One-pot Cascade Reaction for the Synthesis of Phenanthridines via Suzuki Coupling/C?H Oxidation/Aromatization

Article abstract of DOI:10.1002/adsc.202000949

A one-pot cascade coupling/annulation reaction for the synthesis of phenanthridines has been developed from arylboronic acids and o-bromo arylamides with DMSO as a carbon source. The desired phenanthridines were obtained in moderate to good yields by using simple procedure. (Figure presented.).

Full text of DOI:10.1002/adsc.202000949

Title: One-pot cascade reaction for the synthesis of phenanthridines via
Suzuki coupling/C-H oxidation/aromatization
Authors: yi zhang, Renchao Ma, Rener Chen, and Yongmin Ma
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To be cited as: Adv. Synth. Catal. 10.1002/adsc.202000949
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10.1002/adsc.202000949
Advanced Synthesis & Catalysis
FULL PAPER
DOI: 10.1002/adsc.201((will be filled in by the editorial staff))
One-pot cascade reaction for the synthesis of phenanthridines
via Suzuki coupling/C-H oxidation/aromatization
Yi Zhanga,b , Yuxin Dinga,b, Rener Chena and Yongmin Maa,b*
aInstitute of Advanced Studies and School of Pharmaceutical and Chemical Engineering, Taizhou University, 1139 Shifu
Avenue, Taizhou, 318000, P R China
Tel: (+86) 576 88665507; e-mail: yongmin.ma@tzc.edu.cn
bSchool of Pharmaceutical Science, Zhejiang Chinese Medical University, Hangzhou, 310053, P R China
Received: ((will be filled in by the editorial staff))
Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/adsc.201######.((Please
delete if not appropriate))
Abstract. A one-pot cascade coupling/annulation reaction for
the synthesis of phenanthridines has been developed from
arylboronic acids and o-bromo arylamides with DMSO as a
carbon source. The desired phenanthridines were obtained in
moderate to good yields by using simple procedure.
Keywords: phenanthridine; annulation; C-C coupling;
methylenation; oxidation
in Figure 2. Although many methods for building the
phenanthridine motif have been set up[15], simple and
effective methodologies using easily accessible
starting materials are still highly demanded for the
synthesis of the phenanthridines.
In the past few years, an abundance of reports has
shown that dimethyl sulfoxide (DMSO) can be not
only an aprotic solvent, but also thought as a substrate,
Introduction
Phenanthridines, particularly those of 6-unsubstituted
phenanthridines, represent a core substructure of a
number of biologically active natural products and
compounds containing such a motif possess several
pharmacological activities such as antimalarial[1],
cytotoxicity[2], antibacterial[3], anticancer[4], antifungal
properties[5] and SPECT tracers[6]. Figure 1 shows
some biologically active phenanthridines. Because of
these potential therapeutic properties, the development
of effective methods for constructing the
phenanthridine skeleton has attracted great attention
and a wide range of versatile methods have been
developed in the last few decades. In general, the
common strategies for constructing the 6-
unsubstituted phenanthridine skeleton include Suzuki
coupling and condensation[7], reductive cyclization[8],
dehydrogenation of 5,6-dihydrophenanthridine[9],
nitrogenation of 2-acetylbiphenyls[10], nucleophilic
substitution/C-H activation/aromarization cascade
building
block,
or
synthon
in
organic
transformations[16]. In 2013, Zhang et al. revealed that
quinazolines can be efficiently synthesized from
amidines catalyzed by Cu(OTf)2 using DMSO as a
methylene donor[17]. You et al. developed an effective
protocol for the preparation of 1,2-disubstituted
propenones
using
NaAuCl4/Selectfluor/DMSO
system[18]. Very recently, Yi et al. reported cobalt-
catalyzed allylation of amides using DMSO as both the
solvent and the methylene source[19]. Talukdar
demonstrated Ru(II) photo-catalyzed synthesis of
acetals from alcohols by DMSO[20]. In addition, a
reaction[11], hydride-induced anionic cyclization[12]
,
photolysis[13] and cross-ring [5+1] annulation[14]. Some
representative syntheses of phenanthridines are listed
Figure
phenanthridines
1
Some examples of biologically active
Figure 2 Some representative syntheses of 6-unsubstituted
phenanthridines
1
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10.1002/adsc.202000949
Advanced Synthesis & Catalysis
Table 1. Optimization of the reaction conditionsa
cascade [4+1] annulation of sulfonium salts for
synthesis of polyfunctional furans using DMSO as one
carbon source was established[21]. We also used
DMSO as a methylene source to promote a direct
methylenation of 1,3-diketones and acetophenones for
the production of polysubstituted pyridines and 3-
ENTRY
Oxidant
(equiv.)
I2 (1)
H2O2 (1)
SO3Py (1)
K2S2O8 (1)
K2S2O8 (0.5) Cu(OTf)2 (10)
K2S2O8 (1.5) Cu(OTf)2 (10)
K2S2O8 (2)
Catalyst
(mol%)
Cu(OTf)2 (10)
Cu(OTf)2 (10)
Cu(OTf)2 (10)
Cu(OTf)2 (10)
Temp Yield
acylquinolines, respectively[22]
.
(oC)
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
60
(%)b
trace
NR
14
46
trace
58
70
70
65
37
17
23
34
14
58
42
52
63
In 2012, Qiu et al. described a fast and efficient
approach for a cross-coupling of aryl halides and
arylboronic acids in pure water catalyzed by
Pd(OAc)2[23]. Inspired by these excellent pioneering
work and encouraged by our recent work, we envision
a one-pot cascade synthetic approach to the 6-
unsubstituted phenanthridines by coupling of readily
accessible 2’-bromoacetanilides and arylboronic acids
catalyzed by Pd(OAc)2 and followed by
intramolecular annulation in a DMSO/K2S2O8 system.
Herein, we wish to report a new protocol where a
Suzuki coupling[24] is performed first and the resulting
intermediate is cyclized and dehydrogenated mediated
by the DMSO/K2S2O8 system to afford the
phenanthridines. In this regard, DMSO is used as both
the carbon source and the reaction medium.
1
2
3
4
5
6
7
8
Cu(OTf)2 (10)
K2S2O8 (2.5) Cu(OTf)2 (10)
9
K2S2O8 (3)
K2S2O8 (4)
K2S2O8 (2)
K2S2O8 (2)
K2S2O8 (2)
K2S2O8 (2)
K2S2O8 (2)
K2S2O8 (2)
K2S2O8 (2)
K2S2O8 (2)
K2S2O8 (2)
K2S2O8 (2)
K2S2O8 (2)
K2S2O8 (2)
K2S2O8 (2)
K2S2O8 (2)
K2S2O8 (2)
Cu(OTf)2 (10)
Cu(OTf)2 (10)
TfOH (10)
TsOH (10)
K2CO3 (10)
Et3N (10)
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
FeCl3 (10)
ZnCl2 (10)
Cu(OAc)2 (10)
Pd(OAc)2 (10)
Cu(OTf)2 (5)
Cu(OTf)2 (20)
Cu(OTf)2 (10)
Cu(OTf)2 (10)
Cu(OTf)2 (10)
Cu(OTf)2 (10)
--
22
55
NR
17
36
Results and Discussion
80
100
130
120
60
11
In order to elucidate the optimal reaction conditions,
phenyl boronic acid (1a, 1 mmol) and N-(2-
bromophenyl)acetamide (2a, 1 mmol) were chosen as
the initial starting materials and the reaction was
performed in water (2 mL) for 5 min in the presence of
Pd(OAc)2 (0.05 mol%) and (i-Pr)2NH (2 equiv.)
previously before investigating the effect of different
oxidants, catalysts and temperatures on the product
yield. Initial oxidant screening demonstrated that
iodine and hydrogen peroxide are ineffective in the
present protocol while sulfur trioxide pyridine
complex gave low yield of the target product 3aa
(entries 1-3). To our delight, when potassium
persulfate was employed as the oxidant for the
annulation, the expected product 3aa was isolated in
46% yield, indicating that K2S2O8 is the most efficient
oxidant among the oxidants investigated (entry 4). By
screening the amount of oxidant, the best result was
achieved when K2S2O8 at 2 equivalents was applied
and 70% yield of 3aa was afforded (entries 4-7).
Further increase the amount of the oxidant led to
diminished yields, possibly due to an over-oxidation
(entries 8-10). Apart from Cu(OTf)2, other catalysts
such as TfOH, TsOH, K2CO3, Et3N, FeCl3, ZnCl2,
Cu(OAc)2 and Pd(OAc)2 at 10 mol% were also
employed in the protocol and it was clear that the most
efficient catalyst in the present catalytic system was
Cu(OTf)2 (entry 7 vs 11-18). Further investigation of
the amount of the catalyst indicated that 10 mol% was
an ideal amount (entry 7 vs 19-20). The effect of
reaction temperatures on the yields was then
investigated. With decreases of the reaction
temperature, the yield of 3aa was correspondingly
decreased (entries 21-23), whereas an increase of the
aThe reaction was carried out with 1a (1 mmol), 2a (1 mmol),
Pd(OAc)2 (0.25 mol%), (i-Pr)2NH (2 equiv.), H2O (2 mL) at
o
100 C for 5 min, then water was removed and DMSO (2
mL), oxidant and catalyst at the indicated amount were
added and the mixture was heated for 48 hrs; bIsolated yields.
mixture and therefore a diminished yield was achieved
(entry 24). It is worth noting that in the absence of the
catalyst, the reaction can proceed but with only 11%
yield (entry 25). After tedious screening of different
parameters, an optimal reaction condition for the
annulation was set up as in entry 7 of Table 1.
With the optimized reaction conditions in hand, the
substrate scope of the reaction with respect to various
aryl
boronic
acids
(1)
with
N-(2-
bromophenyl)acetamide (2a) was investigated. As
shown in Table 2, a series of para-, meta- and ortho-
substituted phenyl boronic acids bearing electron-
donating groups (-OMe, -Me) and electron-
withdrawing groups (-F, -Cl) were smoothly converted
into the corresponding phenanthridines in moderate to
good yields (3aa-3ja). This result also showed that
aryl boronic acids bearing electron-donating groups
gave slightly higher yields than those bearing electron-
withdrawing groups (3ba-3ea vs 3fa-3ga and 3ha vs
3ia). Unfortunately, 4-CF3 substituted phenyl boronic
acid only provided a complicated unidentified mixture,
which may be due to its strong electron-deficient
property. On the other hand, the position of the group
on the phenyl ring dramatically influenced the yield.
For example, para- and meta-methyl substituted
phenyl boronic acids proceeded in the reaction in 73%
and 72% yields respectively while ortho-methyl
o
temperature to 130 C led to coking of the reaction
2
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10.1002/adsc.202000949
Advanced Synthesis & Catalysis
Table 2. Substrate scope based on arylboronic acids 1a
On the other hand, replacement of the acetyl with
formyl or Tosyl could afford the product, but with
decreased yields (Scheme 1, eqns. 2 and 3).
To further explore the universality of the
coupling/aromatization reaction, several commercially
available substituted 2’-bromoacetanilides (2) were
reacted with aryl boronic acids (1) under the same
optimized conditions (Table 3). It can be found that
electronic nature and steric nature of the substituted 2’-
bromoacetanilides (2) had little influence on the
reaction efficiency. For example, 68% yield of 3ab
was achieved when 2’-bromo-4’-methylacetanilide
(2b) was reacted with 1a under the standard conditions.
Meanwhile, 4’-chloro and 6’-fluoro analogues (2c and
2d) gave the corresponding phenanthridines 3ac and
3ad in 68% and 64% yields, respectively. Very similar
yields were obtained when other aryl boronic acids
such as 1b or 1i was reacted with 2b, 2c and 2d,
respectively (groups of 3bb, 3bc, 3bd and 3ib, 3ic,
3id). On the other side, similar results were obtained
when the substituted 2’-bromoacetanilides (2) were
reacted with different aryl boronic acids, as mentioned
previously. For instance, ortho-substituted phenyl
boronic acids gave relatively lower yield by compared
to their meta- and para-analogues. On the other hand,
meta-substituted phenylboronic acids also gave two
regioisomeric phenanthridines and the less crowded
analogues are the major products.
analogue gave the corresponding phenanthridine in
40% yield only (3ca/3ea vs 3ja). It is worth noting that
when meta-substituted substrates 1 were employed,
two regioisomeric phenanthridines were formed. Due
to the steric effect, the major product was less crowded
phenanthridines which the annulation occurred at the
para-position of the substituted group (see 3da-3ga).
In addition, 1- and 2-naphthylboronic acids (1k and 1l)
were also investigated for the transformation. The
corresponding phenanthridines (3ka and 3la,
respectively) could be afforded, but the production of
3ka required higher temperature and with lower yield.
Other possible regioisomer of 3la (attacking to 3-
rather than 1-position of naphthalene) was not found.
Furthermore, several heterocyclic boronic acids
including 3-furanboronic acid, 2-thienylboronic acid,
3-pyridylboronic acid, 5-pyrimidylboronic acid,
indole-5-boronic acid and 4-isoquinolineboronic acid
as substrates were also attempted but unfortunately all
failed to afford the desired products.
Table 3. Substrate scope based on both 1 and 2a
To investigate the limitation of this tandem
coupling/oxidation system, several different N-
substituted 2’-bromophenylamides (2) were examined
under the optimized reaction conditions. When the
acetyl group of 2a was replaced with hydrogen, the
expected product was not obtained (Scheme 1, eqn. 1).
Scheme 1 The reaction with different N-substituted 2-
bromophenylamines
3
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10.1002/adsc.202000949
Advanced Synthesis & Catalysis
To gain an insight into the reaction mechanism, some
controlled experiments were performed (Scheme 2). A
quantitative yield of the Suzuki coupling intermediate
4aa was obtained from the substrate 1a and 2a
catalyzed by Pd(OAc)2 (Scheme 2, eq. 1). Intermediate
4aa was converted successfully into the desired
product 3aa by Cu(OTf)2/K2S2O8 in DMSO (Scheme
2, eq. 2). When the intermediate 4ka produced from
the coupling of 1k and 2a was performed the
annulation under the standard conditions, the expected
product 3ka was not obtained. Instead, 1-
(benzo[k]phenanthridin-5(6H)-yl)ethanone (5ka) was
identified as the main product where the acetyl group
on N remained. 5ka could be converted into 3ka when
o
the reaction temperature was increased to 140 C
(Scheme 2, eq. 3). This result revealed that the 1-
(phenanthridin-5(6H)-yl)ethanones might be the
intermediates for the production of the
phenanthridines. The kinetic deuterium isotope effect
of the reaction in the presence of DMSO and DMSO-
d6 at 1:1 ratio was investigated under the optimal
conditions and 3ab/[d]-3ab = 1:0.9 was achieved from
the reaction of 1a and 2b (Scheme 2, eq. 4), indicating
that the C(sp3)-H bond cleavage of DMSO might not
be involved in the rate-determining step.
Although a more detailed study might be required to
fully understand the mechanism of this tandem
reaction, a tentative pathway can be proposed based on
the aforementioned results and literature reports[16g, 17,
21, 25] (Scheme 3). Diisopropylamine has been reported
to act as both a base and a ligand, which has a tendency
to coordinate with palladium to form the active
species[26]. Then the oxidative addition of compound 2
to in situ generated Pd0 species occurs, to form a PdII
intermediate A. A couples with aryl boronic acid 1,
Scheme 2 Control experiments
followed by reductive elimination to afforded
intermediate 4 and a Pd0 species, which is reoxidized
to complete the catalytic cycle. The coupling of the N-
aryl acetamide 4 with the copper catalyst affords Cu2+
amide C. Subsequently, the intermediate C reacts with
meth(methylene)sulfonium cation D[27] which is
generated from DMSO activated by K2S2O8 to give
intermediate E. The intermediate E undergoes
demethylthioation in the presence of K2S2O8 to afford
an iminium species F, which follows an intramolecular
electrophilic
annulation
to
provide
dihydrophenanthridine 5. 5 is oxidized with K2S2O8,
followed by an elimination of acetyl cation to give the
aromatic product 3.
Scheme 3 Plausible reaction mechanism
4
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10.1002/adsc.202000949
Advanced Synthesis & Catalysis
127.68, 127.15, 126.94, 124.29, 123.58, 122.05, 121.73,
107.98, 55.58. ESI-MS: m/z [M + H]+ 210.
Conclusion
8-Methylphenanthridine (3ca).[14b] Petroleum ether/ethyl
actate (8:1) as eluent; White solid (140.8 mg, 73%), mp 122-
123 °C. 1H NMR (400 MHz, Chloroform-d) δ 9.22 (s, 1H),
8.54 (d, J = 8 Hz, 1H), 8.49 (d, J = 8.4 Hz, 1H), 8.17 (d, J =
8 Hz, 1H), 7.82 (s, 1H), 7.73 – 7.64 (m, 3H), 2.60 (s, 3H).
13C NMR (101 MHz, Chloroform-d) δ 153.35, 144.18,
137.53, 132.82, 130.45, 130.05, 128.22, 128.17, 127.00,
126.60, 124.25, 122.05, 121.77, 21.53. ESI-MS: m/z [M +
H]+ 194.
In conclusion, we have disclosed a one-pot cascade
reaction for the formation of phenanthridines from
arylboronic acid and o-bromo N-aryl acetamides.
Moderate to good yields of total 50 phenanthridines
were achieved with 22 new compounds by using
simple procedure and reaction conditions. Based on
several control experiments, a plausible mechanism
was also proposed to elucidate the catalytic cycle
pathway. Further investigations DMSO as a carbon
donor for annulation reactions to construct
heterocycles are underway in our laboratory.
9-Methoxyphenanthridine (3da).[30] Petroleum ether/ethyl
actate (10:1) as eluent; White solid (98.0 mg, 47%), mp 68-
1
69 °C. H NMR (400 MHz, Chloroform-d) δ 9.16 (s, 1H),
8.48 (d, J = 8.4 Hz, 1H), 8.16 (d, J = 7.6 Hz, 1H), 7.94 (d, J
= 8.8 Hz, 1H), 7.89 (d, J = 2.0 Hz, 1H), 7.73 (td, J = 8, 1.2
Hz, 1H), 7.64 (td, J = 7.6, 1.2 Hz, 1H), 7.29 (dd, J = 8.8, 3.0
Hz, 1H), 4.03 (s, 3H). 13C NMR (101 MHz, Chloroform-d)
δ 161.79, 152.74, 144.70, 134.58, 130.55, 130.09, 128.76,
126.54, 123.89, 122.20, 121.51, 117.79, 102.53, 55.60. ESI-
MS: m/z [M + H]+ 210.
Experimental Section
General methods. N-(2-bromophenyl)acetamides (2c, 2d)
were prepared according to the previously reported
literature.[28] N-(2-bromophenyl)formamide (2a’’) and N-
7-Methoxyphenanthridine
(3da’).[12]
Petroleum
(2-bromophenyl)-4-methylbenzenesulfonamide
(2a’’’)
were synthesized based on the known literatures.[29] Their
analysis data were identical with the reported data. Other
starting materials, reagents and solvents were purchased
commercial sources and used as received. 1H and 13C NMR
spectra were recorded at 400 and 101 MHz, respectively.
High-resolution mass spectra (HRMS) were performed on a
Waters SYNAPT G2-Si mass spectrometer. HPLC analyses
were carried out on a Agilent 1260 Infinity II instrument.
Melting points were determined using a X-4 digital micro
melting point apparatus. All reactions were monitored by
thin-layer chromatography (TLC) using silica gel plates
(silica gel 60 F254).
ether/ethyl actate (10:1) as eluent; White solid (58.5 mg,
28%), mp 92-93 °C. H NMR (400 MHz, Chloroform-d) δ
1
9.73 (s, 1H), 8.53 (d, J = 8.4 Hz, 1H), 8.19 (d, J = 8.0 Hz,
1H), 8.14 (d, J = 8 Hz, 1H), 7.76-7.72 (m. 2H), 7.65 (t, J =
8 Hz, 1H), 7.04 (d, J = 8 Hz, 1H), 4.05 (s, 3H). 13C NMR
(101 MHz, Chloroform-d) δ 157.43, 148.26, 144.56, 133.92,
131.65, 129.98, 128.74, 126.85, 123.72, 122.66, 117.39,
113.77, 106.70, 55.77. ESI-MS: m/z [M + H]+ 210.
Mixture of 9-methylphenanthridine (3ea) and 7-
methylphenanthridine (3ea’).[12,31] Petroleum ether/ethyl
actate (8:1) as eluent; White solid (139 mg, 72%), mp 119-
1
121 °C. H NMR (400 MHz, Chloroform-d) δ 9.54 (s,
0.57H), 9.21 (s, 0.43H), 8.56 (d, J = 7.6 Hz, 0.57H), 8.54 (d,
J = 8.4 Hz, 0.43H), 8.45 (d, J = 8.0 Hz, 0.57H), 8.35 (s,
0.43H), 8.19 (d, J = 8.4 Hz, 0.57H), 8.17 (d, J = 8.4 Hz,
0.43H), 7.91 (d, J = 8.4 Hz, 0.43H), 7.75-7.62 (m, 2.57H),
7.50 (d, J = 8.4 Hz, 0.43H), 7.46 (d, J = 7.2 Hz, 0.57H), 2.85
(s, 1.7H), 2.63 (s, 1.2H). 13C NMR (101 MHz, Chloroform-
d) δ 153.26, 150.27, 144.56, 144.09, 141.49, 136.57, 132.81,
132.65, 130.72, 130.03, 130.00, 129.22, 128.80, 128.60,
128.53, 127.04, 126.81, 124.86, 124.57, 124.25, 123.97,
122.40, 122.40, 122.18, 121.48, 120.02, 22.46, 18.90. ESI-
MS: m/z [M + H]+ 210.
General Produce for the synthesis of phenanthridine
(3). The reaction was carried out with 1a (1 mmol), 2a (1
mmol), Pd(OAc)2 (0.25 mol%), (i-Pr)2NH (2 equiv.), H2O
o
(2 mL) at 100 C for 5 min, then water was discarded and
DMSO (2 mL), oxidant and catalyst at the indicated amount
were added and the mixture was heated for 48 hrs. After
being cooled to room temperature, the reaction was
extracted with CH2Cl2. The combine organic layer was
washed with H2O and brine, and then dried over anhydrous
Na2SO4. The sovent was removed under reduced pressure
and the residue was purified by chromatography on silica
gel to afford the desired phenanthridine (3).
9-Fluorophenanthridine (3fa).[12] Petroleum ether/ethyl
actate (8:1) as eluent; White solid (Petroleum ether/ethyl
actate (8:1) as eluent; White solid (106 mg, 54%), mp 142-
143 °C. 1H NMR (400 MHz, Chloroform-d) δ 9.24 (s, 1H),
8.43 (d, J = 8.2 Hz, 1H), 8.20-8.16 (m, 2H), 8.05 (dd, J =
8.8, 5.7 Hz, 1H), 7.78 (dt, J = 7.6, 1.4 Hz, 1H), 7.68 (dt, J =
7.6, 1.4 Hz, 1H), 7.43 (td, J = 8.5, 2.4 Hz, 1H). 13C NMR
(101 MHz, Chloroform-d) δ 164.15 (d, J = 251 Hz), 152.59,
144.48, 134.73 (d, J = 9.3 Hz), 131.49 (d, J = 9.6 Hz),
130.23, 129.38, 127.16, 123.58 (d, J = 3.6 Hz), 123.36,
122.38, 116.80 (d, J = 24.2 Hz), 107.18 (d, J = 22.3 Hz).
ESI-MS: m/z [M + H]+ 198.
Phenanthridine (3aa).[14b] Petroleum ether/ethyl actate
(8:1) as eluent; White solid (125.3 mg, 70%), mp 97-98 °C.
1H NMR (400 MHz, Chloroform-d) δ 9.23 (s, 1H), 8.55 (d,
J = 8.0 Hz, 1H), 8.52 (dd, J = 8.4, 1.2 Hz, 1H), 8.13 (dd, J
= 8.0, 1.2 Hz, 1H), 7.98 (d, J = 8.0 Hz, 1H), 7.80 (dt, J = 7.2,
1.2 Hz, 1H), 7.69 – 7.62 (m, 3H). 13C NMR (101 MHz,
Chloroform-d) δ 152.50, 143.36, 131.55, 130.02, 129.06,
127.77, 127.68, 126.48, 126.08, 125.27, 123.10, 121.19,
120.85. ESI-MS: m/z [M + H]+ 180.
8-Methoxyphenanthridine
(3ba).[14b]
Petroleum
ether/ethyl actate (8:1) as eluent; White solid (158.8 mg,
76%), mp 152-153 °C. 1H NMR (400 MHz, Chloroform-d)
δ 9.23 (s, 1H), 8.51-8.46 (m, 2H), 8.16 (d, J = 7.6 Hz, 1H),
7.70-7.62 (m, 2H), 7.47 (dd, J = 9.0, 2.7 Hz, 1H), 7.37 (d, J
= 2.7 Hz, 1H), 3.98 (s, 3H). 13C NMR (101 MHz,
Chloroform-d) δ 158.89, 152.76, 143.61, 130.01, 128.83,
9-Chlorophenanthridine (3ga).[12] Petroleum ether/ethyl
actate (10:1) as eluent; White solid (93.7 mg, 44%), mp 85-
1
86 °C. H NMR (400 MHz, Chloroform-d) δ 9.25 (s, 1H),
8.58 (s, 1H), 8.50 (d, J = 8.4 Hz, 1H), 8.20 (d, J = 8.0 Hz,
1H), 8.00 (d, J = 8.8 Hz, 1H), 7.79 (td, J = 7.6, 1.2 Hz, 1H),
5
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10.1002/adsc.202000949
Advanced Synthesis & Catalysis
7.71 (td, J = 7.6, 1.2 Hz, 1H), 7.67 (dd, J = 8.4, 1.6 Hz, 1H).
13C NMR (101 MHz, Chloroform-d) δ 152.71, 144.63,
137.53, 133.76, 130.26, 130.21, 129.42, 128.26, 127.44,
124.67, 123.03, 122.26, 121.75. ESI-MS: m/z [M + H]+ 213.
7-Chlorophenanthridine (3ga’).[32] Petroleum ether/ethyl
actate (10:1) as eluent; White solid (32.0 mg, 15%), mp 123-
124 °C. 1H NMR (400 MHz, Chloroform-d) δ 9.76 (s, 1H),
8.56 (d, J = 8 Hz, 1H), 8.54 (d, J = 8 Hz, 1H), 8.23 (d, J = 8
Hz, 1H), 7.82-7.69 (m, 4H). 13C NMR (101 MHz,
Chloroform-d) δ 149.59, 144.35, 134.39, 133.92, 130.99,
130.29, 129.35, 128.05, 127.61, 123.17, 123.13, 122.39,
120.88. ESI-MS: m/z [M + H]+ 213.
2-Methylphenanthridine (3ab).[14b] Petroleum ether/ethyl
actate (8:1) as eluent; White solid (131.2 mg, 68%), mp 83-
1
85 °C. H NMR (400 MHz, Chloroform-d) δ 9.21 (s, 1H),
8.57 (d, J = 8.2 Hz, 1H), 8.33 (s, 1H), 8.07 (d, J = 8.3 Hz,
1H), 8.01 (d, J = 8.0 Hz, 1H), 7.82 (ddd, J = 8.3, 7.1, 1.4 Hz,
1H), 7.67 (ddd, J = 8.1, 7.1, 1.1 Hz, 1H), 7.56 (dd, J = 8.3,
1.9 Hz, 1H), 2.62 (s, 3H). 13C NMR (101 MHz, Chloroform-
d) δ 152.63, 142.76, 136.99, 132.30, 130.76, 130.39, 129.81,
128.69, 127.31, 126.47, 123.93, 121.82 (2C), 21.97. ESI-
MS (ESI): m/z [M + H]+ 194.
1
Mixture of 3ab and 6-deuterated 3ab H NMR (400 MHz,
Chloroform-d) δ 9.22 (s, 1H), 8.59 (d, J = 8.2 Hz, 1.9H),
8.35 (s, 1.9H), 8.08 (d, J = 8.3 Hz, 1.9H), 8.03 (d, J = 8.0
Hz, 1.9H), 7.84 (ddd, J = 8.3, 7.1, 1.4 Hz, 1.9H), 7.69 (ddd,
J = 8.1, 7.1, 1.1 Hz, 1.9H), 7.57 (dd, J = 8.3, 1.9 Hz, 1.9H),
2.63 (s, 5.7H).
7,9-Dimethylphenanthridine
(3ha).[31]
Petroleum
ether/ethyl actate (8:1) as eluent; White solid (155.2 mg,
75%), mp 101-102 °C. 1H NMR (400 MHz, Chloroform-d)
δ 9.47 (s, 1H), 8.54 (d, J = 8 Hz, 1H), 8.22 (s, 1H), 8.17 (d,
J = 7.6 Hz, 1H), 7.71 (t, J = 7.6 Hz, 1H), 7.63 (t, J = 7.2 Hz,
1H), 7.29 (s, 1H), 2.80 (s, 3H), 2.58 (s, 3H). 13C NMR (101
MHz, Chloroform-d) δ 150.03, 144.22, 141.03, 136.28,
132.99, 130.61, 129.89, 128.38, 126.74, 124.11, 123.09,
122.37, 119.58, 22.34, 18.71. ESI-MS: m/z [M + H]+ 208.
7,9-Difluorophenanthridine (3ia). Petroleum ether/ethyl
actate (8:1) as eluent; White solid (133.3 mg, 62%), mp
170-171 °C. 1H NMR (400 MHz, Chloroform-d) δ 9.50 (s,
1H), 8.40 (d, J = 8.2 Hz, 1H), 8.21 (d, J = 8.2 Hz, 1H), 7.99
(d, J = 10.1 Hz, 1H), 7.81 (t, J = 7.2 Hz, 1H), 7.70 (t, J = 7.2
Hz, 1H), 7.14 (dt, J = 9.6, 2.2 Hz, 1H). 13C NMR (101 MHz,
Chloroform-d) δ 163.80 (dd, J = 251, 12.7Hz), 161.08 (dd,
J = 257, 13.6 Hz), 145.76 (d, J = 7.4 Hz), 144.84, 135.43
(dd, J = 10.9, 4.8 Hz), 130.51, 130.00, 127.61, 122.71-
122.55 (m), 103.47-102.65 (m). HRMS (ESI): calcd. for
C13H8F2N m/z [M + H]+ 216.0619; found 216.0624.
8-Methoxy-2-methylphenanthridine (3bb).[34] Petroleum
ether/ethyl actate (8:1) as eluent; White solid (169.5 mg,
76%), mp 133-134 °C. 1H NMR (400 MHz, Chloroform-d)
δ 9.17 (s, 1H), 8.49 (d, J = 9.0 Hz, 1H), 8.26 (s, 1H), 8.05
(d, J = 8.3 Hz, 1H), 7.51 (dd, J = 8.3, 1.9 Hz, 1H), 7.46 (dd,
J = 9.0, 2.7 Hz, 1H), 7.36 (d, J = 2.7 Hz, 1H), 3.99 (s, 3H),
2.62 (s, 3H). 13C NMR (101 MHz, Chloroform-d) δ 158.79,
151.82, 141.80, 137.13, 129.62, 129.47, 127.76, 126.76,
124.12, 123.58, 121.95, 121.33, 107.90, 55.59, 22.01. ESI-
MS: m/z [M + H]+ 224.
2,8-dimethylphenanthridine
(3cb).[14b]
Petroleum
ether/ethyl actate (8:1) as eluent; White solid (149.0 mg,
72%), mp 133-134 °C. 1H NMR (400 MHz, Chloroform-d)
δ 9.12 (s, 1H), 8.42 (d, J = 8.4 Hz, 1H), 8.27 (s, 1H), 8.04
(d, J = 8.3 Hz, 1H), 7.74 (s, 1H), 7.61 (dd, J = 8.4, 1.8 Hz,
1H), 7.51 (dd, J = 8.3, 1.9 Hz, 1H), 2.59 (s, 3H), 2.55 (s,
3H). 13C NMR (101 MHz, Chloroform-d) δ 152.41, 142.48,
137.27, 136.84, 132.53, 130.16, 129.90, 129.73, 128.04,
126.64, 124.02, 121.69, 121.63, 21.95, 21.50.
10-Methylphenanthridine (3ja).[14b] Petroleum ether/ethyl
actate (8:1) as eluent; White solid (77.2 mg, 40%), mp 110-
111 °C. 1H NMR (400 MHz, Chloroform-d) δ 9.23 (s, 1H),
8.84 (d, J = 8.8 Hz, 1H), 8.24 (dd, J = 8, 1.2 Hz, 1H), 7.92
(d, J = 7.6 Hz, 1H), 7.75 (dt, J = 8, 1.2 Hz, 1H), 7.68-7.64
(m, 2H), 7.60 (t, J = 7.2 Hz, 1H), 3.11 (s, 3H). 13C NMR
(101 MHz, Chloroform-d) δ 154.53, 145.69, 135.18, 135.12,
131.81, 130.44, 127.96, 127.88 (2C), 126.96, 126.56,
126.37, 125.71, 26.53. ESI-MS: m/z [M + H]+ 194.
ESI-MS: m/z [M + H]+ 208.
Mixture of 2,9-dimethylphenanthridine (3eb) and 2,7-
dimethylphenanthridine (3eb’).[31] Petroleum ether/ethyl
actate (8:1) as eluent; White solid (144.9 mg, 70%), mp 115-
1
117 °C. H NMR (400 MHz, Chloroform-d) δ 9.49 (s,
0.62H), 9.16 (s, 0.38H), 8.46 (d, J = 8.4, 0.62H), 8.36 (s,
0.38H), 8.35 (s, 0.62H), 8.33 (s, 0.38H), 8.08 (d, J = 8.4 Hz,
0.62H), 8.05 (d, J = 8.4 Hz, 0.38H), 7.91 (d, J = 8.4 Hz,
0.38H), 7.70 (t, J = 7.6 Hz, 0.62H), 7.57-7.53 (m, 1H), 7.50
(d, J = 8.4 Hz, 0.38H), 7.47 (d, J = 7.2 Hz, 0.62H), 2.86 (s,
1.9H), 2.64 (s, 1.1H), 2.62 (s, 3H). 13C NMR (101 MHz,
Chloroform-d) δ 152.35, 149.30, 142.84, 142.40, 141.25,
136.92, 136.71, 136.45, 132.53, 132.44, 130.46, 130.30,
130.25, 129.69, 129.68, 129.09, 128.66, 128.58, 124.97,
124.68, 124.10, 123.81, 121.98, 121.79, 121.46, 119.98,
22.44, 22.00, 21.94, 18.90. ESI-MS: m/z [M + H]+ 208.
9-Fluoro-2-methylphenanthridine (3fb). Petroleum
ether/ethyl actate (8:1) as eluent; White solid (109.7 mg,
52%), mp 155-156 °C. 1H NMR (400 MHz, Chloroform-d)
δ 9.17 (s, 1H), 8.20 (dd, J = 10.4, 1.6 Hz, 1H), 8.07 (d, J =
8.4 Hz, 1H), 8.07 (d, J = 8.4 Hz, 1H), 8.02 (dd, J = 6, 8.8
Hz, 1H), 7.59 (dd, J = 8.4, 1.2 Hz, 1H), 7.41 (dt, J = 8.5, 2.3
Hz, 1H), 2.62 (s, 3H). 13C NMR (101 MHz, Chloroform-d)
δ 164.02 (d, J = 250 Hz), 151.67, 142.81, 137.13, 134.44 (d,
J = 9.3 Hz), 131.39 (d, J = 9.7 Hz), 131.08 (2C), 129.94,
123.48, 121.96, 116.61 (d, J = 24.2 Hz), 107.08 (d, J = 22.3
Benzo[k]phenanthridine (3ka).[30] Petroleum ether/ethyl
actate (8:1) as eluent; White solid (71.0 mg, 31%), mp 100-
101 °C. 1H NMR (400 MHz, Chloroform-d) δ 9.35 (s, 1H),
9.20 (d, J = 7.6 Hz, 1H), 9.10 (d, J = 808 Hz, 1H), 8.33 (d,
J = 8.8 Hz, 1H), 8.09-8.06(m, 1H), 8.02 (d, J = 8.4 Hz, 1H),
7.94 (d, J = 8.4 Hz, 1H), 7.83-7.72 (m, 4H). 13C NMR (101
MHz, Chloroform-d) δ 152.61, 146.60, 135.19, 131.21,
130.26, 129.03, 128.99, 128.79, 128.25, 128.14, 127.85,
127.05, 126.93, 126.87, 125.24, 125.11, 124.62. ESI-MS:
m/z [M + H]+ 230.
Benzo[i]phenanthridine (3la).[33] Petroleum ether/ethyl
actate (8:1) as eluent; White solid (146.5 mg, 64%), mp 175-
176 °C. 1H NMR (400 MHz, Chloroform-d) δ 10.20 (s, 1H),
8.88 (d, J = 8.4 Hz, 1H), 8.62 (d, J = 8 Hz, 1H), 8.55 (d, J =
9.2 Hz, 1H), 8.27 (d, J = 8 Hz, 1H), 8.14 (d, J = 8.8 Hz, 1H),
7.99 (d, J = 8 Hz, 1H), 7.81-7.65 (m, 4H). 13C NMR (101
MHz, Chloroform-d) δ 147.82, 145.23, 132.11, 132.02,
130.06, 129.98, 128.91, 128.80, 128.01, 127.10, 127.07,
126.80, 124.26, 122.67, 122.10, 121.72, 119.75. ESI-MS
(ESI): m/z [M + H]+ 230.
6
This article is protected by copyright. All rights reserved.

10.1002/adsc.202000949
Advanced Synthesis & Catalysis
Hz), 21.90. HRMS (ESI): calcd. for C14H11FN m/z [M + H]+
212.0870; found 212.0861.
121.66, 28.80, 21.96, 15.42. HRMS (ESI): calcd. for
C16H16N m/z [M + H]+ 222.1277; found 222.1286.
9-Chloro-2-methylphenanthridine (3gb). Petroleum
ether/ethyl actate (10:1) as eluent; White solid (93.0 mg,
41%), mp 133-134 °C.1H NMR (400 MHz, Chloroform-d)
δ 9.16 (s, 1H), 8.52 (s, 1H), 8.23 (s, 1H), 8.06 (d, J = 8.4 Hz,
1H), 7.94 (d, J = 8.4 Hz, 1H), 7.62 (dd, J = 8.4, 2.0 Hz, 1H),
7.59 (dd, J = 8.4, 1.2 Hz, 1H), 2.62 (s, 3H),. 13C NMR (101
MHz, Chloroform-d) 137.43, 137.19, 133.42, 131.08,
130.14, 129.87, 128.02, 121.80, 121.63, 21.92. HRMS
(ESI): calcd. for C14H11ClN m/z [M + H]+ 228.0575; found
228.0587.
2-Chlorophenanthridine (3ac).[13] Petroleum ether/ethyl
actate (8:1) as eluent; White solid (144.8 mg, 68%), mp 152-
153 °C. 1H NMR (400 MHz, Chloroform-d) δ 9.23 (s, 1H),
8.49-8.46 (m, 2H), 8.09 (d, J = 8.7 Hz, 1H), 8.03 (d, J = 8.0
Hz, 1H), 7.85 (t, J = 8.3 Hz, 1H), 7.72 (t, J = 7.4 Hz, 1H),
7.66 (d, J = 8.8 Hz, 1H). 13C NMR (101 MHz, Chloroform-
d) δ 153.67, 142.77, 132.99, 131.53, 131.48, 131.27, 129.17,
128.79, 128.14, 126.41, 125.14, 121.86, 121.84. ESI-MS:
m/z [M + H]+ 214.
2-Chloro-8-methoxyphenanthridine (3bc). Petroleum
ether/ethyl actate (8:1) as eluent; White solid (187.1 mg,
77%), mp 172-173 °C. 1H NMR (400 MHz, Chloroform-d)
δ 9.19 (s, 1H), 8.43 (s, 1H), 8.42 (d, J = 7.2 Hz, 1H), 8.08
(d, J = 8.4 Hz, 1H), 7.61 (dd, J = 8.8, 2.4 Hz, 1H), 7.49 (dd,
J = 9.2, 2.8 Hz, 1H), 7.38 (d, J = 2.8 Hz, 1H), 4.00 (s, 3H).
13C NMR (101 MHz, Chloroform-d) δ 159.40, 152.94,
141.94, 133.07, 131.45, 128.19, 127.92, 125.89, 125.36,
123.65, 122.33, 121.35, 108.07, 55.65. HRMS (ESI): calcd.
for C14H11ClNO m/z [M + H]+ 244.0524; found 244.0527.
2-Chloro-8-methylphenanthridine (3cc). Petroleum
ether/ethyl actate (8:1) as eluent; White solid (168.0 mg,
74%), mp 161-162 °C. 1H NMR (400 MHz, Chloroform-d)
δ 9.12 (s, 1H), 8.37 (d, J = 2.3 Hz, 1H), 8.28 (d, J = 8.4 Hz,
1H), 8.04 (d, J = 8.8 Hz, 1H), 7.73 (s, 1H), 7.61 (dd, J = 8.4,
1.6 Hz, 1H), 7.60 (dd, J = 8.4, 2 Hz, 1H), 2.56 (s, 3H). 13C
NMR (101 MHz, Chloroform-d) δ 153.43, 142.46, 138.25,
132.97, 132.81, 131.42, 129.29, 128.62, 128.10, 126.55,
125.19, 121.67, 121.60, 21.53. HRMS (ESI): calcd. for
C14H11ClN m/z [M + H]+ 228.0575; found 228.0582.
7-Chloro-2-methylphenanthridine (3gb’).[10c] Petroleum
ether/ethyl actate (10:1) as eluent; White solid (45.4 mg,
20%), mp 172-173 °C. 1H NMR (400 MHz, Chloroform-d)
δ 9.69 (s, 1H), 8.51 (d, J = 7.6 Hz, 1H), 8.33 (s, 1H), 8.11
(d, J = 8.4 Hz, 1H), 7.75-7.68 (m, 2H), 7.61 (dd, J = 8.4, 1.2
Hz, 1H), 2.64 (s, 3H),. 13C NMR (101 MHz, Chloroform-d)
δ 148.64, 142.77, 137.59, 134.10, 133.80, 131.05, 130.66,
130.02, 127.85, 123.28, 122.94, 121.93, 120.83, 21.99. ESI-
MS [M + H]+ 228.
2,7,9-Trimethylphenanthridine
(3hb).
Petroleum
ether/ethyl actate (8:1) as eluent; White solid (172.4 mg,
78%), mp 145-146 °C. 1H NMR (400 MHz, Chloroform-d)
δ 9.40 (s, 1H), 8.30 (s, 1H), 8.20 (s, 1H), 8.05 (d, J = 8.4 Hz,
1H), 7.53 (d, J = 8.4 Hz, 1H), 7.27 (s, 1H), 2.79 (s, 3H), 2.61
(s, 3H), 2.57 (s, 3H). 13C NMR (101 MHz, Chloroform-d) δ
149.10, 142.53, 140.73, 136.57, 136.17, 132.70, 130.45,
130.12, 129.59, 123.93, 123.16, 121.94, 119.54, 22.33,
21.99, 18.76. HRMS (ESI): calcd. for C16H16N m/z [M +
H]+ 222.1277; found 222.1275.
7,9-Difluoro-2-methylphenanthridine (3ib). Petroleum
ether/ethyl actate (8:1) as eluent; White solid (137.4 mg,
60%), mp 180-181 °C. 1H NMR (400 MHz, Chloroform-d)
δ 9.40 (s, 1H), 8.12 (s, 1H), 8.07 (d, J = 8.3 Hz, 1H), 7.93
(d, J = 10.1 Hz, 1H), 7.60 (dd, J = 8.3, 1.8 Hz, 1H), 7.09 (dt,
J = 9.2, 2.2 Hz, 1H), 2.61 (s, 3H). 13C NMR (101 MHz,
Chloroform-d) δ 163.61 (dd, J = 244, 12.7 Hz), 161.04 (dd,
J = 251, 13.7 Hz), 144.71 (d, J = 7.9 Hz), 143.11, 137.65,
135.16 (dd, J = 10.9, 4.9 Hz), 131.68, 130.15, 122.49 (dd, J
= 4.6, 2.8 Hz), 122.06, 113.30 (d, J = 11.8 Hz), 103.32-
102.41 (m), 21.89. HRMS (ESI): calcd. for C14H10F2N m/z
[M + H]+ 230.0776; found 230.0780.
Mixture of 2-chloro-9-methylphenanthridine (3ec) and
2-chloro-7-methylphenanthridine (3ec’).[31] Petroleum
ether/ethyl actate (8:1) as eluent; White solid (154.4 mg,
68%), mp 130-132 °C. 1H NMR (400 MHz, Chloroform-d)
δ 9.50 (s, 0.43H), 9.18 (s, 0.57H), 8.48 (d, J = 9.6 Hz, 0.43H),
8.47 (d, J = 9.6 Hz, 0.57H), 8.34 (d, J = 8 Hz, 0.43H), 8.25
(s, 0.57H), 8.10 (d, J = 9.6 Hz, 0.43H), 8.07 (d, J = 8.8 Hz,
0.57H), 7.91 (d, J = 8.4 Hz, 0.57H), 7.72 (t, J = 8 Hz, 0.43H),
7.67-7.63 (m, 1H), 7.54 (d, J = 8 Hz, 0.57H), 7.51 (d, J =
7.2 Hz, 0.43H), 2.85 (s, 1.3H), 2.64 (s, 1.7H). 13C NMR (101
MHz, Chloroform-d) δ 153.40, 150.41, 142.91, 142.45,
141.91, 136.64, 132.90, 132.71, 131.73, 131.63, 131.45
(2C), 130.94, 129.88, 129.46, 129.05, 129.00, 128.64,
2,10-Dimethylphenanthridine
(3jb).
Petroleum
ether/ethyl actate (8:1) as eluent; White solid (90.7mg, 43%), 125.31, 125.03, 124.93, 124.63, 122.01, 121.80, 121.49,
mp 121-122 °C. 1H NMR (400 MHz, Chloroform-d) δ 9.16
(s, 1H), 8.61 (s, 1H), 8.11 (d, J = 8.4 Hz, 1H), 7.89 (d, J = 8
Hz, 1H), 7.65 (d, J = 7.2 Hz, 1H), 7.60-7.55 (m, 2H), 3.11
(s, 3H), 2.63 (s, 3H). 13C NMR (101 MHz, Chloroform-d) δ
153.63, 143.96, 136.06, 135.16, 134.89, 131.61, 130.11,
129.42, 128.05, 127.79, 126.79, 126.38, 125.59, 26.60,
22.35. HRMS (ESI): calcd. for C15H14N m/z [M + H]+
208.1121; found 208.1123.
119.98, 22.43, 18.83. ESI-MS: m/z [M + H]+ 228.
2-Chloro-9-fluorophenanthridine (3fc).[35] Petroleum
ether/ethyl actate (8:1) as eluent; White solid (131.7 mg,
57%), mp 183-184 °C. 1H NMR (400 MHz, Chloroform-d)
δ 9.21 (s, 1H), 8.37 (d, J = 2.2 Hz, 1H), 8.08 (m, 3H), 7.70
(dd, J = 8.8, 2.3 Hz, 1H), 7.48 (dt, J = 8.5, 2.4 Hz, 1H). 13
C
NMR (101 MHz, Chloroform-d) δ 164.25 (d, J = 251Hz),
152.75 , 142.85, 133.73 (d, J = 9.6 Hz), 133.13, 131.66,
131.58 (d, J = 9.6 Hz), 129.94, 124.64, 123.44, 122.03,
117.55 (d, J = 24.2 Hz), 107.34 (d, J = 22.4 Hz). ESI-MS:
m/z [M + H]+ 232.
8-Ethyl-2-methylphenanthridine
(3mb).
Petroleum
ether/ethyl actate (8:1) as eluent; White solid (161.3 mg,
1
73%), mp 75-76 °C. H NMR (400 MHz, Chloroform-d) δ
9.16 (s, 1H), 8.47 (d, J = 8.4 Hz, 1H), 8.29 (s, 1H), 8.05 (d,
J = 8.3 Hz, 1H), 7.79 (s, 1H), 7.66 (dd, J = 8.5, 1.9 Hz, 1H),
7.52 (dd, J = 8.3, 1.9 Hz, 1H), 2.87 (q, J = 7.6 Hz, 2H), 2.60
(s, 3H), 1.36 (t, J = 7.6 Hz, 3H). 13C NMR (101 MHz,
Chloroform-d) δ 152.56, 143.56, 142.52, 136.84, 131.53,
130.41, 129.92, 129.73, 126.77, 126.73, 124.05, 121.81,
2-Chloro-7,9-dimethylphenanthridine (3hc). Petroleum
ether/ethyl actate (8:1) as eluent; White solid (180.8 mg,
75%), mp 170-171 °C. 1H NMR (400 MHz, Chloroform-d)
δ 9.45 (s, 1H), 8.49 (t, J = 2.2 Hz, 1H), 8.14 (s, 1H), 8.08 (d,
J = 8.7 Hz, 1H), 7.65 (dd, J = 8.8, 2.2 Hz, 1H), 7.35 (s, 1H),
2.82 (s, 3H), 2.60 (s, 3H). 13C NMR (101 MHz, Chloroform-
7
This article is protected by copyright. All rights reserved.

10.1002/adsc.202000949
Advanced Synthesis & Catalysis
d) δ 150.26, 142.67, 141.47, 136.44, 132.63, 132.02, 131.40,
131.29, 128.92, 125.21, 123.23, 122.00, 119.62, 22.33,
18.72. HRMS (ESI): calcd. for C15H13ClN m/z [M + H]+
242.0731; found 242.0725.
Mixture of 4-fluoro-9-methylphenanthridine (3ed) and
4-fluoro-7-methylphenanthridine (3ed’). Petroleum
ether/ethyl actate (8:1) as eluent; White solid (139.3 mg,
66%), mp 135-136 °C. 1H NMR (400 MHz, Chloroform-d)
δ 9.25 (s, 0.6H), 9.23 (s, 0.4H), 8.33-8.21 (m, 2H), 7.97-7.86
(m, 1H), 7.61-7.50 (m, 2H), 7.45-7.37 (m, 1H), 2.65 (s,
1.8H), 2.63 (s, 1.2H). 13C NMR (101 MHz, Chloroform-d)
δ 158.75 (d, J = 253 Hz), 153.39, 142.08, 134.19 (d, J = 10.8
Hz), 131.99 (d, J = 3 Hz), 129.82, 128.80, 126.67 (d, J = 8.6
Hz), 125.98, 126.69, 121.79, 117.75 (d, J = 4.6 Hz), 113.47
(d, J = 19.5 Hz), 22.45. HRMS (ESI): calcd. for C14H11FN
m/z [M + H]+ 212.0870; found 212.0873.
4,9-Difluorophenanthridine (3fd). Petroleum ether/ethyl
actate (8:1) as eluent; White solid (116.1 mg, 54%), mp 178-
179 °C. 1H NMR (400 MHz, Chloroform-d) δ 9.25 (s, 1H),
8.16 (d, J = 8.4 Hz, 1H), 8.11 (dd, J = 10.4, 2.4 Hz, 1H),
8.07 (dd, J = 8.8, 5.6 Hz, 1H), 7.61 (ddd, J = 13.2, 8.0, 5.2
Hz, 1H), 7.51 – 7.41 (m, 2H). 13C NMR (101 MHz,
Chloroform-d) δ 164.26 (d, J = 252 Hz), 158.66 (d, J = 254
Hz), 152.70, 134.12 (d, J = 11.1 Hz), 134.05 (dd, J = 9.7,
2.8 Hz), 131.78 (d, J = 9.7 Hz), 127.13 (d, J = 8.5 Hz),
125.47 (dd, J = 4.3, 1.7 Hz), 123.44 (d, J = 1.3 Hz), 117.93
(d, J = 4.4 Hz), 117.45 (d, J = 24.1 Hz), 114.35 (d, J = 19.4
Hz), 107.56 (d, J = 22.5 Hz). HRMS (ESI): calcd.
forC13H8F2N m/z [M + H]+ 216.0619; found 216.0630.
4-Fluoro-7,9-dimethylphenanthridine (3hd). Petroleum
ether/ethyl actate (8:1) as eluent; White solid (171.0 mg,
76%), mp 175-176 °C. 1H NMR (400 MHz, Chloroform-d)
δ 9.49 (s, 1H), 8.29 (d, J = 8.4 Hz, 1H), 8.17 (s, 1H), 7.58-
7.51 (m, 1H), 7.41 (ddd, J = 10.2, 7.8, 1.2 Hz, 1H), 7.33 (s,
1H), 2.81 (s, 3H), 2.58 (s, 3H). 13C NMR (101 MHz,
Chloroform-d) δ 158.73 (d, J = 253 Hz), 150.19, 141.61,
136.56, 133.95 (d, J = 10.8 Hz), 132.34 (d, J = 2.9 Hz),
131.13, 126.55 (d, J = 8.7 Hz), 126.14 (d, J = 1.9 Hz),
123.24, 119.89, 117.95 (d, J = 4.7 Hz), 113.22 (d, J = 19.3
Hz), 22.36, 18.71. HRMS (ESI): calcd. forC15H13FN m/z [M
+ H]+ 226.1027; found 226.1035.
2-Chloro-7,9-difluorophenanthridine (3ic). Petroleum
ether/ethyl actate (8:1) as eluent; White solid (154.4 mg,
62%), mp 198-199 °C. 1H NMR (400 MHz, Chloroform-d)
δ 9.48 (s, 1H), 8.36 (d, J = 2.3 Hz, 1H), 8.14 (d, J = 8.7 Hz,
1H), 7.93 (d, J = 9.6 Hz, 1H), 7.74 (dd, J = 8.8, 2.2 Hz, 1H),
7.19 (dt, J = 9.2, 2.2 Hz, 1H). 13C NMR (101 MHz,
Chloroform-d) δ 163.93 (dd, J = 252, 12.7 Hz), 161.19 (dd,
J = 258, 13.4 Hz), 145.91 (d, J = 6.3 Hz), 143.23, 134.34
(dd, J = 11, 4.7 Hz), 133.58, 131.97, 130.55, 123.73-123.68
(m), 122.18, 113.43 (d, J = 15 Hz), 103.89-103.38 (m).
HRMS (ESI): calcd. for C13H7ClF2N m/z [M + H]+
250.0230; found 250.0225.
2-Chloro-10-methylphenanthridine (3jc). Petroleum
ether/ethyl actate (8:1) as eluent; White solid (86.9 mg,
45%), mp 125-126 °C. 1H NMR (400 MHz, Chloroform-d)
δ 9.20 (s, 1H), 8.81 (s, 1H), 8.14 (d, J = 8.8 Hz, 1H), 7.93
(d, J = 7.6 Hz, 1H), 7.72-7.67 (m, 2H), 7.65 (t, J = 7.6 Hz,
1H), 3.11 (s, 3H). 13C NMR (101 MHz, Chloroform-d) δ
154.68, 144.02, 135.44, 135.26, 132.14, 131.64, 130.82,
129.48, 128.34, 128.01, 127.66, 126.60, 126.07, 26.31.
HRMS (ESI): calcd. for C14H11ClN m/z [M + H]+ 228.0575;
found 228.0580.
4-Fluorophenanthridine (3ad).[13] Petroleum ether/ethyl
actate (8:1) as eluent; White solid (126.1 mg, 64%), mp 144-
145 °C. 1H NMR (400 MHz, Chloroform-d) δ 9.25 (s, 1H),
8.46 (d, J = 8.3 Hz, 1H), 8.23 (d, J = 8.4 Hz, 1H), 7.99 (d, J
= 7.9 Hz, 1H), 7.81 (dt, J = 8.3, 1.4 Hz, 1H), 7.68 (dt, J =
8.0, 1.1 Hz, 1H), 7.55 (dt, J = 8.1, 5.3 Hz, 1H), 7.43-7.38
(m, 1H). 13C NMR (101 MHz, Chloroform-d) δ 158.68 (d, J
= 253 Hz), 153.63, 133.96 (d, J = 10.7 Hz), 131.75 (d, J =
2.7 Hz), 131.40, 128.88, 128.04, 126.95 (d, J = 8.5 Hz),
126.38, 126.00, 122.12, 117.75 (d, J = 4.3 Hz), 113.60 (d, J
= 19.4 Hz).
ESI-MS: m/z [M + H]+ 198.
4,7,9-Trifluorophenanthridine
(3id).
Petroleum
4-Fluoro-8-methoxyphenanthridine (3bd). Petroleum
ether/ethyl actate (8:1) as eluent; White solid (170.3 mg,
75%), mp 162-163 °C. 1H NMR (400 MHz, Chloroform-d)
δ 9.26 (s, 1H), 8.47 (d, J = 9.0 Hz, 1H), 8.25 (d, J = 8.5 Hz,
1H), 7.58 (dt, J = 8.1, 5.3 Hz, 1H), 7.50 (dd, J = 9.0, 2.7 Hz,
1H), 7.42 – 7.35 (m, 2H), 4.00 (s, 3H). 13C NMR (101 MHz,
Chloroform-d) δ 159.31, 158.80 (d, J = 253 Hz), 152.94,
133.29 (d, J = 10.9 Hz), 127.98, 127.08 (d, J = 8.8 Hz),
126.30, 126.25, 123.98, 122.60, 117.33 (d, J = 4.6 Hz),
112.59 (d, J = 19.5 Hz), 108.10, 55.65. HRMS (ESI): calcd.
for C14H9FNO m/z [M + H]+ 228.0819; found 228.0809.
4-Fluoro-8-methylphenanthridine (3cd). Petroleum
ether/ethyl actate (8:1) as eluent; White solid (151.9 mg,
72%), mp 155-156 °C. 1H NMR (400 MHz, Chloroform-d)
δ 9.20 (s, 1H), 8.37 (d, J = 8.4 Hz, 1H), 8.22 (d, J = 8.0 Hz,
1H), 7.77 (s, 1H), 7.64 (d, J = 8.4 Hz, 1H), 7.57-7.51 (m,
1H), 7.38 (t, J = 7.6 Hz, 1H), 2.56 (s, 3H). 13C NMR (101
MHz, Chloroform-d) δ 158.72 (d, J = 248 Hz), 153.40,
138.20, 133.69 (d, J = 10.8 Hz), 133.18, 129.68 (d, J = 3.2
Hz), 128.26, 126.84 (d, J = 8.8 Hz), 126.61, 126.15, 122.00,
117.58 (d, J = 4.6 Hz), 113.08 (d, J = 19.4 Hz), 21.48.
HRMS (ESI): calcd. for C14H11FN m/z [M + H]+ 212.0870;
found 212.0866.
ether/ethyl actate (8:1) as eluent; White solid (146.8 mg,
63%), mp 200-201 °C. 1H NMR (400 MHz, Chloroform-d)
δ 9.52 (s, 1H), 8.17 (d, J = 8.0 Hz, 1H), 7.96 (d, J = 9.6 Hz,
1H), 7.67-7.62 (m, 1H), 7.51 (ddd, J = 10.1, 7.9, 1.2 Hz, 1H),
7.18 (dt, J = 9.2, 2 Hz, 1H). 13C NMR (101 MHz,
Chloroform-d) δ 163.97 (dd, J = 253, 12.9 Hz), 161.24 (dd,
J = 258, 13.7 Hz), 158.74 (d, J = 255 Hz), 145.99 (d, J = 6.3
Hz), 134.84-134.50 (m), 127.69 (d, J = 8.5 Hz), 124.58,
118.18 (d, J = 4.5 Hz), 115.05 (d, J = 19.4 Hz), 113.52 (d, J
= 13.87 Hz), 103.96-103.37 (m). HRMS (ESI): calcd. for
C13H7F3N m/z [M + H]+ 234.0525; found 234.0534.
4-Fluoro-10-methylphenanthridine (3jd). Petroleum
ether/ethyl actate (8:1) as eluent; White solid (84.4 mg,
40%), mp 130-131 °C. 1H NMR (400 MHz, Chloroform-d)
δ 9.30 (s, 1H), 8.64 (d, J = 8.4 Hz, 1H), 7.99 (d, J = 7.6 Hz,
1H), 7.74 (d, J = 7.2 Hz, 1H), 7.67 (t, J = 7.6 Hz, 1H), 7.61
(dd, J = 7.6, 6 Hz, 1H), 7.49 (t, J = 8.4 Hz, 1H), 3.13 (s, 3H).
13C NMR (101 MHz, Chloroform-d) δ 158.62 (d, J = 251
Hz), 154.69, 135.68, 135.39, 135.26 (d, J = 10.1 Hz), 131.35,
128.22, 128.10, 127.63, 127.54, 126.16 (d, J = 8.8 Hz),
122.16 (d, J = 4.4 Hz), 113.14 (d, J = 19.6 Hz), 26.52.
HRMS (ESI): calcd. for C14H11FN m/z [M + H]+ 212.0870;
found 212.0878.
8
This article is protected by copyright. All rights reserved.

10.1002/adsc.202000949
Advanced Synthesis & Catalysis
4-Fluoro-8-ethylphenanthridine
(3md).
Petroleum
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Tournier, C. Fossey, C. Ballandonne, A. Lesnard, P.
Millet, Y. Charnay, T. Cailly, J.-P. Bouillon, F.
Fabis, Eur. J. Med. Chem. 2015, 94, 386-396.
a) A. Borah, P. Gogoi, Eur. J. Org. Chem. 2016,
2200-2206; b) S. Chamoin, S. Houldsworth, C. G.
Kruse, W. Iwema Bakker, V. Snieckus,
Tetrahedron Lett. 1998, 39, 4179-4182; c) S. Dhara,
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d) M. Ghosh, A. Ahmed, S. Dhara, J. K. Ray,
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Yin, RSC Adv. 2016, 6, 19571-19575.
ether/ethyl actate (8:1) as eluent; White solid (153.0 mg,
68%), mp 160-161 °C. 1H NMR (400 MHz, Chloroform-d)
δ 9.26 (s, 1H), 8.44 (d, J = 8.4 Hz, 1H), 8.27 (d, J = 8.0 Hz,
1H), 7.84 (s, 1H), 7.71 (d, J = 8.4 Hz, 1H), 7.57 (dt, J = 8.3,
5.6 Hz, 1H), 7.40 (t, J = 9.2 Hz, 1H), 2.89 (q, J = 7.6 Hz,
2H), 1.37 (t, J = 7.6 Hz, 3H). 13C NMR (101 MHz,
Chloroform-d) δ 158.75 (d, J = 253 Hz), 153.62, 144.48,
133.77 (d, J = 10.7 Hz), 132.24, 129.98 (d, J = 2.7 Hz),
127.05, 126.88 (d, J = 8.5 Hz), 126.75, 126.33 (d, J = 1.7
Hz), 122.19, 117.65 (d, J = 4.4 Hz), 113.16 (d, J = 19.4 Hz),
28.79, 15.35. HRMS (ESI): calcd. for C15H13FN m/z [M +
H]+ 226.1077; found 226.1065.
[5]
[6]
1-(Benzo[k]phenanthridin-5(6H)-yl)ethanone
(5ka).
Petroleum ether/ethyl actate (8:1) as eluent; White solid
1
(147.4 mg, 54%), mp 164-165 °C. H NMR (400 MHz,
Chloroform-d) δ 7.89 (d, J = 8 Hz, 1H), 7.81 (d, J = 8 Hz,
1H), 7.77 (d, J = 7.2 Hz, 1H), 7.72 (d, J = 7.2 Hz, 1H), 7.56
(d, J = 8 Hz, 1H), 7.53-7.50 (m, 1H), 7.46-7.38 (m, 3H),
7.31-7.28 (m, 1H), 5.71 (d, J = 15.6 Hz, 1H), 4.46 (d, J =
15.6 Hz, 1H), 1.97 (s, 3H). 13C NMR (101 MHz,
Chloroform-d) δ 168.81, 142.99, 138.53, 135.72, 135.29,
134.97, 132.48, 130.76, 130.38, 129.51, 129.09, 128.39,
128.14, 127.52, 126.28, 125.50, 125.18, 55.11, 22.22.
HRMS (ESI): calcd. for C19H16NO m/z [M + H]+ 274.1226;
found 274.1215.
[7]
Acknowledgements
Financial support from the Leading Innovative and Entrepreneur
Team Introduction Program of Zhejiang (No. 2019R01005) is
gratefully acknowledged.
[8]
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a) S. Some, J. K. Ray, M. G. Banwell, M. T. Jones,
Tetrahedron Lett. 2007, 48, 3609-3612; b) S.
Bhowmik, G. Pandey, S. Batra, Chem.-Eur. J. 2013,
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[21]
[22]
10
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10.1002/adsc.202000949
Advanced Synthesis & Catalysis
FULL PAPER
One-pot cascade reaction for the synthesis of
phenanthridines via Suzuki coupling/C-H
oxidation/aromatization
Adv. Synth. Catal. Year, Volume, Page – Page
Yi Zhang , Yuxin Ding, Rener Chen and Yongmin
Ma *
11
This article is protected by copyright. All rights reserved.