Povarov reaction of β-enamino esters and isatin-3-imines for diastereoselective synthesis of spiro[indoline-3,2′-quinolines]

Article abstract of DOI:10.1055/s-0033-1340459

The p-toluenesulfonic acid catalyzed Povarov reaction of isatin-3-imines with β-enamino esters, which were generated in situ from the reaction of arylamines and methyl propiolate in ethanol, afforded the polysubstituted spiro[indoline-3,2′-quinolines] in

Full text of DOI:10.1055/s-0033-1340459

PAPER
▌489
paper
Povarov Reaction of β-Enamino Esters and Isatin-3-imines for Diastereoselective
Synthesis of Spiro[indoline-3,2′-quinolines]
Synthesis of Spiro[indoline-3,2′-quinolines]
Hong Gao, Jing Sun, Chao-Guo Yan*
College of Chemistry & Chemical Engineering, Yangzhou University, Yangzhou 225002, P. R. of China
Fax +86(514)87975244; E-mail: cgyan@yzu.edu.cn
Received: 22.10.2013; Accepted after revision: 18.11.2013
in-3-imines for the efficient synthesis of polysubstituted
Abstract: The p-toluenesulfonic acid catalyzed Povarov reaction
spiro[indoline-3,2′-quinolines].
of isatin-3-imines with β-enamino esters, which were generated in
situ from the reaction of arylamines and methyl propiolate in eth-
anol, afforded the polysubstituted spiro[indoline-3,2′-quinolines] in
high yields and with high diastereoselectivity.
It has been known that the isatin react easily with aryl-
amines to form isatin-3-imines, which are reactive inter-
mediates in many substitution and addition reactions.16
Even though many Povarov reactions with different types
of aldimines and ketimines have been reported, there are
only two examples of isatin-3-imines utilized in Povarov
reaction.17 Thus, it is of great interest to investigate the re-
activity of isatin-3-imines in the Povarov reaction. There-
fore, according to our previously established reaction
conditions,15 p-toluidine was allowed to react with methyl
propiolate in ethanol overnight at room temperature to
form the desired β-enamino ester. Then, isatin-3-imine
and p-toluenesulfonic acid were added and the resulting
mixture was stirred at room temperature for about twelve
hours. After workup, we were pleased to find that the
functionalized spiro[indoline-3,2′-quinoline] (1a) was ob-
tained in 75% yield (Table 1). The spiro compound 1a
was obviously formed by the imino-Diels–Alder reaction
(Povarov reaction)13 of the in situ generated β-enamino
ester with isatin-3-imine. Thus, a domino Povarov reac-
tion for isatin-3-imine is successfully established here.
Similarly, various arylamines and isatin-3-imines were
used in the reactions under the same conditions. The re-
sults are summarized in Table 1. It should be pointed out
that in order to avoid the cross reaction, the same aryl-
amine was used for the formation of both β-enamino ester
and isatin-3-imine in each reaction. Isatin itself and its 5-
flouoro, 5-chloro, 5-methyl, 1-benzyl, and 1-butyl deriva-
tives showed similar reactivity and reacted efficiently to
yield the final products. It is interesting to find that aniline
and arylamines with alkyl or methyl substituents proceed-
ed smoothly to afford the corresponding functionalized
spiro[indoline-3,2′-quinolines] 1a–q in satisfactory yields
(58–85%). On the other hand, arylamines bearing halo
groups afforded very complicated mixture of products.
Because m-nitro- and p-nitroaniline can not react with
methyl propiolate to give the β-enamino ester,15 they were
not used in this Povarov reaction.
Key words: Povarov reaction, hetero-Diels–Alder reaction, β-en-
amino ester, isatinimine, spiro[indoline-3,2′-quinolines]
Over fifty years ago, Povarov and co-workers described
an addition reaction between aromatic Schiff bases (di-
enes) and activated alkenes (dienophiles) for the synthesis
of tetrahydroquinolines.1 Since then much development
of the imino-Diels–Alder reaction (Povarov reaction) has
been achieved.2,3 In recent years, Povarov reaction has be-
come the most powerful synthetic tool for the construction
of N-containing six-membered heterocyclic compounds
including tetrahydroquinolines.4–6 The Povarov reaction
was usually catalyzed by various Lewis acid or Brønsted
acid.7 On the other hand, the intramolecular Povarov reac-
tion is also an important tool for the synthesis of tetrahy-
droquinoline ring system fused with other carbocycles or
different heterocycles.8 In recent years, multicomponent
imino-Diels–Alder reactions have gained popularity.9 In
the traditional Povarov reaction, the dienophiles are usu-
ally electron-rich alkenes such as vinyl enol ethers, vinyl
enamides, vinyl sulfide, cyclopentadiene, indene, al-
kynes, and enamines.10,11 β-Enaminones and β-enamino
esters are also electron-rich alkenes, which have shown
versatile reactivity and have been widely used as key in-
termediates in a number of domino reactions to construct
heterocyclic system.12–14 We envisioned that β-enamin-
ones and β-enamino esters should accomplish the Povarov
reaction as special kinds of electron-rich alkenes. Howev-
er, a survey of literature revealed that there are no reports
of Povarov reactions with β-enamino ester as dienophiles.
Very recently, we have successfully developed a domino-
Povarov reaction with both in situ formed aldimines and
in situ generated β-enamino esters for the facile synthesis
of the functionalized tetrahydroquinolines.15 In order to
further elucidate the potential synthetic values of this
method, herein we wish to report the one-pot Povarov re-
action of the in situ generated β-enamino esters with isat-
The structures of the above prepared functionalized 3′,4′-
dihydro-1′H-spiro[indoline-3,2′-quinolines] 1a–q were
characterized by 1H and 13C NMR, HRMS, and IR spec-
tra. The structures of 1d (Figure 1) and 1e (Figure 2) were
further confirmed by single-crystal X-ray diffraction.18
When m-toluidine was used in the reaction (Table 1, entry
5) the cycloaddition reaction might occur at the ortho- or
para-position relative to the methyl group. The crystal
SYNTHESIS 2014, 46, 0489–0495
Advanced online publication: 10.12.2013
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DOI: 10.1055/s-0033-1340459; Art ID: SS-2013-F0691-OP
© Georg Thieme Verlag Stuttgart · New York

490
H. Gao et al.
PAPER
and a triplet at 5.61 ppm. In the 1H NMR spectrum of 1q
these two CH units display a doublet at 5.76 ppm with a
vicinal coupling constant of J = 9.6 Hz and a triplet at 5.60
ppm. These results indicate that the trans-isomer exists in
each sample of the spiro compounds 1a–q. From the crys-
tal structures of compounds 1d and 1e, it is clear that the
3-methoxycarbonyl group and 4-arylamino group at cy-
clic 3- and 4-positions exist in trans configuration. On the
other hand, the aryl group of the oxindole moiety and 3-
methoxycarbonyl group also exist in the trans configura-
tion. Thus, the three relative large groups at 2,3,4-posi-
tions in spiro[indoline-3,2′-quinolines] are in the 2,3-
trans/3,4-trans configuration. We can conclude that this
one-pot Povarov reaction is also a highly diastereoselec-
tive reaction.
Table 1 Synthesis of 3′,4′-Dihydro-1′H-spiro[indoline-3,2′-quino-
lines]a
R1
N
R2
R1
R1
R1
O
CO2Me
EtOH
r.t.
N
R3
p-TsOH, r.t.
R2
+
NH
HN
NH2
CO2Me
O
N
R3
Entry
Product R1
R2
R3
Yield (%)b
1
2
1a
1b
1c
1d
1e
1f
4-Me
H
H
H
H
H
H
H
H
H
H
H
H
H
75
82
60
65
68
80
85
58
62
60
61
82
72
82
80
61
78
4-t-Bu
H
H
3
Me
Me
Me
Me
Me
Me
F
4
4-Me
3-Me
4-i-Pr
4-t-Bu
4-MeO
4-Me
4-Me
4-i-Pr
4-t-Bu
H
5
6
7
1g
1h
1i
8
9
Figure 1 Molecular structure of compound 1d
10
11
12
13
14
15
16
17
1j
Cl
1k
1l
Cl
Cl
1m
1n
1o
1p
1q
Me
Me
Me
Me
Me
Bn
4-Me
4-i-Pr
4-t-Bu
4-Me
Bn
Bn
Bn
n-Bu
a Reaction conditions: 1) arylamine (2.0 mmol), methyl propiolate
(2.0 mmol) in EtOH (5.0 mL), r.t., 24 h; 2) isatin-3-imine (1.5 mmol),
p-TsOH (0.5 mmol), r.t., 12 h.
b Isolated yields.
structure of 1e (Figure 2) clearly indicated that the cyclo-
addition occurred at the anticipitated para-position of
methyl group. Because the methoxycarbonyl group and
arylamino group at 3,4-positions in the newly formed tet-
rahydropyridyl ring might be in relatively cis or trans con-
figuration, two diastereoisomers would exist in the
Figure 2 Molecular structure of compound 1e
A reaction mechanism for this domino Povarov reaction is
briefly outlined in Scheme 1 based on the published dom-
ino Povarov reaction.3,9,17 At first, arylamine adds to
methyl propiolate to form the β-enamino ester A. Then, in
the presence of p-TsOH as catalyst, the nucleophilic addi-
tion of intermediate A to isatin-3-imine gives the interme-
diate B. Thereafter, an intramolecular electrophilic
aromatic substitution at the ortho-position of the activated
N-aryl ring gives spiro[indoline-3,2′-quinoline] 1. In the
last cyclization step, due to the steric effect of the substit-
1
prepared spiro[indoline-3,2′-quinolines] 1a–q. The H
NMR spectra of compounds 1a–q usually show one dou-
blet and one triplet signs for the two cyclic CH units in tet-
rahydropyridyl ring. For example, in the 1H NMR
spectrum of 1a these two CH units display a doublet at
5.72 ppm with a vicinal coupling constant of J = 9.6 Hz
Synthesis 2014, 46, 489–495
© Georg Thieme Verlag Stuttgart · New York

PAPER
Synthesis of Spiro[indoline-3,2′-quinolines]
491
R1
N
R2
R1
R1
O
CO2Me
N
EtOH
R3
+
CO2Me
N
p-TsOH, r.t.
H
NH2
A
R1
R1
R1
R1
NH
NH
HN
HN
R2
R2
CO2Me
O
CO2Me
O
N
N
R3
R3
B
1
Scheme 1 The proposed mechanism for domino reaction
Methyl 6′-Methyl-2-oxo-4′-(p-tolylamino)-3′,4′-dihydro-1′H-
spiro[indoline-3,2′-quinoline]-3′-carboxylate (1a)
Yield: 0.481 g (75%); white solid; mp 168.6–168.9 °C.
uents, the thermodynamic stable trans-isomer is predom-
inately formed as the final separated product.
In summary, we have successfully developed a one-pot
IR (KBr): 3624, 3478, 3295, 3023, 2918, 1728, 1701, 1619, 1516,
1474, 1441, 1403, 1323, 1288, 1249, 1199, 1159, 1110, 995, 963,
Povarov reaction between the β-enamino ester and isatin-
3-imine for the first time. This one-pot Povarov reaction 921, 821 cm–1.
1H NMR (600 MHz, DMSO-d6): δ = 10.28 (s, 1 H, NH), 7.28 (d,
J = 7.2 Hz, 1 H, ArH), 7.23 (t, J = 7.8 Hz, 1 H, ArH), 6.98 (t, J = 7.8
Hz, 1 H, ArH), 6.91 (s, 1 H, NH), 6.86 (d, J = 7.8 Hz, 2 H, ArH),
6.79–6.76 (m, 2 H, ArH), 6.54 (d, J = 8.4 Hz, 2 H, ArH), 6.47 (d,
J = 4.8 Hz, 2 H, ArH, NH), 5.72 (d, J = 9.6 Hz, 1 H, NH), 5.61 (t,
J = 10.2 Hz, 1 H, CH), 3.30 (d, J = 14.4 Hz, 1 H, CH), 3.06 (s, 3 H,
OCH3), 2.14 (s, 3 H, CH3), 2.08 (s, 3 H, CH3).
13C NMR (150 MHz, DMSO-d6): δ = 177.9, 171.3, 146.5, 142.3,
140.6, 129.6, 129.4, 128.8, 127.9, 126.3, 124.6, 124.2, 124.1, 122.9,
121.5, 114.0, 112.4, 109.4, 60.9, 51.3, 51.2, 48.6, 20.4, 20.0.
provided a convenient procedure for the diastereoselec-
tive synthetic method for the functionalized spiro[in-
doline-3,2′-quinolines] in good yields. The short reaction
time, readily variable substrates, and easiness of handling
render this domino reaction applicable to the synthesis of
structurally diverse heterocyclic compounds. The poten-
tial uses of this reaction in synthetic and medicinal chem-
istry might be quite significant. Further expansion of the
reaction scope and synthetic applications of this method-
ology are in progress in our laboratory.
HRMS (ESI): m/z calcd for C26H25N3O3 + Na ([M + Na]+):
450.1788; found: 450.1781.
All reactions were monitored by TLC. Melting points were taken on
a hot-plate microscope apparatus. IR spectra were obtained on a
Bruker Tensor 27 spectrometer (KBr disc). NMR spectra were re-
corded with a Bruker AV-600 spectrometer with DMSO-d6 as sol-
Methyl 6′-tert-Butyl-4′-(4-tert-butylphenylamino)-2-oxo-3′,4′-
dihydro-1′H-spiro[indoline-3,2′-quinoline]-3′-carboxylate (1b)
Yield: 0.629 g (82%); light yellow solid; mp 226.5–226.8 °C.
IR (KBr): 3668, 3378, 3322, 3026, 2959, 2866, 1741, 1614, 1512,
1472, 1398, 1364, 1322, 1279, 1254, 1197, 1139, 1079, 995, 895,
825, 754 cm–1.
vent and TMS as internal standard (600 and 150 MHz for 1H and 13
C
NMR spectra, respectively). High-resolution mass (ESI) were ob-
tained with a Bruker MicroTOF spectrometer. X-ray data were col-
1H NMR (600 MHz, DMSO-d6): δ = 10.29 (s, 1 H, NH), 7.27 (d,
J = 7.2 Hz, 1 H, ArH), 7.23 (t, J = 7.8 Hz, 1 H, ArH), 7.18 (s, 1 H,
NH), 7.10 (d, J = 8.4 Hz, 2 H, ArH), 7.00–6.97 (m, 2 H, ArH), 6.79
(d, J = 7.2 Hz, 1 H, ArH), 6.61 (d, J = 8.4 Hz, 2 H, ArH), 6.49 (d,
J = 9.0 Hz, 2 H, ArH, NH), 5.65–5.59 (m, 2 H, CH, NH), 3.30 (d,
J = 10.2 Hz, 1 H, CH), 3.05 (s, 3 H, OCH3), 1.21 (s, 9 H, CH3), 1.09
(s, 9 H, CH3).
13C NMR (150 MHz, DMSO-d6): δ = 178.0, 171.5, 146.9, 142.3,
140.5, 138.4, 138.3, 129.5, 128.9, 125.4, 124.2, 124.1, 122.7, 122.3,
121.5, 113.5, 112.8, 109.4, 61.0, 51.6, 51.1, 49.3, 33.4, 31.4, 31.3.
lected on
a Bruker Smart APEX-2 CCD diffractometer.
Arylamines, methyl propiolate, isatins, and other reagents are com-
mercial reagents and used as received. Isatin-3-imines were pre-
pared by condensation of isatins with arylamines according to the
published methods.16
Polysubstituted Spiro[indoline-3,2′-quinolines] 1a–q from One-
Pot Domino Reactions of Arylamines, Methyl Propiolate, and
Isatin-3-imines; General Procedure
A mixture of arylamine (2.0 mmol) and methyl propiolate (2.0
mmol) in EtOH (5.0 mL) was stirred at r.t. for 8–12 h. Then, isatin-
3-imine (1.5 mmol) and p-TsOH (0.5 mmol) were added and the so-
lution was stirred at r.t. for an additional 12 h. The resulting precip-
itate was collected by filtration and washed with cold EtOH to give
the solid product, which was recrystallized from EtOH to give the
respective pure product.
HRMS (ESI): m/z calcd for C32H37N3O3 + Na ([M + Na]+):
534.2717; found: 534.2715.
© Georg Thieme Verlag Stuttgart · New York
Synthesis 2014, 46, 489–495

492
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Methyl 5-Methyl-2-oxo-4′-(phenylamino)-3′,4′-dihydro-1′H-
spiro[indoline-3,2′-quinoline]-3′-carboxylate (1c)
Yield: 0.372 g (60%); white solid; mp 174.8–175.0 °C.
J = 8.4 Hz, 2 H, ArH), 6.83 (d, J = 7.8 Hz, 1 H, ArH), 6.68 (d,
J = 7.8 Hz, 1 H, ArH), 6.57 (d, J = 8.4 Hz, 2 H, ArH), 6.49 (d,
J = 8.4 Hz, 1 H, ArH), 6.44 (s, 1 H, NH), 5.68 (d, J = 10.2 Hz, 1 H,
NH), 5.60 (t, J = 10.2 Hz, 1 H, CH), 3.27 (d, J = 14.4 Hz, 1 H, CH),
3.05 (s, 3 H, OCH3), 2.75–2.70 (m, 1 H, CH), 2.65–2.60 (m, 1 H,
CH), 2.26 (s, 3 H, CH3), 1.13 (d, J = 6.6 Hz, 6 H, CH3), 1.06–1.04
(m, 6 H, CH3).
13C NMR (150 MHz, DMSO-d6): δ = 178.1, 171.3, 147.0, 140.9,
139.8, 136.0, 135.9, 135.8, 130.3, 129.8, 129.0, 126.5, 125.1, 124.6,
123.9, 122.7, 113.8, 112.7, 109.2, 61.0, 51.5, 51.1, 49.1, 32.7, 32.4,
24.2, 24.1, 20.6.
IR (KBr): 3615, 3464, 3358, 3298, 3027, 2950, 1725, 1627, 1601,
1492, 1441, 1368, 1341, 1301, 1251, 1206, 1174, 1123, 1093, 1067,
996, 941, 872, 813, 754 cm–1.
1H NMR (600 MHz, DMSO-d6): δ = 10.23 (s, 1 H, NH), 7.12 (s, 1
H, NH), 7.07–7.04 (m, 4 H, ArH), 6.94 (d, J = 6.6 Hz, 1 H, ArH),
6.70 (d, J = 7.2 Hz, 1 H, ArH), 6.63 (t, J = 7.2 Hz, 3 H, ArH), 6.56
(d, J = 7.8 Hz, 1 H, ArH), 6.52 (d, J = 6.0 Hz, 2 H, ArH, NH), 5.97
(d, J = 9.0 Hz, 1 H, NH), 5.69 (t, J = 10.2 Hz, 1 H, CH), 3.30 (d,
J = 10.2 Hz, 1 H, CH), 3.10 (s, 3 H, OCH3), 2.27 (s, 3 H, CH3).
HRMS (ESI): m/z calcd for C31H35N3O3 + Na ([M + Na]+):
13C NMR (150 MHz, DMSO-d6): δ = 177.9, 171.2, 148.8, 143.0,
139.8, 130.4, 129.9, 129.0, 128.7, 127.4, 126.0, 124.7, 122.6, 116.2,
115.9, 113.8, 112.4, 109.3, 60.9, 51.3, 50.9, 48.3, 20.6.
HRMS (ESI): m/z calcd for C25H23N3O3 + Na ([M + Na]+):
436.1632; found: 436.1625.
520.2561; found: 520.2558.
Methyl 6′-tert-Butyl-4′-(4-tert-butylphenylamino)-5-methyl-2-
oxo-3′,4′-dihydro-1′H-spiro[indoline-3,2′-quinoline]-3′-carbox-
ylate (1g)
Yield: 0.670 g (85%); white solid; mp 258.6–258.8 °C.
IR (KBr): 3689, 3332, 3026, 2959, 2866, 1741, 1613, 1501, 1468,
1398, 1362, 1298, 1198, 1168, 1126, 1080, 995, 920, 817 cm–1.
Methyl 5,6′-Dimethyl-2-oxo-4′-(p-tolylamino)-3′,4′-dihydro-
1′H-spiro[indoline-3,2′-quinoline]-3′-carboxylate (1d)
Yield: 0.430 g (65%); white solid; mp 176.0–176.3 °C.
1H NMR (600 MHz, DMSO-d6): δ = 10.21 (s, 1 H, NH), 7.18 (s, 1
H, NH), 7.09 (t, J = 5.4 Hz, 3 H, ArH), 7.04 (d, J = 8.4 Hz, 1 H,
ArH), 6.97 (d, J = 7.8 Hz, 1 H, ArH), 6.68 (d, J = 8.4 Hz, 1 H, ArH),
6.60 (d, J = 8.4 Hz, 2 H, ArH), 6.48 (t, J = 7.8 Hz, 2 H, ArH, NH),
5.68 (d, J = 10.2 Hz, 1 H, NH), 5.61 (t, J = 10.2 Hz, 1 H, CH), 3.28
(d, J = 10.2 Hz, 1 H, CH), 3.06 (s, 3 H, OCH3), 2.27 (s, 3 H, CH3),
1.21 (s, 9 H, CH3), 1.09 (s, 9 H, CH3).
13C NMR (150 MHz, DMSO-d6): δ = 178.1, 171.4, 146.9, 140.5,
139.8, 138.3, 138.2, 130.2, 129.8, 129.0, 125.4, 124.7, 124.2, 122.7,
122.2, 113.5, 112.8, 109.2, 61.0, 51.6, 51.1, 49.4, 33.4, 31.4, 31.3,
20.6.
IR (KBr): 3619, 3480, 3377, 3300, 3025, 2952, 2919, 2863, 1726,
1699, 1621, 1502, 1441, 1367, 1340, 1295, 1246, 1204, 1176, 1123,
1037, 994, 962, 921, 889 cm–1.
1H NMR (600 MHz, DMSO-d6): δ = 10.17 (s, 1 H, NH), 7.09 (s, 1
H, NH), 7.03 (d, J = 7.2 Hz, 1 H, ArH), 6.91 (s, 1 H, ArH), 6.86 (d,
J = 7.2 Hz, 2 H, ArH), 6.76 (d, J = 7.8 Hz, 1 H, ArH), 6.68 (d,
J = 7.2 Hz, 1 H, ArH), 6.52 (d, J = 7.2 Hz, 2 H, ArH), 6.46 (d,
J = 7.8 Hz, 1 H, ArH), 6.43 (s, 1 H, NH), 5.74 (d, J = 10.8 Hz, 1 H,
NH), 5.60 (t, J = 10.2 Hz, 1 H, CH), 3.27 (d, J = 6.0 Hz, 1 H, CH),
3.08 (s, 3 H, OCH3), 2.26 (s, 3 H, CH3), 2.14 (s, 3 H, CH3), 2.08 (s,
3 H, CH3).
HRMS (ESI): m/z calcd for C33H39N3O3 + Na ([M + Na]+):
13C NMR (150 MHz, DMSO-d6): δ = 178.0, 171.3, 146.5, 140.7,
139.8, 130.3, 129.8, 129.4, 128.9, 127.9, 126.3, 124.7, 124.5, 124.1,
122.8, 113.9, 112.4, 109.2, 60.9, 51.3, 51.2, 48.6, 20.6, 20.4, 20.0.
HRMS (ESI): m/z calcd for C27H27N3O3 + Na ([M + Na]+):
464.1945; found: 464.1937.
548.2884; found: 548.2878.
Methyl 5-Methyl-6′-methoxy-2-oxo-4′-(p-methoxyphenylami-
no)-3′,4′-dihydro-1′H-spiro[indoline-3,2′-quinoline]-3′-carbox-
ylate (1h)
Yield: 0.412 g (58%); white solid; mp 202.8–203.1 °C.
IR (KBr): 3373, 3303, 2996, 2947, 2831, 1736, 1706, 1625, 1497,
1459, 1368, 1334, 1281, 1232, 1200, 1174, 1149, 1078, 1041, 992,
957, 918, 880, 809 cm–1.
Methyl 5-Methyl-2-oxo-4′-(m-tolylamino)-3′,4′-dihydro-1′H-
spiro[indoline-3,2′-quinoline]-3′-carboxylate (1e)
Yield: 0.450 g (68%); light yellow solid; mp 145.6–145.7 °C.
1H NMR (600 MHz, DMSO-d6): δ = 10.16 (s, 1 H, NH), 7.10 (s, 1
H, ArH), 7.03 (d, J = 8.4 Hz, 1 H, ArH), 6.73 (d, J = 3.0 Hz, 1 H,
ArH), 6.71 (d, J = 9.0 Hz, 2 H, ArH), 6.68 (d, J = 7.8 Hz, 1 H, ArH),
6.62–6.58 (m, 3 H, ArH), 6.49 (d, J = 8.4 Hz, 1 H, ArH), 6.28 (s, 1
H, NH), 5.58–5.51 (m, 2 H, CH, NH), 3.63 (s, 3 H, OCH3), 3.54 (s,
3 H, OCH3), 3.30 (d, J = 10.8 Hz, 1 H, CH), 3.11 (s, 3 H, OCH3),
2.26 (s, 3 H, CH3).
13C NMR (150 MHz, DMSO-d6): δ = 178.0, 171.4, 151.0, 150.8,
142.8, 139.8, 136.9, 130.3, 129.8, 129.0, 124.7, 124.3, 114.6, 113.9,
113.2, 112.0, 109.1, 61.0, 55.2, 55.1, 51.3, 51.2, 49.7, 20.6.
IR (KBr): 3620, 3474, 3350, 3298, 3026, 2948, 2921, 1728, 1621,
1493, 1438, 1369, 1301, 1198, 1129, 1082, 1035, 994, 940, 843,
808, 772 cm–1.
1H NMR (600 MHz, DMSO-d6): δ = 10.22 (s, 1 H, NH), 7.09 (s, 1
H, NH), 7.05 (d, J = 7.8 Hz, 1 H, ArH), 6.94–6.92 (m, 2 H, ArH),
6.55 (s, 1 H, ArH), 6.45 (s, 1 H, NH), 6.40 (d, J = 7.2 Hz, 1 H, ArH),
6.34 (t, J = 7.8 Hz, 3 H, ArH), 5.84 (d, J = 9.6 Hz, 1 H, NH), 5.61
(t, J = 10.2 Hz, 1 H, CH), 3.25 (d, J = 14.4 Hz, 1 H, CH), 3.10 (s, 3
H, OCH3), 2.27 (s, 3 H, CH3), 2.16 (s, 3 H, CH3), 2.12 (s, 3 H, CH3).
13C NMR (150 MHz, DMSO-d6): δ = 177.9, 171.2, 149.0, 142.9,
139.8, 137.9, 136.3, 130.3, 129.9, 128.9, 128.8, 125.9, 124.7, 120.1,
117.2, 116.8, 114.1, 113.0, 109.6, 109.2, 61.0, 51.4, 51.2, 48.1,
21.4, 20.9, 20.6.
HRMS (ESI): m/z calcd for C27H27N3O5 + Na ([M + Na]+):
496.1856; found: 496.1861.
Methyl 5-Fluoro-6′-methyl-2-oxo-4′-(p-tolylamino)-3′,4′-di-
hydro-1′H-spiro[indoline-3,2′-quinoline]-3′-carboxylate (1i)
Yield: 0.414 g (62%); white solid; mp188.9–190.1 °C.
HRMS (ESI): m/z calcd for C27H27N3O3 + Na ([M + Na]+):
464.1945; found: 464.1938.
IR (KBr): 3634, 3488, 3365, 3297, 3022, 2919, 2864, 2737, 1853,
1730, 1617, 1515, 1444, 1368, 1339, 1293, 1249, 1195, 1126, 1091,
1043, 993, 959, 920, 870, 815 cm–1.
1H NMR (600 MHz, DMSO-d6): δ = 10.32 (s, 1 H, NH), 7.21–7.19
(m, 1 H, ArH), 7.09–7.06 (m, 1 H, ArH), 6.91 (s, 1 H, ArH), 6.87
(d, J = 7.8 Hz, 2 H, ArH), 6.80–6.77 (m, 2 H, ArH), 6.54 (d, J = 7.8
Hz, 3 H, ArH, NH), 6.46 (d, J = 7.8 Hz, 1 H, ArH), 5.71 (d, J = 10.2
Hz, 1 H, NH), 5.60 (t, J = 7.2 Hz, 1 H, CH), 3.30 (d, J = 10.8 Hz, 1
H, CH), 3.11 (s, 3 H, OCH3), 2.14 (s, 3 H, CH3), 2.08 (s, 3 H, CH3).
Methyl 6′-Isopropyl-4′-(4-isopropylphenylamino)-5-methyl-2-
oxo-3′,4′-dihydro-1′H-spiro[indoline-3,2′-quinoline]-3′-carbox-
ylate (1f)
Yield: 0.597 g (80%); white solid; mp 218.0–218.4 °C.
IR (KBr): 3621, 3477, 3311, 3025, 2958, 2870, 1729, 1616, 1503,
1466, 1281, 1250, 1202, 1170, 1050, 996, 896, 816 cm–1.
1H NMR (600 MHz, DMSO-d6): δ = 10.18 (s, 1 H, NH), 7.08 (s, 1
H, NH), 7.03 (d, J = 7.8 Hz, 1 H, ArH), 7.00 (s, 1 H, ArH), 6.94 (d,
Synthesis 2014, 46, 489–495
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PAPER
Synthesis of Spiro[indoline-3,2′-quinolines]
493
13C NMR (150 MHz, DMSO-d6): δ = 178.0, 171.2, 158.7, 157.1,
146.5, 140.4, 138.5, 130.6 (d, J = 7.5 Hz), 129.4, 128.0, 126.3,
124.8, 124.2, 122.9, 116.0 (d, J = 23.0 Hz), 114.0, 112.5, 112.0 (d,
J = 24.3 Hz), 110.3 (d, J = 7.8 Hz), 61.4, 51.3, 51.2, 48.5, 20.4,
20.0.
HRMS (ESI): m/z calcd for C26H24FN3O3 + Na ([M + Na]+):
468.1712; found: 468.1712.
HRMS (ESI): m/z calcd for C32H36ClN3O3 + Na ([M + Na]+):
568.2311; found: 568.2321.
Methyl 1-Benzyl-5-methyl-2-oxo-4′-(phenylamino)-3′,4′-di-
hydro-1′H-spiro[indoline-3,2′-quinoline]-3′-carboxylate (1m)
Yield: 0.543 g (72%); light yellow solid; mp 260.6–261.0 °C.
IR (KBr): 3681, 3343, 3023, 2927, 2866, 1867, 1717, 1617, 1499,
1439, 1353, 1291, 1187, 1123, 1079, 1025, 954, 889, 810 cm–1.
1H NMR (600 MHz, DMSO-d6): δ = 7.40 (d, J = 7.8 Hz, 2 H, ArH),
7.34 (t, J = 7.8 Hz, 2 H, ArH), 7.26 (t, J = 7.2 Hz, 1 H, ArH), 7.22
(s, 1 H, ArH), 7.11 (d, J = 7.8 Hz, 1 H, ArH), 7.08–7.05 (m, 3 H,
ArH), 6.97 (t, J = 7.8 Hz, 1 H, ArH), 6.79 (s, 1 H, NH), 6.68 (d,
J = 7.8 Hz, 1 H, ArH), 6.64 (d, J = 7.8 Hz, 2 H, ArH), 6.60 (d,
J = 7.8 Hz, 1 H, ArH), 6.56–6.52 (m, 2 H, ArH), 6.04 (d, J = 9.6 Hz,
1 H, NH), 5.75 (t, J = 10.8 Hz, 1 H, CH), 4.84 (s, 2 H, CH2), 3.39
(d, J = 11.4 Hz, 1 H, CH), 3.08 (s, 3 H, OCH3), 2.27 (s, 3 H, CH3).
13C NMR (150 MHz, DMSO-d6): δ = 176.1, 171.2, 148.8, 142.8,
140.4, 136.2, 131.5, 129.9, 129.0, 128.5, 128.0, 127.5, 127.3, 127.2,
126.0, 124.6, 122.5, 116.4, 116.0, 113.8, 112.4, 109.0, 60.8, 51.4,
48.5, 42.8, 20.6.
Methyl 5-Chloro-6′-methyl-2-oxo-4′-(p-tolylamino)-3′,4′-di-
hydro-1′H-spiro[indoline-3,2′-quinoline]-3′-carboxylate (1j)
Yield: 0.415 g (60%); light yellow solid; mp 176.4–176.7 °C.
IR (KBr): 3639, 3490, 3292, 3022, 2966, 2920, 1731, 1618, 1518,
1480, 1440, 1344, 1292, 1250, 1198, 1121, 1080, 1045, 995, 959,
881, 813 cm–1.
1H NMR (600 MHz, DMSO-d6): δ = 10.43 (s, 1 H, NH), 7.34 (s, 1
H, NH), 7.29 (d, J = 8.4 Hz, 1 H, ArH), 6.92 (s, 1 H, ArH), 6.87 (d,
J = 7.8 Hz, 2 H, ArH), 6.82–6.77 (m, 2 H, ArH), 6.54 (d, J = 4.2 Hz,
3 H, ArH, NH), 6.46 (d, J = 7.8 Hz, 1 H, ArH), 5.72 (d, J = 9.6 Hz,
1 H, NH), 5.59 (t, J = 10.2 Hz, 1 H, CH), 3.31 (d, J = 7.8 Hz, 1 H,
CH), 3.12 (s, 3 H, OCH3), 2.14 (s, 3 H, CH3), 2.08 (s, 3 H, CH3).
13C NMR (150 MHz, DMSO-d6): δ = 177.7, 171.2, 146.4, 141.2,
140.3, 131.0, 129.5 129.4, 128.0, 126.4, 125.5, 124.9, 124.3, 124.2,
122.9, 114.0, 112.5, 111.0, 61.2, 51.4, 51.0, 48.6, 20.4, 20.0.
HRMS (ESI): m/z calcd for C26H24ClN3O3 + Na ([M + Na]+):
484.1398; found: 484.1388.
HRMS (ESI): m/z calcd for C32H29N3O3 + Na ([M + Na]+):
526.2101; found: 526.2093.
Methyl 1-Benzyl-5,6′-dimethyl-2-oxo-4′-(p-tolylamino)-3′,4′-di-
hydro-1′H-spiro[indoline-3,2′-quinoline]-3′-carboxylate (1n)
Yield: 0.653 g (82%); light yellow solid; mp 228.7–229.2 °C.
IR (KBr): 3674, 3356, 3028, 2920, 2866, 1876, 1720, 1614, 1504,
1444, 1351, 1280, 1183, 1076, 1027, 997, 887, 813 cm–1.
Methyl 5-Chloro-6′-isopropyl-4′-(4-isopropylphenylamino)-2-
oxo-3′,4′-dihydro-1′H-spiro[indoline-3,2′-quinoline]-3′-carbox-
ylate (1k)
1H NMR (600 MHz, DMSO-d6): δ = 7.39 (d, J = 7.2 Hz, 2 H, ArH),
7.33 (t, J = 7.2 Hz, 2 H, ArH), 7.26 (t, J = 7.2 Hz, 1 H, ArH), 7.19
(s, 1 H, ArH), 7.04 (d, J = 7.8 Hz, 1 H, ArH), 6.95 (s, 1 H, ArH),
6.88 (d, J = 7.8 Hz, 2 H, ArH), 6.79 (d, J = 7.8 Hz, 1 H, ArH), 6.65
(d, J = 7.8 Hz, 1 H, ArH), 6.58 (s, 1 H, NH), 6.56 (d, J = 7.8 Hz, 2
H, ArH), 6.50 (d, J = 7.8 Hz, 1 H, ArH), 5.80 (d, J = 9.6 Hz, 1 H,
NH), 5.66 (t, J = 10.8 Hz, 1 H, CH), 4.83 (s, 2 H, CH2), 3.37 (s, 1
H, CH), 3.06 (s, 3 H, OCH3), 2.26 (s, 3 H, CH3), 2.14 (s, 3 H, CH3),
2.09 (s, 3 H, CH3).
13C NMR (150 MHz, DMSO-d6): δ = 176.7, 171.7, 147.0, 141.0,
140.9, 136.8, 131.9, 130.3, 129.9, 128.9, 128.7, 128.5, 127.8, 127.7,
126.9, 125.2, 125.1, 124.7, 123.3, 114.5, 113.0, 109.4, 61.3, 51.8,
49.4, 43.3, 21.1, 20.9, 20.5.
Yield: 0.473 g (61%); light yellow solid; mp 178.3–178.5 °C.
IR (KBr): 3483, 3323, 3024, 2957, 2867, 1742, 1617, 1511, 1478,
1438, 1329, 1287, 1252, 1193, 1118, 1080, 1053, 994, 959, 924,
884, 817 cm–1.
1H NMR (600 MHz, DMSO-d6): δ = 10.44 (s, 1 H, NH), 7.33 (s, 1
H, NH), 7.29 (d, J = 7.2 Hz, 1 H, ArH), 7.01 (s, 1 H, ArH), 6.94 (d,
J = 6.0 Hz, 2 H, ArH), 6.85–6.80 (m, 2 H, ArH), 6.57 (t, J = 6.6 Hz,
3 H, ArH, NH), 6.48 (d, J = 7.2 Hz, 1 H, ArH), 5.66 (d, J = 9.0 Hz,
1 H, NH), 5.60–5.57 (m, 1 H, CH), 3.45 (s, 1 H, CH), 3.09 (s, 3 H,
OCH3), 2.72 (s, 1 H, CH), 2.63 (s, 1 H, CH), 1.10 (t, J = 27.6 Hz, 12
H, CH3).
13C NMR (150 MHz, DMSO-d6): δ = 177.8, 171.2, 146.9, 141.2,
140.6, 136.3, 136.0, 131.0, 129.5, 126.6, 125.4, 125.2, 124.3, 123.9,
122.7, 113.9, 112.8, 110.9, 61.2, 51.3, 51.2, 49.0, 32.7, 32.4, 24.2,
24.1.
HRMS (ESI): m/z calcd for C34H33N3O3 + Na ([M + Na]+):
554.2414; found: 554.2408.
Methyl 1-Benzyl-6′-isopropyl-4′-(4-isopropylphenylamino)-5-
methyl-2-oxo-3′,4′-dihydro-1′H-spiro[indoline-3,2′-quinoline]-
3′-carboxylate (1o)
HRMS (ESI): m/z calcd for C30H32ClN3O3 + Na ([M + Na]+):
540.1998; found: 540.2007.
Yield: 0.705 g (80%); light yellow solid; mp 197.0–197.1 °C.
Methyl 6′-tert-Butyl-4′-(4-tert-butylphenylamino)-5-chloro-2-
oxo-3′,4′-dihydro-1′H-spiro[indoline-3,2′-quinoline]-3′-carbox-
ylate (1l)
IR (KBr): 3678, 3437, 3357, 3031, 2956, 1723, 1609, 1505, 1354,
1277, 1184, 1027, 999, 898, 819 cm–1.
Yield: 0.671 g (82%); light yellow solid; mp 218.5–218.7 °C.
1H NMR (600 MHz, DMSO-d6): δ = 7.39 (d, J = 7.8 Hz, 2 H, ArH),
7.33 (t, J = 7.8 Hz, 2 H, ArH), 7.26 (t, J = 7.2 Hz, 1 H, ArH), 7.18
(s, 1 H, ArH), 7.04 (s, 2 H, ArH), 6.95 (d, J = 7.8 Hz, 2 H, ArH),
6.86 (d, J = 8.4 Hz, 1 H, ArH), 6.66 (d, J = 8.4 Hz, 1 H, ArH), 6.59
(d, J = 3.6 Hz, 3 H, ArH, NH), 6.52 (d, J = 7.8 Hz, 1 H, ArH), 5.75
(d, J = 10.2 Hz, 1 H, NH), 5.66 (t, J = 10.8 Hz, 1 H, CH), 4.83 (s, 2
H, CH2), 3.37 (s, 1 H, CH), 3.03 (s, 3 H, OCH3), 2.76–2.70 (m, 1 H,
CH), 2.66–2.62 (m, 1 H, CH), 2.26 (s, 3 H, CH3).
13C NMR (150 MHz, DMSO-d6): δ = 176.2, 171.3, 147.0, 140.8,
140.4, 136.3, 136.2, 135.9, 131.3, 129.8, 128.4, 128.2, 127.3, 127.2,
126.6, 125.1, 124.6, 124.0, 122.6, 113.9, 112.7, 108.9, 60.8, 51.5,
51.3, 49.3, 42.8, 32.7, 32.4, 24.2, 24.1, 20.6.
IR (KBr): 3392, 3320, 3029, 2960, 2863, 1744, 1719, 1614, 1513,
1475, 1437, 1398, 1363, 1332, 1289, 1255, 1192, 1123, 1079, 991,
956 cm–1.
1H NMR (600 MHz, DMSO-d6): δ = 10.45 (s, 1 H, NH), 7.33 (s, 1
H, ArH), 7.30–7.28 (m, 1 H, ArH), 7.19 (s, 1 H, ArH), 7.10 (d,
J = 8.4 Hz, 2 H, ArH), 6.99 (d, J = 8.4 Hz, 2 H, ArH), 6.99 (d,
J = 8.4 Hz, 1 H, ArH), 6.81 (d, J = 8.4 Hz, 1 H, ArH), 6.62 (d,
J = 8.4 Hz, 2 H, ArH), 6.56 (s, 1 H, NH), 6.48 (d, J = 8.4 Hz, 1 H,
ArH), 5.65–5.58 (m, 2 H, CH, NH), 3.32 (d, J = 14.4 Hz, 1 H, CH),
3.11 (s, 3 H, OCH3), 1.21 (s, 9 H, CH3), 1.10 (s, 9 H, CH3).
13C NMR (150 MHz, DMSO-d6): δ = 177.8, 171.3, 146.8, 141.2,
140.2, 138.5, 138.4, 131.0, 129.5, 125.5, 125.4, 124.3, 124.2, 122.7,
122.3, 113.6, 112.9, 110.9, 61.2, 51.4, 51.3, 49.3, 33.5, 31.4, 31.3.
HRMS (ESI): m/z calcd for C38H41N3O3 + Na ([M + Na]+):
610.3040; found: 610.3031.
© Georg Thieme Verlag Stuttgart · New York
Synthesis 2014, 46, 489–495

494
H. Gao et al.
PAPER
(4) (a) Palacios, A.; Herran, E.; Alonso, C.; Rubiales, G.
Methyl 1-Benzyl-6′-tert-butyl-4′-(4-tert-butylphenylamino)-5-
methyl-2-oxo-3′,4′-dihydro-1′H-spiro[indoline-3,2′-quinoline]-
3′-carboxylate (1p)
Tetrahedron 2006, 62, 7661. (b) Alves, M. J.; Azoia, N. G.;
Fortes, A. G. Tetrahedron 2007, 63, 727. (c) Jin, G. F.; Zhao,
J. W.; Han, J. W.; Zhu, S. Z.; Zhang, J. M. Tetrahedron
2010, 66, 913.
Yield: 0.563 g (61%); light yellow solid; mp 212.5–212.7 °C.
IR (KBr): 3684, 3438, 3032, 2958, 1722, 1608, 1503, 1351, 1274,
1192, 1165, 1028, 817 cm–1.
(5) (a) Maiti, G.; Kundu, P. Tetrahedron Lett. 2006, 47, 5733.
(b) Chen, Z. L.; Lin, L. L.; Chen, D. H.; Li, J. T.; Liu, X. H.;
Feng, X. M. Tetrahedron Lett. 2010, 51, 3088.
1H NMR (600 MHz, DMSO-d6): δ = 7.39 (d, J = 7.8 Hz, 2 H, ArH),
7.34 (t, J = 7.8 Hz, 2 H, ArH), 7.26 (t, J = 7.2 Hz, 1 H, ArH), 7.21
(s, 1 H, ArH), 7.18 (s, 1 H, ArH), 7.11 (d, J = 8.4 Hz, 1 H, ArH),
7.04 (d, J = 7.8 Hz, 1 H, ArH), 7.00 (d, J = 8.4 Hz, 1 H, ArH), 6.66
(d, J = 7.8 Hz, 1 H, ArH), 6.62 (d, J = 8.4 Hz, 2 H, ArH), 6.59 (s, 1
H, NH), 6.52 (d, J = 8.4 Hz, 1 H, ArH), 5.72 (d, J = 10.2 Hz, 1 H,
NH), 5.66 (t, J = 10.8 Hz, 1 H, CH), 4.82 (s, 2 H, CH2), 3.36 (s, 1
H, CH), 3.04 (s, 3 H, OCH3), 2.27 (s, 3 H, CH3), 1.21 (s, 9 H, CH3),
1.10 (s, 9 H, CH3).
13C NMR (150 MHz, DMSO-d6): δ = 176.7, 171.9, 147.3, 140.9,
140.8, 138.9, 136.8, 131.8, 130.3, 128.9, 128.7, 127.7, 125.9, 125.1,
124.8, 123.2, 122.7, 114.1, 113.3, 109.4, 61.4, 52.1, 51.7, 50.1,
43.3, 33.9, 31.9, 31.8, 21.1.
(c) Rajanarendar, E.; Reddy, M. N.; Reddy, K. G.; Krishna,
S. R. Tetrahedron Lett. 2012, 53, 2909.
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Nikitina, E. V. Synthesis 2007, 375. (b) Kouznestov, V. V.;
Romero Bohorquez, A. R.; Astudillo Saavedra, L.; Fierro
Medina, R. Mol. Diversity 2006, 10, 29. (c) Sridharan, V.;
Suryavanshi, P. A.; Menendez, J. C. Chem. Rev. 2011, 111,
7157.
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Tetrahedron Lett. 2003, 44, 3653. (e) Muhuni, J.; Spaller,
M. R. J. Org. Chem. 2006, 71, 5515.
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Sabitha, G. Synthesis 2001, 1065. (b) Kouznetsov, V. V.;
Gómez, C. M.; Ruíz, F. R.; del Olmo, E. Tetrahedron Lett.
2012, 53, 3115. (c) Maiti, G.; Karmakar, R.; Kayal, U.
Tetrahedron Lett. 2013, 54, 2920.
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Lett. 1988, 29, 547. (b) Spanedda, M. V.; Hoang, V. D.;
Crousse, B.; Bonnet-Delphon, D.; Begue, J. P. Tetrahedron
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2013, 69, 7045. (b) Rong, Z. T.; Li, Q. J.; Jia, Y. X.
Tetrahedron Lett. 2013, 54, 4432.
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67, 215. (b) Elassara, A. Z.; El-Khair, A. A. Tetrahedron
2003, 59, 8463.
HRMS (ESI): m/z calcd for C40H45N3O3 + Na ([M + Na]+):
638.3353; found: 638.3343.
Methyl 1-Butyl-5,6′-dimethyl-2-oxo-4′-(p-tolylamino)-3′,4′-di-
hydro-1′H-spiro[indoline-3,2′-quinoline]-3′-carboxylate (1q)
Yield: 0.582 g (78%); white solid; mp 262.4–262.8 °C.
IR (KBr): 3679, 3290, 3054, 2949, 1887, 1721, 1672, 1607, 1437,
1358, 1293, 1231, 1092, 1001, 952, 921, 890, 825, 789 cm–1.
1H NMR (600 MHz, DMSO-d6): δ = 7.13 (t, J = 9.0 Hz, 2 H, ArH),
6.92–6.86 (m, 4 H, ArH), 6.77 (d, J = 7.8 Hz, 1 H, ArH), 6.52 (d,
J = 7.2 Hz, 2 H, ArH), 6.46 (d, J = 7.8 Hz, 2 H, ArH, NH), 5.76 (d,
J = 9.6 Hz, 1 H, NH), 5.60 (t, J = 10.2 Hz, 1 H, CH), 3.62–3.58 (m,
1 H, CH), 3.55–3.51 (m, 1 H, CH), 3.29 (d, J = 10.8 Hz, 1 H, CH),
3.05 (s, 3 H, OCH3), 2.28 (s, 3 H, CH3), 2.14 (s, 3 H, CH3), 2.08 (s,
3 H, CH3), 1.54 (t, J = 6.6 Hz, 2 H, CH2), 1.37–1.33 (m, 2 H, CH2),
0.91 (t, J = 7.2 Hz, 3 H, CH3).
13C NMR (150 MHz, DMSO-d6): δ = 175.9, 171.0, 146.5, 140.7,
140.6, 130.9, 129.9, 129.4, 128.3, 127.9, 126.4, 124.5, 124.1, 122.8,
113.9, 112.4, 108.3, 60.6, 51.4, 51.2, 48.7, 29.0, 20.6, 20.4, 20.0,
19.6, 13.7.
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Okada, E.; Shibata, D. J. Fluorine Chem. 2007, 128, 1286.
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Gerus, I. I. Tetrahedron Lett. 2013, 54, 4091.
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12, 678. (b) Sun, J.; Wu, Q.; Xia, E. Y.; Yan, C. G. Eur. J.
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1069.
HRMS (ESI): m/z calcd for C31H35N3O3 ([M + Na]+): 520.2571;
found: 520.2562.
Acknowledgment
This work was financially supported by the National Natural Sci-
ence Foundation of China (Grant No. 21272200) and the Priority
Academic Program Development of Jiangsu Higher Education In-
stitutions. We also thank Analysis and Test Center of Yangzhou
University for providing necessary instruments for analysis.
Supporting Information for this article is available online at
(15) Sun, J.; Gao, H.; Wu, Q.; Yan, C. G. Beilstein J. Org. Chem.
2012, 8, 1839.
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n
nfomartit
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(18) CCDC 933878 and CCDC 971471 contain the
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Synthesis 2014, 46, 489–495
© Georg Thieme Verlag Stuttgart · New York

PAPER
1e, respectively, of this paper. These data can be obtained
Synthesis of Spiro[indoline-3,2′-quinolines]
495
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© Georg Thieme Verlag Stuttgart · New York
Synthesis 2014, 46, 489–495