3-Phenacylideneoxindoles with tosylmethyl isocyanide and MeOH through C-C bond cleavage: Facile synthesis of pyrrole and 2H-pyrrolo[3,4-c]quinoline derivatives

Article abstract of DOI:10.1016/j.tet.2012.11.088

A novel reaction of 3-phenacylideneoxindoles (1) with tosylmethyl isocyanide (2a) and MeOH through C-C bond cleavage has been developed. The reaction proceeded under mild conditions, providing a powerful synthetic tool for the construction of pyrrole derivatives (3) from easily accessible starting materials and synthesis of 2H-pyrrolo[3,4-c]quinolines (4) by further dehydration of 3.

Full text of DOI:10.1016/j.tet.2012.11.088

Accepted Manuscript
3-Phenacylideneoxindoles with Tosylmethyl Isocyanide and MeOH through C–C Bond
Cleavage: Facile Synthesis of Pyrrole and 2H-pyrrolo[3,4-c]quinoline Derivatives†
Rong Wang, Xiao-Ping Xu, Hua Meng, Shun-Yi Wang, Shun-Jun Ji
PII:
S0040-4020(12)01806-6
10.1016/j.tet.2012.11.088
TET 23799
DOI:
Reference:
To appear in: Tetrahedron
Received Date: 15 October 2012
Revised Date: 21 November 2012
Accepted Date: 27 November 2012
Please cite this article as: Wang R, Xu X-P, Meng H, Wang S-Y, Ji S-J, 3-Phenacylideneoxindoles with
Tosylmethyl Isocyanide and MeOH through C–C Bond Cleavage: Facile Synthesis of Pyrrole and 2H-
pyrrolo[3,4-c]quinoline Derivatives†, Tetrahedron (2013), doi: 10.1016/j.tet.2012.11.088.
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3-Phenacylideneoxindoles with Tosylmethyl Isocyanide and MeOH through C–C
Bond Cleavage: Facile Synthesis of Pyrrole and 2H-pyrrolo[3,4-c]quinoline
Derivatives
Rong Wang, Xiao-Ping Xu, Hua Meng, Shun-Yi Wang*and Shun-Jun Ji*
College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123,
P.R.China

ACCEPTED MANUSCRIPT
Tetrahedron
journal homepage: www.elsevier.com
3-Phenacylideneoxindoles with Tosylmethyl Isocyanide and MeOH through C–C
Bond Cleavage: Facile Synthesis of Pyrrole and 2H-pyrrolo[3,4-c]quinoline
Derivatives†
Rong Wang, Xiao-Ping Xu, Hua Meng, Shun-Yi Wang*and Shun-Jun Ji*
Key Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry , Chemical Engineering and Materials Science, Soochow University, Suzhou
215123, China
ARTICLE INFO
ABSTRACT
Article history:
Received
Received in revised form
Accepted
A novel reaction of 3-phenacylideneoxindoles (1) with tosylmethyl isocyanide (2a) and MeOH through C–C
bond cleavage has been developed. The reaction proceeded under mild conditions, providing a powerful
synthetic tool for the construction of pyrrole derivatives (3) from easily accessible starting materials and
synthesis of 2H-pyrrolo[3,4-c]quinolines (4) by further dehydration of 3.
Available online
Keywords:
C-C bonds cleavage
3-phenacylideneoxindoles
Tosylmethyl isocyanide
Pyrrole
© 2012 Elsevier Ltd. All rights reserved.
2H-pyrrolo[3,4-c]quinolines
1. Introduction
very useful, it has some drawbacks such as lengthy steps and poor
Nitrogen-containing heterocycles are prevalent in numerous
natural products, and are extremely important in materials chemistry
and medicinal chemistry.1,2 Pyrroles and pyrroloquinolines, in
particular, have attracted much attention because of their biological
activities and many applications;3 examples are the ATP-ase
inhibitor (I),4 and caspase inhibitor (II),5 and the compounds with
serotonergic activity (III)6 (Figure 1)
overall yields. As a result of our continued synthetic interest in the
nitrogen-containing heterocycles,9 we report a simple and convenient
synthetic approach toward pyrrole and 2H-pyrrolo[3,4-c]quinoline
derivatives.
Van Leusen’s pyrrole synthesis10 through the reaction of
tosylmethyl isocyanide (TosMIC) with Michael acceptors is one of
the most convenient methods for obtaining 3,4-disubstituted 1H-
pyrroles. The mechanism for Van Leusen’s reaction involved the
Ar
R2
N
N
O
O
elimination of toluenesulfinate anion, followed by
a final
S
R3
aromatization (Scheme 1). When 3-phenacylideneoxindole (1a)11
and TosMIC (2a) were treated with 1.0 equiv of K2CO3 in MeOH at
room temperature under the similar Van Leusen pyrrole conditions,
the expected intermediate could not follow the classical mechanism
of Van Leusen’s reaction. Surprisingly, methyl [2-(4-benzoyl-1H-
pyrrol-3-yl)phenyl]carbamate (3a) was obtained in 11% yield
(Scheme 1) through C–C bond cleavage (the C2–C3 bond of 1a)
during final aromatization step, followed by the reaction with solvent
(Table 1, entry 1). The structure of product 3a was confirmed by
NMR spectroscopy and unambiguously demonstrated by X-ray
diffraction analysis (Figure 2).
N
R
N
R1
II
OMe
ATP-ase inhibitors ( )
I
Caspase inhibitors (
)
R1
N
N
R3
R2
N
O
Compounds (III) with serotonergic activity
Figure. 1 Examples of biologically active pyrroloquinoline
derivatives.
The efficient synthesis of pyrroles and pyrroloquinolines have
become important challenges for both synthetic and pharmaceutical
chemists. Although much attention has been paid to the synthesis of
pyrroloquinolines using different methods,7 there are only few
reports in the literature on the synthesis of 2H-pyrrolo[3,4-
c]quinoline derivatives (Scheme 1).5,6,8 Although these methods are
1

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2. Results and discussion
When 3.0 equiv of K2CO3 were used, the yield of 3a increased to
43% (Table 1, entry 3). In our efforts to increase the yield of 3a, we
used different bases, i.e., Cs2CO3, DBU, NEt3, NaOH, KOH and t-
BuOK, for this reaction. It was found that only trace amounts of
product 3a were formed when DBU or NEt3 was used as the additive
(Table 1, entries 5 and 6). However, it was found that 3.0 equiv of t-
BuOK were sufficient to promote this reaction, and the yield of the
desired product was increased to 65% (Table 1, entry 9). Increasing
the amount of t-BuOK did not increase the yield of the desired
product (Table 1, entry 10). After carefully checking the effects of
temperature on the reaction, the optimal reaction conditions were
obtained. The reaction of 1a (0.5 mmol) and 2a (0.6 mmol) in 2.0
mL of MeOH, using t-BuOK (3.0 equiv) as the additive, was
initiated at 0 °C, and then the mixture was warmed to room
temperature.
Scheme 2. Classical Van Leusen's pyrrole synthesis and this work
Figure 2. ORTEP diagram of 3a
Table 1. Optimization of Reaction Conditionsa
Ph
O
NH
Ph
base
+
CN
Ts
O
MeOH
NH
N
H
O
1.2eq
O
OMe
1a
2a
3a
entry
1
Base (equiv)
time (h)
Temp (°C)
Yield(%)b
11
K2CO3 (1.0 eq.)
K2CO3 (2.0 eq.)
K2CO3 (3.0 eq.)
12
3
25
2
25
26
3
3
25
43
4
Cs2CO3 (3.0 eq.)
DBU (3.0 eq.)
3
25
37
5
12
12
3
25
trace
trace
58
6
NEt3 (3.0 eq.)
25
7
NaOH (3.0 eq.)
KOH (3.0 eq.)
25
8
3
25
56
9
t-BuOK (3.0 eq.)
t-BuOK (4.0 eq.)
t-BuOK (3.0 eq.)
t-BuOK (3.0 eq.)
t-BuOK (3.0 eq.)
t-BuOK (3.0 eq.)
t-BuOK (3.0 eq.)
3
25
65
10
11
12
13
14
15
3
25
64
3
40
50
50
3
27
12
3
0
71
0°C to rt
-10°C to rt
69
3
65
a The reactions were performed with 1a (0.5 mmol, 1.0 eq.) and TosMIC (0.6 mmol, 1.2 eq.) in the presence of base in 2 mL
MeOH.
b Isolated yield.
1

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With the reaction conditions optimized, we analyzed the scope of
the reaction. The results are summarized in Table 2. These reactions
tolerated wide variety of functional groups. 3-
Phenacylideneoxindoles bearing not only an electron-donating group
but also an electron-withdrawing group worked well, affording the
desired 3,4-disubstituted 1H-pyrrole derivatives in moderate to good
yields (Table 2, entries 1–14). A yield of 83% was obtained in the
case of 4-Br-substituted 1 as the starting material (Table 2, entry
12). When 3-acetonylideneoxindole was used in this reaction, the
desired product 3s was obtained in 51% yield (Table 2, entry 18).
However, when the reaction was extended to other substituted
TosMIC derivatives under identical conditions, no desired products
were isolated (Table 2, entries 15–17); this was caused by steric
hindrance of the TosMIC derivatives. However, poor yield(19%)
was obtained when the reaction was applied ethanol as the solvent
(Table 2, entry 19). When other alcohols were used as solvents, such
as isopropanol, no desired products were isolated.
a
Table 2. Substrate Scope for Synthesis of 3,4-Disubstituted 1H-Pyrrolesa
R2
R3
NH
O
R3
R2
t-BuOK
+
R1
CN
Ts
R1
MeOH
O
NH
OMe
N
O
1.2eq
H
O
1
2
3
entry
1
R1
5-CH3
5-Cl
5-Br
6-Br
4-Cl
H
R2
R3
H
time(h)
product
3b
3c
yield(%)b
62
C6H5
C6H5
C6H5
C6H5
C6H5
5
4
2
H
68
3
H
4
3d
3e
67
4
H
4
79
5
H
5
3f
59
6
4-CH3C6H4
2-CH3C6H4
4-OCH3C6H4
4-NH2C6H4
4-FC6H4
4-ClC6H4
4-Br C6H4
3-Cl C6H4
4-NO2 C6H4
C6H5
H
4
3g
3h
3i
58
7
H
H
4
56
8
H
H
12
5
66
9
H
H
3j
69
10
11
12
13
14
15
16
17
18
19c
H
H
9
3k
3l
62
H
H
4
71
H
H
4
3m
3n
3o
3p
3q
3r
83
H
H
4
76
H
H
3
67
H
CH3
Bn
Allyl
H
24
24
24
2
trace
trace
trace
51
H
C6H5
H
C6H5
H
C6H5
3s
H
C6H5
H
6
3t
19
a The reactions were performed with 1 (0.5 mmol, 1.0 eq.) and 2 (0.6 mmol, 1.2 eq.) in the presence of t-BuOK in 2 mL MeOH.
b Isolated yield.
c The reactions were performed with 1 (0.5 mmol, 1.0 eq.) and 2 (0.6 mmol, 1.2 eq.) in the presence of t-BuOK in 2 mL EtOH.
With the 3,4-disubstituted 1H-pyrroles 3 in hand, we next focused
on the construction of the 4-phenyl-2H-pyrrolo[3,4-c]quinoline unit
through an intramolecular dehydration reaction using 10.0 equiv of
POCl3. The dehydrations of 3a, 3c, 3e, 3l, and 3m were investigated
in anhydrous MeCN under reflux conditions. The results are
summarized in Scheme 3. All the desired 4-aryl-2H-pyrrolo[3,4-
c]quinolines 4 were obtained in similar good yields. The structure of
4-phenyl-2H-pyrrolo[3,4-c]quinoline (4a) was also confirmed by
single-crystal X-ray crystallographic analysis (Figure 3). The 4-aryl-
2H-pyrrolo[3,4-c]quinolines 4 not only had the useful pyrrolo[3,4-
c]quinoline core structure, but also contained useful functional
groups such as Br and Cl, making it possible to modify them and
synthesize more complex molecules by cross-coupling reactions.
3

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reference. High resolution mass spectra (HRMS) were obtained on a
TOF MS instrument with ESI source. X-ray diffraction data were
recorded with graphite monochromatic Mo-Kα radiation.
General procedures for products 3a-3t:
To a suspension of t-BuOK (0.204 g, 1.5 mmol) in 2 mL of
anhydrous MeOH was added
a
solution of 3-
phenacylideneoxindoles 1 (0.5 mmol) and TosMIC 2 (0.6 mmol)
in 2 mL of anhydrous MeOH at 0 oC. After stirring for 10 min at
0 oC, the reaction was stirred at room temperature for appropriate
time. After reaction completion (monitored by TLC), the solvent
was removed under reduced pressure. The residue was purified
by preparative silica gel column chromatography to give the
corresponding products 3 as white solid.
Figure 3.ORTEP diagram of 4a
R2
NH
O
POCl3
R1
NH
CH3CN reflux
N
R1
R2
NH
OMe
4
O
General procedures for products 4a, 4c, 4e, 4l, 4m:
3
NH
NH
Cl
To a solution of 3 (0.50 mmol) in 10 mL of dry CH3CN was
added freshly distilled POCl3 (0.46 mL, 5.0 mmol) under N2 at room
temperature. The reaction mixture was warmed to reflux and stirred
overnight. The reaction mixture was cooled to room temperature,
diluted with water, treated with aqueous 10% NaOH solution to
pH=8 and extracted with ethyl acetate (3×20 mL). The combined
organic layer was washed with brine, dried over Na2SO4, filtered
and concentrated in vacuo. The residue was purified by flash column
chromatography on silica gel to provide 4 as yellow solid.
N
Br
N
4c
4e
, 73%yield
, 71%yield
NH
NH
N
N
Cl
Br
4l,
4m
, 70%yield
69%yield
Scheme 3 Synthesis of 4-Phenyl-2H-pyrrolo[3,4-c]quinolines
4a
a
The reactions were performed with 3 (0.5 mmol, 1.0 eq.) and
POCl3 (5.0 mmol, 10.0 eq.) in CH3CN.
4.2. Methyl (2-(4-benzoyl-1H-pyrrol-3-yl)phenyl)carbamate
(3a). Yield: 69%; White solid; melting point: 215.5-216.4 ºC; 1H
NMR (400 MHz, d6-DMSO): δ 11.76 (s, 1H), 8.01 (s, 1H), 7.71
(d, J = 7.6 Hz, 2H), 7.56 (dd, J = 15.2, 7.6 Hz, 2H), 7.45 (t, J =
7.4 Hz, 2H), 7.32 (s, 1H), 7.24 (t, J = 7.6 Hz, 1H), 7.16 (d, J =
7.4 Hz, 1H), 7.04 (t, J = 7.4 Hz, 1H), 6.96 (s, 1H), 3.48 (s, 3H).
13C NMR (d6-DMSO, 75 MHz): δ 191.0, 154.4, 140.0, 136.5,
131.9, 131.5, 129.3, 129.0, 128.5, 128.1, 127.3, 123.9, 122.7,
121.9, 121.4, 121.1, 51.9; MS: Anal. Calcd. For C19H16N2O3:
320.1161 Found: 319.1089 (M-H+); IR (KBr, cm-1): ν 3338,
3127, 2949, 1726, 1618, 1518, 1444, 1297, 1206, 1055. Crystal
data for 3a, which has been deposited at the Cambridge
Crystallographic Data Centre as supplementary publication with
No. CCDC 902575. Copies of this information may be obtained
free of charge from The Director, CCDC, 12 Union Road,
Cambridge, CB2 1EZ, UK (E-mail: linstead@ccdc.cam.ac.uk or
deposit@ccdc.cam.ac.uk; fax: +44 01223 336033): Structural
parameters for product 3a: data collection: Rigaku Mercury CCD
area detector; crystal size: 0.80×0.25×0.19 mm3; C19H15N2O3,
Mr= 319.33, monoclinic, space group P 21/n, a = 13.611(4), b=
7.2333(16), c = 17.110(5) Å, a = 90.00, b=110.804 (6), g =
90.00, V = 1574.7(7) Å3, Z = 4, Dc= 1.347 g cm-3, R[ I > 2σ(I )]
= 0.0775, wR[I > 2 s (I )] =0.1828.
3. Conclusion
In conclusion, we have demonstrated a simple and highly
efficient synthetic strategy for preparing of pyrrole derivatives via
C-C bond cleavage in good yields and obtaining 2H-pyrrolo[3,4-
c]quinoline derivatives by further dehydration. This method
involved a non-classical Van Leusen’s pyrrole synthesis through the
reaction of 3-phenacylideneoxindoles with TosMIC in MeOH under
basic conditions, and intramolecular dehydration of 3,4-disubstituted
1H-pyrroles using POCl3. It would be interesting to synthesize more
functionalized 2H-pyrrolo[3,4-c]quinoline derivatives by cross-
coupling reactions of Br- or Cl-substituted 4, which have potential
applications in pharmaceutical chemistry and materials chemistry.
These results will be reported in due course.
4. Experimental Section
4.1. General
All reactions were carried out at ambient temperature in oven-
dried glassware. All solvents were dried and distilled according to
standard procedures. Column chromatography was generally
performed on silica gel (300-400 mesh) and reactions were
monitored by thin layer chromatography (TLC) using UV light to
visualize the course of the reactions. Melting points were recorded
on an Electrothermal digital melting point apparatus and are
uncorrected. IR spectra were recorded on an FT-IR spectrometer
using KBr optics. NMR spectra were recorded at room temperature
in d6-DMSO at 300/400 Hz and 75/100 Hz with TMS as an internal
4.3. Methyl
(2-(4-benzoyl-1H-pyrrol-3-yl)-4-
methylphenyl)carbamate (3b). Yield: 62%; White solid;
1
melting point: 208.5-209.6 ºC; H NMR (400 MHz, d6-DMSO):
δ 11.73 (s, 1H), 7.95 (s, 1H), 7.70 (d, J = 7.1 Hz, 2H), 7.54 (t, J
= 6.8 Hz, 1H), 7.46-7.43 (m, 3H), 7.30 (s, 1H), 7.03 (d, J = 7.8
Hz, 1H), 6.95 (d, J = 8.7 Hz, 2H), 3.47 (s, 3H), 2.22 (s, 3H). 13C
NMR (d6-DMSO, 75 MHz): δ 191.1, 154.6, 140.1, 134.0, 133.0,
132.0, 131.9, 129.3, 128.5, 128.1, 127.8, 123.1, 122.0, 121.6,
121.0, 51.8, 20.7; MS: Anal. Calcd. For C20H18N2O3: 334.1317
4

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Found: 333.1223 (M-H+); IR (KBr, cm-1): ν 3181, 2943, 2687,
1737, 1597, 1390, 1302, 1218, 1074.
For C20H18N2O3: 334.1317 Found: 333.1247 (M-H+); IR (KBr,
cm-1): ν 3412, 3198, 2951, 1733, 1609, 1517, 1307, 1217, 1071.
4.4. Methyl
(2-(4-benzoyl-1H-pyrrol-3-yl)-4-
4.10. Methyl
(2-(4-(4-methoxybenzoyl)-1H-pyrrol-3-
chlorophenyl)carbamate (3c). Yield: 68%; White solid;
melting point: 211.5-213.4 ºC; H NMR (400 MHz, d6-DMSO):
yl)phenyl)carbamate (3i). Yield: 66%; White solid; melting
point: 179.5-180.8 ºC; H NMR (400 MHz, d6-DMSO): δ 11.71
1
1
δ 11.81 (s, 1H), 8.11 (s, 1H), 7.71 (d, J = 7.1 Hz, 2H), 7.56 (t, J
= 7.4 Hz, 2H), 7.46 (t, J = 7.4 Hz, 2H), 7.33-7.28 (m, 2H), 7.19
(d, J = 2.5 Hz, 1H), 7.04 (s, 1H), 3.46 (s, 3H). 13C NMR (d6-
DMSO, 75 MHz): δ190.7, 154.4, 139.9, 135.5, 131.9, 131.1,
130.7, 129.3, 128.5, 128.2, 127.8, 127.0, 124.4, 121.8, 121.5,
120.0, 52.0; MS: Anal. Calcd. For C19H15N2O3Cl: 354.0771
Found: 353.0710 (M-H+); IR (KBr, cm-1): ν 3125, 2945, 1720,
1625, 1371, 1220, 1074.
(s, 1H), 8.16 (s, 1H), 7.74 (d, J = 8.3 Hz, 2H), 7.58 (d, J = 6.9
Hz, 1H), 7.31 (s, 1H), 7.24 (t, J = 7.4 Hz, 1H), 7.14 (d, J = 7.2
Hz, 1H), 7.04 (t, J = 7.3 Hz, 1H), 6.99 (d, J = 8.4 Hz, 2H), 6.94
(s, 1H), 3.82 (s, 3H), 3.49 (s, 3H). 13C NMR (d6-DMSO, 100
MHz): δ 195.0, 167.5, 159.4, 141.5, 137.3, 136.8, 136.5, 132.3,
132.1, 128.9, 127.8, 127.0, 126.3, 125.8, 118.7, 60.8, 56.9; MS:
Anal. Calcd. For C20H18N2O4: 350.1267 Found: 349.1186 (M-
H+); IR (KBr, cm-1): ν 3418, 3154, 1738, 1594, 1378, 1306,
1237, 1156, 1074.
4.5. Methyl
(2-(4-benzoyl-1H-pyrrol-3-yl)-4-
bromophenyl)carbamate (3d). Yield: 67%; White solid;
melting point: 191.4-193.1 ºC; H NMR (400 MHz, d6-DMSO):
4.11. Methyl
(2-(4-(4-aminobenzoyl)-1H-pyrrol-3-
1
yl)phenyl)carbamate (3j). Yield: 69%; White solid; melting
point: 237.8-238.8 ºC; H NMR (400 MHz, d6-DMSO): δ 11.60
1
δ 11.81 (s, 1H), 8.09 (s, 1H), 7.72 (dd, J = 7.2, 1.0 Hz, 2H), 7.58-
7.54 (m, 2H), 7.48-7.41 (m, 3H), 7.33 (d, J = 2.3 Hz, 2H), 7.04
(d, J = 1.8 Hz, 1H), 3.46 (s, 3H). 13C NMR (d6-DMSO, 100
MHz): δ 195.7, 159.3, 144.9, 141.00, 138.5, 136.9, 136.3, 134.9,
134.3, 133.4, 133.2, 129.6, 126.8, 126.5, 124.9, 120.8, 57.0; MS:
Anal. Calcd. For C19H15N2O3Br: 398.0266 Found: 397.0196 (M-
H+); IR (KBr, cm-1): ν 3132, 2955, 1723, 1620, 1301, 1217,
1071.
(s, 1H), 8.61 (s, 1H), 7.55 (d, J = 8.1 Hz, 3H), 7.24 (s, 2H), 7.11
(d, J = 7.2 Hz, 1H), 7.03 (d, J = 7.2 Hz, 1H), 6.88 (s, 1H), 6.53
(d, J = 8.1 Hz, 2H), 5.94 (s, 2H), 3.52 (s, 3H). 13C NMR (d6-
DMSO, 75 MHz): δ 189.9, 154.5, 153.5, 136.9, 132.4, 131.8,
129.5, 127.4, 126.6, 125.7, 123.9, 122.8, 122.4, 121.3, 120.4,
112.8, 51.9; MS: Anal. Calcd. For C20H18N2O4: 335.1270 Found:
334.1191 (M-H+); IR (KBr, cm-1): ν 3345, 3147, 1718, 1591,
1533, 1448, 1377, 1305, 1226, 1158, 1063.
4.6. Methyl
(2-(4-benzoyl-1H-pyrrol-3-yl)-5-
bromophenyl)carbamate (3e). Yield: 79%; White solid;
melting point: 219.0-220.2 ºC; 1H NMR (400 MHz, d6-DMSO):
δ 11.79 (s, 1H), 8.11 (s, 1H), 7.82 (s, 1H), 7.71 (d, J = 7.1 Hz,
2H), 7.58-7.54 (m, 1H), 7.48-7.44 (m, 2H), 7.33 (s, 1H), 7.23 (d,
J = 7.8 Hz, 1H), 7.11 (d, J = 8.1 Hz, 1H), 6.99 (s, 1H), 3.48 (s,
3H). 13C NMR (d6-DMSO, 100 MHz): δ 195.7, 159.2, 144.9,
143.0, 138.0, 136.9, 134.3, 133.5, 133.3, 132.9, 131.4, 129.5,
126.8, 126.2, 125.1, 124.7, 57.1; MS: Anal. Calcd. For
C19H15N2O3Br: 398.0266 Found: 397.0193 (M- H+); IR (KBr,
cm-1): ν 3402, 3191, 2948, 1738, 1513, 1215, 1067.
4.12. Methyl
(2-(4-(4-fluorobenzoyl)-1H-pyrrol-3-
yl)phenyl)carbamate (3k). Yield: 62%; White solid; melting
point: 197.5-198.8 ºC; H NMR (400 MHz, d6-DMSO): δ 11.77
1
(s, 1H), 8.04 (s, 1H), 7.79-7.76 (m, 2H), 7.55 (d, J = 7.5 Hz, 1H),
7.35 (s, 1H), 7.26-7.21 (m, 3H), 7.14 (d, J = 7.4 Hz, 1H), 7.03 (t,
J = 7.4 Hz, 1H), 6.97 (s, 1H), 3.47 (s, 3H). 13C NMR (d6-DMSO,
100 MHz): δ 194.5, 170.6, 168.2, 159.5, 141.4, 141.3, 137.1,
137.0, 136.4, 132.8, 132.3, 129.0, 126.8, 126.3, 126.0, 120.4,
120.2, 56.9; MS: Anal. Calcd. For C19H15N2O3F: 338.1067
Found: 337.0895 (M-H+); IR (KBr, cm-1): ν 3356, 3127, 1722,
1614, 1517, 1441, 1298, 1220.
4.7. Methyl
(2-(4-benzoyl-1H-pyrrol-3-yl)-3-
chlorophenyl)carbamate (3f). Yield: 59%; White solid; melting
point: 235.3-237.0 ºC; H NMR (400 MHz, d6-DMSO): δ 11.80
4.13. Methyl
(2-(4-(4-chlorobenzoyl)-1H-pyrrol-3-
1
yl)phenyl)carbamate (3l). Yield: 71%; White solid; melting
point: 156.7-158.1 ºC; H NMR (400 MHz, d6-DMSO): δ 11.79
1
(s, 1H), 7.71-7.66 (m, 4H), 7.53 (t, J = 7.4 Hz, 1H), 7.43 (t, J =
7.5 Hz, 2H), 7.38 (s, 1H), 7.24 (t, J = 8.1 Hz, 1H), 7.14 (d, J =
8.0 Hz, 1H), 6.95 (s, 1H), 3.54 (s, 3H). 13C NMR (d6-DMSO, 75
MHz): δ 190.1, 154.1, 139.8, 138.7, 134.5, 131.8, 129.1, 128.53,
127.6, 127.3, 124.4, 122.5, 121.4, 119.8, 116.7, 52.3. MS: Anal.
Calcd. For C19H15N2O3Cl: 354.0771 Found: 353.0694 (M-H+);
IR (KBr, cm-1): ν 3337, 3127, 2949, 1726, 1618, 1444, 1297,
1055.
(s, 1H), 8.03 (s, 1H), 7.71 (d, J = 8.5 Hz, 2H), 7.56-7.48 (m, 3H),
7.36 (s, 1H), 7.23 (t, J = 7.7 Hz, 1H), 7.14 (d, J = 7.5 Hz, 1H),
7.03 (t, J = 7.4 Hz, 1H), 6.97 (s, 1H), 3.47 (s, 3H). 13C NMR (d6-
DMSO,100 MHz): δ 194.7, 159.5, 143.6, 141.7, 141.4, 136.4,
136.2, 133.9, 133.5, 133.1, 132.3, 129.0, 127.9, 126.7, 126.3,
126.1, 56.9; MS: Anal. Calcd. For C19H15N2O3Cl: 354.0771
Found: 353.0681 (M-H+); IR (KBr, cm-1): ν 3404, 3128, 2350,
1720, 1514, 1297, 1216, 1076.
4.8. Methyl
(2-(4-(4-methylbenzoyl)-1H-pyrrol-3-
yl)phenyl)carbamate (3g). Yield: 58%; White solid; melting
point: 188.2-189.8 ºC; H NMR (400 MHz, d6-DMSO): δ11.74
4.14. Methyl
(2-(4-(4-bromobenzoyl)-1H-pyrrol-3-
1
yl)phenyl)carbamate (3m). Yield: 83%; White solid; melting
point: 118.1-119.5 ºC; H NMR (400 MHz, d6-DMSO): δ 11.81
1
(s, 1H), 8.07 (s, 1H), 7.64 (d, J = 7.8 Hz, 2H), 7.58 (d, J = 7.5
Hz, 1H), 7.31 (s, 1H), 7.27-7.22 (m, 3H), 7.15 (d, J = 7.3 Hz,
1H), 7.04 (t, J = 7.4 Hz, 1H), 6.95 (s, 1H), 3.48 (s, 3H), 2.37 (s,
3H). 13C NMR (d6-DMSO, 75 MHz): δ 196.1, 159.7, 147.4,
142.5, 141.8, 136.8, 134.9, 134.3, 133.1, 132.6, 129.2, 126.6,
126.3, 57.2, 26.7; MS: Anal. Calcd. For C20H18N2O3: 334.1317
Found: 333.1249 (M-H+); IR (KBr, cm-1): ν 3190, 2944, 1731,
1589, 1389, 1296, 1219, 1064.
(s, 1H), 8.04 (s, 1H), 7.64 (s, 4H), 7.56 (d, J = 7.8 Hz, 1H), 7.37-
7.36 (m, 1H), 7.23 (t, J = 7.7 Hz, 1H), 7.16 (d, J = 7.5 Hz, 1H),
7.04 (t, J = 7.5 Hz, 1H), 6.98 (s, 1H), 3.48 (s, 3H). 13C NMR (d6-
DMSO,75 MHz): δ 189.8, 154.5, 139.0, 136.4, 131.5, 131.4,
129.0, 128.2, 127.3, 125.7, 124.0, 123.0, 121.7, 121.4. 121.2,
51.9; MS: Anal. Calcd. For C19H15N2O3Br: 398.0266 Found:
397.0176 (M-H+); IR (KBr, cm-1): ν 3550, 3467, 1719, 1614,
1457, 1382, 1304, 1232, 1069.
4.9. Methyl
(2-(4-(2-methylbenzoyl)-1H-pyrrol-3-
yl)phenyl)carbamate (3h). Yield: 56%; White solid; melting
point: 178.8-180.2 ºC; H NMR (400 MHz, d6-DMSO): δ11.76
4.15. Methyl
(2-(4-(3-chlorobenzoyl)-1H-pyrrol-3-
1
yl)phenyl)carbamate (3n). Yield: 76%; White solid; melting
point: 138.1-140.2 ºC; H NMR (400 MHz, d6-DMSO): δ 11.79
(s, 1H), 8.02 (s, 1H), 7.66-7.64 (m, 1H), 7.61 (s, 1H), 7.58-7.53
(m, 2H), 7.45 (t, J = 7.8 Hz, 1H), 7.37 (s, 1H), 7.24-7.15 (m,
2H), 7.04 (t, J = 7.4 Hz, 1H), 6.97 (s, 1H), 3.46 (s, 3H). 13C
NMR (d6-DMSO, 100 MHz): δ 194.2, 159.4, 146.9, 141.3,
1
(s, 1H), 7.82 (s, 1H), 7.65 (d, J = 7.3 Hz, 1H), 7.35-7.29 (m, 2H),
7.26-7.19 (m, 4H), 7.09-7.04 (m, 2H), 6.93 (s, 1H), 3.55 (s, 3H),
2.24 (s, 3H). 13C NMR (d6-DMSO, 75 MHz): δ193.1, 154.4,
141.2, 136.6, 135.3, 131.5, 131.0, 129.8, 129.6, 127.9, 127.5,
125.4, 123.9, 123.2, 121.8, 120.9, 52.0, 19.5; MS: Anal. Calcd.
5

ACCEPTED MANUSCRIPT
138.2, 136.5, 136.3, 135.4, 133.8, 132.2, 132.8, 132.3, 129.0,
128.9, 128.8, 126.2, 124.4, 122.4, 121.0, 116.3, 115.1, 111.6;
MS: Anal. Calcd. For C14H14N2O3: 278.0611 Found: 277.0550
(M-H+); IR (KBr, cm-1): ν 3041, 2849, 1786, 1585, 1464, 1395,
1158, 1081.
127.9, 126.6, 126.4, 126.2, 56.8; MS: Anal. Calcd. For
C19H15N2O3Cl: 354.0771 Found: 353.0698 (M-H+); IR (KBr, cm-
1): ν 3125, 2945, 1720, 1625, 1371, 1302, 1220, 1074.
4.16. Methyl
(2-(4-(4-nitrobenzoyl)-1H-pyrrol-3-
4.21. 7-Bromo-4-phenyl-2H-pyrrolo[3,4-c]quinoline
(4e).
yl)phenyl)carbamate (3o). Yield: 67%; White solid; melting
point: 184.6-186.5 ºC; H NMR (400 MHz, d6-DMSO): δ 11.88
Yield: 71%; Yellow solid; melting point: 227.8-229.7 ºC; 1H
NMR (400 MHz, d6-DMSO): δ 12.76 (s, 1H), 8.19 (d, J = 8.4
Hz, 1H), 8.10 (d, J = 6.0 Hz, 3H), 8.03 (s, 1H), 7.79 (s, 1H), 7.63
(dd, J = 8.5, 1.4 Hz, 1H), 7.58 (d, J = 7.1 Hz, 3H). 13C NMR (d6-
DMSO, 75 MHz): δ 157.0, 143.6, 139.7, 131.3, 130.0, 129.0,
128.8, 128.1, 125.1, 122.1, 121.2, 118.2, 116.3, 115.5, 111.2;
MS: Anal. Calcd. For C14H14N2O3: 322.0106 Found: 321.0033
(M-H+); IR (KBr, cm-1): ν 3139, 2914, 1716, 1594, 1453, 1075.
1
(s, 1H), 8.25 (d, J = 8.5 Hz, 2H), 8.02 (s, 1H), 7.87 (d, J = 8.5
Hz, 2H), 7.53 (d, J = 7.7 Hz, 1H), 7.39 (s, 1H), 7.22 (t, J = 7.6
Hz, 1H), 7.16 (d, J = 7.3 Hz, 1H), 7.05-7.00 (m, 2H), 3.48 (s,
3H). 13C NMR (d6-DMSO, 75 MHz): δ 189.2, 154.6, 151.9,
149.1, 145.6, 136.3, 135.9, 131.4, 130.3, 129.0, 127.4, 124.1,
123.6, 121.6, 121.5, 121.4, 51.9; MS: Anal. Calcd. For
C19H15N3O5: 365.1012 Found: 364.0942 (M-H+); IR (KBr, cm-1):
ν 3408, 3274, 2940, 1732, 1607, 1518, 1488, 1351, 1216, 1058.
4.22. 8-Bromo-4-phenyl-2H-pyrrolo[3,4-c]quinoline
(4l).
Yield: 69%; Yellow solid; melting point: 245.6-247.2 ºC; 1H
NMR (400 MHz, d6-DMSO): δ 12.69 (s, 1H), 8.236-8.20 (m,
1H), 8.14 (d, J = 8.3 Hz, 2H), 7.99 (s, 1H), 7.95-7.93 (m, 1H),
7.78 (s, 1H), 7.63 (d, J = 8.3 Hz, 2H), 7.50-7.48 (m, 2H). 13C
NMR (d6-DMSO, 75 MHz): δ 154.2, 153.5, 142.3, 138.9, 134.4,
130.5, 129.5, 129.0, 126.5, 126.2, 123.1, 121.9, 116.1, 114.7,
110.7; MS: Anal. Calcd. For C14H14N2O3: 278.0611 Found:
277.0545 (M-H+); IR (KBr, cm-1): ν 3060, 2859, 1797, 1588,
1462, 1399, 1263, 1090.
4.17. Methyl (2-(4-acetyl-1H-pyrrol-3-yl)phenyl)carbamate
(3s). Yield: 51%; White solid; melting point: 142.7-144.3 ºC; H
1
NMR (400 MHz, d6-DMSO): δ 11.71 (s, 1H), 7.77 (s, 1H), 7.70
(s, 1H), 7.62 (d, J = 7.4 Hz, 1H), 7.26 (t, J = 7.6 Hz, 1H), 7.13
(d, J = 7.4 Hz, 1H), 7.05 (t, J = 7.3 Hz, 1H), 6.82 (s, 1H), 3.53 (s,
3H), 2.28 (s, 3H). 13C NMR (d6-DMSO, 75 MHz): δ 194.3,
154.4, 136.7, 131.5, 129.1, 127.7, 127.6, 123.93, 123.4, 122.3,
121.3, 120.0, 52.1, 28.3; MS: Anal. Calcd. For C14H14N2O3:
258.1004 Found: 257.0925 (M-H+); IR (KBr, cm-1): ν 3420,
3126, 2954, 1733, 1632, 1511, 1300, 1229, 1144, 1070.
4.23. 4-(4-Bromophenyl)-2H-pyrrolo[3,4-c]quinoline (4m).
Yield: 70%; Yellow solid; melting point: 229.5-231.6 ºC; 1H
NMR (400 MHz, d6-DMSO): δ 12.69 (s, 1H), 8.22-8.20 (m, 1H),
8.07 (d, J = 8.3 Hz, 2H), 7.98 (s, 1H), 7.95-7.931 (m, 1H), 7.76
(d, J = 8.2 Hz, 3H), 7.50-7.48 (m, 2H). 13C NMR (d6-DMSO, 75
MHz): δ 154.3, 142.4, 139.3, 131.9, 130.8, 129.6, 126.5, 126.2,
123.1, 123.0, 121.9, 116.1, 114.6, 110.7; MS: Anal. Calcd. For
C14H14N2O3: 322.0106 Found: 321.0035 (M-H+); IR (KBr, cm-1):
ν 3061, 2860, 1732, 1586, 1461, 1398, 1265, 1160, 1082.
4.18. Ethyl (2-(4-benzoyl-1H-pyrrol-3-yl)phenyl)carbamate
(3t). Yield: 19%; White solid; melting point: 147.9-149.4 ºC; H
1
NMR (400 MHz, d6-DMSO): δ 11.76 (s, 1H), 7.87 (s, 1H), 7.72
(d, J = 7.4 Hz, 2H), 7.57 (dd, J = 18.3, 7.8 Hz, 2H), 7.45 (t, J =
7.5 Hz, 2H), 7.32 (s, 1H), 7.23 (t, J = 7.6 Hz, 1H), 7.16 (d, J =
7.3 Hz, 1H), 7.04 (t, J = 7.4 Hz, 1H), 6.96 (s, 1H), 3.92 (q, J =
7.0 Hz, 2H), 1.04 (t, J = 7.0 Hz, 3H). 13C NMR (d6-DMSO, 75
MHz): δ 196.1, 159.2, 145.3, 141.7, 137.2, 136.6, 134.6, 134.6,
133.7, 133.4, 132.6, 129.1, 127.8, 127.2, 126.6, 126.4, 65.7,
20.0; MS: Anal. Calcd. For C20H18N2O3: 334.1317 Found:
333.1237 (M-H+); IR (KBr, cm-1): ν 3417, 3301, 2923, 1730,
1619, 1588, 1527, 1443, 1376, 1211, 1066.
Acknowledgements
We gratefully acknowledge support from the National Natural
Science Foundation of China (No. 21172162), the Young National
Natural Science Foundation of China (No. 21202111), the Young
Natural Science Foundation of Jiangsu Province (BK2012174),
Natural Science Basic Research of Jiangsu Province for Higher
Education (No. 10KJB150016), PAPD, and Soochow University for
financial support.
4.19. 4-Phenyl-2H-pyrrolo[3,4-c]quinoline (4a). Yield: 72%;
Yellow solid; melting point: 217.6-219.5 ºC; 1H NMR (400
MHz, d6-DMSO): δ 12.65 (s, 1H), 8.22-8.20 (m, 1H), 8.10 (d, J
= 7.1 Hz, 2H), 7.97 (s, 1H), 7.95-7.93 (m, 1H), 7.75 (s, 1H), 7.57
(dd, J = 15.7, 8.2 Hz, 3H), 7.48 (dd, J = 5.7, 3.4 Hz, 2H). 13C
NMR (d6-DMSO, 75 MHz): δ 155.6, 142.4, 140.1, 129.7,
129.47, 128.9, 128.8, 126.3, 126.2, 123.1, 123.0, 121.9, 116.4,
114.9, 110.6; MS: Anal. Calcd. For C14H14N2O3: 244.2906
Found: 243.0932 (M-H+); IR (KBr, cm-1): ν 3138, 2910, 1726,
1586, 1456, 1395, 1215, 1075. Crystal data for 4a, which has
been deposited at the Cambridge Crystallographic Data Centre as
supplementary publication with No. CCDC 894400. Copies of
this information may be obtained free of charge from The
Director, CCDC, 12 Union Road, Cambridge, CB2 1EZ, UK (E-
mail: linstead@ccdc.cam.ac.uk or deposit@ccdc.cam.ac.uk; fax:
+44 01223 336033): Structural parameters for product 4a: data
collection: Rigaku Mercury CCD area detector; crystal size:
0.50×0.30×0.20 mm3; C17H12N2, Mr= 244.29, monoclinic,
space group P 21/c, a = 11.1391(19), b= 15.066(3), c =
7.2723(14) Å, a = 90.00, b=99.299 (5), g = 90.00, V = 1204.4(4)
Å3, Z = 4, Dc= 1.347 g cm-3, R[ I > 2σ(I )] = 0.0526, wR[I > 2 s
(I )] =0.1248.
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7