Indium-Mediated Intramolecular Reaction of N-(2-Iodobenzoyl)azabenzonorbornadienes: A General Access to Dihydrobenzo[c]phenanthridinones

Article abstract of DOI:10.1021/acs.joc.6b00839

An efficient synthesis of dihydrobenzo[c]phenanthridinones was achieved by utilizing an indium(0)-mediated intramolecular cyclization reaction under ligand- and base-free conditions. A variety of functional groups were tolerated in the present protocol.

Full text of DOI:10.1021/acs.joc.6b00839

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Article
Indium-mediated Intramolecular Reaction of N-(2-
iodobenzoyl)-Azabenzonorbornadienes: A General
Access to Dihydroben-zo[c]phenanthridinones
Yang Liu, Na Liu, Dong-Wei Sun, Xue-Wen Hua, Ya-Juan Li, Kang Lei, and Xiao-Hua Xu
J. Org. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.joc.6b00839 • Publication Date (Web): 31 May 2016
Downloaded from http://pubs.acs.org on May 31, 2016
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The Journal of Organic Chemistry
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Indium-mediated Intramolecular Reaction of N-(2-iodobenzoyl)-
Azabenzonorbornadienes: A General Access to Dihydroben-
zo[c]phenanthridinones
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Yang Liu, Na Liu, DongꢀWei Sun, XueꢀWen Hua, YaꢀJuan Li, Kang Lei* and XiaoꢀHua Xu*
State Key Laboratory and Institute of Elementoꢀorganic Chemistry, Collaborative Innovation Center of Chemical Science
and Engineering (Tianjin), Nankai University, Tianjin 300071, China
O
R2
R2
O
HN
In (2.5 eq)
DMF, 110 o
N
C
I
R1
R1
ligand free, base free, easy operation
20 examples 58%-91%
ABSTRACT: An efficient synthesis of dihydrobenzo[c]phenanthridinones was achieved through utilizing an indium(0)ꢀmediated
intramolecular cyclization reaction under ligandꢀ and baseꢀfree conditions. A variety of functional groups were tolerated in the preꢀ
sent protocol.
INTRODUCTION
Benzo[c]phenanthridines are an important group of naturally occurring alkaloids that widely exist in Papaveraceae and Putaceae
plants.1 Many members of this family (Figure 1), such as chelidonine, chelamidine, chelamine, homochelidonine, sanguinarine, and
nitidine, often possess various interesting biological activities,2 which has made them attractive targets for chemical and biological
community.3–8 Related the aromatic congeners, synthesis of the partial unsaturated dihydrobenzo[c]phenanthridine alkaloids of this
family still remains challenging due to the existence of two contiguous chiral bridge carbon atoms. Among the previously described
methods for them, much attention has been paid to the ringꢀopening reaction of azabenzonorbornadienes resulting in the benꢀ
zo[c]phenanthridine skeletons. In particular, Lautens et al. reported a highly efficient synthesis of natural dihydrobenꢀ
zo[c]phenanthridines through using Pdꢀcatalyzed ringꢀopening reactions of azabenzonorbornadienes with an aryl boronic acid as
the key step.4, 5 Our group also developed an efficient method to construct dihydrobenzo[c]phenanthridinones through the ringꢀ
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opening reaction of azabenzonorbornadienes with methyl oꢀiodobenzoates, which was successfully applied to the total synthesis of
five natural benzo[c]phenanthridines.6–8 (Scheme 1) All these reports involved an elaborated Pd catalytic system and there were few
studies on the intramolecular cyclization reaction of azabenzonorbornadienes. From a practical perspective, the ringꢀopening reacꢀ
tion of azabenzonorbornadienes with a cheaper metal, simple reaction system is highly desirable.
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Figure 1. Naturally occuring benzo[c]phenanthridine alkaloids
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As a relatively inexpensive metal, Indium exhibits a low heterophilicity in many organic reactions and thus oxygenꢀ and nitroꢀ
genꢀcontaining functional groups are usually tolerated by these organoindium reagents. In the past few decades, indiumꢀmediated
organic reactions have elicited considerable attention. Most synthetically useful indiumꢀmediated reactions are mainly limited to the
Ferrierꢀtype alkynylation reactions and allyl alkylation of carbonyl compounds and imine derivatives,9,10 while few reports involved
the indiumꢀmediated ringꢀopening reaction of azabicyclic olefins.11,12 Cheng and coꢀworkers have reported a Pdꢀcatalyzed ringꢀ
opening process of azabicyclic olefins with organic halides via an abnormal Heckꢀtype reaction.13 Wang et al. reported an indiꢀ
um(III)ꢀcatalyzed Heck reaction and suggested that the organoindium intermediate, generated in situ from the reaction of phenyl
iodide and indium salt, could easily react with styrene to provide the Heck reaction compound.14 Recently, we also turned our interꢀ
est to the indiumꢀmediated Heckꢀtype reactions. To this end, we envisaged that the ringꢀopening reaction of azabenzonorbornadiꢀ
enes could be promoted by an indium reagent.
Scheme 1. Synthesis of Benzo[c]phenanthridines
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Our continuous efforts on synthesis of benzo[c]phenanthridines6–8 in combination with indium chemistry15,16 has resulted in deꢀ
velopment of a few new approaches to dihydrobenzo[c]phenanthridinones through a Pdꢀcatalyzed intermolecular cascade reaction
(Scheme 1). As parts of our ongoing project about indium chemistry, we herein report a new methodology for synthesis of dihydroꢀ
benzo[c]phenanthridines based on an intramolecular cyclization reaction of Nꢀ(2ꢀiodobenzoyl)ꢀazabenzonorbornadienes.
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RESULTS AND DISCUSSION
As we know, an organoindium reagent can be formed by treatment of aryl iodide with the indium(0) metal.17 Thus, the substrates
bearing an iodide group, Nꢀ(2ꢀiodobenzoyl)ꢀazabenzonorbornadiene 1a, were prepared smoothly according to the previously reꢀ
ported methods.18 With substrates 1a in hand, we subsequently examine its behavior with indium metal. In our initial attempts, the
reaction of 1a with 1.5 equiv indium in the presence of 2.0 equiv LiCl at 110 oC did not produce any desired products 2a (entry 1,
Table 1). To our delight, when LiCl was removed from the reaction system, the reaction produced 2a in 52 % yield with incomplete
conversion of the starting material (entry 2, Table 1). Further studies have demonstrated that DMF proved to be the optimal solvent
for this process (entries 8 and 9, Table 1), while other solvents such as toluene, dioxane, THF, DME, and methanol failed to provide
the desired products (entries 11ꢀ14, Table 1). The molar quantity of the indium metal also significantly influenced the reaction effiꢀ
cacy. The highest yield was obtained with a 2.5 equivalent of In(0) metal (entry 8, Table 1). Finally, the cisꢀstereochemistry of
pruduct 2a was confirmed by Xꢀray diffraction crystallographic analysis (see the Supporting Information).19
Table 1. Intramolecular Reaction of Compound 1aa
Temp.
(°C)
Yield
(%)b
Entry
In (Equiv.)
Solvent
1c
2
1.5
1.5
1.5
1.5
1.5
1.0
2.0
2.5
3.0
2.5
2.5
2.5
2.5
2.5
DMF
DMF
110
110
120
130
140
110
110
110
110
110
110
110
110
110
0
52
49
51
52
33
70
84
84
56
0
3
DMF
4
DMF
5
DMF
6
DMF
7
DMF
8
DMF
9
DMF
10d
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12
13
14
DMF
toluene
1,4ꢀdioxane
THF
0
0
DME
0
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17e
2.5
2.5
2.5
DMSO
MeOH
DMF
110
110
110
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21
67
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5
6
a Reaction conditions: 1a (0.2 mmol), In, solvent (2.5 mL), 20
b
c
h, under an argon atmosphere. Isolated yield. In·LiCl was
used. d Reaction time:10 h. e 1 mmol of 1a was used.
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Next, using the abovementioned optimized reaction conditions, we examined the scope and limitations of this present protocol.
The results are summarized in Table 2. A range of Nꢀ(2ꢀiodobenzoyl)ꢀazabenzonorbornadienes 1b–1p with various substituents in
the aromatic ring was examined. Fifteen dihydrobenzo[c]phenanthridinones 2b–2p were successfully obtained under the optimal
conditions with a yield of 58 to 91 % (entries 1 to 16, Table 2). Both the electronꢀdonating and electronꢀwithdrawing groups were
tolerated in the present procedure. Related to the electronic properties in compounds 1, the steric characters of the substrates signifꢀ
icantly influenced the efficacy of the reactions. The substrates possessing a substituent adjacent to the iodide group generally gave a
decreased yield (entries 2 to 4, Table 2). It is noteworthy that compounds 2o and 2p represent the mature precursors for naturally
occurring alkaloids chelidonine and nitidine. Unfortunately, reactions with the corresponding aryl bromide and chloride did not
yield the target benzo[c]phenanthridies (entries 17 and 18, Table 2).
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Table 2. Intramolecular Reaction of Compounds 1a-1ra
Entry
Substrates
Products
Yield (%)b
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HN
N
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F
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HN
N
CF3
Br
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CF3
2g
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1h
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Br
HN
HN
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2h
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Cl
F
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Cl
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F
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N
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HN
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I
1j
2j
Me
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Me
HN
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N
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90
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1l
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HN
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HN
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1n
2n
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HN
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N
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O
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I
1o
2o
OMe
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OMe
HN
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N
91
0
OMe
O
O
O
O
OMe
2p
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1p
O
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HN
HN
N
Cl
1q
2q
O
O
N
18
0
Br
1r
2r
a Reaction conditions: 1 (0.2 mmol), In (0.5 mmol), DMF (2.5
mL), 110 °C, 20 h, under an argon atmosphere. b isolated yield.
To examine the generality of the present methodology, the chainꢀextending substrates Nꢀ(2ꢀiodiophenylacetyl)ꢀ
azabenzonorbornadiene derivatives 3 and Nꢀ(2ꢀiodiophenylpropionyl)ꢀazabenzonorbornadiene 5 were also subject to the indiumꢀ
mediated cyclization process and the results are shown in Scheme 2. To our delight, under optimized reaction conditions the reacꢀ
tions of phenylacetic acidꢀderived subsrates 3a and 3b provided smoothly the desired products 4a and 4b in a yield 84 % and 91 %,
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respectively. However, the 3ꢀphenylpropanyl acidꢀderived Nꢀ(2ꢀiodiophenylpropionyl)ꢀazabenzonorbornadiene 5 proved to be not
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an effective substrate.
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Scheme 2. Examination of the substrates scope
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Subsequently, regioselectivity of the present reaction was further studied (Scheme 3). For compounds 6a and 6b containing a
methyl group in the bridgehead atom, two possible cyclization products might be afforded. Nevertheless, only a single regioꢀisomer
dihydrobenzo[c]phenanthridinones 7a and 7b were obtained in 72 % and 63 % yield, respectively. Unexpectedly, compound 6c,
which incorporates a methyl group at the double bond, did not supply the desired phenanthridine derivative under the optimal reacꢀ
tion conditions. It was presumed that the presence of the methyl group on the CꢀC double bond of olefin possible hampered the
coordination to the indium center generated in situ.
Scheme 3. Investigation of the regioselectivity
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Based on the abovementioned results and previously reported work,13,14,17 a plausible mechanism for the synthesis of dihydrobenꢀ
zo[c]phenanthridinones is putatively outlined in Scheme 4. At the outset, an organoindium immediate 8 was formed in situ. The
subsequent intramolecular insertion reaction into carbonꢀcarbon double bond of the olefin produced a cyclic intermediate 9, which
underwent a βꢀelimination/ring opening to give the full scaffold 10. Finally, the protonation of 10 provided the benzophenanthridine
2a.
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Scheme 4. Plausible reaction mechanism
CONCLUSION
In conclusion, we have described an efficient In(0)ꢀmediated intramolecular cyclization strategy for synthesis of dihydrobenꢀ
zo[c]phenanthridinone derivatives from Nꢀ(2ꢀiodobenzoyl)ꢀazabenzonorbornadienes. This present methodology was demonstrated
to have widely functional group tolerance and highly regioselectivity. Further investigation on the enantioselective synthesis of
benzo[c]phenanthridinones utilizing the protocol is currently under development and will be reported in the future.
EXPERIMENT SECTON
Chemicals and solvents were purchased from commercial suppliers and used as received unless otherwise stated. 1H NMR (400 MHz) and
13C NMR (100 MHz) were recorded with CDCl3 or DMSOꢀd6 as solvent. The chemical shifts are reported as δ values (ppm) relative to
tetramethylsilane. HRMS spectra were recorded with a QꢀTOF mass spectrometer, equipped with an ESI source. Melting points were deꢀ
termined with a melting point apparatus and are uncorrected.
General procedure for synthesis of substrates 1a to 1r, 3a, 3b and 5
Compounds 1a to 1r, 3a, 3b and 5 were synthesized according to the previous reported method.18
To NꢀBoc pyrrole (16.7 g, 100 mmol) in DME (40 mL) at 55 oC in a flame dried threeꢀneck flask fitted with a reflux condenser and two
addition funnels was simultaneously added a solution of anthranilic acid (13.8 g, 100 mmol) in DME (100 mL) and a separate solution of
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isoamylnitrite (16.8 mL, 125 mmol) in DME (50 mL). The addition took about 45 minutes. The reaction was allowed to stir at 55 oC for 30
min until no further gas was evolved. The crude red solution was reduced in volume by rotovap distillation to approximately half the origiꢀ
nal volume. The reaction mixture was then partitioned between EtOAc and saturated K2CO3 and the aqueous layer was extracted three
times with EtOAc. The combined organic layers were washed with brine, dried over Na2SO4 and concentrated. The resulting dark brown
oil was purified by column chromatography on silica gel (petroleum ether/ethyl acetate 20/1 v/v) to give NꢀBoc intermediate (13.85 g, 57%)
as light yellow solid.
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NꢀBoc intermediate (600 mg, 2.4 mmol) was dissolved in 10 mL DCM followed by the addition of Et3N (0.4 mL) and heating to reflux.
TMSI (0.4 mL, 2.6 mmol) was added dropwise over 5 min and the reaction was heated at reflux for an additional 15 minutes, after which
time TLC analysis showed complete consumption of NꢀBoc intermediate. The reaction mixture was cooled to 0 oC then MeOH (0.1 mL, 3
mmol) was added dropwise. After 10 minutes at 0 oC, 2ꢀiodobenzoyl chloride (954 mg, 3.6 mmol) was added and the reaction was allowed
to warm to room temperature. The reaction was stirred at room temperature for an additional hour. Water (10 mL) and DCM was added
until all precipitates dissolved. The organic and aqueous phases were separated and the aqueous phase was extracted twice with DCM. The
organic fractions were combined, dried over Na2SO4 and concentrated. The resulting crude product was purified by column chromatogꢀ
raphy on silica gel (petroleum ether/ethyl acetate=10/1 v/v) to give compound 1a (682 mg, 74 %) as a white solid.
The rest of substrates 1b to 1r, 3a, 3b and 5 were prepared by the similar procedure to 1a.
1
(1,4-Dihydro-1,4-epiminonaphthalen-9-yl)(2-iodophenyl)methanone (1a): light yellow solid, 600 mg, 74 %; m.p. 123–125 °C; H
NMR (400 MHz, CDCl3) δ: 7.83 (dd, J = 7.9, 0.5 Hz, 1H), 7.36–7.32 (m, 2H), 7.17–7.05 (m, 4H), 7.02–6.92 (m, 3H), 6.09 (s, 1H), 5.07 (s,
1H); 13C NMR (100 MHz, CDCl3) δ: 163.9, 147.9, 147.8, 143.7, 142.8, 140.8, 139.7, 130.9, 128.1, 127.6, 125.4, 125.2, 121.5, 120.6, 92.2,
66.7, 63.0; HRMS (ESI): m/z calcd for C17H12INO [M+H]+ 374.0042, found 374.0042.
(3-Chloro-2-iodophenyl)(1,4-dihydro-1,4-epiminonaphthalen-9-yl)methanone (1b): light yellow solid, 664 mg, 68 %; m.p. 186–188
1
°C; H NMR (400 MHz, CDCl3) δ: 7.51 (dd, J = 8.0, 1.5 Hz, 1H), 7.39 (d, J = 6.6 Hz, 1H), 7.33 (t, J = 7.7 Hz, 1H), 7.22–7.12 (m, 2H),
7.05–6.97 (m, 4H), 6.13 (s, 1H), 5.08 (s, 1H); 13C NMR (100 MHz, CDCl3) δ: 161.8, 146.7, 146.6, 142.9, 142.5, 141.7, 139.1, 128.8,
128.5, 124.4, 124.2, 124.1, 120.5, 119.6, 95.7, 65.4, 61.9; HRMS (ESI): m/z calcd for C17H11ClINO [M+H]+ 407.9652, found 407.9645.
(1,4-Dihydro-1,4-epiminonaphthalen-9-yl)(3-fluoro-2-iodophenyl)methanone (1c): off white solid, 572 mg, 61 %; m.p. 183–185 °C;
1H NMR (400 MHz, CDCl3) δ: 7.40–7.33 (m, 2H), 7.21–7.08 (m, 3H), 7.07–6.97 (m, 3H), 6.95 (d, J = 7.4 Hz, 1H), 6.12 (s, 1H), 5.09 (s,
1H); 13C NMR (100 MHz, CDCl3) δ: 161.6 (d, J = 2.3 Hz), 160.9 (d, J = 247.0 Hz), 146.6 (d, J = 14.0 Hz), 142.6, 142.0, 141.6, 129.3,
129.2, 124.3 (d, J = 14.8 Hz), 122.1 (d, J = 3.5 Hz), 120.5, 119.6, 115.2 (d, J = 24.6 Hz), 79.6 (d, J = 27.4 Hz), 65.6, 61.9; HRMS (ESI):
m/z calcd for C17H11FINO [M+H]+ 391.9948, found 391.9948.
(1,4-Dihydro-1,4-epiminonaphthalen-9-yl)(2-iodo-3-methylphenyl)methanone (1d): white solid, 669 mg, 72 %; m.p. 153–155 °C;
1H NMR (400 MHz, CDCl3) δ: 7.36 (d, J = 6.7 Hz, 1H), 7.28–7.22 (m, 2H), 7.15–7.11(m, 2H), 7.04–6.94 (m, 3H), 6.88 (s, 1H), 6.12 (s,
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1H), 5.07 (s, 1H), 2.47 (s, 3H).; 13C NMR (100 MHz, CDCl3) δ: 162.9, 146.9, 141.9, 141.8, 141.0, 129.2, 127.1, 124.3, 124.1, 123.6,
120.4, 119.5, 97.8, 65.5, 61.8, 27.9; HRMS (ESI): m/z calcd for C18H14INO [M+H]+ 388.0198, found 388.0197.
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5
1
(4-Chloro-2-iodophenyl)(1,4-dihydro-1,4-epiminonaphthalen-9-yl)methanone (1e): light yellow oil, 752 mg, 77 %; H NMR (400
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MHz, CDCl3) δ: 7.88 (s, 1H), 7.41–7.33 (m, 2H), 7.22–7.11 (m, 2H), 7.07 (d, J = 8.1 Hz, 1H), 7.04–6.97 (m, 3H), 6.09 (s, 1H), 5.09 (s,
1H); 13C NMR (100 MHz, CDCl3) δ: 163.2, 147.8, 147.6, 143.7, 142.6, 139.3, 139.2, 135.8, 128.5, 128.4, 125.4, 125.3, 121.6, 120.6, 92.4,
66.8, 63.1; HRMS (ESI): m/z calcd for C17H11ClINO [M+H]+ 407.9652, found 407.9650.
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(1,4-Dihydro-1,4-epiminonaphthalen-9-yl)(4-fluoro-2-iodophenyl)methanone (1f): light yellow solid, 601 mg, 64 %; m.p. 112–114
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°C; H NMR (400 MHz, CDCl3) δ: 7.46 (dd, J = 8.1, 2.3 Hz, 1H), 7.24 (d, 7.0 Hz, 1H), 7.07–6.92 (m, 4H), 6.91–6.81 (m, 3H), 5.95 (s,
1H), 4.95 (s, 1H); 13C NMR (100 MHz, CDCl3) δ: 162.4, 161.2 (d, J = 254.5 Hz), 146.7 (d, J = 20.1 Hz), 142.7, 141.5, 136.0 (d, J = 3.6
Hz), 127.9 (d, J = 8.5 Hz), 125.9, 125.7, 124.4, 124.2, 120.5 119.5, 114.4 (d, J = 21.5 Hz), 91.1 (d, J = 8.2 Hz), 65.8, 62.0; HRMS (ESI):
m/z calcd for C17H11FINO [M+H]+ 391.9948, found 391.9942.
(1,4-Dihydro-1,4-epiminonaphthalen-9-yl)(2-iodo-4-(trifluoromethyl)phenyl)methanone (1g): light yellow solid, 751 mg, 71 %,
m.p. 128–130 °C; 1H NMR (400 MHz, CDCl3) δ: 8.10 (s, 1H), 7.63 (d, J = 7.8 Hz, 1H), 7.38 (d, J = 6.6 Hz, 1H), 7.29–7.20 (m, 1H), 7.19–
7.10 (m, 2H), 7.03–6.98 (m, 3H), 6.10 (s, 1H), 5.05 (s, 1H); 13C NMR (100 MHz, CDCl3) δ: 162.6, 147.5 (d, J = 17.6 Hz), 144.4, 143.6,
142.6, 136.6 (q, J = 3.8 Hz), 132.7 (q, J = 33.1 Hz), 127.8, 125.5, 125.4, 125.2 (q, J = 3.6 Hz), 123.9, 121.6, 121.2, 120.7, 92.0, 66.6, 63.0;
HRMS (ESI): m/z calcd for C18H11F3INO [M+H]+ 441.9916, found 441.9909.
(5-Bromo-2-iodophenyl)(1,4-dihydro-1,4-epiminonaphthalen-9-yl)methanone (1h): light yellow solid, 714 mg, 66 %; m.p. 150–152
°C; 1H NMR (400 MHz, CDCl3) δ: 7.67 (d, J = 8.3 Hz, 1H), 7.35 (d, J = 7.1 Hz, 1H), 7.26–7.19 (m, 2H), 7.17 (d, J = 6.1 Hz, 1H), 7.11 (dd,
J = 5.5, 2.4 Hz, 1H), 7.04–6.92 (m, 3H), 6.06 (s, 1H), 5.08 (s, 1H); 13C NMR (100 MHz, CDCl3) δ: 162.3, 147.7, 147.5, 143.6, 142.7,
142.6, 141.1, 133.9, 130.6, 125.5, 125.3, 122.6, 121.6, 120.7, 90.1, 66.7, 63.0; HRMS (ESI): m/z calcd for C17H11BrINO [M+H]+
451.9147, found 451.9138.
(5-Chloro-2-iodophenyl)(1,4-dihydro-1,4-epiminonaphthalen-9-yl)methanone (1i): off white solid, 713 mg, 73 %; m.p. 128–130 °C;
1H NMR (400 MHz, CDCl3) δ: 7.78 (d, J = 8.3 Hz, 1H), 7.41–7.37 (d, J = 7.0 Hz, 1H), 7.23–7.18 (d, J = 7.0 Hz, 1H), 7.18–7.08 (m, 3H),
7.07–6.98 (m, 3H), 6.10 (s, 1H), 5.12 (s, 1H); 13C NMR (100 MHz, CDCl3) δ: 161.4, 146.6, 146.5, 142.6, 141.6, 141.3, 139.9, 133.7,
130.0, 126.7, 124.4, 124.3, 120.5, 119.7, 88.2, 65.6, 61.9; HRMS (ESI): m/z calcd for C17H11ClINO [M+H]+ 407.9652, found 407.9647.
(1,4-Dihydro-1,4-epiminonaphthalen-9-yl)(5-fluoro-2-iodophenyl)methanone (1j): off white solid, 535 mg, 57 %; m.p. 152–153 °C;
1H NMR (400 MHz, CDCl3) δ: 7.82 (dd, J = 9.2, 5.3 Hz, 1H), 7.39 (d, J = 6.3 Hz, 1H), 7.21 (d, J = 6.3 Hz, 1H), 7.16 (dd, J = 5.6, 2.5 Hz,
1H), 7.08–6.97 (m, 3H), 6.94–6.84 (m, 2H), 6.11 (s, 1H), 5.11 (s, 1H); 13C NMR (100 MHz, CDCl3) δ: 162.6 (d, J = 250.3 Hz), 162.5,
147.7, 147.5, 143.6, 142.6, 142.5 (d, J = 6.3 Hz), 141.3 (d, J = 7.6 Hz), 125.5, 125.3, 121.6, 120.7, 118.5 (d, J = 21.7 Hz), 115.3 (d, J =
23.5 Hz), 85.2 (d, J = 3.5 Hz), 66.6, 63.0; HRMS (ESI): m/z calcd for C17H11FINO [M+H]+ 391.9948, found 391.9940.
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(1,4-Dihydro-1,4-epiminonaphthalen-9-yl)(2-iodo-5-methylphenyl)methanone (1k): white solid, 697 mg, 75 %; m.p. 172–174 °C;
1H NMR (400 MHz, CDCl3) δ: 7.63 (d, J = 8.0 Hz, 1H), 7.29 (d, J = 6.3 Hz, 1H), 7.09 (d, J = 6.4 Hz, 1H), 7.06 (dd, J = 5.6, 2.5 Hz, 1H),
6.98–6.89 (m, 3H), 6.89–6.81 (m, 2H), 6.02 (s, 1H), 5.03 (s, 1H), 2.21 (s, 3H); 13C NMR (100 MHz, CDCl3) δ: 164.1, 147.9, 147.9, 143.7,
142.8, 140.7, 139.4, 138.4, 131.9, 128.4, 125.3, 125.2, 121.5, 120.6, 87.9, 66.7, 62.9, 20.9; HRMS (ESI): m/z calcd for C18H14INO [M+H]+
388.0198, found 388.0196.
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(1,4-Dihydro-1,4-epiminonaphthalen-9-yl)(2-iodo-5-methoxyphenyl)methanone (1l): white solid, 667 mg, 69 %; m.p.139–140 °C;
1H NMR (400 MHz, CDCl3) δ: 7.71 (d, J = 8.5 Hz, 1H), 7.38 (d, J = 6.6 Hz, 1H), 7.19 (d, J = 6.5 Hz, 1H), 7.15 (dd, J = 5.6, 2.5 Hz, 1H),
7.06–6.94 (m, 3H), 6.75–6.67 (m, 2H), 6.11 (s, 1H), 5.13 (s, 1H), 3.77 (s, 3H); 13C NMR (100 MHz, CDCl3) δ: 162.5, 158.7, 146.8, 146.7,
142.5, 141.7, 140.5, 139.4, 124.3, 124.2, 120.5, 119.6, 116.4, 112.2, 79.4, 65.6, 61.9, 54.5; HRMS (ESI): m/z calcd for C18H14INO2
[M+H]+ 404.0147, found 404.0145.
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(1,4-Dihydro-1,4-epiminonaphthalen-9-yl)(2-iodo-4,5-dimethoxyphenyl)methanone (1m): white solid, 655 mg, 63 %; m.p. 172–175
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°C; H NMR (400 MHz, CDCl3) δ: 7.38 (d, J = 6.7 Hz, 1H), 7.24 (s, 1H), 7.19 (d, J = 6.6 Hz, 1H), 7.15 (dd, J = 5.5, 2.3 Hz, 1H), 7.04–
6.97 (m, 3H), 6.65 (s, 1H), 6.08 (s, 1H), 5.15 (s, 1H), 3.91 (s, 3H), 3.80 (s, 3H); 13C NMR (100 MHz, CDCl3) δ: 164.2, 150.2, 149.2, 148.0,
147.9, 143.6, 142.7, 133.1, 125.3, 125.2, 121.8, 121.5, 120.5, 110.8, 80.8, 67.0, 63.1, 56.3, 56.1; HRMS (ESI): m/z calcd for C19H16INO3
[M+H]+ 434.0253, found 434.0252.
(1,4-Dihydro-1,4-epiminonaphthalen-9-yl)(5-iodobenzo[d][1,3]dioxol-4-yl)methanone (1n): white solid, 711 mg, 71 %; m.p. 193–
195 °C; 1H NMR (400 MHz, DMSO) δ: 7.40 (dd, J = 5.0, 2.8 Hz, 1H), 7.32 (d, J = 7.9 Hz, 1H), 7.28 (d, J = 5.0 Hz, 1H), 7.18 (dd, J = 5.5,
2.4 Hz, 1H), 7.09 (dd, J = 5.4, 2.4 Hz, 1H), 7.00–6.91 (m, 2H), 6.82 (d, J = 8.2 Hz, 1H), 5.99 (s, 3H), 5.33 (bs, 1H); 13C NMR (100 MHz,
DMSO) δ: 149.0, 148.4, 148.3, 145.4, 144.3, 143.9, 132.6, 125.4, 125.3, 121.5, 121.1, 111.6, 102.6, 82.4, 66.3, 62.8; HRMS (ESI): m/z
calcd for C18H12INO3 [M+H]+ 417.9940, found 417.9935.
(5,8-Dihydro-5,8-epiminonaphtho[2,3-d][1,3]dioxol-10-yl)(5-iodobenzo[d][1,3]dioxol-4-yl)methanone (1o): white solid, 741 mg, 67
%; m.p. 194–196 °C; 1H NMR (400 MHz, CDCl3) δ: 7.31 (d, J = 8.1 Hz, 1H), 7.19–7.09 (m, 1H), 7.05 (s, 1H), 6.95 (s, 1H), 6.80 (s, 1H),
6.63 (d, J = 8.2 Hz, 1H), 6.05–5.91 (m, 5H), 5.14 (s, 1H); 13C NMR (100 MHz, CDCl3) δ: 158.2, 148.2, 145.3, 144.6, 144.6, 143.9, 143.3,
142.2, 141.9, 132.5, 121.9, 111.1, 104.9, 104.1, 102.2, 101.3, 81.0, 66.4, 62.8; HRMS (ESI): m/z calcd for C19H12INO5 [M+H]+ 461.9838,
found 461.9828.
(5,8-Dihydro-5,8-epiminonaphtho[2,3-d][1,3]dioxol-10-yl)(2-iodo-4,5-dimethoxyphenyl)methanone (1p): white solid, 836 mg, 73 %;
m.p. 192–194 °C; 1H NMR (400 MHz, CDCl3) δ: 7.23 (s, 1H), 7.14 (dd, J = 5.5, 2.4 Hz, 1H), 6.99 (dd, J = 5.4, 2.3 Hz, 1H), 6.95 (s, 1H),
6.76 (s, 1H), 6.66 (s, 1H), 5.98 (s, 1H), 5.96 (d, J = 1.3 Hz, 1H), 5.90 (d, J = 1.4 Hz, 1H), 5.06 (s, 1H), 3.89 (s, 3H), 3.81 (s, 3H); 13C NMR
(100 MHz, CDCl3) δ: 162.7, 149.2, 148.2, 143.6, 143.6, 142.9, 142.0, 141.3, 141.1, 132.0, 120.8, 109.8, 104.0, 103.1, 100.2, 79.9, 66.1,
62.1, 55.2, 55.1; HRMS (ESI): m/z calcd for C20H16INO5 [M+H]+ 478.0151, found 478.0147.
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(2-Chlorophenyl)(1,4-dihydro-1,4-epiminonaphthalen-9-yl)methanone (1q): brown oil, 526 mg, 78 %; H NMR (400 MHz, CDCl3)
δ: 7.43–7.35 (m, J = 7.5, 4.6 Hz, 3H), 7.30 (t, J = 7.9 Hz, 1H), 7.24 (d, J = 7.3 Hz, 1H), 7.20–7.12 (m, 2H), 7.05–6.95 (m, 3H), 6.14 (s,
1H), 5.15 (s, 1H); 13C NMR (100 MHz, CDCl3) δ: 160.5, 146.7, 142.8, 141.7, 133.6, 130.0, 129.7, 128.9, 127.3, 125.9, 124.3, 124.2,
120.4, 119.4, 65.5, 61.9; HRMS (ESI): m/z calcd for C17H12ClNO [M+H]+ 282.0686, found 282.0684.
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δ: 7.59 (dd, J = 7.9, 1.0 Hz, 1H), 7.39–7.24 (m, 3H), 7.21–7.14 (m, 2H), 7.12 (dd, J = 5.6, 2.5 Hz, 1H), 7.04–6.91 (m, 3H), 6.11 (s, 1H),
5.12 (s, 1H); 13C NMR (100 MHz, CDCl3) δ: 162.3, 147.8, 143.7, 142.8, 136.9, 133.2, 130.9, 128.3, 127.5, 125.3, 125.2, 121.4, 120.5,
119.5, 66.6, 62.9; HRMS (ESI): m/z calcd for C17H12BrNO [M+H]+ 326.0181, found 326.0176.
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1-(1,4-Dihydro-1,4-epiminonaphthalen-9-yl)-2-(2-iodophenyl)ethanone (3a): white solid, 715 mg, 77 %; m.p. 159–161 °C; 1H NMR
(400 MHz, CDCl3) δ: 7.84 (dd, J = 7.9, 0.8 Hz, 1H), 7.32 (d, J = 6.5 Hz, 1H), 7.24–7.15 (m, 2H), 7.13 (dd, J = 7.7, 1.4 Hz, 1H), 7.09 (dd, J
= 5.6, 2.5 Hz, 1H), 7.03–6.90 (m, 4H), 5.97 (s, 1H), 5.61 (s, 1H), 3.83–3.56 (m, 2H); 13C NMR (100 MHz, CDCl3) δ: 165.3, 148.2, 147.9,
143.9, 142.5, 139.4, 137.6, 130.2, 128.7, 128.4, 125.3, 125.0, 121.4, 120.4, 101.1, 65.8, 63.5, 45.9; HRMS (ESI): m/z calcd for C18H14INO
[M+H]+ 388.0198, found 388.0197.
1-(1,4-Dihydro-1,4-epiminonaphthalen-9-yl)-2-(2-iodo-5-methylphenyl)ethanone (3b): white solid, 674 mg, 70 %; m.p. 142–144
°C; 1H NMR (400 MHz, CDCl3) δ: 7.71 (d, J = 8.0 Hz, 1H), 7.33 (d, J = 6.8 Hz, 1H), 7.14–7.05 (m, 2H), 7.02–6.91 (m, 3H), 6.86 (s, 1H),
6.81–6.71 (m, 1H), 5.97 (s, 1H), 5.57 (s, 1H), 3.71 (s, 2H), 2.15 (s, 3H); 13C NMR (100 MHz, CDCl3) δ: 165.4, 148.2, 148.0, 143.7, 142.5,
139.1, 138.4, 137.1, 131.0, 129.7, 125.2, 124.9, 121.4, 120.4, 96.9, 65.8, 63.5, 45.9, 20.8; HRMS (ESI): m/z calcd for C19H16INO [M+H]+
402.0355, found 402.0354.
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1-(1,4-dihydro-1,4-epiminonaphthalen-9-yl)-3-(2-iodophenyl)propan-1-one (5): brown oil, 683 mg, 71 %; H NMR (400 MHz,
CDCl3) δ: 7.82 (d, J = 7.8 Hz, 1H), 7.31 (d, J = 5.8 Hz, 1H), 7.26 – 7.18 (m, 3H), 7.11 – 7.04 (m, 1H), 7.02 – 6.94 (m, 2H), 6.94 – 6.84 (m,
2H), 5.93 (s, 1H), 5.61 (s, 1H), 3.13 – 2.81 (m, 2H), 2.60 – 2.45 (m, 2H); 13C NMR (100 MHz, CDCl3) δ: 167.8, 148.2, 147.9, 144.3, 143.5,
142.3, 139.5, 130.0, 128.6, 128.2, 125.3, 125.1, 121.4, 120.4, 100.1, 65.7, 63.3, 35.8, 34.1. HRMS (ESI): m/z calcd for C19H16INO [M+H]+
402.0355, found 402.0352.
General procedure for synthesis of substrates 6a and 6b
Compounds 6a and 6b were synthesized according to the previous reported method.4
A mixture of dibromide (2.78 g, 10 mmol) and freshly distilled NꢀBoc 2ꢀmethylpyrrole (2.7 g, 15 mmol) in toluene (20 mL) was cooled
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to ꢀ78 C. nꢀButyllithium (1.6 M in hexane; 13.8 mL, 22 mmol) was added dropwise over a period of 1.5 h. The resulting bright orange
solution was allowed to warm up to 25 oC over 3 h and then left for a further 17 h at 25 oC. The reaction mixture was then quenched with
water and the phases were separated. The aqueous layer was extracted with EtOAc and the organic layers were combined, dried over
Na2SO4 and concentrated to give brown oil. The resulting crude product was purified by column chromatography on silica gel (petroleum
ether/ethyl acetate=20/1 v/v) to give 1ꢀmethylꢀNꢀBoc intermediate (2.29 g, 76 %) as a yellow oil.
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1ꢀmethylꢀNꢀBoc intermediate (722 mg, 2.4 mmol) was dissolved in 10 mL DCM followed by the addition of Et3N (0.4 mL) and heating
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after which time TLC analysis showed complete consumption of 1ꢀmethylꢀNꢀBoc intermediate. The reaction mixture was cooled to 0 C
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then MeOH (0.1 mL, 3 mmol) was added dropwise. After 10 minutes at 0 oC, oꢀiodobenzoyl chloride (1.0 g, 3.6 mmol) was added and the
reaction was allowed to warm to room temperature. The reaction was stirred at room temperature for an additional hour. Water (10 mL)
and DCM was added until all precipitates dissolved. The organic and aqueous phases were separated and the aqueous phase was extracted
twice with DCM. The organic fractions were combined, dried over Na2SO4 and concentrated. The resulting crude product was purified by
column chromatography on silica gel (petroleum ether/ethyl acetate=10/1 v/v) to give compound 6a (0.61 g, 57 %) as a light yellow solid.
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The substrate 6b was prepared by the similar procedure to 6a.
(2-Iodo-5-methylphenyl)(5-methyl-5,8-dihydro-5,8-epiminonaphtho[2,3-d][1,3]dioxol-10-yl)methanone (6a): light yellow solid,
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610 mg, 57 %; m.p. 279–281 °C; H NMR (400 MHz, DMSO) δ: 10.23 (s, 1H), 7.81 (d, J = 7.9 Hz, 1H), 7.52 (s, 1H), 7.47 (s, 1H), 7.40
(d, J = 8.5 Hz, 2H), 7.24 (d, J = 7.1 Hz, 1H), 7.07 (d, J = 7.4 Hz, 1H), 6.17 (s, 2H), 2.50 (s, 3H), 2.36 (s, 3H); 13C NMR (100 MHz,
DMSO) δ: 168.9, 147.9, 147.7, 143.7, 139.2, 138.3, 132.1, 131.9, 131.4, 130.2, 129.3, 126.4, 125.2, 122.1, 101.9, 101.3, 100.8, 89.9, 20.8,
19.9; HRMS (ESI): m/z calcd for C20H16INO3 [M+H]+ 446.0253, found 446.0249.
(5-Iodobenzo[d][1,3]dioxol-4-yl)(5-methyl-5,8-dihydro-5,8-epiminonaphtho[2,3-d][1,3]dioxol-10-yl)methanone (6b): off white solꢀ
id, 730 mg, 64 %; m.p. decomposed at 236 °C; 1H NMR (400 MHz, DMSO) δ :10.41 (s, 1H), 7.51 (s, 1H), 7.44–7.32 (m, 3H), 7.24 (d, J =
7.5 Hz, 1H), 6.87 (d, J = 8.1 Hz, 1H), 6.20 (s, 2H), 6.17 (s, 2H), 2.57 (s, 3H); 13C NMR (100 MHz, DMSO) δ: 163.9, 147.9, 147.5, 147.2,
145.1, 131.6, 131.6, 130.5, 129.7, 125.8, 124.8, 124.7, 121.4, 110.9, 102.2, 101.4, 100.9, 99.9, 82.8, 19.4; HRMS (ESI): m/z calcd for
C20H14INO5 [M+H]+ 475.9995, found 475.9994.
General procedure for synthesis of substrates 6c
A mixture of dibromide (2.78 g, 10 mmol) and freshly distilled NꢀBoc 3ꢀmethylpyrrole (2.7 g, 15 mmol) in toluene (20 mL) was cooled
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to ꢀ78 C. nꢀButyllithium (1.6 M in hexane; 13.8 mL, 22 mmol) was added dropwise over a period of 1.5 h. The resulting bright orange
solution was allowed to warm up to 25 oC over 3 h and then left for a further 17 h at 25 oC. The reaction mixture was then quenched with
water and the phases were separated. The aqueous layer was extracted with EtOAc and the organic layers were combined, dried over
Na2SO4 and concentrated to give a brown oil. The resulting crude product was purified by column chromatography on silica gel (petroleum
ether/ethyl acetate=10/1 v/v) to give 2ꢀmethylꢀNꢀBoc intermediate (1.62 g, 63 %) as a pink solid.
2ꢀmethylꢀNꢀBoc intermediate (722 mg, 2.4 mmol) was dissolved in 10 mL DCM followed by the addition of Et3N (0.4 mL) and heating
to reflux. TMSI (0.4 mL, 2.6 mmol) was added dropwise over 5 min and the reaction was heated at reflux for an additional 15 minutes,
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after which time TLC analysis showed complete consumption of 1ꢀmethylꢀNꢀBoc intermediate. The reaction mixture was cooled to 0 C
then MeOH (0.1 mL, 3 mmol) was added dropwise. After 10 minutes at 0 oC, oꢀiodobenzoyl chloride (1.0 g, 3.6 mmol) was added and the
reaction was allowed to warm to room temperature. The reaction was stirred at room temperature for an additional hour. Water (10 mL)
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and DCM was added until all precipitates dissolved. The organic and aqueous phases were separated and the aqueous phase was extracted
twice with DCM. The organic fractions were combined, dried over Na2SO4 and concentrated. The resulting crude product was purified by
column chromatography on silica gel (petroleum ether/ethyl acetate=10/1 v/v) to give compound 6c (0.86 g, 57 %) as a light yellow solid.
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(5-Iodobenzo[d][1,3]dioxol-4-yl)(6-methyl-5,8-dihydro-5,8-epiminonaphtho[2,3-d][1,3]dioxol-10-yl)methanone (6c): light yellow
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solid, 860 mg, 57 %; m.p.>300 °C; H NMR (400 MHz, DMSO) δ :10.32 (s, 1H), 7.65 (d, J = 8.3 Hz, 1H), 7.53 (s, 1H), 7.42 (d, J = 8.1
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Hz, 1H), 7.33 (s, 1H), 7.28 (d, J = 8.4 Hz, 1H), 6.89 (d, J = 8.2 Hz, 1H), 6.23 (s, 2H), 6.13 (s, 2H), 2.45 (s, 3H); 13C NMR (100 MHz,
DMSO) δ: 163.9, 148.3, 148.3, 147.2, 145.8, 132.5, 131.9, 130.4, 129.8, 128.1, 127.4, 126.6, 125.3, 111.5, 104.1, 102.7, 101.7, 100.4,
83.0, 19.2; HRMS (ESI): m/z calcd for C20H14INO5 [M+H]+ 475.9995, found 475.9992.
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General procedure for synthesis of target compounds 2a to 2p, 4a, 4b, 7a and 7b
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To a solution of 1a (74.6 mg, 0.2 mmol) in DMF (2.5 ml), In (57.5 mg, 0.5 mmol) was added. The mixture was heated to 110 C and
stirred for 20 h. The mixture was poured into water and extracted with EtOAc. The organic fractions were combined, dried over Na2SO4
and concentrated. The resulting crude product was purified by column chromatography on silica gel (petroleum ether/ethyl acetate=4/1
v/v) to give compound 2a (41.5 mg, 84 %) as an off white solid.
The rest of substrates 2b to 2p, 4a, 4b, 7a and 7b were prepared by the similar procedure to 2a. The known compounds 2aꢀ2m and 2oꢀ
2p showed satisfactory spectroscopic data in agreement with those reported in the literature.6,7
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13,14-Cis-dihydrobenzo[c]phenanthridin-6-one (2a): off white solid, 41.5 mg, 84 %; m.p. 173–174 °C (lit.173–175 °C)7; H NMR
(400 MHz, CDCl3) δ: 8.08 (dd, J = 7.7, 1.1 Hz, 1H), 7.53 (td, J = 7.5, 1.4 Hz, 1H), 7.39 (td, J = 7.6, 1.0 Hz, 1H), 7.35 – 7.25 (m, 4H), 7.16
(d, J = 7.2 Hz, 1H), 6.58 (dd, J = 9.6, 2.7 Hz, 1H), 5.81 (d, J = 2.6 Hz, 1H), 5.79 (d, J = 2.7 Hz, 1H), 5.76 (s, 1H), 4.87 (d, J = 5.7 Hz, 1H),
3.89 (dt, J = 5.4, 2.6 Hz, 1H); 13C NMR (100 MHz, CDCl3) δ: 165.1, 139.6, 133.0, 132.7, 131.9, 129.3, 128.6, 128.4, 128.0, 127.9, 127.7,
127.6, 127.3, 127.1, 127.1, 52.2, 38.7; HRMS (ESI): m/z calcd for C17H13NO [M+H]+ 248.1075, found 248.1074.
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10-Chloro-13,14-cis-dihydrobenzo[c]phenanthridin-6-one (2b): white solid, 32.5 mg, 58 %; m.p. 183–184 °C (lit.182–184 °C)7; H
NMR (400 MHz, CDCl3) δ: 7.96 (d, J = 7.7 Hz, 1H), 7.52 (d, J = 7.9 Hz, 1H), 7.30–7.26 (m, 2H), 7.23–7.08 (m, 3H), 6.53 (dd, J = 9.5, 2.9
Hz, 1H), 5.55 (d, J = 9.5 Hz, 1H), 5.27 (s, 1H), 4.72 (d, J = 5.1 Hz, 1H), 4.23 (s, 1H); 13C NMR (100 MHz, CDCl3) δ: 163.9, 136.9, 133.6,
132.9, 132.8, 130.9, 129.9, 129.9, 128.6, 128.4, 128.4, 127.6, 127.4, 126.9, 126.9, 51.7, 36.7; HRMS (ESI): m/z calcd for C17H12ClNO
[M+H]+ 282.0686, found 282.0680.
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10-Fluoro-13,14-cis-dihydrobenzo[c]phenanthridin-6-one (2c): white solid, 33.4 mg, 63 %; m.p. 179–180 °C (lit.178–180 °C)7; H
NMR (400 MHz, CDCl3) δ: 7.96 (d, J = 7.8 Hz, 1H), 7.48–7.38 (m, 2H), 7.37–7.30 (m, 2H), 7.28 (d, J = 4.5 Hz, 3H), 7.24 (d, J = 7.5 Hz,
1H), 6.64 (dd, J = 9.6, 3.1 Hz, 1H), 5.69 (d, J = 9.5 Hz, 1H), 5.31 (s, 1H), 4.86 (d, J = 5.3 Hz, 1H), 4.26 (s, 1H); 13C NMR (100 MHz,
CDCl3) δ: 163.9, 159.4 (d, J = 247.0 Hz), 132.7, 130.9, 129.8, 128.7 (d, J = 8.0 Hz), 128.4, 128.3, 127.6 (d, J = 8.6 Hz), 127.3, 127.3,
126.5 (d, J = 17.3 Hz), 123.9 (d, J = 3.3 Hz), 119.6 (d, J = 21.5 Hz), 51.8, 32.8, 32.7; HRMS (ESI): m/z calcd for C17H12FNO [M+H]+
266.0981, found 266.0974.
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10-Methyl-13,14-cis-dihydrobenzo[c]phenanthridin-6-one (2d): white solid, 31.8 mg, 61 %; m.p. 201–202 °C (lit.201–203 °C)7; H
NMR (400 MHz, CDCl3) δ: 8.00 (d, J = 7.6 Hz, 1H), 7.46–7.16 (m, 6H), 6.62 (dd, J = 9.5, 3.1 Hz, 1H), 5.59 (d, J = 9.5 Hz, 1H), 5.30 (s,
1H), 4.77 (d, J = 5.2 Hz, 1H), 4.03 (s, 1H), 2.38 (s, 3H); 13C NMR (100 MHz, CDCl3) δ: 165.3, 137.6, 135.0, 134.7, 132.8, 131.6, 129.7,
128.4, 128.3, 128.0, 127.7, 127.5, 127.3, 127.3, 126.2, 51.9, 35.9, 18.9; HRMS (ESI): m/z calcd for C18H15NO [M+H]+ 262.1232, found
262.1229.
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9-Chloro-13,14-cis-dihydrobenzo[c]phenanthridin-6-one (2e): white solid, 47.2 mg, 84 %; m.p. 203–204 °C (lit.202–204 °C)7; H
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NMR (400 MHz, CDCl3) δ: 8.06 (d, J = 8.3 Hz, 1H), 7.44–7.28 (m, 5H), 7.21 (d, J = 7.3 Hz, 1H), 6.65 (dd, J = 9.6, 2.5 Hz, 1H), 5.84 (dd, J
= 9.6, 2.8 Hz, 1H), 5.59 (s, 1H), 4.90 (d, J = 5.5 Hz, 1H), 4.02–3.81 (m, 1H); 13C NMR (100 MHz, CDCl3) δ: 164.3, 141.4, 139.0, 132.5,
131.9, 129.7, 129.4, 128.6, 128.1, 127.9, 127.6, 127.4, 127.3, 127.2, 126.6, 52.2, 38.4; HRMS (ESI): m/z calcd for C17H12ClNO [M+H]+
282.0686, found 282.0675.
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9-Fluoro-13,14-cis-dihydrobenzo[c]phenanthridin-6-one (2f): white solid, 42.9 mg, 81 %; m.p. 176–179 °C (lit.176–178 °C)7; H
NMR (400 MHz, CDCl3) δ: 8.11 (dd, J = 8.5, 5.9 Hz, 1H), 7.38–7.26 (m, 3H), 7.19 (d, J = 7.2 Hz, 1H), 7.08 (td, J = 8.5, 2.2 Hz, 1H), 7.03
(d, J = 8.9 Hz, 1H), 6.65 (dd, J = 9.5, 2.0 Hz, 1H), 5.94 (s, 1H), 5.86 (dd, J = 9.5, 3.1 Hz, 1H), 4.91 (d, J = 5.6 Hz, 1H), 3.91 (s, 1H); 13C
NMR (100 MHz, CDCl3) δ: 165.6 (d, J = 249.9 Hz), 164.3, 142.5 (d, J = 8.4 Hz), 132.6, 132.0, 130.9 (d, J = 9.4 Hz), 129.3, 128.5, 127.9,
127.5, 127.4, 127.2, 124.5 (d, J = 2.7 Hz), 114.9 (d, J = 21.8 Hz), 113.9 (d, J = 22.2 Hz), 52.3, 38.6; HRMS (ESI): m/z calcd for
C17H12FNO [M+H]+ 266.0981, found 266.0975.
9-(Trifluoromethyl)-13,14-cis-dihydrobenzo[c]phenanthridin-6-one (2g): white solid, 54.2 mg, 86 %; m.p. 210–212 °C (lit.211–213
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°C)7; H NMR (400 MHz, CDCl3) δ: 8.19 (d, J = 8.0 Hz, 1H), 7.65 (d, J = 8.0 Hz, 1H), 7.58 (s, 1H), 7.38–7.26 (m, 3H), 7.18 (d, J = 7.2
Hz, 1H), 6.64 (dd, J = 9.6, 2.4 Hz, 1H), 6.03 (s, 1H), 5.84 (dd, J = 9.5, 3.0 Hz, 1H), 4.91 (d, J = 5.7 Hz, 1H), 4.10–3.78 (m, 1H); 13C NMR
(100 MHz, CDCl3) δ: 163.8, 140.5, 134.6, 134.3, 132.5, 131.7, 131.2, 129.5, 128.7, 128.6, 128.1, 127.5, 127.3, 124.9, 124.6 (q, J = 3.5
Hz), 124.1 (q, J = 3.4 Hz), 122.2, 52.2, 38.5; HRMS (ESI): m/z calcd for C18H12F3NO [M+H]+ 316.0949, found 316.0941.
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8-Bromo-13,14-cis-dihydrobenzo[c]phenanthridin-6-one (2h): white solid, 52.7 mg, 81 %; m.p. 242–244 °C (lit.243–245 °C)7; H
NMR (400 MHz, CDCl3) δ: 8.24 (d, J = 2.0 Hz, 1H), 7.66 (dd, J = 8.1, 2.1 Hz, 1H), 7.41–7.32 (m, 1H), 7.30–7.27 (m, 2H), 7.21 (t, J = 8.4
Hz, 1H), 6.61 (dd, J = 9.6, 2.5 Hz, 1H), 5.78 (dd, J = 9.5, 2.8 Hz, 1H), 5.54 (s, 1H), 4.87 (d, J = 5.6 Hz, 1H), 3.89 – 3.86 (m, 1H); 13C NMR
(100 MHz, CDCl3) δ: 162.6, 137.4, 134.9, 131.5, 130.6, 129.9, 128.7, 128.5, 127.9, 127.5, 126.8, 126.7, 126.5, 126.3, 120.6, 51.2, 37.2;
HRMS (ESI): m/z calcd for C17H12BrNO [M+H]+ 326.0181, found 326.0175.
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8-Chloro-13,14-cis-dihydrobenzo[c]phenanthridin-6-one (2i): white solid, 45.0 mg, 80 %; m.p. 219–220 °C (lit.219–221 °C)7; H
NMR (400 MHz, CDCl3) δ: 8.06 (d, J = 2.3 Hz, 1H), 7.49 (dd, J = 8.1, 2.3 Hz, 1H), 7.38–7.30 (m, 1H), 7.28 (dd, J = 4.0, 1.7 Hz, 2H), 7.26
(s, 1H), 7.17 (d, J = 7.3 Hz, 1H), 6.60 (dd, J = 9.6, 2.6 Hz, 1H), 5.78 (dd, J = 9.6, 2.8 Hz, 1H), 5.72 (s, 1H), 4.86 (d, J = 5.7 Hz, 1H), 3.89
(dd, J = 5.5, 2.7 Hz, 1H); 13C NMR (100 MHz, CDCl3) δ: 163.9, 137.9, 133.8, 133.0, 132.6, 131.7, 129.6, 129.5, 128.7, 128.6, 128.0,
127.9, 127.7, 127.5, 127.3, 52.2, 38.2; HRMS (ESI): m/z calcd forC17H12ClNO [M+H]+ 282.0686, found 282.0684.
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8-Fluoro-13,14-cis-dihydrobenzo[c]phenanthridin-6-one (2j): white solid, 44.0 mg, 83 %; m.p. 223–225 °C (lit.222–225 °C)7; H
NMR (400 MHz, CDCl3) δ: 7.77 (dd, J = 9.0, 2.8 Hz, 1H), 7.39–7.27 (m, 4H), 7.23 (td, J = 8.3, 2.8 Hz, 1H), 7.18 (d, J = 7.3 Hz, 1H), 6.59
(dd, J = 9.6, 2.6 Hz, 1H), 5.77 (dd, J = 9.5, 2.6 Hz, 1H), 5.70 (s, 1H), 4.86 (d, J = 5.7 Hz, 1H), 4.03 – 3.74 (m, 1H); 13C NMR (100 MHz,
CDCl3) δ: 163.9 (d, J = 2.1 Hz), 162.2 (d, J = 246.6 Hz), 135.3 (d, J = 3.2 Hz), 132.6, 131.7, 130.0 (d, J = 7.5 Hz), 129.5, 128.9 (d, J = 7.5
Hz), 128.5, 128.3, 127.6, 127.5, 127.2, 120.1 (d, J = 22.0 Hz), 114.7 (d, J = 23.1 Hz), 52.4, 38.1; HRMS (ESI): m/z calcd for C17H12FNO
[M+H]+ 266.0981, found 266.0975.
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8-Methyl-13,14-cis-dihydrobenzo[c]phenanthridin-6-one (2k): white solid, 43.8 mg, 84 %; m.p. 196–199 °C (lit.196–198 °C)7; H
NMR (400 MHz, CDCl3) δ: 7.85 (s, 1H), 7.27 (ddd, J = 11.0, 7.5, 3.6 Hz, 2H), 7.21 (d, J = 5.2 Hz, 2H), 7.16 (d, J = 7.7 Hz, 1H), 7.11 (d, J
= 7.3 Hz, 1H), 6.51 (dd, J = 9.6, 2.7 Hz, 1H), 5.72 (dd, J = 9.5, 2.5 Hz, 1H), 5.43 (s, 1H), 4.79 (d, J = 5.7 Hz, 1H), 3.96–3.62 (m, 1H), 2.34
(s, 3H); 13C NMR (100 MHz, CDCl3) δ: 165.3, 137.6, 136.6, 133.9, 132.8, 131.9, 129.4, 128.9, 128.4, 128.3, 127.7, 127.6, 127.1, 52.4,
38.4, 21.1; HRMS (ESI): m/z calcd for C18H15NO [M+H]+ 262.1232, found 262.1228.
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8-Methoxy-13,14-cis-dihydrobenzo[c]phenanthridin-6-one (2l): white solid, 48.2 mg, 87 %; m.p. 183–185 °C (lit.182–184 °C)7; H
NMR (400 MHz, CDCl3) δ: 7.63 (d, J = 2.8 Hz, 1H), 7.38–7.32 (m, 1H), 7.30–7.28 (m, 1H), 7.26 (d, J = 8.4 Hz, 1H), 7.19 (d, J = 7.3 Hz,
1H), 7.12 (dd, J = 8.4, 2.8 Hz, 1H), 6.59 (dd, J = 9.6, 2.7 Hz, 1H), 5.79 (dd, J = 9.5, 2.3 Hz, 1H), 5.51 (s, 1H), 4.87 (d, J = 5.7 Hz, 1H),
3.88 (s, 3H); 13C NMR (100 MHz, CDCl3) δ: 165.0, 159.2, 132.8, 131.9, 131.6, 129.4, 129.1, 128.9, 128.4, 128.3, 127.7, 127.1, 127.0,
120.7, 111.1, 55.6, 52.5, 38.1; HRMS (ESI): m/z calcd for C18H15NO2 [M+H]+ 278.1181, found 278.1177.
8,9-Dimethoxy-13,14-cis-dihydrobenzo[c]phenanthridin-6-one (2m): white solid, 55.3 mg, 90 %; m.p. 238–240 °C (lit.238–241 °C)7;
1H NMR (400 MHz, CDCl3) δ: 7.91 (s, 1H), 7.44 (s, 1H), 7.32–7.26 (m, 2H), 7.21 (td, J = 7.5, 1.2 Hz, 1H), 7.11 (d, J = 7.4 Hz, 1H), 6.73
(s, 1H), 6.57 (dd, J = 9.6, 2.3 Hz, 1H), 5.77 (dd, J = 9.6, 3.3 Hz, 1H), 4.87 (d, J = 6.3 Hz, 1H), 3.95 (s, 3H), 3.82 (s, 3H); 13C NMR (100
MHz, CDCl3) δ: 167.3, 153.3, 147.5, 132.8, 131.3, 129.4, 128.5, 127.8, 127.1, 126.7, 126.0, 125.9, 117.1, 109.5, 108.1, 55.3, 55.2, 51.6,
36.1; HRMS (ESI): m/z calcd for C19H17NO3 [M+H]+ 308.1287, found 308.1285.
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7,8-Methylenedioxy-13,14-cis-dihydrobenzo[c]phenanthridin-6-one (2n): white solid, 49.5 mg, 85 %; m.p. 236–238 °C; H NMR
(400 MHz, CDCl3) δ: 7.38 – 7.31 (m, 1H), 7.29 (t, J = 1.8 Hz, 2H), 7.18 (d, J = 7.3 Hz, 1H), 6.95 (d, J = 7.9 Hz, 1H), 6.78 (d, J = 8.1 Hz,
1H), 6.59 (dd, J = 9.6, 2.6 Hz, 1H), 6.15 (dd, J = 6.7, 1.1 Hz, 2H), 5.80 (dd, J = 9.5, 2.6 Hz, 1H), 5.63 (s, 1H), 4.82 (d, J = 5.4 Hz, 1H),
3.92–3.68 (m, 1H); 13C NMR (100 MHz, CDCl3) δ: 163.1, 148.3, 147.9, 132.9, 132.7, 131.9, 129.3, 129.2, 128.3, 127.5, 127.3, 127.1,
119.7, 111.9, 111.5, 102.5, 52.7, 38.7, 29.7; HRMS (ESI): m/z calcd for C18H13NO3 [M+H]+ 292.0974, found 292.0972.
7,8-Methylenedioxy-13,14-cis-dihydrobenzodioxolebenzo[c]phenanthridin-6-one (2o): white solid, 58.3 mg, 87 %; m.p. decomꢀ
posed at 260 °C (lit. decomposed at 260 °C)7; H NMR (400 MHz, CDCl3) δ: 6.93 (d, J = 7.9 Hz, 1H), 6.79–6.73 (m, 2H), 6.66 (s, 1H),
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6.44 (dd, J = 9.5, 2.5 Hz, 1H), 6.14 (dd, J = 8.4, 1.2 Hz, 2H), 5.98 (s, 2H), 5.69 (dd, J = 9.5, 2.6 Hz, 1H), 5.64 (s, 1H), 4.70 (d, J = 5.5 Hz,
1H), 3.76 (dt, J = 5.5, 2.8 Hz, 1H); 13C NMR (100 MHz, CDCl3) δ: 163.2, 148.3, 148.0, 147.9, 147.2, 133.0, 127.4, 127.3, 127.1, 119.6,
111.8, 111.4, 108.3, 107.7, 102.6, 101.4, 52.8, 38.6, 29.7; HRMS (ESI): m/z calcd for C19H13NO5 [M+Na]+ 358.0691, found 358.0689.
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8,9-Dimethoxy-13,14-cis-dihydrobenzodioxolebenzo[c]phenanthridin-6-one (2p). white solid, 63.9 mg, 91 %; m.p. decomposed at
270 °C (lit. decomposed at 270 °C)7; 1H NMR (400 MHz, CDCl3) δ: 7.59 (s, 1H), 6.79 (s, 1H), 6.76 (s, 1H), 6.68 (s, 1H), 6.47 (dd, J = 9.5,
2.6 Hz, 1H), 6.00 (dd, J = 2.6, 1.3 Hz, 2H), 5.70 (dd, J = 9.5, 2.6 Hz, 1H), 5.51 (s, 1H), 4.77 (d, J = 5.8 Hz, 1H), 3.97 (s, 3H), 3.95 (s, 3H),
3.84–3.72 (m, 1H); 13C NMR (100 MHz, CDCl3) δ: 164.2, 151.9, 147.4, 147.0, 146.2, 132.2, 126.3, 125.9, 125.7, 124.9, 119.5, 108.9,
108.1, 107.4, 106.7, 100.3, 55.1, 51.7, 37.4; HRMS (ESI): m/z calcd for C20H17NO5 [M+Na]+ 374.1004, found 374.0996.
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7,13-Cis-dihydro-1H-benzo[d]naphtho[1,2-b]azepin-2-one (4a): white solid, 43.8 mg, 84 %; m.p. 168–170 °C; H NMR (400 MHz,
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CDCl3) δ: 7.50–7.09 (m, 8H), 6.71 (dd, J = 9.5, 2.9 Hz, 1H), 6.02 (d, J = 8.6 Hz, 1H), 5.44 (s, 1H), 5.01 (t, J = 4.2 Hz, 1H), 4.24 (d, J =
15.3 Hz, 1H), 4.11 (s, 1H), 3.77 (d, J = 15.2 Hz, 1H); 13C NMR (100 MHz, CDCl3) δ: 171.8, 137.9, 133.5, 132.5, 132.1, 131.6, 130.8,
130.2, 129.3, 128.2, 127.8, 127.7, 127.7, 127.4, 127.0, 53.5, 43.9, 42.5; HRMS (ESI): m/z calcd for C18H15NO [M+H]+ 262.1232, found
262.1227.
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5-Methyl-7,13-cis-dihydro-1H-benzo[d]naphtho[1,2-b]azepin-2-one (4b): white solid, 50.1 mg, 91 %; m.p. 149–151 °C; H NMR
(400 MHz, CDCl3) δ: 7.42–7.35 (m, 1H), 7.29 (d, J = 8.4 Hz, 3H), 7.24 (d, J = 7.3 Hz, 1H), 7.20 (d, J = 7.8 Hz, 1H), 7.13 (d, J = 7.8 Hz,
1H), 7.01 (s, 1H), 6.69 (dd, J = 9.5, 2.7 Hz, 1H), 6.00 (d, J = 9.4 Hz, 1H), 5.44 (s, 1H), 4.98 (t, J = 4.3 Hz, 1H), 4.20 (d, J = 15.2 Hz, 1H),
4.07 (s, 1H), 3.71 (d, J = 15.2 Hz, 1H), 2.35 (s, 3H); 13C NMR (100 MHz, CDCl3) δ: 170.9, 135.9, 133.7, 132.5, 131.5, 131.3, 130.4, 130.2,
129.0, 128.2, 127.5, 127.1, 126.7, 126.4, 125.9, 52.5, 42.4, 41.4, 19.8; HRMS (ESI): m/z calcd for C19H17NO [M+H]+ 276.1388, found
276.1384.
8,12-Dimethyl-13,14-cis-dihydrobenzodioxolebenzo[c]phenanthridin-6-one (7a): light yellow solid, 45.9 mg, 72 %; m.p. 232–234
°C; 1H NMR (400 MHz, CDCl3) δ: 7.89 (s, 1H), 7.33 (d, J = 7.5 Hz, 1H), 7.17 (d, J = 7.7 Hz, 1H), 6.86 (s, 1H), 6.78 (s, 1H), 5.98 (s, 1H),
5.53 (s, 1H), 5.47 (s, 1H), 4.69 (d, J = 5.4 Hz, 1H), 3.75 (s, 1H), 2.39 (s, 1H), 2.02 (s, 1H). 13C NMR (100 MHz, CDCl3) δ: 164.3, 147.2,
145.8, 136.3, 136.2, 132.7, 130.5, 128.2, 127.3, 126.6, 125.9, 125.4, 122.9, 107.3, 103.9, 100.3, 51.9, 37.3, 20.1, 18.3; HRMS (ESI): m/z
calcd for C20H18NO3 [M+H]+ 320.1287, found 320.1285.
7,8-Methylenedioxy-12-methyl-13,14-cis-dihydrobenzodioxolebenzo[c]phenanthridin-6-one (7b): light yellow solid, 44.0 mg, 63 %;
m.p. 244–246 °C; 1H NMR (400 MHz, CDCl3) δ: 6.91 (d, J = 7.8 Hz, 1H), 6.86 (s, 1H), 6.78 (s, 1H), 6.72 (d, J = 7.9 Hz, 1H), 6.13 (d, J =
9.1 Hz, 1H), 5.99 (s, 1H), 5.48 (s, 1H), 4.65 (d, J = 5.3 Hz, 1H), 3.71 (s, 1H), 2.03 (s, 1H); 13C NMR (100 MHz, CDCl3) δ 162.1, 147.2,
146.8, 145.9, 132.6, 130.7, 128.2, 125.3, 123.1, 118.6, 110.7, 110.4, 107.2, 104.0, 101.5, 100.4, 52.2, 37.7, 28.7, 18.3; HRMS (ESI): m/z
calcd for C20H16NO5 [M+H]+ 350.1028, found 350.1024.
ASSOCIATED CONTENT
Supporting Information
Xꢀray crystallography data, NMR spectra, HRMS. This material is available free of charge via the Internet at http://pubs.acs.org.
AUTHOR INFORMATION
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Corresponding Author
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*Eꢀmail: chenke7758@163.com
*Eꢀmail: xiaohuaxu@nankai.edu.cn
Notes
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The authors declare no competing financial interests.
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ACKNOWLEDGMENT
This work was financially supported by National Key Technology R&D program (grant No2011BAE06B05).
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