg; mp 73−74 °C; petroleum ether/ethyl acetate =
100:1−60:1 (v/v) as an eluent for column chromatography; 1H NMR
(400 MHz, CDCl3)δ 8.03−7.98 (m, 1H), 7.72−7.67 (m, 1H), 7.41−
7.34 (m, 1H), 7.25−7.20 (m, 1H), 3.08−3.00 (m, 1H), 1.41−1.35
(m, 2H), 1.24−1.18 (m, 2H); 13C{1H} NMR (101 MHz, CDCl3) δ
190.0, 160.0, 157.5, 131.2, 128.3, 121.3, 118.5, 115.7, 18.8, 12.7; HR-
MS (ESI) m/z calcd for C11H10NO2 [M + H]+ 188.0706, found
188.0700.
132.0, 131.5, 131.4, 129.2, 128.7, 121.7, 121.5, 115.8; HR-MS (ESI)
m/z calcd for C14H9BrNO2 [M + H]+ 301.9811, found 301.9802.
Benzo[c]isoxazol-3-yl(4-(trifluoromethyl)phenyl)methanone
(2g): yellow solid; 51% yield, 44.5 mg; mp 107−108 °C; petroleum
ether/ethyl acetate = 100:1−50:1 (v/v) as an eluent for column
1
chromatography; H NMR (400 MHz, DMSO-d6) δ 8.34−8.30 (m,
2H), 8.03−7.97 (m, 3H), 7.93−7.87 (m, 1H), 7.60−7.55 (m, 1H),
7.47−7.41 (m, 1H); 13C{1H} NMR (101 MHz, DMSO-d6) δ 180.4,
2
159.5, 156.9, 139.2, 132.9 (C−F, JC−F = 31.8 Hz), 132.2, 130.5,
129.5, 125.8 (C−F, 3JC−F = 3.7 Hz), 123.7 (C−F, 1JC−F = 271.2 Hz),
120.9, 120.8, 115.8; 19F NMR (376 MHz, DMSO-d6) δ −61.70; HR-
MS (ESI) m/z calcd for C15H9F3NO2 [M + H]+ 292.0580, found
292.0577.
Benzo[c]isoxazol-3-yl(4-(tert-butyl)phenyl)methanone (2h): yel-
low oil; 70% yield, 58.6 mg; petroleum ether/ethyl acetate = 100:1−
1
60:1 (v/v) as an eluent for column chromatography; H NMR (400
MHz, CDCl3) δ 8.28−8.23 (m, 2H), 8.17−8.12 (m, 1H), 7.77−7.72
(m, 1H), 7.62−7.57 (m, 2H), 7.44−7.38 (m, 1H), 7.30−7.24 (m,
D
https://dx.doi.org/10.1021/acs.joc.1c00012
J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
pubs.acs.org/joc
Note
Benzo[c]isoxazol-3-yl(ferrocenylvinyl)methanone (2p): purple
solid; 33% yield, 32.8 mg; mp 141−142 °C; petroleum ether/ethyl
acetate = 100:1−60:1 (v/v) as an eluent for column chromatography;
1H NMR (600 MHz, CDCl3) δ 8.15 (d, J = 9.0 Hz, 1H), 7.72 (d, J =
9.0 Hz, 1H), 7.41−7.37 (m, 1H), 7.25−7.23 (m, 1H), 5.40 (t, J = 1.8
Hz, 2H), 4.76 (t, J = 2.4 Hz, 2H), 4.20 (s, 5H); 13C{1H} NMR (151
MHz, CDCl3) δ 184.6, 161.1, 157.3, 131.4, 134.9, 127.8, 122.1, 120.1,
115.5, 73.9, 71.0, 70.5; HR-MS (ESI) m/z calcd for C18H14FeNO2 [M
+ H]+ 332.0368, found 332.0363.
acetate = 50:1−10:1 (v/v) as an eluent for column chromatography;
1H NMR (400 MHz, CDCl3) δ 8.91−8.87 (m, 1H), 8.52−8.48 (m,
1H), 8.31−8.27 (m, 2H), 7.71−7.65 (m, 1H), 7.60−7.54 (m, 2H),
7.29−7.25 (m, 1H); 13C{1H} NMR (101 MHz, CDCl3) δ 180.9,
165.4, 161.8, 158.6, 135.1, 134.3, 131.3, 130.2, 128.9, 123.8, 114.7;
HR-MS (ESI) m/z calcd for C13H9N2O2 [M + H]+ 225.0659, found
225.0657.
ASSOCIATED CONTENT
* Supporting Information
The Supporting Information is available free of charge at
https://pubs.acs.org/doi/10.1021/acs.joc.1c00012.
■
(5-Chlorobenzo[c]isoxazol-3-yl)(phenyl)methanone (2s): orange
solid; 85% yield, 65.5 mg; mp 80−81 °C; petroleum ether/ethyl
acetate = 100:1−50:1 (v/v) as an eluent for column chromatography;
1H NMR (400 MHz, CDCl3) δ 8.29−8.25 (m, 2H), 8.15−8.12 (m,
1H), 7.71−7.64 (m, 2H), 7.59−7.54 (m, 2H), 7.35−7.30 (m, 1H);
13C{1H} NMR (101 MHz, CDCl3) δ 180.9, 159.9, 155.6, 135.6,
134.7, 133.9, 133.3, 130.0, 128.7, 121.8, 120.1, 117.3; HR-MS (ESI)
m/z calcd for C14H9ClNO2 [M + H]+ 258.0316, found 258.0308.
(6-Methoxybenzo[c]isoxazol-3-yl)(phenyl)methanone (2t): yel-
low solid; 56% yield, 42.5 mg; mp 173−174 °C; petroleum ether/
ethyl acetate = 80:1−50:1 (v/v) as an eluent for column
chromatography; 1H NMR (600 MHz, CDCl3) δ 8.29−8.25 (m,
2H), 7.97 (d, J = 9.3 Hz, 1H), 7.68−7.64 (m, 1H), 7.58−7.54 (m,
2H), 6.97−6.93 (m, 1H), 6.81 (d, J = 1.8 Hz, 1H), 3.89 (s, 3H);
13C{1H} NMR (151 MHz, CDCl3) δ 181.5, 161.8, 159.5, 158.6,
135.9, 133.8, 130.1, 128.7, 125.6, 122.3, 118.7, 90.0, 55.5; HR-MS
(ESI) m/z calcd for C15H12NO3 [M + H]+ 254.0812, found 254.0807.
(6-Fluorobenzo[c]isoxazol-3-yl)(phenyl)methanone (2u): yellow
solid; 84% yield, 60.7 mg; mp 96−97 °C; petroleum ether/ethyl
acetate = 100:1−60:1 (v/v) as an eluent for column chromatography;
1H NMR (600 MHz, CDCl3) δ 8.29−8.25 (m, 2H), 8.18−8.13 (m,
1H), 7.70−7.66 (m, 1H), 7.59−7.55 (m, 2H), 7.31−7.27 (m, 1H),
7.12−7.07 (m, 1H); 13C{1H} NMR (151 MHz, CDCl3) δ 181.1,
sı
NMR spectra for compounds 2, optimization of the
reaction conditions, amperometric curve, on/off experi-
ment, cyclic voltammetry studies, and crystal data
(PDF)
Accession Codes
CCDC 2051812 contains the supplementary crystallographic
data for this paper. These data can be obtained free of charge
via www.ccdc.cam.ac.uk/data_request/cif, or by emailing
data_request@ccdc.cam.ac.uk, or by contacting The Cam-
bridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: +44 1223 336033.
AUTHOR INFORMATION
Corresponding Authors
■
Hai-Tao Tang − State Key Laboratory for Chemistry and
Molecular Engineering of Medicinal Resources, School of
Chemistry and Pharmaceutical Sciences of Guangxi Normal
University, Guilin 541004, People’s Republic of China;
orcid.org/0000-0001-7531-0458; Email: httang@
gxnu.edu.cn
1
4
163.8 (C−F, JC−F = 254.1 Hz), 160.7 (C−F, JC−F = 1.8 Hz), 157.5
3
(C−F, JC−F = 12.9 Hz), 135.6, 134.0, 130.1, 128.8, 124.3 (C−F,
3JC−F = 10.5 Hz), 121.5 (C−F, JC−F = 30.3 Hz), 119.3, 98.2 (C−F,
2
2JC−F = 25.4 Hz); 19F NMR (376 MHz, CDCl3) δ −104.17; HR-MS
(ESI) m/z calcd for C14H9FNO2 [M + H]+ 242.0612, found
242.0610.
Ying-Ming Pan − State Key Laboratory for Chemistry and
Molecular Engineering of Medicinal Resources, School of
Chemistry and Pharmaceutical Sciences of Guangxi Normal
University, Guilin 541004, People’s Republic of China;
orcid.org/0000-0002-3625-7647; Email: panym@
mailbox.gxnu.edu.cn
(6-chloroBenzo[c]isoxazol-3-yl)(phenyl)methanone (2v): orange
solid; 76% yield, 58.6 mg; mp 134−135 °C; petroleum ether/ethyl
acetate = 100:1−60:1 (v/v) as an eluent for column chromatography;
1H NMR (600 MHz, CDCl3) δ 8.29−8.26 (m, 2H), 8.10−8.07 (m,
1H), 7.75−7.73 (m, 1H), 7.69−7.66 (m, 1H), 7.59−7.55 (m, 2H),
7.21−7.18 (m, 1H); 13C{1H} NMR (151 MHz, CDCl3) δ 181.0,
160.9, 157.3, 137.8, 135.5, 134.1, 130.3, 130.1, 128.8, 123.0, 120.0,
114.3; HR-MS (ESI) m/z calcd for C14H9ClNO2 [M + H]+ 258.0316,
found 258.0311.
Authors
Lin-Wei Wang − State Key Laboratory for Chemistry and
Molecular Engineering of Medicinal Resources, School of
Chemistry and Pharmaceutical Sciences of Guangxi Normal
University, Guilin 541004, People’s Republic of China
Yu-Feng Feng − State Key Laboratory for Chemistry and
Molecular Engineering of Medicinal Resources, School of
Chemistry and Pharmaceutical Sciences of Guangxi Normal
University, Guilin 541004, People’s Republic of China
Hong-Min Lin − State Key Laboratory for Chemistry and
Molecular Engineering of Medicinal Resources, School of
Chemistry and Pharmaceutical Sciences of Guangxi Normal
University, Guilin 541004, People’s Republic of China
Phenyl(5-(trifluoromethyl)benzo[c]isoxazol-3-yl)methanone
(2w): red solid; 89% yield, 75.1 mg; mp 109−110 °C; petroleum
ether/ethyl acetate = 100:1−60:1 (v/v) as an eluent for column
chromatography; 1H NMR (600 MHz, CDCl3) δ 8.31−8.25 (m, 3H),
8.12−8.09 (m, 1H), 7.71−7.67 (m, 1H), 7.60−7.56 (m, 2H), 7.42−
7.39 (m, 1H); 13C{1H} NMR (151 MHz, CDCl3) δ 180.9, 161.4,
2
156.0, 135.4, 134.2, 133.5 (C−F, JC−F = 32.6 Hz), 130.1, 128.9,
3
1
123.9(C−F, JC−F = 2.7 Hz), 123.8, 123.0 (C−F, JC−F = 271.4 Hz),
121.7, 114.8 (C−F, 3JC−F = 5.3 Hz); 19F NMR (376 MHz, CDCl3) δ
−64.51; HR-MS (ESI) m/z calcd for C15H9F3NO2 [M + H]+
292.0580, found 292.0591.
Complete contact information is available at:
https://pubs.acs.org/10.1021/acs.joc.1c00012
(7-Chlorobenzo[c]isoxazol-3-yl)(phenyl)methanone (2x): yellow
solid; 82% yield, 63.2 mg; mp 110−111 °C; petroleum ether/ethyl
acetate = 80:1−50:1 (v/v) as an eluent for column chromatography;
1H NMR (400 MHz, CDCl3) δ 8.30−8.23 (m, 2H), 8.07−8.01 (m,
1H), 7.71−7.64 (m, 1H), 7.60−7.54 (m, 2H), 7.45−7.39 (m, 1H),
7.23−7.16 (m, 1H); 13C{1H} NMR (101 MHz, CDCl3) δ 181.0,
161.6, 155.7, 135.5, 134.1, 130.5, 130.1, 128.8, 128.7, 122.6, 122.0,
120.4; HR-MS (ESI) m/z calcd for C14H9ClNO2 [M + H]+ 258.0316,
found 258.0307.
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
We thank the National Natural Science Foundation of China
(22061003 and 21861006), Guangxi Natural Science Founda-
tion of China (2019GXNSFAA245027), Guangxi Key R&D
Isoxazolo[3,4-b]pyridin-3-yl(phenyl)methanone (2y): yellow
solid; 86% yield, 57.8 mg; mp 140−142 °C; petroleum ether/ethyl
E
https://dx.doi.org/10.1021/acs.joc.1c00012
J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
pubs.acs.org/joc
Note
Organoselenium-catalyzed synthesis of indoles through intramolecular
C-H amination. Org. Chem. Front. 2015, 2, 1334−1337. (d) Kawa-
mata, Y.; Hashimoto, T.; Maruoka, K. A Chiral Electrophilic Selenium
Catalyst for Highly Enantioselective Oxidative Cyclization. J. Am.
Chem. Soc. 2016, 138, 5206−5209.
Program (AB18221005), Science and Technology Major
Project of Guangxi (AA17204058-21), Guangxi science and
technology base and special talents (AD19110027) for
financial support.
(10) (a) Guo, R.; Huang, J.; Huang, H.; Zhao, X. Organoselenium-
Catalyzed Synthesis of Oxygen- and Nitrogen-Containing Hetero-
cycles. Org. Lett. 2016, 18, 504−507. (b) Liao, L.; Zhang, H.; Zhao, X.
Selenium-π-Acid Catalyzed Oxidative Functionalization of Alkynes:
Facile Access to Ynones and Multisubstituted Oxazoles. ACS Catal.
2018, 8, 6745−6750. (c) Cresswell, A. J.; Eey, S. T.-C.; Denmark, S.
E. Catalytic, stereospecific syn-dichlorination of alkenes. Nat. Chem.
2015, 7, 146−152. (d) Yan, D.; Wang, G.; Xiong, F.; Sun, W.-Y.; Shi,
Z.; Lu, Y.; Li, S.; Zhao, J. A selenium-catalysed para-amination of
phenols. Nat. Commun. 2018, 9, 4293−4301.
REFERENCES
■
(1) (a) MacMillan, D. W. C. The advent and development of
organocatalysis. Nature 2008, 455, 304−308. (b) Dalko, P. I.; Moisan,
L. In the Golden Age of Organocatalysis. Angew. Chem., Int. Ed. 2004,
43, 5138−5175. (c) Qin, Y.; Zhu, L.; Luo, S. Organocatalysis in Inert
C-H Bond Functionalization. Chem. Rev. 2017, 117, 9433−9520.
(2) (a) Wang, M.; Huang, Z.; Xu, J.; Chi, Y. R. N-Heterocyclic
Carbene-Catalyzed [3 + 4] Cycloaddition and Kinetic Resolution of
Azomethine Imines. J. Am. Chem. Soc. 2014, 136, 1214−1217.
(b) Zhu, T.; Mou, C.; Li, B.; Smetankova, M.; Song, B.-A.; Chi, Y. R.
N-Heterocyclic Carbene-Catalyzed δ-Carbon LUMO Activation of
Unsaturated Aldehydes. J. Am. Chem. Soc. 2015, 137, 5658−5661.
(3) Chauhan, P.; Mahajan, S.; Enders, D. Achieving Molecular
Complexity via Stereoselective Multiple Domino Reactions Promoted
by a Secondary Amine Organocatalyst. Acc. Chem. Res. 2017, 50,
2809−2821.
(4) (a) Feng, J.; Huang, Y. Phosphine-Catalyzed Remote 1,7-
Addition for Synthesis of Diene Carboxylates. ACS Catal. 2020, 10,
3541−3547. (b) Xie, P.; Wang, L.; Yang, L.; Li, E.; Ma, J.; Huang, Y.;
Chen, R. Domino Reaction for the Chemo- and Stereoselective
Synthesis of trans-2,3-Dihydrobenzofurans from N-Thiophosphinyl
Imines and Sulfur Ylides. J. Org. Chem. 2011, 76, 7699−7705.
(5) (a) Picard, J.-P.; Calas, R.; Dunogués, J.; Duffaut, N.; Gerval, J.;
Lapouyade, P. Reductive Silylation of Benzoates: Convenient
Synthesis of Aroylsilanes. J. Org. Chem. 1979, 44, 420−424.
(b) Hori, T.; Sharpless, K. B. Selenium-catalyzed nonradical
chlorination of olefins with N-chlorosuccinimide. J. Org. Chem.
1979, 44, 4204−4208.
(6) (a) Ortgies, S.; Breder, A. Oxidative Alkene Functionalizations
via Selenium-π-Acid Catalysis. ACS Catal. 2017, 7, 5828−5840.
(b) Singh, F. V.; Wirth, T. Selenium reagents as catalysts. Catal. Sci.
Technol. 2019, 9, 1073−1091. (c) Shao, L.; Li, Y.; Lu, J.; Jiang, X.
Recent progress in selenium-catalyzed organic reactions. Org. Chem.
Front. 2019, 6, 2999−3041. (d) Torii, S.; Uneyama, K.; Ono, M.;
Bannou, T. Generation and Recycle Use of Selenenylating Reagents in
Electrochemical Oxyselenenylation-Deselenenylation of Olefins. J.
Am. Chem. Soc. 1981, 103, 4606−4608. (e) Smith, D.S.; Winnick, J.;
Ding, Y.; Bottomley, L. A. Electrosynthesis of a-keto acetals by a
selenium-catalyzed transformation of aryl methyl ketones. Electrochim.
Acta 1998, 43, 335−339. (f) Niyomura, O.; Cox, M.; Wirth, T.
Electrochemical Generation and Use of Selenium Electrophiles.
Synlett 2006, 2, 251−254.
(11) (a) Kingston, C.; Palkowitz, M. D.; Takahira, Y.; Vantourout, J.
C.; Peters, B. K.; Kawamata, Y.; Baran, P. S. A Survival Guide for the
“Electro-curious. Acc. Chem. Res. 2020, 53, 72−83. (b) Xiong, P.; Xu,
H.-C. Chemistry with Electrochemically Generated N-Centered
Radicals. Acc. Chem. Res. 2019, 52, 3339−3350. (c) Yuan, Y.; Lei,
A. Electrochemical Oxidative Cross-Coupling with Hydrogen
Evolution Reactions. Acc. Chem. Res. 2019, 52, 3309−3324.
̈
(d) Rockl, J. L.; Pollok, D.; Franke, R.; Waldvogel, S. R. A Decade
of Electrochemical Dehydrogenative C,C-Coupling of Aryls. Acc.
Chem. Res. 2020, 53, 45−61. (e) Moeller, K. D. Using Physical
Organic Chemistry To Shape the Course of Electrochemical
Reactions. Chem. Rev. 2018, 118, 4817−4833. (f) He, M.-X.; Mo,
Z.-Y.; Wang, Z.-Q.; Cheng, S.-Y.; Xie, R.-R.; Tang, H.-T.; Pan, Y.-M.
Electrochemical Synthesis of 1-Naphthols by Intermolecular Annula-
tion of Alkynes with 1,3-Dicarbonyl Compounds. Org. Lett. 2020, 22,
724−728. (g) Jiang, Y.; Xu, K.; Zeng, C. Use of Electrochemistry in
the Synthesis of Heterocyclic Structures. Chem. Rev. 2018, 118,
4485−4540. (h) Wang, P.; Gao, X.; Huang, P.; Lei, A. Recent
Advances in Electrochemical Oxidative Cross-Coupling of Alkenes
with H2 Evolution. ChemCatChem 2020, 12, 27−40. (i) Hu, X.; Nie,
L.; Zhang, G.; Lei, A. Electrochemical Oxidative [4 + 2] Annulation
for the π-Extension of Unfunctionalized Heterobiaryl Compounds.
Angew. Chem., Int. Ed. 2020, 59, 15238−15243.
(12) (a) Zhao, H.-B.; Hou, Z.-W.; Liu, Z.-J.; Zhou, Z.-F.; Song, J.;
Xu, H.-C. Amidinyl Radical Formation through Anodic N-H Bond
Cleavage and Its Application in Aromatic C-H Bond Functionaliza-
tion. Angew. Chem., Int. Ed. 2017, 56, 587−590. (b) Mo, Z.-Y.; Zhang,
Y.-Z.; Huang, G-b.; Wang, X.-Y.; Pan, Y-m.; Tang, H.-T. Electro-
chemical Sulfonylation of Alkynes with Sulfonyl Hydrazides: A Metal-
and Oxidant-Free Protocol for the Synthesis of Alkynyl Sulfones. Adv.
Synth. Catal. 2020, 362, 2160−2167. (c) Wang, X.-Y.; Zhong, Y.-F.;
Mo, Z.-Y.; Wu, S.-H.; Xu, Y.-L.; Tang, H.-T.; Pan, Y.-M. Synthesis of
Seleno Oxindoles via Electrochemical Cyclization of N-arylacryla-
mides with Diorganyl Diselenides. Adv. Synth. Catal. 2021, 363, 208.
(13) (a) Jiang, Y-y.; Wang, Q.-Q.; Liang, S.; Hu, L.-M.; Little, R. D.;
Zeng, C.-C. Electrochemical Oxidative Amination of Sodium
Sulfinates: Synthesis of Sulfonamides Mediated by NH4I as a Redox
Catalyst. J. Org. Chem. 2016, 81, 4713−4719. (b) Jiang, Y.-Y.; Liang,
S.; Zeng, C.-C.; Hu, L.-M.; Sun, B.-G. Electrochemically initiated
formation of sulfonyl radicals: synthesis of oxindoles via difunction-
alization of acrylamides mediated by bromide ion. Green Chem. 2016,
18, 6311−6319.
(14) (a) Qian, X.-Y.; Li, S.-Q.; Song, J.; Xu, H.-C. TEMPO-
Catalyzed Electrochemical C-H Thiolation: Synthesis of Benzothia-
zoles and Thiazolopyridines from Thioamides. ACS Catal. 2017, 7,
2730−2734. (b) Cai, C.-Y.; Xu, H.-C. Dehydrogenative reagent-free
annulation of alkenes with diols for the synthesis of saturated O-
heterocycles. Nat. Commun. 2018, 9, 3551−3557.
(15) (a) Zhang, Y.-Z.; Mo, Z.-Y.; Wang, H.-S.; Wen, X.-A.; Tang, H.-
T.; Pan, Y.-M. Electrochemically enabled chemoselective sulfonylation
hydrazination of indoles. Green Chem. 2019, 21, 3807−3811.
(b) Zhong, P.-F.; Lin, H.-M.; Wang, L.-W.; Mo, Z.-Y.; Meng, X.-J.;
Tang, H.-T.; Pan, Y.-M. Electrochemically enabled synthesis of
sulphide imidazopyridines via a radical cyclization cascade. Green
(7) (a) Yu, L.; Ye, J.; Zhang, X.; Ding, Y.; Xu, Q. Recyclable
(PhSe)2-catalyzed selective oxidation of isatin by H2O2: a practical
and waste-free access to isatoic anhydride under mild and neutral
conditions. Catal. Sci. Technol. 2015, 5, 4830−4838. (b) Wang, X.;
Wang, Q.; Xue, Y.; Sun, K.; Wu, L.; Zhang, B. An organoselenium-
catalyzed N1- and N2-selective aza-Wacker reaction of alkenes with
benzotriazoles. Chem. Commun. 2020, 56, 4436−4439. (c) Jing, X.;
Yuan, D.; Yu, L. Green and Practical Oxidative Deoximation of
Oximes to Ketones or Aldehydes with Hydrogen Peroxide/Air by
Organoselenium Catalysis. Adv. Synth. Catal. 2017, 359, 1194−1201.
(8) (a) Browne, D. M.; Niyomura, O.; Wirth, T. Catalytic Use of
Selenium Electrophiles in Cyclizations. Org. Lett. 2007, 9, 3169−
3171. (b) Singh, F. V.; Wirth, T. Selenium-Catalyzed Regioselective
Cyclization of Unsaturated Carboxylic Acids Using Hypervalent
Iodine Oxidants. Org. Lett. 2011, 13, 6504−6507.
(9) (a) Ortgies, S.; Breder, A. Selenium-Catalyzed Oxidative C(sp2)-
H Amination of Alkenes Exemplified in the Expedient Synthesis of
(Aza-)Indoles. Org. Lett. 2015, 17, 2748−2751. (b) Trenner, J.;
Depken, C.; Weber, T.; Breder, A. Direct Oxidative Allylic and Vinylic
Amination of Alkenes through Selenium Catalysis. Angew. Chem., Int.
Ed. 2013, 52, 8952−8956. (c) Zhang, X.; Guo, R.; Zhao, X.
F
https://dx.doi.org/10.1021/acs.joc.1c00012
J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
pubs.acs.org/joc
Note
Chem. 2020, 22, 6334−6339. (c) Meng, X.-J.; Zhong, P.-F.; Wang, Y.-
M.; Wang, H-s.; Tang, H.-T.; Pan, Y-m. Electrochemical Difunction-
alization of Olefines: Access to Selen omethyl-Substituted Cyclic
Ethers or Lactones. Adv. Synth. Catal. 2020, 362, 506−511.
(16) (a) Mallick, S.; Baidya, M.; Mahanty, K.; Maiti, D.; Sarkar, S. D.
Electrochemical Chalcogenation of β,γ-Unsaturated Amides and
Oximes to Corresponding Oxazolines and Isoxazolines. Adv. Synth.
Catal. 2020, 362, 1046−1052. (b) Wilken, M.; Ortgies, S.; Breder, A.;
Siewert, I. Mechanistic Studies on the Anodic Functionalization of
Alkenes Catalyzed by Diselenides. ACS Catal. 2018, 8, 10901−10912.
(c) Hua, J.; Fang, Z.; Xu, J.; Bian, M.; Liu, C.; He, W.; Zhu, N.; Yang,
Z.; Guo, K. Electrochemical oxidative cyclization of activated alkynes
with diselenides or disulfides: access to functionalized coumarins or
quinolinones. Green Chem. 2019, 21, 4706−4711.
(17) (a) Asao, N.; Sato, K.; Yamamoto, Y. AuBr3-catalyzed
cyclization of o-(alkynyl)nitrobenzenes. Efficient synthesis of
isatogens and anthranils. Tetrahedron Lett. 2003, 44, 5675−5677.
(18) Fu, W.; Yang, K.; Chen, J.; Song, Q. Gold(I)-catalyzed
synthesis of 2-substituted indoles from 2-alkynylnitroarenes with
diboron as reductant. Org. Biomol. Chem. 2017, 15, 8354−8360.
G
https://dx.doi.org/10.1021/acs.joc.1c00012
J. Org. Chem. XXXX, XXX, XXX−XXX