Metal-Free Electrochemical Coupling of Vinyl Azides: Synthesis of Phenanthridines and β-Ketosulfones

Article abstract of DOI:10.1002/ejoc.202001059

We reported an efficient and environmentally benign electrochemical synthesis of phenanthridines by oxidative coupling of vinyl azides with sodium azide or benzenesulfonyl hydrazides, for the first time. The reaction conditions are mild, and no additional metal-catalyst or exogenous oxidants are needed. The protocol has broad substrate scope and high functional group tolerance. Furthermore, this green electrochemical procedure can be readily extended to the synthesis of β-ketosulfones. Gram scale reactions further demonstrate the practicability.

Full text of DOI:10.1002/ejoc.202001059

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Phenanthridines
Metal-Free Electrochemical Coupling of Vinyl Azides: Synthesis
of Phenanthridines and ꢀ-Ketosulfones
Guodong Li,[a][‡] Xianqiang Kong,[a,b][‡] Qi Liang,[a] Long Lin,[a] Ke Yu,[a] Bo Xu,*[a] and
Qianjin Chen*[a]
Abstract: We reported an efficient and environmentally benign needed. The protocol has broad substrate scope and high func-
electrochemical synthesis of phenanthridines by oxidative cou- tional group tolerance. Furthermore, this green electrochemical
pling of vinyl azides with sodium azide or benzenesulfonyl procedure can be readily extended to the synthesis of ꢀ-keto-
hydrazides, for the first time. The reaction conditions are mild, sulfones. Gram scale reactions further demonstrate the practica-
and no additional metal-catalyst or exogenous oxidants are bility.
Introduction
cyclization procedure, it is still highly desirable to develop reac-
tion with metal-free and mild conditions.
Phenanthridine and its derivatives are essential subunits in nu-
merous natural products, bioactive molecules and pharmaceuti-
cals.[1] As a consequence, the development of efficient and
practical protocols for the synthesis of phenanthridine from
readily available starting materials has attracted considerable
attention.[2] Among them, the tandem radical addition/cycliza-
tion has been considered one of the most important strategies.
Isocyanides could efficiently undergo such a tandem process
with various radical precursors to afford a variety of substituted
phenanthridines. For instance, preparation of 6-substituted
phenanthridines by oxidative cyclization of 2-isocyanobiphenyls
have been reported with many radical precursors including
mono-/difluoroacetate,[3] CF3SiMe3,[4] fluorinated sulfones,[5]
alkylboronic acids,[6] alkyl bromide,[7] α-oxocarboxylates,[8] aro-
matic aldehydes,[9] formamides,[10] and others.[11] Recently,
groups of Chila, Studer, and Yu adopted this tandem radical
addition/cyclization using vinyl azides as versatile synthons to
construct functional phenanthridines (Scheme 1a).[12] In
all the above methods, exogenous oxidants,[4,12c] metal-
catalysts,[2c,6,8–10] or expensive photoredox,[3,5,7,12a,12d] are em-
ployed. Considering the high efficiency of this radical addition/
Scheme 1. Strategies for the synthesis of a phenanthridine skeleton from
vinyl azides.
In the past decades, electrochemistry has resurged as an en-
vironmentally benign and atom-economical method for the
synthesis of chemicals.[13] Electroanalytical techniques provide
additional insights into studying synthetic organic and organo-
metallic reaction mechanisms.[14] Electrochemical anodic oxid-
ation presents the prospect of efficient synthesis of complex
molecules and has been utilized for constructing C–C, C–N,
C–O, and C–S bonds.[15] We have recently reported the synthe-
sis of enaminones by anodic decarboxylative acylation of vinyl
azides with α-keto acids.[16] Herein, we continue interest in the
electrochemically oxidative cyclization of biaryl vinyl azide with
readily available sodium azide and benzenesulfonyl hydrazide
as radical precursors (Scheme 1b). Diverse phenanthridines
were prepared at room temperature and under metal-catalyst-
[a] G. Li, X. Kong, Q. Liang, L. Lin, K. Yu, Prof. B. Xu, Prof. Q. Chen
Key Lab of Science and Technology of Eco-Textile, Ministry of Education,
College of Chemistry, Chemical Engineering and Biotechnology, Donghua
University,
Shanghai, 201620, China
E-mail: bo.xu@dhu.edu.cn
qianjinchen@dhu.edu.cn
https://www.x-mol.com/groups/qianjinchen2105
[b] X. Kong
School of Chemical Engineering and Materials, Changzhou Institute of
Technology,
No. 666 Liaohe Road, Changzhou 213032, China
[‡] These authors contribute equally to this work.
Supporting information and ORCID(s) from the author(s) for this article are
available on the WWW under https://doi.org/10.1002/ejoc.202001059.
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free, exogenous additive/oxidant-free conditions. Moreover, this
With the optimized reaction condition in hand, we investi-
low cost and the operationally safe electrochemical protocol gated the substrate scope of this electrochemical oxidative cy-
was readily extended to the synthesis of ꢀ-ketosulfones.
clization. Table 2 shows biphenyl vinyl azides bearing electron-
donating (MeO, Me, tBu) or electron-withdrawing (F, Cl, COOMe,
CF3) groups at meta-position of the top benzene ring gave the
corresponding phenanthridine products in good yields (2b–h).
MeO substituted at para-position and meta-position are also
good, giving a yield of 81 % (2i) and 65 % (2j), respectively. In
addition, biphenyl vinyl azide substrates with MeO, CH3, F, Cl,
and CF3 moieties at benzene ring B also reacted smoothly and
afforded products 2k–s in good yields. The vinyl azide contain-
ing a naphthalene moiety is also a suitable substrate (2t, 74 %).
Results and Discussion
Initially, we used α-(biaryl-2-yl)vinyl azide (1a) and sodium azide
as the model substrates. The optimized reaction condition was
obtained in a mixture solvent of MeCN:H2O at 10:1 ratio using
0.1
M LiClO4 as the supporting electrolyte and C(+)/Pt(–) as the
electrodes at a constant potential of 2.3 V for 2 hours, leading
to the isolation of product 2a in 83 % yield (Table 1, entry 1).
The constant potential at 2.0 or 2.5 V ended up with similar
yields (entries 2–3), while constant current at 8 mA and 12 mA
gave lower yields (entries 4–5). Using a different reaction mix-
ture with higher or lower water content gave much lower
yields, while pure MeCN only gave trace products (entries
6–10). Decreasing or increasing the amount of NaN3 led to
slightly lower yields (entries 11–12). The use of metal catalysts
(MnBr2·4H2O or Cu(OAc)2) decreased the yield to 80 % and
65 %, respectively (entries 13–14), indicating metal catalysis is
not necessary. Use of RVC(+)/Pt(–) or C(+)/C(–) as the working
electrodes resulted in poorer results (entries 15–16). Besides, a
control experiment suggested that electricity was indispensable
(entry 17).
Table 2. Scope of biarylvinyl azides.[a,b]
Table 1. Optimization of the reaction conditions.[a]
[a] Standard reaction conditions: C plate (52.5 mm × 8.0 mm × 1.5 mm) an-
ode, Pt plate (52.5 mm × 8.0 mm × 1.5 mm) cathode, undivided cell, E = 2.3 V,
1a (0.20 mmol), NaN3 (0.24 mmol), LiClO4 (0.1 mol/L), in 4.0 mL solution of
MeCN:H2O = 10:1 at room temperature under N2 for 2 h. [b] Isolated yield.
[c] Catalyst (5 mol-%). [d] NR = not reaction.
[a] Standard reaction conditions: C plate (52.5 mm × 8.0 mm × 1.5 mm) an-
ode, Pt plate (52.5 mm × 8.0 mm × 1.5 mm) cathode, undivided cell, E = 2.3 V,
1 (0.20 mmol), NaN3 (0.24 mmol), LiClO4 (0.1 mol/L), in 4.0 mL solution of
MeCN:H2O = 10:1 at room temperature under N2 for 2 h. [b] Isolated yield.
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Next, the generality of this electrochemical cyclization of bi- lead to a decreased yield of product (entries 10–12). More de-
aryl vinyl azides was further investigated using sulfonyl hydraz- tails of condition optimization are included in the Supporting
ide as the radical precursor (Table 3). We started with biphenyl Information. As shown in Table 3, the reaction showed good
vinyl azides (1a) and p-toluenesulfonyl hydrazide (3a) as model functional group tolerance. Vinyl azides containing electron-
substrates. Based on the previously established procedure with donating (MeO, tBu) or withdrawing (F, CF3) groups at meta-
sodium azide, the optimized reaction for sulfonylation/cycliza- position of the top benzene ring gave the product with excel-
tion was obtained in slightly different reaction conditions. lent yields (81–86 % for 4b–e). However, the vinyl azide contain-
A mixture solvent of MeCN:H2O at 18:1 was used with 0.1
M
ing a naphthalene group gave a poor yield (4f). Finally, the
nBu4NBF4 as the supporting electrolyte, while a constant cur- reactions show excellent tolerance to various functional groups
rent of 12 mA for 3 h afforded the product 4a in 86 % yield. such as halides, MeO, CF3 at the bottom benzene ring (4g–m).
Higher or lower current resulted in lower yields (70 % at 6 mA
and 40 % at 18 mA for entries 5 and 6, respectively, in the
Supporting Information section 4.2) and constant potential
gave further low yields (entries 7 and 8). It is previously re-
ported that addition of base helped the electrooxidation of sulf-
onyl hydrazide.[17] The removal or replacement of base K2CO3
The scope of sulfonyl hydrazide was further studied using
α-(biaryl-2-yl)vinyl azide (1a) as the reaction partner under the
optimized conditions (Table 4). In general, sulfonyl hydrazide 3
with electron-withdrawing (F, Cl, Br, CN, OCF3) or electron elec-
tron-donating (MeO) groups at the para-position of the benz-
ene moiety all reacted smoothly and produced the correspond-
Table 4. Scope of sulfonyl hydrazides.[a,b]
Table 3. Scope of biarylvinyl azides.[a,b]
[a] Standard reaction conditions: C plate (52.5 mm × 8.0 mm × 1.5 mm) an-
ode, Pt plate (52.5 mm × 8.0 mm × 1.5 mm) cathode, undivided cell, constant
current = 12 mA, 1 (0.20 mmol), 3a (0.30 mmol), nBu4NBF4 (0.08 mmol), in
4.0 mL solution of MeCN:H2O = 18:1 at room temperature under N2 for 3 h.
[b] Isolated yield.
[a] Standard reaction conditions: C plate (52.5 mm × 8.0 mm × 1.5 mm) an-
ode, Pt plate (52.5 mm × 8.0 mm × 1.5 mm) cathode, undivided cell, constant
current = 12 mA, 1a (0.20 mmol), 3 (0.30 mmol), nBu4NBF4 (0.08 mmol), in
4.0 mL solution of MeCN:H2O = 18:1 at room temperature under N2 for 3 h.
[b] Isolated yield.
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ing phenanthridine with excellent yields (4n–s, 81–94 %). Sulf-
onyl hydrazide 3 substituted with Br at meta-position or two Cl
also afford excellent yields (4t–u). Besides, sulfonyl hydrazide
with ethyl group gave a yield of 96 % (4x). Finally, sulfonyl
hydrazides containing naphthalene and thiophene moiety are
also suitable substrates (4w, 4z).
Table 5. Electrochemical synthesis of ꢀ-ketosulfones and substrate scopes.[a,b]
To further verify this electrochemically oxidative coupling of
vinyl azides, we used α-tolyl vinyl azide (5a) and p-toluenesulf-
onyl hydrazide (3a) as the model substrates. Interestingly, we
found the product was a mixture of ꢀ-ketosulfones (6a) and the
dimerization of the transient iminyl radical (7a), as defined by
NMR and HRMS (Table 5). We continued to transform 7a to
more valuable 6a by treating with 3
N HCl (3 equiv.) in THF, a
protocol previously established for hydrolysis of azine to ket-
ones.[18] The optimal reaction condition with 80 % yield was
obtained in a slightly different solvent system (MeCN:H2O =
10:1) and higher current density (18 mA). Higher or lower cur-
rent resulted in lower yields (75 % at 12 mA and 73 % at 24 mA)
and constant potential at 2.3 V gave a yield of 58 %. More de-
tailed optimization of reaction conditions can be found in the
Supporting Information. As shown in Table 5, a good range
of derivatives were found to be compatible with the reaction
condition. Satisfactorily, α-aryl vinyl azides bearing electron-
donating (F, Cl, Br, Me, Et) and electron-withdrawing (COOMe)
substituents at the benzene ring provided moderate to good
yields (6b–k). The naphthalene substituent afforded a moderate
yield of 61 % (6I). On the other hand, sulfonyl hydrazide 3 with
electron-withdrawing (F, Cl, OCF3, CN) or electron-donating
(MeO) groups at the para-position of the benzene moiety all
reacted smoothly and produced the corresponding ꢀ-keto-
sulfones with good yields, while the Br substitution ended with
moderate yield 57 % (6m–r). Sulfonyl hydrazide 3 substituted
two chloride, three methyl, naphthalene, and ethyl groups were
all tolerated (6t–w). The structure assignment of our obtained
product was confirmed by the single-crystal X-ray diffraction of
a typical product (see the OTTEP drawing of 6n[19] in Table 5).
[a] Standard reaction conditions: C plate (52.5 mm × 8.0 mm × 1.5 mm) an-
ode, Pt plate (52.5 mm × 8.0 mm × 1.5 mm) cathode, undivided cell, constant
current = 18 mA, 5 (0.20 mmol), 3 (0.30 mmol), nBu4NBF4 (0.08 mmol), in
4.0 mL solution of MeCN:H2O = 10:1 at room temperature under N2 for 2 h.
[b] Isolated yield.
Our electrochemical oxidative coupling procedure with vinyl
azides is scalable: the reaction of 5 mmol 1a and 7.5 mmol 3a
was performed at a constant current of 12 mA, and 1.4 g of
phenanthridines product 4a was obtained in 81 % yield after
isolation (Scheme 2). Meanwhile, the electrochemical formation
of ꢀ-ketosulfones 6a can be obtained at gram-scale with a yield
of 68 % after hydrolysis treatment of the mixture. Finally, one
example of azide functionalization for click chemistry using
phenylacetylene as coreactant is demonstrated.
To get more mechanistic insights, we obtained the cyclic vol-
tammograms of related compounds using the glassy carbon
electrode in a solution similar to the reaction mixture. As shown
in Figure 1, the oxidation of vinyl azide 1a did not occur until
at +1.5 V, whereas an oxidation peak of sulfonyl hydrazide 3a
was observed at +1.2 V. Addition of vinyl azide 1a to the sulf-
onyl hydrazide 3a led to an obvious current increase. At the
same time, the onset potential remained the same as 3a alone.
To gain insight into the reaction mechanism, we examined This observation suggested the intermediate/radical generated
control experiments using radical scavengers. Formation of de- from the oxidation of sulfonyl hydrazide 3a undergoes a cou-
sired product 2a was inhibited entirely with the addition of pling reaction with 1a.
TEMPO or BHT into the reaction mixture of α-(biaryl-2-yl)vinyl
azide 1a and sodium azide under the standard reaction condi-
tions (Scheme 3a). Similarly, when BHT (2.0 equiv.) was added
to the reaction mixture of 1a and p-toluenesulfonyl hydrazide
3a under the standard reaction conditions, we were able to
obtain the product 4a in 54 % yield (determined by 1H-NHR)
Based on the above CV studies and control experiments, we
propose a plausible pathway for the electrochemical oxidative
coupling reaction between the vinyl azide and sulfonyl hydraz-
ide as shown in Scheme 4. The reaction commenced with elec-
tro-oxidation of sulfonyl hydrazide, leading to the generation
of sulfonyl radical A together with the release of N2. Next, the
while TEMPO only afforded trace product. This result indicates sulfonyl radical A adds to the vinyl azide, forming the iminyl
that the reaction proceeds through a radical process, and sulf- radical intermediate B with the release of N2. Subsequently, rad-
onyl radicals come from electro-oxidation of sulfonyl hydrazide. ical B would undergo intramolecular cyclization with the aryl
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Scheme 2. Gram-scale synthesis of 4a and 6a and azide functionalization.
Scheme 3. Investigation of the reaction mechanism.
Scheme 4. Proposed mechanism for the electrochemical synthesis of phen-
anthridines.
Conclusion
In summary, we have developed a facile electrochemical oxid-
ative coupling of vinyl azides to construct functionalized phen-
anthridines and ꢀ-ketosulfones. In the reaction, readily available
sodium azides and sulfonyl hydrazides are used as radical pre-
cursors. Moreover, the reaction has the advantages of mild and
metal-free reaction conditions, broad substrate scope, and high
functional group tolerance.
Figure 1. Cyclic voltammograms of background solution with 0.1
M
nBu4NBF4,
5 mM
α-(biaryl-2-yl)vinyl azide (1a) with 0.1
M
nBu4NBF4, 5 mM p-toluene-
sulfonyl hydrazide (3a) with 0.1
M
nBu4NBF4, and 5 mM 1a + 3a with 0.1 M
nBu4NBF4 in the MeCN:H2O mixture solution at scan rate of 0.1 V/s. A 3 mm
diameter glassy carbon electrode, Ag/AgCl and Pt wire were used as the
working, reference, and counter electrode, respectively.
Experimental Section
General Procedure for the Synthesis of 2: Under N2 protection,
an undivided cell was equipped with a carbon plate as an-
moiety, yielding radical species C. After further oxidation at the
anode, the carbon cation D was formed, and finally deproto-
nated to product 4a.
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ode (52.5 mm × 8.0 mm × 1.5 mm), Pt plate as cathode
(52.5 mm × 8.0 mm × 0.1 mm), and connected to an IKA power
Methyl 6-(azidomethyl)phenanthridine-3-carboxylate (2g):
White solid, 79 % yield (41.4 mg). 1H NMR (400 MHz, CDCl3) δ 8.89
(s, 1H), 8.70 (d, J = 8.3 Hz, 1H), 8.62 (d, J = 8.6 Hz, 1H), 8.31 (dd, J =
8.6, 1.8 Hz, 1H), 8.23 (d, J = 8.2 Hz, 1H), 7.93 (t, J = 7.7 Hz, 1H), 7.81
(t, J = 7.7 Hz, 1H), 5.00 (s, 2H), 4.02 (s, 3H). 13C NMR (150 MHz, CDCl3)
δ = 166.8, 156.0, 142.7, 132.6, 132.4, 131.3, 130.4, 128.9, 127.6, 127.4,
125.9, 125.0, 123.3, 122.4, 54.4, 52.5. HRMS (ESI+) m/z Calcd. for
supply. Vinyl azides 1 (0.2 mmol), NaN3 (0.24 mmol) and 0.1
M/L
LiClO4 with 4.0 mL solution of CH3CN:H2O (10:1) were added into
the cell. The mixture was electrolyzed using a constant voltage of
2.3 V at room temperature under magnetic stirring. When TLC anal-
ysis indicated that the electrolysis was completed (witnessed by the
disappearance of the 1a), the solvent was removed under reduced
pressure. The residue was then extracted with DCM (3 × 20 mL),
dried with Na2SO4, and concentrated in vacuo. The residue was
purified by column chromatography on silica gel using a mixture
of petroleum ether/ethyl acetate (20:1) as eluent to afford the de-
sired pure product 2.
C
16H12N4NaO2 [M + Na]+: m/z 318.0852, found 315.0846.
6-(Azidomethyl)-3-(trifluoromethyl)phenanthridine (2h): White
solid, 82 % yield (49.5 mg). 1H NMR (600 MHz, CDCl3) δ 8.64 (dd,
J = 14.8, 8.4 Hz, 2H), 8.49 (d, J = 1.9 Hz, 1H), 8.22 (dd, J = 8.2, 1.2 Hz,
1H), 7.94 (ddd, J = 8.3, 7.0, 1.3 Hz, 1H), 7.87 (dd, J = 8.5, 1.9 Hz, 1H),
7.82 (ddd, J = 8.2, 7.0, 1.2 Hz, 1H), 4.99 (s, 2H). 13C NMR (150 MHz,
CDCl3) δ = 156.5, 142.5, 132.4, 131.5, 130.7 (q, J = 32.7 Hz), 128.9,
127.8 (q, J = 4.1 Hz), 126.5, 125.8, 124.8, 123.3 (q, J = 3.3 Hz), 123.1,
123.0, 54.2. 19F NMR (565 MHz, CDCl3) δ = –62.28. HRMS (ESI+) m/z
Calcd. for C15H9F3N4Na[M + Na]+: m/z 325.0672, found 325.0633.
6-(Azidomethyl)phenanthridine (2a): White solid, 83 % yield
1
(38.8 mg). H NMR (400 MHz, CDCl3) δ 8.63 (d, J = 8.3 Hz, 1H), 8.54
(d, J = 8.1 Hz, 1H), 8.18 (t, J = 7.4 Hz, 2H), 7.85 (t, J = 7.7 Hz, 1H),
7.80–7.63 (m, 3H), 4.96 (s, 2H). 13C NMR (150 MHz, CDCl3) δ = 154.8,
143.2, 133.2, 130.9, 130.2, 128.9, 127.6, 127.4, 125.7, 124.3, 124.2,
122.6, 122.0, 54.5. HRMS (ESI+) m/z Calcd. for C14H10N4Na [M + Na]+:
m/z 257.0798, found 257.0804.
6-(Azidomethyl)-2-methoxyphenanthridine (2i): White solid,
81 % yield (42.8 mg). 1H NMR (400 MHz, CDCl3) δ 8.57 (d, J = 8.3 Hz,
1H), 8.18 (d, J = 8.2 Hz, 1H), 8.10 (d, J = 8.9 Hz, 1H), 7.93–7.80 (m,
2H), 7.72 (t, J = 7.8 Hz, 1H), 7.37 (dd, J = 8.9, 2.7 Hz, 1H), 4.95 (s,
2H), 4.02 (s, 3H). 13C NMR (150 MHz, CDCl3) δ = 158.9, 152.2, 138.5,
132.8, 131.7, 130.5, 127.8, 125.8, 125.5, 124.5, 122.6, 118.7, 103.0,
55.7, 54.6. HRMS (ESI+) m/z Calcd. for C15H13N4O [M + H]+: m/z
265.1084, found 265.1102.
6-(Azidomethyl)-3-methoxyphenanthridine (2b): White solid,
73 % yield (38.5 mg). 1H NMR (400 MHz, CDCl3) δ 8.56 (d, J = 8.3 Hz,
1H), 8.45 (d, J = 9.0 Hz, 1H), 8.17 (d, J = 8.3 Hz, 1H), 7.84 (t, J =
7.8 Hz, 1H), 7.65 (t, J = 7.7 Hz, 1H), 7.60 (d, J = 2.5 Hz, 1H), 7.32 (dd,
J = 9.0, 2.5 Hz, 1H), 4.98 (s, 2H), 4.00 (s, 3H). 13C NMR (150 MHz,
CDCl3) δ = 160.3, 155.3, 144.9, 133.5, 130.9, 126.6, 125.7, 123.4,
123.2, 122.1, 118.6, 118.3, 110.0, 55.6, 54.5. HRMS (ESI+) m/z Calcd.
for C15H12N4NaO [M + Na]+: m/z 287.0903, found 287.0910.
6-(Azidomethyl)-1-methoxyphenanthridine (2j): White solid,
1
65 % yield (34.3 mg). H NMR (600 MHz, CDCl3) δ 9.65 (dd, J = 8.6,
1.1 Hz, 1H), 8.26–8.14 (m, 1H), 7.94–7.83 (m, 2H), 7.78–7.66 (m, 2H),
7.22 (dd, J = 8.0, 1.1 Hz, 1H), 5.01 (s, 2H), 4.18 (s, 3H). 13C NMR
(150 MHz, CDCl3) δ = 158.1, 155.3, 145.3, 133.3, 130.7, 128.5, 128.4,
126.9, 125.1, 124.7, 123.1, 115.0, 108.7, 55.9, 54.5. HRMS (ESI+) m/z
Calcd. for C15H13N4O [M + H]+: m/z 265.1084, found 265.1101.
6-(Azidomethyl)-3-methylphenanthridine (2c): White solid, 83 %
yield (41.1 mg). 1H NMR (400 MHz, CDCl3) δ 8.57 (d, J = 8.4 Hz, 1H),
8.40 (d, J = 8.3 Hz, 1H), 8.13 (d, J = 8.3 Hz, 1H), 7.97 (s, 1H), 7.81 (t,
J = 7.7 Hz, 1H), 7.65 (t, J = 7.7 Hz, 1H), 7.48 (dd, J = 8.4, 1.9 Hz, 1H),
4.94 (s, 2H), 2.58 (s, 3H). 13C NMR (150 MHz, CDCl3) δ = 154.8, 143.4,
139.1, 133.3, 130.8, 129.8, 129.2, 127.2, 125.7, 124.0, 122.4, 121.9,
121.8, 54.5, 21.5. HRMS (ESI+) m/z Calcd. for C15H12N4Na [M + Na]+:
m/z 271.0954, found 271.0965.
6-(Azidomethyl)-8-methoxyphenanthridine (2k): White solid,
79 % yield (41.7 mg). 1H NMR (400 MHz, CDCl3) δ 8.53–8.47 (m, 1H),
8.42 (d, J = 8.0 Hz, 1H), 8.15 (d, J = 7.9 Hz, 1H), 7.69–7.61 (m, 2H),
7.44 (dd, J = 7.7, 2.0 Hz, 2H), 4.90 (s, 2H), 3.96 (s, 3H). 13C NMR
(150 MHz, CDCl3) δ = 158.8, 153.9, 142.3, 130.1, 127.8, 127.5, 127.5,
125.6, 124.3, 124.2, 121.5, 121.4, 105.8, 55.6, 54.8. HRMS (ESI+) m/z
Calcd. for C15H13N4O [M + H]+: m/z 265.1084, found 265.1102.
6-(Azidomethyl)-3-(tert-butyl)phenanthridine (2d): White solid,
73 % yield (42.3 mg). 1H NMR (600 MHz, CDCl3) δ 8.66 (d, J = 8.3 Hz,
1H), 8.52 (d, J = 8.6 Hz, 1H), 8.21 (t, J = 4.6 Hz, 2H), 7.88 (ddd, J =
8.2, 7.1, 1.1 Hz, 1H), 7.80 (dd, J = 8.6, 2.1 Hz, 1H), 7.72 (ddd, J = 8.1,
7.2, 1.0 Hz, 1H), 5.02 (s, 2H), 1.50 (s, 9H). 13C NMR (150 MHz, CDCl3)
δ = 154.8, 152.4, 143.3, 133.3, 130.9, 127.3, 126.2, 125.9, 125.8, 124.2,
122.5, 122.0, 121.8, 54.7, 35.1, 31.4. HRMS (ESI+) m/z Calcd. for
C18H9N4 [M + H]+: m/z 291.1602, found 291.1604.
6-(Azidomethyl)-8-methylphenanthridine (2l): White solid, 81 %
yield (40.2 mg). 1H NMR (400 MHz, CDCl3) δ 8.52 (dt, J = 8.3, 4.0 Hz,
2H), 8.26–8.09 (m, 1H), 7.94 (d, J = 2.8 Hz, 1H), 7.84–7.58 (m, 3H),
4.95 (d, J = 1.9 Hz, 2H), 2.60 (d, J = 1.9 Hz, 3H). 13C NMR (150 MHz,
CDCl3) δ = 154.5, 142.9, 137.7, 131.1, 130.2, 128.4, 127.4, 125.2,
124.5, 124.4, 122.5, 121.9, 54.5, 21.9. HRMS (ESI+) m/z Calcd. for
C15H12N4Na [M + Na]+: m/z 271.0954, found 271.0963.
6-(Azidomethyl)-3-fluorophenanthridine (2e): White solid, 76 %
yield (38.3 mg). 1H NMR (400 MHz, CDCl3) δ 8.61–8.43 (m, 2H), 8.16
(d, J = 8.2 Hz, 1H), 7.96–7.77 (m, 2H), 7.70 (t, J = 7.7 Hz, 1H), 7.42
(td, J = 8.4, 2.1 Hz, 1H), 4.95 (s, 2H). 13C NMR (150 MHz, CDCl3) δ =
162.7 (d, J = 248.7 Hz), 156.3, 144.5 (d, J = 11.9 Hz), 133.0, 131.3,
127.5, 125.8, 124.0 (d, J = 9.5 Hz), 123.9, 122.4, 121.0 (d, J = 2.2 Hz),
116.5 (d, J = 23.8 Hz), 114.8 (d, J = 20.5 Hz), 54.31. 19F NMR
(376 MHz, CDCl3) δ = –111.62. HRMS (ESI+) m/z Calcd. For
C14H9FN4Na [M + Na]+: m/z 275.0703, found 275.0706.
6-(Azidomethyl)-8-fluorophenanthridine (2m): White solid, 81 %
yield (40.8 mg). 1H NMR (400 MHz, CDCl3) δ 9.78 (d, J = 8.6 Hz, 1H),
8.21 (d, J = 8.2 Hz, 1H), 8.13 (d, J = 8.1 Hz, 1H), 7.93 (d, J = 7.7 Hz,
1H), 7.79 (t, J = 7.5 Hz, 1H), 7.72–7.66 (m, 1H), 7.60 (t, J = 7.9 Hz,
1H), 4.94 (s, 2H). 13C NMR (150 MHz, CDCl3) δ = 161.4 (d, J =
249.3 Hz), 154.0 (d, J = 4.0 Hz), 142.9, 130.4, 129.9 (d, J = 2.0 Hz),
128.8, 127.9, 125.5 (d, J = 8.1 Hz), 125.2 (d, J = 8.4 Hz), 123.8, 121.8,
120.2 (d, J = 23.8 Hz), 110.5 (d, J = 21.6 Hz), 57.6. 19F NMR (376 MHz,
CDCl3) δ = –110.97. HRMS (EI+) m/z Calcd. for C14H9FN4 [M]+: m/z
252.0811, found 252.0816.
6-(Azidomethyl)-3-chlorophenanthridine (2f): White solid, 64 %
yield (34.3 mg). 1H NMR (400 MHz, CDCl3) 1H NMR (400 MHz, CDCl3)
δ 8.57 (d, J = 8.3 Hz, 1H), 8.44 (d, J = 8.8 Hz, 1H), 8.17 (d, J = 5.1 Hz,
2H), 7.87 (t, J = 7.7 Hz, 1H), 7.73 (t, J = 7.6 Hz, 1H), 7.65–7.58 (m,
1H), 4.95 (s, 2H). 13C NMR (150 MHz, CDCl3) δ = 156.2, 143.9, 134.6,
6-(Azidomethyl)-8-chlorophenanthridine (2n): White solid, 76 %
yield (40.7 mg). 1H NMR (400 MHz, CDCl3) δ 8.57 (dd, J = 8.9, 2.4 Hz,
132.8, 131.3, 129.5, 128.0, 128.0, 125.8, 124.2, 123.4, 122.7, 122.6, 1H), 8.50 (d, J = 7.9 Hz, 1H), 8.24–8.11 (m, 2H), 7.84–7.73 (m, 2H),
54.3. HRMS (ESI+) m/z Calcd. for C14H10ClN4 [M + H]+: m/z 269.0589, 7.70 (t, J = 7.6 Hz, 1H), 4.93 (d, J = 1.5 Hz, 2H). 13C NMR (150 MHz,
found 269.0585.
CDCl3) δ = 153.8, 143.2, 133.7, 131.7, 131.5, 130.4, 129.3, 128.0,
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125.2, 125.2, 124.4, 123.7, 121.9, 54.5. HRMS (ESI+) m/z Calcd. for power supply. Vinyl azides 1 (0.2 mmol), K2CO3 (0.3 mmol),
C14H9ClN4Na [M + Na]+: m/z 291.0408, found 291.0418.
nBu4NBF4 (0.08 mmol), benzenesulfonohydrazide 3 (0.3 mmol) in
4.0 mL solution of CH3CN:H2O (18:1) were added into the cell. The
mixture was electrolyzed using constant current of 12 mA at room
temperature under magnetic stirring. When TLC analysis indicated
that the electrolysis was completed (witnessed by the disappear-
ance of the 1), the solvent was removed under reduced pressure.
The residue was then extracted with DCM (3 × 20 mL), dried with
Na2SO4, and concentrated in vacuo. The residue was purified by
column chromatography on silica gel using a mixture of petroleum
ether/ethyl acetate (20:1) as eluent to afford the desired pure prod-
uct 4.
6-(Azidomethyl)-8-(trifluoromethyl)phenanthridine (2o): White
solid, 78 % yield (47.1 mg). 1H NMR (400 MHz, CDCl3) δ 8.74 (d, J =
8.7 Hz, 1H), 8.55 (d, J = 8.2 Hz, 1H), 8.44 (s, 1H), 8.22 (d, J = 8.1 Hz,
1H), 8.04 (d, J = 8.7 Hz, 1H), 7.82 (t, J = 7.6 Hz, 1H), 7.73 (t, J =
7.6 Hz, 1H), 4.99 (s, 2H). 13C NMR (101 MHz, CDCl3). 13C NMR
(150 MHz, CDCl3) δ = 154.8, 143.9, 135.4, 130.5, 130.1, 129.4 (q, J =
32.8 Hz), 128.1, 126.8 (t, J = 3.3 Hz), 124.8, 123.7, 123.6, 123.3 (d,
J = 4.6 Hz), 122.9, 122.4, 54.4. 19F NMR (376 MHz, CDCl3) δ = –62.22.
HRMS (ESI+) m/z Calcd. for C15H9F3N4Na [M + Na]+: m/z 325.0672,
found 325.0684.
6-(Tosylmethyl)phenanthridine (4a): White solid, 86 % yield
(59.7 mg). 1H NMR (400 MHz, CDCl3) δ 8.61 (d, J = 8.3 Hz, 1H), 8.57–
8.49 (m, 1H), 8.33 (d, J = 8.2 Hz, 1H), 7.91–7.79 (m, 2H), 7.71 (t,
J = 7.7 Hz, 1H), 7.68–7.62 (m, 2H), 7.56 (d, J = 8.1 Hz, 2H), 7.17 (d,
J = 7.9 Hz, 2H), 5.14 (s, 2H), 2.36 (s, 3H). 13C NMR (150 MHz, CDCl3)
δ = 149.8, 144.8, 143.3, 135.6, 133.2, 131.0, 129.9, 129.5, 128.8,
128.72, 127.7, 127.1, 125.6, 124.1, 122.3, 122.0, 62.6, 21.6.
6-(Azidomethyl)-9-methylphenanthridine (2p): White solid, 73 %
yield (36.2 mg). 1H NMR (400 MHz, CDCl3) δ 8.50 (d, J = 7.8 Hz, 1H),
8.37 (s, 1H), 8.16 (d, J = 8.1 Hz, 1H), 8.03 (d, J = 8.2 Hz, 1H), 7.71 (t,
J = 7.5 Hz, 1H), 7.64 (t, J = 7.5 Hz, 1H), 7.49 (d, J = 8.1 Hz, 1H), 4.91
(s, 2H), 2.61 (s, 3H). 13C NMR (150 MHz, CDCl3) δ = 154.7, 143.4,
141.4, 133.4, 130.2, 129.4, 128.8, 127.2, 125.6, 124.2, 122.4, 122.2,
122.0, 54.5, 22.3. HRMS (ESI+) m/z Calcd. for C15H12N4Na [M + Na]+:
m/z 271.0954, found 271.0990.
3-Methoxy-6-(tosylmethyl)phenanthridine (4b): White solid,
86 % yield (64.9 mg). 1H NMR (600 MHz, CDCl3) δ 8.53 (d, J = 8.3 Hz,
1H), 8.44 (d, J = 8.9 Hz, 1H), 8.29 (d, J = 8.3 Hz, 1H), 7.84 (t, J =
7.8 Hz, 1H), 7.65 (t, J = 7.6 Hz, 1H), 7.61 (d, J = 8.2 Hz, 2H), 7.34–
7.30 (m, 2H), 7.22 (d, J = 8.0 Hz, 2H), 5.16 (s, 2H), 3.94 (s, 3H), 2.40
(s, 3H). 13C NMR (150 MHz, CDCl3) δ = 160.2, 150.1, 144.7, 135.7,
133.5, 131.2, 129.6, 129.5, 128.7, 128.1, 127.1, 126.7, 124.7, 123.3,
121.8, 119.0, 118.2, 109.3, 62.6, 55.6, 21.6. HRMS (ESI+) m/z Calcd.
for C22H20NO3S [M + H]+: m/z 378.1158, found 378.1157.
6-(Azidomethyl)-10-chlorophenanthridine (2q): White solid, 51 %
1
yield (27.3 mg). H NMR (400 MHz, CDCl3) δ 8.58 (ddd, J = 8.0, 5.4,
1.8 Hz, 1H), 8.44 (d, J = 8.1 Hz, 1H), 8.17 (d, J = 8.0 Hz, 1H), 7.87–
7.70 (m, 2H), 7.66 (t, J = 7.5 Hz, 1H), 7.62–7.49 (m, 1H), 4.88 (s, 2H).
13C NMR (150 MHz, CDCl3) δ = 154.5, 144.3, 134.7, 132.0, 130.6,
130.3, 129.3, 127.5, 127.1, 126.9, 126.4, 125.2, 123.5, 55.1. HRMS
(ESI+) m/z Calcd. for C14H10ClN4 [M + H]+: m/z 269.0589, found
269.0589.
3-(tert-Butyl)-6-(tosylmethyl)phenanthridine (4c): White solid,
82 % yield (66.1 mg). 1H NMR (600 MHz, CDCl3) δ 8.62 (d, J = 8.3 Hz,
1H), 8.50 (d, J = 8.6 Hz, 1H), 8.31 (d, J = 8.2 Hz, 1H), 7.89–7.81 (m,
2H), 7.77 (dd, J = 8.6, 1.9 Hz, 1H), 7.70 (t, J = 7.6 Hz, 1H), 7.59 (d,
J = 8.1 Hz, 2H), 7.21 (d, J = 8.0 Hz, 2H), 5.16 (s, 2H), 2.40 (s, 3H), 1.45
(s, 9H). 13C NMR (150 MHz, CDCl3) δ = 152.2, 149.6, 144.6, 143.3,
135.5, 133.2, 130.9, 129.5, 128.8, 127.3, 126.9, 126.0, 125.8, 125.4,
122.2, 121.7, 62.7, 35.0, 31.3, 21.6. HRMS (ESI+) m/z Calcd. for
6-(Azidomethyl)-9-chlorophenanthridine (2r): White solid, 75 %
yield (53.0 mg). 1H NMR (600 MHz, CDCl3) δ 8.58 (d, J = 2.0 Hz, 1H),
8.45 (dd, J = 8.2, 1.3 Hz, 1H), 8.20 (dd, J = 8.2, 1.3 Hz, 1H), 8.12 (d,
J = 8.7 Hz, 1H), 7.79 (ddd, J = 8.3, 7.1, 1.3 Hz, 1H), 7.71 (ddd,
J = 8.3, 7.0, 1.3 Hz, 1H), 7.66 (dd, J = 8.7, 2.0 Hz, 1H), 4.95 (s, 2H).
13C NMR (150 MHz, CDCl3) δ = 154.4, 143.6, 137.4, 134.6, 130.4,
129.6, 128.3, 127.8, 127.4, 123.2, 122.6, 122.3, 122.0, 54.5. HRMS
(ESI+) m/z Calcd. for C14H10ClN4 [M + H]+: m/z 269.0589, found
269.0588.
C
25H26NO2S [M + H]+: m/z 404.1674, found 404.1679.
3-Fluoro-6-(tosylmethyl)phenanthridine (4d): White solid, 83 %
yield (60.6 mg). 1H NMR (600 MHz, CDCl3) δ 8.53 (d, J = 8.3 Hz, 1H),
8.51–8.47 (m, 1H), 8.34 (d, J = 8.2 Hz, 1H), 7.86 (t, J = 7.6 Hz, 1H),
7.71 (t, J = 7.6 Hz, 1H), 7.59 (d, J = 8.2 Hz, 2H), 7.49 (dd, J = 9.6,
2.6 Hz, 1H), 7.41 (dd, J = 11.8, 5.4 Hz, 1H), 7.21 (d, J = 8.0 Hz, 2H),
5.14 (s, 2H), 2.40 (s, 3H). 13C NMR (150 MHz, CDCl3) δ = 162.5 (d, J =
248.6 Hz), 151.2, 144.9, 144.5 (d, J = 12.0 Hz), 135.6, 132.9, 131.3,
129.5, 128.7, 127.5, 127.2, 126.0, 125.2, 124.0 (d, J = 9.5 Hz), 122.1,
120.7, 120.7, 116.8 (d, J = 23.8 Hz), 115.2 (d, J = 21.5 Hz), 114.2 (d,
J = 20.5 Hz), 62.6, 21.6. 19F NMR (565 MHz, CDCl3) δ = –110.94.
HRMS (ESI+) m/z Calcd. for C21H17FNO2S [M + H]+: m/z 366.0959,
found 366.0958.
6-(Azidomethyl)-7-fluoro-10-methylphenanthridine (2s): White
solid, 69 % yield (36.7 mg). H NMR (400 MHz, CDCl3) δ 8.76 (d, J =
1
8.5 Hz, 1H), 8.25 (d, J = 8.4 Hz, 1H), 7.77 (t, J = 7.5 Hz, 1H), 7.71–
7.57 (m, 2H), 7.33–7.26 (m, 1H), 5.06 (d, J = 4.8 Hz, 2H), 3.07 (s, 3H).
13C NMR (150 MHz, CDCl3) δ = 158.7 (d, J = 252.5 Hz), 152.6 (d, J =
6.7 Hz), 144.3, 135.4 (d, J = 9.8 Hz), 134.8 (d, J = 2.9 Hz), 131.5 (d,
J = 4.1 Hz), 130.6, 128.8 (d, J = 14.5 Hz), 128.8, 126.6 (d, J = 15.9 Hz),
124.3 (d, J = 3.1 Hz), 115.2 (d, J = 13.1 Hz), 113.2 (d, J = 23.8 Hz),
57.2 (d, J = 17.1 Hz), 30.9, 26.6. 19F NMR (376 MHz, CDCl3)
δ = –111.02. HRMS (ESI+) m/z Calcd. for C15H11FN4Na [M + Na]+:
m/z 289.0860, found 289.0872.
6-(Azidomethyl)benzo[k]phenanthridine (2t):White solid, 74 %
yield (42.0 mg). 1H NMR (400 MHz, CDCl3) 1H NMR (400 MHz, CDCl3)
δ 9.10 (dd, J = 6.4, 3.5 Hz, 1H), 8.98 (d, J = 8.4 Hz, 1H), 8.30 (dd, J =
8.3, 1.4 Hz, 1H), 8.09–8.01 (m, 2H), 7.98 (d, J = 8.8 Hz, 1H), 7.79 (ddd,
J = 8.3, 7.0, 1.3 Hz, 1H), 7.72 (ddd, J = 9.7, 7.4, 5.1 Hz, 3H), 5.04 (s,
2H). 13C NMR (150 MHz, CDCl3) δ = 153.9, 145.2, 134.7, 132.5, 130.2,
129.1, 128.8, 128.7, 128.5, 128.5, 128.1, 127.1, 127.1, 124.6, 123.2,
121.7, 54.9. HRMS (ESI+) m/z Calcd. for C18H12N4Na [M + Na]+:
m/z 307.0954, found 307.0949.
6-(Tosylmethyl)-3-(trifluoromethyl)phenanthridine (4e): White
solid, 81 % yield (67.2 mg). 1H NMR (600 MHz, CDCl3) δ 8.65 (t, J =
8.2 Hz, 2H), 8.43 (d, J = 8.2 Hz, 1H), 8.11 (s, 1H), 7.95 (t, J = 7.6 Hz,
1H), 7.88–7.83 (m, 2H), 7.59 (d, J = 8.2 Hz, 2H), 7.22 (d, J = 8.1 Hz,
2H), 5.17 (s, 2H), 2.41 (s, 3H). 13C NMR (150 MHz, CDCl3) δ = 151.6,
145.0, 142.5, 135.4, 132.4, 131.6, 130.5 (q, J = 33.1 Hz), 129.6, 128.9,
128.7, 127.4 (q, J = 4.2 Hz), 127.4, 126.3, 126.2, 124.0 (q, J =
272.2 Hz), 123.4 (q, J = 6.5 Hz), 123.2, 122.7, 62.7, 21.5. 19F NMR
(565 MHz, CDCl3)
δ = –62.37. HRMS (ESI+) m/z Calcd. for
Typical Procedure for the Synthesis of Compound 4: Under pro-
tection by nitrogen, an undivided cell was equipped with a
carbon plate as anode (52.5 mm × 8.0 mm × 1.5 mm), Pt plate as
cathode (52.5 mm × 8.0 mm × 0.1 mm), and connected to an IKA
C22H17F3NO2S [M + H]+: m/z 416.0927, found 416.0927.
5-(Tosylmethyl)benzo[a]phenanthridine (4f): White solid, 30 %
yield (23.8 mg). 1H NMR (600 MHz, CDCl3) δ 8.73 (d, J = 8.4 Hz, 1H),
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8.53 (d, J = 9.0 Hz, 1H), 8.50 (dd, J = 8.2, 3.3 Hz, 2H), 8.02 (d, J =
8.9 Hz, 1H), 7.94 (t, J = 7.6 Hz, 2H), 7.82 (t, J = 7.6 Hz, 1H), 7.66 (t,
J = 7.3 Hz, 1H), 7.58 (d, J = 7.8 Hz, 1H), 7.54 (d, J = 8.1 Hz, 2H), 7.12
(d, J = 8.0 Hz, 2H), 5.29 (s, 2H), 2.28 (s, 3H). 13C NMR (150 MHz,
CDCl3) δ = 148.2, 144.6, 140.0, 135.2, 133.5, 133.1, 131.4, 130.8,
129.4, 128.9, 128.5, 127.6, 127.4, 126.8, 126.5, 126.2, 124.7, 122.8,
121.1, 119.7, 62.4, 21.5. HRMS (ESI+) m/z Calcd. for C25H20NO2S
[M + H]+: m/z 398.1205, found 398.1209.
125.9, 123.9, 123.8, 122.0, 121.9, 62.7, 22.3, 21.6. HRMS (ESI+) m/z
Calcd. for C22H20NO2S [M + H]+: m/z 362.1209, found 362.1207.
9-Chloro-6-(tosylmethyl)phenanthridine (4m): White solid, 87 %
yield (66.3 mg). 1H NMR (600 MHz, CDCl3) δ 8.58 (s, 1H), 8.45 (d, J =
7.9 Hz, 1H), 8.30 (d, J = 8.8 Hz, 1H), 7.88–7.83 (m, 1H), 7.74–7.66 (m,
3H), 7.57 (d, J = 8.2 Hz, 2H), 7.21 (d, J = 8.0 Hz, 2H), 5.12 (s, 2H),
2.40 (s, 3H). 13C NMR (150 MHz, CDCl3) δ = 149.4, 144.9, 143.6, 137.6,
135.4, 134.5, 130.0, 129.6, 129.5, 128.8, 128.7, 128.3, 128.0, 123.9,
123.0, 122.1, 122.0, 62.7, 21.6. HRMS (ESI+) m/z Calcd. for
8-Methoxy-6-(tosylmethyl)phenanthridine (4g): White solid,
88 % yield (66.4 mg). 1H NMR (600 MHz, CDCl3) δ 8.56 (d, J = 9.1 Hz,
1H), 8.48 (d, J = 8.0 Hz, 1H), 7.81 (dd, J = 8.0, 1.2 Hz, 1H), 7.71 (d,
J = 2.1 Hz, 1H), 7.67–7.61 (m, 2H), 7.57 (d, J = 8.2 Hz, 2H), 7.52 (dd,
J = 9.0, 2.4 Hz, 1H), 7.19 (d, J = 8.1 Hz, 2H), 5.16 (s, 2H), 4.05 (s, 3H),
2.39 (s, 3H). 13C NMR (150 MHz, CDCl3) δ = 158.9, 149.0, 144.7, 142.5,
135.5, 129.8, 129.5, 128.7, 127.7, 127.6, 127.0, 124.2, 123.9, 122.0,
121.5, 106.9, 63.1, 55.7, 21.6. HRMS (ESI+) m/z Calcd. for C22H20NO3S
[M + H]+: m/z 378.1158, found 378.1158.
C
21H17ClNO2S [M + H]+: m/z 382.0663, found 382.0663.
6-(((4-Fluorophenyl)sulfonyl)methyl)phenanthridine (4n): White
solid, 94 % yield (66.0 mg). 1H NMR (400 MHz, CDCl3) δ 8.67 (d, J =
8.3 Hz, 1H), 8.60–8.56 (m, 1H), 8.37 (d, J = 8.2 Hz, 1H), 7.91 (t, J =
7.7 Hz, 1H), 7.81–7.75 (m, 2H), 7.71–7.68 (m, 2H), 7.68–7.63 (m, 2H),
7.09–7.02 (m, 2H), 5.18 (s, 2H). 13C NMR (100 MHz, CDCl3) δ = 165.9
(d, J = 256.3 Hz), 149.6, 143.2, 134.3, 133.3, 131.8, 131.7, 131.1, 129.8,
128.9, 127.9, 127.8, 126.9, 125.5, 124.0, 122.2 (d, J = 38.0 Hz),
116.1(d, J = 22.7 Hz), 62.6. 19F NMR (565 MHz, CDCl3) δ –103.54.
HRMS (ESI+) m/z Calcd. for C20H15FNO2S [M + H]+: m/z 352.0801,
found 352.0802.
8-Methyl-6-(tosylmethyl)phenanthridine (4h):White solid, 89 %
yield (64.3 mg). 1H NMR (600 MHz, CDCl3) δ 8.52 (d, J = 7.6 Hz, 2H),
8.02 (s, 1H), 7.88–7.81 (m, 1H), 7.70–7.64 (m, 3H), 7.56 (d, J = 8.2 Hz,
2H), 7.19 (d, J = 8.0 Hz, 2H), 5.15 (s, 2H), 2.60 (s, 3H), 2.39 (s, 3H).
13C NMR (150 MHz, CDCl3) δ = 149.5, 144.7, 143.0, 137.7, 135.6,
132.7, 131.1, 129.8, 129.4, 128.8, 128.3, 127.6, 126.3, 125.7, 124.1,
122.2, 121.8, 62.6, 21.9, 21.6. HRMS (ESI+) m/z Calcd. for C22H20NO2S
[M + H]+: m/z 362.1209, found 362.1208.
6-(((4-Chlorophenyl)sulfonyl)methyl)phenanthridine (4o): White
solid, 85 % yield (62.4 mg). 1H NMR (400 MHz, CDCl3) δ 8.66 (d, J =
8.3 Hz, 1H), 8.56 (dd, J = 6.4, 3.1 Hz, 1H), 8.35 (d, J = 8.3 Hz, 1H),
7.90 (t, J = 7.6 Hz, 1H), 7.82–7.73 (m, 2H), 7.72–7.66 (m, 2H), 7.58 (d,
J = 8.5 Hz, 2H), 7.36 (d, J = 8.5 Hz, 2H), 5.17 (s, 2H). 13C NMR
(100 MHz, CDCl3) δ = 149.5, 143.2, 140.5, 136.8, 133.3, 131.2, 130.3,
129.8, 129.1, 129.0, 127.9, 127.8, 126.9, 125.5, 124.0, 122.4, 122.1,
8-Fluoro-6-(tosylmethyl)phenanthridine (4i): White solid, 82 %
yield (59.9 mg). 1H NMR (600 MHz, CDCl3) δ 8.64 (dd, J = 9.1, 5.3 Hz,
1H), 8.52–8.49 (m, 1H), 7.95 (dd, J = 9.7, 2.5 Hz, 1H), 7.91–7.87 (m,
1H), 7.72–7.68 (m, 2H), 7.66–7.58 (m, 3H), 7.23 (d, J = 8.1 Hz, 2H),
5.10 (s, 2H), 2.42 (s, 3H). 13C NMR (150 MHz, CDCl3) δ = –161.5 (d,
J = 249.5 Hz), 149.0, 149.0, 144.9, 143.0, 135.5, 130.1, 129.9, 129.6,
128.7, 128.7, 128.1, 126.9 (d, J = 8.0 Hz), 124.9 (d, J = 8.5 Hz), 123.6,
121.8, 120.3 (d, J = 23.9 Hz), 111.7 (d, J = 22.2 Hz), 62.8, 21.6.
19F NMR (565 MHz, CDCl3) δ = –110.94. HRMS (ESI+) m/z Calcd. for
62.5. HRMS (ESI+) m/z Calcd. for
m/z 368.0507, found 368.0506.
C20H15ClNO2S [M +
H]+:
6-(((4-Bromophenyl)sulfonyl)methyl)phenanthridine (4p): White
solid, 86 % yield (70.7 mg). 1H NMR (400 MHz, CDCl3) δ 8.67 (d, J =
8.3 Hz, 1H), 8.58 (dd, J = 6.4, 3.2 Hz, 1H), 8.35 (d, J = 8.3 Hz, 1H),
7.91 (t, J = 7.7 Hz, 1H), 7.82–7.75 (m, 2H), 7.73–7.68 (m, 2H), 7.56–
7.49 (m, 4H), 5.17 (s, 2H). 13C NMR (100 MHz, CDCl3) δ = 149.4,
143.2, 137.3, 133.3, 132.1, 131.1, 130.4, 129.8, 129.1, 129.0, 127.9,
127.8, 126.9, 125.5, 124.0, 122.4, 122.1, 62.4. HRMS (ESI+) m/z Calcd.
for C20H15BrNO2S [M + H]+: m/z 412.0001, found 412. 0001.
C
21H17FNO2S [M + H]+: m/z 366.0959, found 366.0958.
8-Chloro-6-(tosylmethyl)phenanthridine (4j): White solid, 83 %
yield (63.3 mg). 1H NMR (600 MHz, CDCl3) δ 8.54 (d, J = 8.8 Hz, 1H),
8.49 (d, J = 7.4 Hz, 1H), 8.16 (s, 1H), 7.93–7.89 (m, 1H), 7.78 (dd, J =
8.8, 1.5 Hz, 1H), 7.74–7.68 (m, 2H), 7.58 (d, J = 8.1 Hz, 2H), 7.21 (d,
J = 8.0 Hz, 2H), 5.10 (s, 2H), 2.41 (s, 3H). 13C NMR (150 MHz, CDCl3)
δ = 148.8, 145.0, 143.3, 135.5, 133.7, 131.5, 131.5, 130.2, 129.6, 129.1,
128.7, 128.2, 126.4, 126.2, 124.1, 123.4, 121.9, 62.6, 21.6. HRMS (ESI+)
m/z Calcd. for C21H17ClNO2S [M + H]+: m/z 382.0663, found
382.0663.
4-((Phenanthridin-6-ylmethyl)sulfonyl)benzonitrile (4q): White
solid, 81 % yield (58.0 mg). 1H NMR (400 MHz, CDCl3) δ 8.69 (d, J =
8.4 Hz, 1H), 8.57 (dd, J = 6.4, 2.9 Hz, 1H), 8.37 (d, J = 8.3 Hz, 1H),
7.92 (d, J = 7.2 Hz, 1H), 7.81 (d, J = 8.1 Hz, 1H), 7.75 (d, J = 8.5 Hz,
2H), 7.69 (dt, J = 12.8, 5.8 Hz, 5H), 5.21 (s, 2H). 13C NMR (100 MHz,
CDCl3) δ = 149.0, 143.0, 142.3, 133.3, 132.4, 131.3, 129.6, 129.1,
128.1, 128.0, 126.7, 125.4, 124.0, 122.6, 122.1, 117.4, 117.2, 62.1.
HRMS (ESI+) m/z Calcd. for C21H15N2O2S [M + H]+: m/z 359.0849,
found 359.0847.
6-(Tosylmethyl)-8-(trifluoromethyl)phenanthridine (4k): White
solid, 92 % yield (76.4 mg). 1H NMR (600 MHz, CDCl3) δ 8.64 (d, J =
4.3 Hz, 1H), 8.48 (d, J = 3.5 Hz, 1H), 8.39 (s, 1H), 7.94 (d, J = 7.6 Hz,
2H), 7.71 (dd, J = 27.2, 5.4 Hz, 2H), 7.56 (d, J = 7.9 Hz, 2H), 7.18 (d,
J = 7.7 Hz, 2H), 5.14 (s, 2H), 2.37 (s, 3H). 13C NMR (150 MHz, CDCl3)
δ = 149.6, 145.1, 144.0, 135.4, 135.2, 130.2, 130.0, 129.2 (q, J =
31.5 Hz), 128.6, 128.3, 126.6, 124.7, 124.3 (q, J = 4.1 Hz), 123.8 (q,
J = 272.6 Hz), 123.5, 122.9, 122.4, 62.5, 21.3. 19F NMR (565 MHz,
CDCl3) δ = –62.21, –62.22. HRMS (ESI+) m/z Calcd. for C22H17F3NO2S
[M + H]+: m/z 416.0927, found 416.0925.
6-(((4-(Trifluoromethoxy)phenyl)sulfonyl)methyl)phenanthrid-
ine (4r):White solid, 89 % yield (74.2 mg). 1H NMR (400 MHz, CDCl3)
δ 8.67 (d, J = 8.3 Hz, 1H), 8.57 (dd, J = 6.2, 3.2 Hz, 1H), 8.35 (d, J =
8.3 Hz, 1H), 7.91 (t, J = 7.7 Hz, 1H), 7.77 (t, J = 7.7 Hz, 1H), 7.73 (dd,
J = 7.0, 2.6 Hz, 1H), 7.72–7.64 (m, 4H), 7.19 (d, J = 8.5 Hz, 2H), 5.19
(s, 2H). 13C NMR (150 MHz, CDCl3) δ = 153.0, 149.4, 143.1, 136.4,
133.3, 131.2, 131.2, 130.2, 129.7, 128.4 (q, J = 258.5 Hz), 128.1, 127.9,
127.8, 127.3, 125.9, 124.0, 122.8, 122.5, 122.0, 121.0, 120.9, 120.7,
62.4. 19F NMR (565 MHz, CDCl3) δ = –57.69. HRMS (ESI+) m/z Calcd.
for C21H15F3NO3S [M + H]+: m/z 418.0719, found 418.0717.
9-Methyl-6-(tosylmethyl)phenanthridine (4l): White solid, 79 %
1
yield (57.1 mg). H NMR (600 MHz, CDCl3) δ 8.54–8.50 (m, 1H), 8.40
6-(((4-Methoxyphenyl)sulfonyl)methyl)phenanthridine (4s):
1
(s, 1H), 8.23 (d, J = 8.4 Hz, 1H), 7.83 (dd, J = 7.1, 2.3 Hz, 1H), 7.69–
7.63 (m, 2H), 7.61–7.52 (m, 3H), 7.18 (d, J = 8.1 Hz, 2H), 5.13 (s, 2H),
2.64 (s, 3H), 2.38 (s, 3H). 13C NMR (150 MHz, CDCl3) δ = 149.6, 144.7,
White solid, 91 % yield (66.1 mg). H NMR (400 MHz, CDCl3) δ 8.66
(d, J = 8.3 Hz, 1H), 8.57 (dd, J = 6.2, 3.4 Hz, 1H), 8.37 (d, J = 8.3 Hz,
1H), 7.93–7.82 (m, 2H), 7.75 (t, J = 7.7 Hz, 1H), 7.72–7.64 (m, 2H),
143.4, 141.6, 129.8, 129.5, 129.5, 129.4, 128.7, 128.6, 127.4, 127.0, 7.62–7.55 (m, 2H), 6.84 (d, J = 8.9 Hz, 2H), 5.15 (s, 2H), 3.82 (s, 3H).
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13C NMR (150 MHz, CDCl3) δ = 163.8, 150.0, 143.3, 133.2, 131.0,
130.9, 130.0, 128.8, 127.7, 127.7, 127.6, 127.1, 125.6, 124.1, 122.3, solid, 56 % yield (36.6 mg). H NMR (600 MHz, CDCl3) δ 8.69 (d, J =
6-((Thiophen-2-ylsulfonyl)methyl)phenanthridine (4z): White
1
122.0, 114.2, 114.1, 62.8, 55.7. HRMS (ESI+) m/z Calcd. for
8.3 Hz, 1H), 8.60 (dd, J = 6.5, 3.0 Hz, 1H), 8.37 (d, J = 8.2 Hz, 1H),
7.93–7.90 (m, 2H), 7.79–7.76 (m, 1H), 7.73–7.70 (m, 2H), 7.64 (dd, J =
4.9, 1.3 Hz, 1H), 7.46 (dd, J = 3.8, 1.3 Hz, 1H), 7.03 (dd, J = 4.9, 3.8 Hz,
1H), 5.30 (s, 2H). 13C NMR (150 MHz, CDCl3) δ = 149.6, 143.3, 139.0,
135.2, 134.6, 133.3, 131.1, 130.1, 128.8, 127.8, 127.8, 127.7, 126.9,
125.6, 124.1, 122.4, 122.1, 63.6. HRMS (ESI+) m/z Calcd. For
C18H14NO2S2 [M + H]+: m/z 340.0460, found 340.0460.
C21H18NO3S [M + H]+: m/z 364.1002, found 364.1000.
6-(((3-Bromophenyl)sulfonyl)methyl)phenanthridine (4t): White
1
solid, 88 % yield (72.3 mg). H NMR (400 MHz, CDCl3) δ 8.67 (d, J =
8.3 Hz, 1H), 8.57 (dd, J = 6.2, 3.4 Hz, 1H), 8.34 (d, J = 8.3 Hz, 1H),
7.90 (t, J = 7.6 Hz, 1H), 7.85–7.74 (m, 3H), 7.69 (td, J = 6.9, 3.4 Hz,
3H), 7.57 (d, J = 7.9 Hz, 1H), 7.25 (t, J = 7.9 Hz, 1H), 5.18 (s, 2H). 13
C
NMR (100 MHz, CDCl3) δ = 149.3, 143.2, 140.1, 136.7, 133.3, 131.9, Typical Procedure for the Synthesis of Compound 6: Under pro-
131.2, 130.3, 129.9, 128.9, 127.9, 127.8, 127.3, 126.8, 125.5, 124.1, tection by nitrogen, an undivided cell was equipped with a
122.9, 122.5, 122.1, 62.4. HRMS (ESI+) m/z Calcd. for C20H15BrNO2S carbon plate as anode (52.5 mm × 8.0 mm × 1.5 mm), Pt plate as
[M + H]+: m/z 412.0001, found 412.0001.
cathode (52.5 mm × 8.0 mm × 0.1 mm), and connected to an IKA
power supply. Vinyl azides 5 (0.2 mmol), nBu4NBF4 (0.08 mmol),
benzenesulfonohydrazide 3 (0.3 mmol) in 4.0 mL solution of
CH3CN:H2O (10:1) were added into the cell. The mixture was electro-
lyzed using constant current of 18 mA at room temperature under
magnetic stirring. When TLC analysis indicated that the electrolysis
was complete (witnessed by the disappearance of the 5), the sol-
vent was removed under reduced pressure. The residue was then
extracted with DCM (3 × 20 mL), dried with Na2SO4. After removal
of solvents under reduced pressure, the crude mixture was treated
6-(((3,4-Dichlorophenyl)sulfonyl)methyl)phenanthridine (4u):
White solid, 88 % yield (58.0 mg). 1H NMR (400 MHz, CDCl3) δ 8.68
(d, J = 8.3 Hz, 1H), 8.58 (dd, J = 6.5, 3.1 Hz, 1H), 8.34 (d, J = 8.2 Hz,
1H), 7.92 (t, J = 7.7 Hz, 1H), 7.83–7.76 (m, 2H), 7.76–7.68 (m, 3H),
7.44 (d, J = 2.0 Hz, 2H), 5.18 (s, 2H). 13C NMR (100 MHz, CDCl3) δ =
149.2, 138.8, 137.9, 133.6, 133.4, 131.3, 131.0, 130.8, 129.7, 129.1,
128.1, 127.9, 127.9, 126.8, 125.5, 124.1, 122.6, 122.1, 62.3. HRMS
(ESI+) m/z Calcd. for C20H14Cl2NO2S [M + H]+: m/z 402.0117, found
402.0117.
with HCl (3 N, 0.12 mL) in THF (2 mL) at 80 °C in a sealed tube for
6-((Mesitylsulfonyl)methyl)phenanthridine (4v): White solid,
68 % yield (51.0 mg). 1H NMR (600 MHz, CDCl3) δ 8.64 (d, J = 8.3 Hz,
1H), 8.57–8.54 (m, 1H), 8.39 (d, J = 8.2 Hz, 1H), 7.89–7.85 (m, 1H),
7.84–7.81 (m, 1H), 7.76–7.72 (m, 1H), 7.70–7.66 (m, 2H), 6.85 (s, 2H),
5.18 (s, 2H), 2.37 (s, 6H), 2.28 (s, 3H). 13C NMR (150 MHz, CDCl3) δ =
150.1, 143.4, 143.3, 140.5, 133.0, 132.6, 132.0, 130.9, 130.0, 128.7,
127.7, 127.6, 127.1, 125.8, 123.9, 122.3, 122.0, 62.6, 22.9, 21.0. HRMS
(ESI+) m/z Calcd. for C23H22NO2S [M + H]+: m/z 376.1336, found
376.1365.
12 h. After the reaction mixture was diluted with water and ethyl
acetate, the aqueous layer was extracted with EtOAc. The combined
organic layers were washed with brine, dried with MgSO4, and con-
centrated. The residue was purified by column chromatography on
silica gel using a mixture of petroleum ether/ethyl acetate (20:1) as
eluent to afford the desired pure product 6.
1-Phenyl-2-tosylethan-1-one (6a): White solid, 80 % yield
1
(43.8 mg). H NMR (400 MHz, CDCl3) δ 7.94 (d, J = 7.7 Hz, 2H), 7.76
(d, J = 8.2 Hz, 2H), 7.62 (t, J = 7.4 Hz, 1H), 7.48 (t, J = 7.7 Hz, 2H),
7.33 (d, J = 8.1 Hz, 2H), 4.72 (s, 2H), 2.44 (s, 3H). 13C NMR (100 MHz,
CDCl3) δ = 188.2, 145.4, 135.8, 135.8, 134.3, 129.9, 129.3, 128.9,
128.6, 63.6, 21.7. HRMS (ESI+) m/z Calcd. For C15H15O3S [M + H]+:
m/z 275.0736, found 275.0735.
6-((Naphthalen-2-ylsulfonyl)methyl)phenanthridine (4w): White
solid, 68 % yield (51.0 mg). 1H NMR (600 MHz, CDCl3) δ 8.67–8.64
(m, 1H), 8.55 (d, J = 7.8 Hz, 1H), 8.40 (d, J = 8.3 Hz, 1H), 8.31 (d, J =
1.2 Hz, 1H), 7.91–7.84 (m, 3H), 7.81 (d, J = 8.2 Hz, 1H), 7.75–7.72 (m,
1H), 7.69–7.64 (m, 4H), 7.62–7.55 (m, 2H), 5.27 (s, 2H). 13C NMR
(150 MHz, CDCl3) δ = 149.7, 143.2, 135.5, 135.4, 133.3, 132.1, 131.0,
130.7, 129.9, 129.4, 129.2, 129.0, 128.7, 127.9, 127.7, 127.7, 127.4,
127.0, 125.7, 124.1, 123.4, 122.4, 122.0, 62.6. HRMS (ESI+) m/z Calcd.
for C24H18NO2S [M + H]+: m/z 384.1053, found 384.1051.
1,2-Bis(1-phenyl-2-tosylethylidene)hydrazine (7a): White solid,
31 % yield (17.0 mg). 1H NMR (400 MHz, CDCl3) δ 7.77 (d, J = 7.7 Hz,
4H), 7.59 (d, J = 8.2 Hz, 4H), 7.48 (d, J = 7.4 Hz, 2H), 7.41 (t, J =
7.6 Hz, 4H), 7.05 (d, J = 8.1 Hz, 4H), 4.87 (s, 4H), 2.28 (s, 6H). 13C
NMR (100 MHz, CDCl3) δ = 155.7, 144.8, 136.8, 135.3, 131.2, 129.5,
128.4, 128.4, 128.0, 55.1, 21.6. HRMS (ESI+) m/z Calcd. For
6-((Ethylsulfonyl)methyl)phenanthridine (4x): White solid, 94 %
yield (53.6 mg). 1H NMR (400 MHz, CDCl3) δ 8.64 (d, J = 8.3 Hz, 1H),
8.57 (d, J = 7.9 Hz, 1H), 8.37 (d, J = 8.2 Hz, 1H), 8.11 (dd, J = 8.1,
1.1 Hz, 1H), 7.87 (t, J = 7.6 Hz, 1H), 7.79–7.67 (m, 3H), 5.00 (s, 2H),
3.20 (q, J = 7.4 Hz, 2H), 1.47 (t, J = 7.5 Hz, 3H). 13C NMR (100 MHz,
CDCl3) δ = 150.4, 143.3, 133.4, 131.2, 130.0, 129.0, 127.9, 127.1,
125.6, 124.3, 122.4, 122.2, 77.4, 77.1, 76.8, 58.2, 46.7, 6.6. HRMS
(ESI+) m/z Calcd. For C16H16NO2S [M + H]+: m/z 286.0896, found
286.0895.
C
30H29N2O4S2 [M + H]+: m/z 545.1563, found 545.1566.
1-(2-Chlorophenyl)-2-tosylethan-1-one (6b): White solid, 69 %
yield (42.5 mg). 1H NMR (400 MHz, CDCl3) δ 7.76 (d, J = 7.9 Hz, 2H),
7.56 (d, J = 7.6 Hz, 1H), 7.47–7.41 (m, 1H), 7.39– 7.33 (m, 4H), 4.82
(s, 2H), 2.45 (s, 3H). 13C NMR (100 MHz, CDCl3) δ = 190.4, 145.4,
137.3, 135.9, 133.1, 131.6, 130.7, 130.6, 129.9, 128.6, 127.2, 66.5, 21.7.
HRMS (ESI+) m/z Calcd. For C15H14ClO3S [M + H]+: m/z 309.0347,
found 309.0346.
(1R,4S)-7,7-dimethyl-1-(((phenanthridin-6-ylmethyl)sulfonyl)-
methyl)bicyclo[2.2.1]heptan-2-one (4y): White solid, 64 % yield
(52.1 mg). 1H NMR (400 MHz, CDCl3) δ 8.68 (d, J = 8.3 Hz, 1H), 8.63–
8.59 (m, 1H), 8.39 (d, J = 8.3 Hz, 1H), 8.16–8.11 (m, 1H), 7.90 (t,
J = 7.7 Hz, 1H), 7.78 (d, J = 7.9 Hz, 1H), 7.74–7.69 (m, 2H), 5.37 (d,
J = 14.1 Hz, 1H), 5.20 (d, J = 14.1 Hz, 1H), 4.08 (d, J = 15.0 Hz, 1H),
3.18 (d, J = 15.0 Hz, 1H), 2.46–2.29 (m, 2H), 2.11 (t, J = 4.3 Hz, 1H),
1-(3-Fluorophenyl)-2-tosylethan-1-one (6c): White solid, 85 %
yield (49.7 mg). 1H NMR (400 MHz, CDCl3) δ 7.76 (d, J = 7.8 Hz, 3H),
7.61 (d, J = 9.2 Hz, 1H), 7.47–7.42 (q, 1H), 7.35–7.30 (m, 3H), 4.70 (s,
2H), 2.45 (s, 3H). 13C NMR (100 MHz, CDCl3) δ = 187.14, 187.12, 162.8
(d, J = 248.9 Hz), 145.60, 137.8 (d, J = 6.5 Hz), 135.61, 130.6 (d, J =
7.7 Hz), 129.94, 128.59, 125.4(d, J = 3.0 Hz), 121.55, 121.34, 115.94,
115.71, 63.72, 21.73. 19F NMR (376 MHz, CDCl3) δ = –111.03. HRMS
(ESI+) m/z Calcd. For C15H14FO3S [M + H]+: m/z 293.0642, found
293.0641.
2.04–1.91 (m, 3H), 1.49–1.42 (m, 1H), 1.01 (s, 3H), 0.94 (s, 3H). 13
C
NMR (100 MHz, CDCl3) δ = 214.8, 150.7, 143.4, 133.4, 131.1, 130.0,
128.9, 127.9, 127.8, 127.1, 125.9, 124.3, 122.4, 122.2, 61.3, 59.3, 50.3,
48.5, 42.7, 42.7, 27.2, 25.5, 19.9, 19.9. HRMS (ESI+) m/z Calcd. For 1-(3-Chlorophenyl)-2-tosylethan-1-one (6d): White solid, 74 %
C24H26NO3S [M + H]+: m/z 408.1628, found 408.1627. yield (45.6 mg). 1H NMR (400 MHz, CDCl3) δ 7.84 (d, J = 6.9 Hz, 2H),
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7.75 (d, J = 7.8 Hz, 2H), 7.58 (d, J = 7.7 Hz, 1H), 7.43 (t, J = 8.0 Hz,
1H), 7.34 (d, J = 7.9 Hz, 2H), 4.70 (s, 2H), 2.45 (s, 3H). 13C NMR
(100 MHz, CDCl3) δ = 187.1, 145.6, 137.2, 135.6, 135.2, 134.2, 130.2,
2-((4-Methoxyphenyl)sulfonyl)-1-phenylethan-1-one (6m):
White solid, 70 % yield (40.6 mg). 1H NMR (400 MHz, CDCl3) δ 7.94
(d, J = 7.8 Hz, 2H), 7.80 (d, J = 8.9 Hz, 2H), 7.61 (t, J = 7.4 Hz, 1H),
130.0, 129.2, 128.6, 127.6, 63.7, 21.8. HRMS (ESI+) m/z Calcd. For 7.47 (t, J = 7.7 Hz, 2H), 6.97 (d, J = 8.8 Hz, 2H), 4.72 (s, 2H), 3.86 (s,
C15H14ClO3S [M + H]+: m/z 309.0347, found 309.0346.
3H). 13C NMR (100 MHz, CDCl3) δ = 188.4, 164.2, 135.8, 134.3, 130.9,
130.2, 129.3, 128.9, 114.4, 63.7, 55.7. HRMS (ESI+) m/z Calcd. For
C15H15O4S [M + H]+: m/z 291.0686, found 291.0684.
1-(3-Bromophenyl)-2-tosylethan-1-one (6e): White solid, 87 %
yield (61.2 mg). 1H NMR (400 MHz, CDCl3) δ 7.99 (s, 1H), 7.89 (d, J =
7.7 Hz, 1H), 7.73 (t, J = 8.2 Hz, 3H), 7.38–7.33 (m, 3H), 4.69 (s, 2H), 2-((4-Fluorophenyl)sulfonyl)-1-phenylethan-1-one (6n): White
2.44 (s, 3H). 13C NMR (100 MHz, CDCl3) δ = 187.0, 145.7, 137.4, 137.1, solid, 76 % yield (42.3 mg). 1H NMR (400 MHz, CDCl3) δ 7.92 (ddd,
135.6, 132.1, 130.4, 130.0, 128.6, 128.1, 123.2, 63.6, 21.8. HRMS (ESI+) J = 8.8, 5.2, 2.7 Hz, 4H), 7.63 (t, J = 7.4 Hz, 1H), 7.49 (t, J = 7.8 Hz,
m/z Calcd. For C15H14BrO3S [M + H]+: m/z 352.9842, found 352.9841.
2H), 7.21 (t, J = 8.6 Hz, 2H), 4.75 (s, 2H). 13C NMR (100 MHz, CDCl3)
δ = 188.0, 166.1 (d, J = 257.3 Hz), 135.6, 134.7 (d, J = 3. Hz), 134.5,
131.7, 131.6, 129.3, 129.0, 116.7, 116.4, 63.4. 19F NMR (376 MHz,
CDCl3) δ = –102.37. HRMS (ESI+) m/z Calcd. For C14H12FO3S [M +
H]+: m/z 279.0486, found 279.0484.
1-(4-Fluorophenyl)-2-tosylethan-1-one (6f): White solid, 82 %
yield (47.9 mg). 1H NMR (400 MHz, CDCl3) δ 8.00 (dd, J = 7.6, 5.9 Hz,
2H), 7.75 (d, J = 7.9 Hz, 2H), 7.34 (d, J = 7.9 Hz, 2H), 7.15 (t, J =
8.4 Hz, 2H), 4.70 (s, 2H), 2.45 (s, 3H). 13C NMR (100 MHz, CDCl3) δ =
186.6, 166.5 (d, J = 257.6 Hz), 145.5, 135.6, 132.3, 132.3, 132.2, 129.9,
128.6, 116.2, 116.0, 63.7, 21.7. 19F NMR (376 MHz, CDCl3) δ =
2-((4-Chlorophenyl)sulfonyl)-1-phenylethan-1-one (6o): White
solid, 74 % yield (43.5 mg). 1H NMR (400 MHz, CDCl3) δ 7.96–7.89
–102.41. HRMS (ESI+) m/z Calcd. For C15H14FO3S [M + H]+: m/z (m, 2H), 7.83 (d, J = 8.6 Hz, 2H), 7.63 (t, J = 7.4 Hz, 1H), 7.52–7.46
293.0642, found 293.0641.
(m, 4H), 4.75 (s, 2H). 13C NMR (100 MHz, CDCl3) δ = 188.07, 141.1,
137.2, 135.6, 134.5, 130.2, 129.5, 129.3, 129.0, 63.3. HRMS (ESI+) m/z
Calcd. For C14H12ClO3S [M + H]+: m/z 295.0190, found 295.0190.
1-(4-Chlorophenyl)-2-tosylethan-1-one (6g): White solid, 75 %
yield (46.2 mg). 1H NMR (400 MHz, CDCl3) δ 7.90 (d, J = 8.3 Hz, 2H),
7.74 (d, J = 7.9 Hz, 2H), 7.45 (d, J = 8.3 Hz, 2H), 7.34 (d, J = 7.9 Hz,
2-((4-Bromophenyl)sulfonyl)-1-phenylethan-1-one (6p): White
2H), 4.69 (s, 2H), 2.45 (s, 3H). 13C NMR (100 MHz, CDCl3) δ = 187.1, solid, 57 % yield (38.5 mg). 1H NMR (400 MHz, CDCl3) δ 7.93 (d, J =
145.6, 141.1, 135.6, 134.1, 130.8, 129.9, 129.2, 128.6, 63.7, 21.8. HRMS
(ESI+) m/z Calcd. For C15H14ClO3S [M + H]+: m/z 309.0347, found
309.0346.
7.9 Hz, 2H), 7.76 (d, J = 8.4 Hz, 2H), 7.68 (d, J = 7.5 Hz, 2H), 7.64 (t,
J = 7.4 Hz, 1H), 7.49 (t, J = 7.4 Hz, 2H), 4.75 (s, 2H). 13C NMR
(100 MHz, CDCl3) δ = 187.9, 137.6, 135.6, 134.6, 132.6, 130.2, 129.8,
129.3, 129.0, 63.3. HRMS (ESI+) m/z Calcd. For C14H12BrO3S [M + H]+:
m/z 338.9685, found 338.9685.
1-(4-Bromophenyl)-2-tosylethan-1-one (6h): White solid, 77 %
yield (54.2 mg). 1H NMR (400 MHz, CDCl3) δ 7.82 (d, J = 8.1 Hz, 2H),
7.74 (d, J = 7.9 Hz, 2H), 7.66–7.57 (m, 2H), 7.34 (d, J = 7.6 Hz, 2H),
4.69 (s, 2H), 2.45 (s, 3H). 13C NMR (100 MHz, CDCl3) δ = 187.3, 145.6,
1-Phenyl-2-((4-(trifluoromethoxy)phenyl)sulfonyl)ethan-1-one
(6q): White solid, 78 % yield (53.7 mg). 1H NMR (400 MHz, CDCl3) δ
135.6, 134.5, 132.2, 130.9, 129.9, 128.6, 63.7, 21.8. HRMS (ESI+) m/z 7.99–7.94 (m, 2H), 7.91 (d, J = 8.2 Hz, 2H), 7.64–7.59 (m, 1H), 7.47
Calcd. For C15H14BrO3S [M + H]+: m/z 352.9842, found 352.9841.
(t, J = 7.8 Hz, 2H), 7.34 (d, J = 8.8 Hz, 2H), 4.78 (s, 2H). 13C NMR
(100 MHz, CDCl3) δ = 187.97, 153.33, 136.93, 135.60, 134.53, 131.11,
129.18, 128.94, 128.77 (q, J = 59.7 Hz), 120.78, 120.18 (q, J =
260.0 Hz), 120.78, 63.23. 19F NMR (376 MHz, CDCl3) δ = –57.63.
HRMS (ESI+) m/z Calcd. For C15H12F3O4S [M + H]+: m/z 345.0403,
found 345.0402.
Methyl 4-(2-tosylacetyl)benzoate (6i): White solid, 76 % yield
(50.5 mg). 1H NMR (400 MHz, CDCl3) δ 8.12 (d, J = 8.0 Hz, 2H), 8.00
(d, J = 7.9 Hz, 2H), 7.75 (d, J = 7.8 Hz, 2H), 7.34 (d, J = 7.9 Hz, 2H),
4.75 (s, 2H), 3.96 (s, 3H), 2.44 (s, 3H). 13C NMR (100 MHz, CDCl3) δ =
187.9, 165.9, 145.6, 138.8, 135.6, 134.8, 130.0, 129.9, 129.3, 128.6,
63.8, 52.6, 21.7. HRMS (ESI+) m/z Calcd. For C17H17O5S [M + H]+: m/z
333.0791, found 333.0790.
4-((2-Oxo-2-phenylethyl)sulfonyl)benzonitrile (6r): White solid,
77 % yield (47.3 mg). 1H NMR (400 MHz, CDCl3) δ 8.04 (d, J = 8.4 Hz,
2H), 7.94–7.89 (m, 2H), 7.84 (d, J = 8.4 Hz, 2H), 7.65 (t, J = 7.4 Hz,
1H), 7.50 (t, J = 7.8 Hz, 2H), 4.82 (s, 2H). 13C NMR (100 MHz, CDCl3)
δ = 187.8, 142.7, 135.4, 134.8, 132.9, 129.5, 129.2, 129.1, 117.9, 117.1,
62.9. HRMS (ESI+) m/z Calcd. For C15H12NO3S [M + H]+: m/z
308.0352, found 308.3051.
1-(p-Tolyl)-2-tosylethan-1-one (6j): White solid, 81 % yield
(46.7 mg). 1H NMR (400 MHz, CDCl3) δ 7.84 (d, J = 7.8 Hz, 2H), 7.75
(d, J = 7.8 Hz, 2H), 7.32 (d, J = 7.9 Hz, 2H), 7.27 (d, J = 7.8 Hz, 2H),
4.69 (s, 2H), 2.42 (d, J = 7.0 Hz, 6H). 13C NMR (100 MHz, CDCl3) δ =
187.7, 145.6, 145.3, 135.8, 133.4, 129.8, 129.6, 129.5, 128.6, 63.6, 21.8,
21.7. HRMS (ESI+) m/z Calcd. For C16H17O3S [M + H]+: m/z 289.0893,
found 289.0892.
2-((3-Bromophenyl)sulfonyl)-1-phenylethan-1-one (6s): White
solid, 77 % yield (52.1 mg). 1H NMR (400 MHz, CDCl3) δ 8.03 (d, J =
1.2 Hz, 1H), 7.92 (d, J = 7.9 Hz, 2H), 7.84 (d, J = 7.8 Hz, 1H), 7.77 (d,
J = 7.9 Hz, 1H), 7.62 (t, J = 6.9 Hz, 1H), 7.48 (dd, J = 7.6 Hz, 2H), 7.42
(t, J = 7.9 Hz, 1H), 4.77 (s, 2H). 13C NMR (100 MHz, CDCl3) δ = 187.8,
140.6, 137.3, 135.6, 134.6, 131.5, 130.7, 129.2, 129.0, 127.3, 123.2,
63.2. HRMS (ESI+) m/z Calcd. For C14H12BrO3S [M + H]+: m/z
338.9685, found 338.9685.
1-(4-Ethylphenyl)-2-tosylethan-1-one (6k): White solid, 83 % yield
(50.1 mg). 1H NMR (400 MHz, CDCl3) δ 7.87 (d, J = 7.9 Hz, 2H), 7.76
(d, J = 7.9 Hz, 2H), 7.33–7.28 (m, 4H), 4.70 (s, 2H), 2.71 (q, J = 7.6 Hz,
2H), 2.43 (s, 3H), 1.25 (t, J = 7.6 Hz, 3H). 13C NMR (100 MHz, CDCl3)
δ = 187.7, 151.6, 145.3, 135.8, 133.6, 129.8, 129.6, 128.6, 128.4, 63.6,
29.0, 21.7, 15.1. HRMS (ESI+) m/z Calcd. For C17H19O3S [M + H]+: m/z
303.1049, found 303.1048.
2-((3,4-Dichlorophenyl)sulfonyl)-1-phenylethan-1-one (6t):
White solid, 81 % yield (56.7 mg). 1H NMR (400 MHz, CDCl3) δ 7.98
(d, J = 1.8 Hz, 1H), 7.91 (d, J = 7.8 Hz, 2H), 7.73 (dd, J = 8.4, 1.8 Hz,
1H), 7.66–7.60 (m, 2H), 7.49 (t, J = 7.7 Hz, 2H), 4.78 (s, 2H). 13C NMR
(100 MHz, CDCl3) δ = 187.8, 139.4, 138.4, 135.5, 134.7, 133.9, 131.3,
130.7, 129.2, 129.0, 127.9, 63.1. HRMS (ESI+) m/z Calcd. For
C14H10Cl2NaO3S [M + Na]+: m/z 350.9620, found 350.9620.
1-(Naphthalen-2-yl)-2-tosylethan-1-one (6l): White solid, 61 %
yield (39.5 mg). 1H NMR (400 MHz, CDCl3) δ 8.45 (s, 1H), 7.96 (d, J =
8.2 Hz, 2H), 7.88 (d, J = 9.3 Hz, 2H), 7.77 (d, J = 7.6 Hz, 2H), 7.64 (t,
J = 7.4 Hz, 1H), 7.57 (t, J = 7.5 Hz, 1H), 7.31 (d, J = 7.8 Hz, 2H), 4.85
(s, 2H), 2.40 (s, 3H). 13C NMR (100 MHz, CDCl3) δ = 188.1, 145.4,
136.0, 135.7, 133.1, 132.3, 132.2, 130.0, 129.9, 129.4, 128.8, 128.7,
127.8, 127.1, 124.0, 63.8, 21.7. HRMS (ESI+) m/z Calcd. For C19H17O3S
[M + H]+: m/z 325.0893, found 325.0891.
2-(Mesitylsulfonyl)-1-phenylethan-1-one (6u): White solid, 79 %
yield (47.3 mg). 1H NMR (400 MHz, CDCl3) δ 7.97 (d, J = 7.9 Hz, 2H),
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doi.org/10.1002/ejoc.202001059
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7.61 (t, J = 7.4 Hz, 1H), 7.48 (t, J = 7.7 Hz, 2H), 6.95 (s, 2H), 4.72 (s,
2H), 2.58 (s, 6H), 2.30 (s, 3H). 13C NMR (100 MHz, CDCl3) δ = 188.4,
144.0, 140.3, 136.1, 134.3, 132.9, 132.4, 129.4, 128.8, 63.6, 23.0, 21.1.
HRMS (ESI+) m/z Calcd. For C17H19O3S [M + H]+: m/z 303.1049, found
303.1049.
2-(Naphthalen-2-ylsulfonyl)-1-phenylethan-1-one (6v): White
solid, 73 % yield (45.3 mg). 1H NMR (400 MHz, CDCl3) δ 8.45 (s, 1H),
7.97–7.85 (m, 6H), 7.65 (t, J = 7.4 Hz, 1H), 7.62–7.53 (m, 2H), 7.42 (t,
J = 7.7 Hz, 2H), 4.82 (s, 2H). 13C NMR (100 MHz, CDCl3) δ = 188.1,
135.8, 135.7, 135.5, 134.4, 132.0, 130. 7, 129.6, 129.6, 129.5, 129.3,
128.9, 128.0, 127.8, 123.0, 63.5. HRMS (ESI+) m/z Calcd. For
C18H15O3S [M + H]+: m/z 311.0736, found 311.0735.
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2-(Ethylsulfonyl)-1-phenylethan-1-one (6w): Colorless oil, 64 %
yield (27.1 mg). 1H NMR (400 MHz, CDCl3) δ 8.04–7.98 (m, 2H), 7.68–
7.62 (m, 1H), 7.52 (t, J = 7.8 Hz, 2H), 4.58 (s, 2H), 3.28 (q, J = 7.5 Hz,
2H), 1.45 (t, J = 7.5 Hz, 3H). 13C NMR (100 MHz, CDCl3) δ = 189.3,
135.8, 134.6, 58.8, 48.3, 6.6. HRMS (ESI+) m/z Calcd. For C10H13O3S
[M + H]+: m/z 213.0580, found 213.0580.
9-Chloro-6-((4-phenyl-1H-1,2,3-triazol-1-yl)methyl)phen-
anthridine (2ra): Yellow solid, 82 % yield (60.7 mg). 1H NMR
(400 MHz, CDCl3) δ 8.58 (d, J = 1.8 Hz, 1H), 8.48 (d, J = 8.0 Hz, 1H),
8.37 (d, J = 8.8 Hz, 1H), 8.19 (d, J = 8.1 Hz, 1H), 7.87 (s, 1H), 7.80 (d,
J = 8.1 Hz, 1H), 7.74 (dd, J = 11.5, 7.5 Hz, 3H), 7.63 (d, J = 8.8, 1.9 Hz,
1H), 7.35 (t, J = 7.5 Hz, 2H), 7.27 (t, J = 5.0 Hz, 1H), 6.23 (s, 2H).
13C NMR (150 MHz, CDCl3) δ = 153.0, 137.9, 134.8, 130.4, 129.7,
128.8, 128.8, 128.3, 128.2, 127.4, 125.7, 122.4, 122.2, 55.0. HRMS
(ESI+) m/z Calcd. For C22H16N4Cl [M + H]+: m/z 371.1058, found
371.1054.
Conflict of interest.
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There are no conflicts to declare.
Acknowledgments
We acknowledge the financial support from the National Sci-
ence Foundation of China (NSFC-21804018) and Shanghai
(19ZR1470800), as well as the Fundamental Research Funds for
the Central Universities (2232020A-09).
Keywords: Phenanthridines · Vinyl azides · Electrochemical
synthesis · Oxidative cyclization
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Received: August 3, 2020
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