Palladium-catalyzed C-7 alkenylation of indolines using molecular oxygen as the sole oxidant

Article abstract of DOI:10.1039/c5ra02245b

A general and efficient method for the intermolecular direct C-7-selective C-H alkenylation of indolines using palladium(ii) as the catalyst and molecular oxygen as the sole oxidant has been developed. The reaction showed complete regio- and stereoselectivity. All products were E-isomers at the C-7 position, and no Z-isomers or other position substituted products could be detected. The approach also presented an efficient route for the synthesis of C-7 alkenylated indoles.

Full text of DOI:10.1039/c5ra02245b

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Palladium-catalyzed C-7 alkenylation of indolines
using molecular oxygen as the sole oxidant†
Cite this: RSC Adv., 2015, 5, 23727
Dong Yang, Shuai Mao, Ya-Ru Gao, Dong-Dong Guo, Shi-Huan Guo, Bin Li
*
and Yong-Qiang Wang
A general and efficient method for the intermolecular direct C-7-selective C–H alkenylation of indolines
using palladium(II) as the catalyst and molecular oxygen as the sole oxidant has been developed. The
reaction showed complete regio- and stereoselectivity. All products were E-isomers at the C-7 position,
and no Z-isomers or other position substituted products could be detected. The approach also
presented an efficient route for the synthesis of C-7 alkenylated indoles.
Received 5th February 2015
Accepted 25th February 2015
DOI: 10.1039/c5ra02245b
www.rsc.org/advances
was utilized to regenerate the catalyst;6 (2) stoichiometric amounts
of reduced products of the oxidants were produced as waste which
Introduction
increased work-up cost; and (3) substrate scope was limited and
some cases were of poor yield.5 Herein, we report a general, effi-
cient and structurally versatile palladium(II)-catalyzed intermo-
lecular C-7-selective C–H alkenylation of indolines, characterized
by using molecular oxygen as the sole oxidizing agent, complete
regio- and stereoselectivity. Compared with N-uoro-2,4,6-
trimethyl-pyridiniumtriate, Cu(OAc)2 and BQ, oxygen is an
ideal oxidant and offers attractive industrial prospects in terms of
green and sustainable chemistry while no reduced waste is
produced.7
The indoline ring is a ubiquitous structural unit in bioactive
natural products, pharmaceuticals, and organic materials.1
The development of efficient strategies for the functionaliza-
tion of indoline nucleus has been received considerable
attention in organic synthesis.2 Among them metal-catalyzed
direct C-7 C–H alkenylation is an attractive approach due
to 7-vinylindoline motifs found in numerous bioactive
moleculars and important synthetic intermediates.3 However,
to date efficient direct regioselective C-7 alkenylation of
indoline has been limited. In 2011, Caretero et al. reported an
elegant Pd(II)-catalyzed ortho C–H olenation of aniline and
arylalkamine derivatives with electron-poor alkenes using
the 2-pyridylsulfonyl group as a removable directing group
with N-uoro-2,4,6-trimethylpyridiniumtriate (2.0 equiv.) as
the oxidant.4a Later in 2013, with the similar reaction condi-
tions they disclosed a pioneering example of Pd(II)-catalyzed
direct C-7 C–H alkenylation of N-(2-pyridyl)-sulfonyl indoline
with butyl acrylate.4b Then Oestreich et al. employed urea
units as directing group to realize an elegant Pd(II)-catalyzed
C-7 alkenylation of indolines using 1,4-benzoquinone (BQ,
2.0 equiv.) as the oxidant.5 Almost at the same time, with the
similar urea directing group, Antonchick et al. disclosed a
Rhodium(III)-catalyzed C-7 alkenylation of indolines using AgSbF6
(20 mol%) as an activator and Cu(OAc)2 (2.5 equiv.) as the oxidant,
followed by one-pot subsequent oxidation to provide 7-vinyl-
indoles.6 Despite these important advances, some challenging
issues still remain: for example, (1) large excess of oxidants
Results and discussion
Initially, we chose Pd(OAc)2 as catalyst. Considering triuoro-
acetic acid (TFA) and Pd(OAc)2 can facilitate the generation of
more electropositive [Pd(II)O2CCF3]+ species which, compared
with [Pd(II)OAc]+, possesses higher activity for electrophilic
substitution of C–H bonds to form s-indoline–Pd complex,8 TFA
was introduced as the additive. The study commenced by
investigating the indoline N-protecting groups which have
potential directing feature for the C-7 position. A set of pro-
tecting groups were tested for the reaction of indoline deriva-
tives (1) and ethyl acrylate (2a) using 10 mol% Pd(OAc)2 as
catalyst, triuoroacetic acid (TFA, 4 equiv.) as the additive and
oxygen as the oxidant in 1,2-dichloroethane (DCE) at 80 ꢀC
(Table 1). The reaction was found to proceed in low conversion
(<10%) when the N-protecting group was Ts, Ac or 2-pyr-
idylcarbonyl (Table 1, entries 1–3). To our delight, the N-(2-
pyridyl)sulfonyl protecting group gave the desired product 3da
in 62% conversion and 55% isolated yield (Table 1, entry 4).
Moreover, the reaction possessed complete C-7 regioselectivity
and E stereoselectivity by analyzing the reaction mixtures. Then
the palladium source was investigated (Table 1, entries 5–6),
Pd(TFA)2 or PdCl2 did not improve the yield of the desired
Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of
Education, Department of Chemistry & Materials Science, Northwest University, Xi'an
710069, P. R. China. E-mail: wangyq@nwu.edu.cn; Fax: +86-29-81535025; Tel: +86-
29-81535025
† Electronic supplementary information (ESI) available: 1H and 13C NMR spectra.
CCDC 1046800 and 1046801. For ESI and crystallographic data in CIF or other
electronic format see DOI: 10.1039/c5ra02245b
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Table 1 Optimization of reaction conditionsa
Entry
Indoline
Cat.
Solvent
Time (h)
Yieldb (%)
1
2
3
4
5
6
7
8
1a
1b
1c
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
Pd(TFA)2
PdCl2
DCE
DCE
DCE
DCE
DCE
DCE
DCE
Anisole
16
16
16
16
16
16
16
16
16
16
16
12
12
12
—
—
—
62f (55)
45
<10
—
52
30
47
<20
100f (95)
100f (93)
<30
1d
1d
1d
1d
1d
1d
1d
1d
1d
1d
1d
—
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
9
Toluene
10
11
12
13d
14de
AcOH
Solventsc
Anisole : AcOH (10 : 1)
Anisole : AcOH (10 : 1)
Anisole : AcOH (10 : 1)
a
Reaction conditions: 1 (1.0 mmol), 2a (2.0 mmol), catalyst (0.1 mmol), O2 (1 atm) and TFA (4.0 mmol) in solvent (10 mL) at 80 ꢀC. b Isolated yield
aer purication by ash column chromatography. c Solvents: 1,4-dioxane, DMSO, MeOH, CH3CN, THF, CH3NO2. d TFA (2.0 mmol). e Catalyst (0.05
mmol). f The conversion. The yield was in parentheses.
product. In the absence of palladium catalyst, the reaction 1,1-disubstituted alkenes successfully coupled with indoline
would not occur (Table 1, entry 7). Aer careful solvent at C-7 position to give the corresponding double-bond-
screening, anisole/AcOH (10 : 1) proved to be the best solvent isomerized product in high yield (Table 2, entry 11). Particu-
to give complete conversion and excellent yield (Table 1, larly noticeable is the performance of 1,2-disubstituted
entries 8–12). Finally we checked the amount of the additive alkenes, given the few precedents and lower reactivity of this
TFA and the catalyst Pd(OAc)2. TFA (2 equiv.) provided almost kind of olen in oxidative alkenylation (Fujiwara–Moritani)
the same results, but less amount of TFA led to incomplete reactions.9 Under this reaction conditions, (E)-methyl croto-
reaction (Table 1, entry 13). The conversion decreased nate and dimethyl maleate underwent smooth reaction with
remarkably while Pd(OAc)2 was reduced to 5% (Table 1, 1d to afford the corresponding trisubstituted alkene products
entry 14).
3dl and 3dm in excellent yields, respectively (Table 2, entries
Accordingly, the reaction conditions were optimized as 12 and 13). The molecular structures of compound 3da and
follows: Pd(OAc)2 (10% mol), TFA (2 equiv.) under 3dk were conrmed by X-ray crystallographic analysis
oxygen atmosphere in the solvent (anisole/AcOH ¼ 10 : 1) at (Fig. 1).20
ꢀ
80 C.
Next, we explored the reaction of various indoline deriva-
Aer identifying the optimized conditions, we moved on to tives with n-butyl acrylate (2b) and 4-uorostyrene (2g)
explore the scope of the transformation. First, we studied the (Table 3). We chose 4-uorostyrene as model substrate due to
effect of electronic and structural variations on the alkene organouorine molecules possessing distinctive properties
(Table 2). The present reaction tolerated a variety of alkenes. and having many valuable applications in medicinal chem-
Monosubstituted alkenes, not only electrophilic alkenes but istry, agrochemistry, and materials science.10 Indolines,
also the more challenging non-activated styrene derivatives, bearing either electron-withdrawing groups or electron-
reacted with 1d to give the corresponding C-7 alkenylation donating groups, all reacted smoothly and provided C-7 alke-
products in good to excellent yields (72–95%) with complete nylation products 3 in moderate to good yields (50–83%). Many
regio- and stereoselectivity (Table 2, entries 1–9). Indoline functional substituents such as F, Cl, Br and MeO were
phosphonate 3dj could also be generated from vinyl phos- compatible with these conditions, which could be further
phonate 2j in excellent yield (Table 2, entry 10). Pleasedly, transformed into other functionalities.
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Table 2 C-7-alkenylation of indoline (1d) with alkenesa
Table 2 (Contd.)
Time (h) Yieldb (%)
Entry Alkene
Product
Time (h) Yieldb (%)
Entry Alkene
Product
1
12
16
26
30
95
88
91
79
13
24
95
a
2
Reaction conditions: 1d (1.0 mmol),
2 (2.0 mmol), Pd(OAc)2
(0.1 mmol), O2 (1 atm) and TFA (2.0 mmol) in anisole/AcOH (10 : 1,
10 mL) at 80 ꢀC. Isolated yield. c Anisole/AcOH (2 : 1). Double bond
b
d
isomer of the alkenylation product.
3c
4
5
6
7
8
24
20
20
20
92
83
72
86
Fig. 1 X-ray of 3da and 3dk.
A plausible mechanism for the reaction is showed in Scheme
1. Pd(OAc)2 is treated with TFA to get active Pd(O2CCF3)+,8,11
which affords the C-7-palladated cyclopalladation species I
through coordination of palladium(II) to the nitrogen in the
2-pyridylsulfonyl group. Then coordination of alkene (interme-
diate II) and insertion of C]C bond result in the palladium(II)
complex III. Indoline/alkene adduct would be released from III
upon b-H elimination, and the Pd(0) can be re-oxidized to
Pd(O2CCF3)+ by O2 in the presence of TFA to complete the
catalytic cycle.12
Aer developing efficient approach for synthesis of 7-vinyl-
indolines, we were interested in synthesizing 7-vinylindoles
because the motifs are also prevalent in many natural products
and pharmaceutical targets.3b–d Delightedly, indoline deriva-
tives could be easily oxidized with DDQ (1.2 equiv.) to generate
7-substituted indole derivatives (Scheme 2). The 2-pyr-
idylsulfonyl group in indolines (3) or indoles (4) can be facilely
removed under mild conditions with the stereochemistry of the
olen moiety untouched. The reaction was carried out with zinc
in NH4Cl (aq.)/THF (1 : 1) at room temperature to afford the
product in good yield.
9
20
82
10
20
20
16
94
80
85
11d
12
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Table 3 C-7-alkenylation of various indoline derivatives with ethyl
acrylate and 4-fluorostyreneab
Indoline
Product of 2b
Product of 2g
Scheme 1 Plausible mechanism for the transformation.
Scheme 2 Deprotection and synthesis of 7-vinylindoles.
internally to the residual proton resonance in CDCl3
(d 7.26 ppm) with tetramethylsilane (TMS, d 0.00 ppm) as the
internal standard. Chemical shis (d) were reported as part per
million (ppm) in d scale downeld from TMS. Multiplicities are
reported as follows: s ¼ singlet, d ¼ doublet, t ¼ triplet,
q ¼ quartet, m ¼ multiplet. Infrared (IR) spectra were recorded
using KBr Solid on a Bruker EQUINOX55 instrument. High
resolution mass spectrometry data were obtained on a micro
TOF-QII (hybrid quadrupolar/time-of-ight) API US system by
electrospray ionization (ESI) in the positive ion mode using a
Bruker instrument. X-ray crystal structure analyses were
measured on Bruker Smart APEXIICCD instrument using
Mo-Ka radiation. The structures were solved and rened using
the SHELXTL soware package.
a
Reaction conditions: 1 (1.0 mmol), 2b or 2g (2.0 mmol), Pd(OAc)2
(0.1 mmol), O2 (1 atm) and TFA (2.0 mmol) in anisole/AcOH (10 : 1,
b
10 mL) at 80 ꢀC. Isolated yield aer purication by ash column
chromatography.
General experimental procedure for synthesis
Experimental
General information
Synthesis of substituted indolines.6 Substituted indole
(1.5 mmol) was dissolved in glacial acetic acid (6 mL) and cooled
in an ice bath just until the solution began to become partially
frozen. At this point, the solution was treated portion-wise with
sodium cyanoborohydride (4.5 mmol), then allowed to warm to
room temperature and stir for 15 hours. The reaction mixture
was concentrated to a thick residue and diluted with saturated
aqueous NaHCO3. The resulting solution was extracted with
EtOAc. The combined organic layers were washed with satu-
rated aqueous NaHCO3 and brine, then dried over anhydrous
Na2SO4 and concentrated. Then product was puried by normal
All commercial reagents and solvents were used as received
without further purication. Reactions were followed with TLC
(0.254 mm silica gel 60 F plates). Visualization was accom-
plished with UV light. Flash chromatographies were carried out
on silica gel 200–300 mesh. All NMR spectra were obtained at
ambient temperature using Varian INOVA-400 MHz or Bruker-
400 MHz spectrometer. 1H NMR and 13C NMR spectra were
recorded using CDCl3 as solvent. Spectra were referenced
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silica gel column chromatography with EtOAc/petroleum ether the system via syringe under an oxygen atmosphere (if alkene 2
as eluent. is response to a solid, it can be charged with N-(2-pyridyl)sul-
Synthesis of 1-tosylindoline (1a).13 To a vigorously stirring fonylindoline derivative 1 in the full oxygen tube). The mixture
solution of indoline (240 mg, 2.0 mmol) and tetrabutylammo- was heated to 80 ꢀC for 12–48 h (indicated in each case). It was
nium hydrogen sulfate (TBAHS) (33.6 mg, 0.2 mmol) in CH2Cl2 allowed to reach room temperature, diluted with EtOAc (30 mL)
(5 mL) at 0 ꢀC was added 50% aqueous sodium hydroxide (3 mL) and washed with saturated aqueous NaHCO3 (3 ꢁ 2 mL). The
and sulfonyl chloride (419 mg, 2.2 mmol). The resultant solu- combined organic phase was dried (Na2SO4) and concentrated
tion was stirred at room temperature until completion of the under reduced pressure. Purication by ash chromatography
reaction (TLC). Aer this time, the organic layer was separated, afforded the C-7 alkenylated indoline derivative 3.
washed with 1 M HCl, saturated aqueous NaHCO3, water and
Oxidation of indoline derivatives.18 Indoline derivative
brine; dried over MgSO4 and concentrated under reduced (150 mg, 0.42 mmol) was dissolved in dry toluene (2 mL) in a
pressure. The residue was puried by ash chromatography to round bottomed ask equipped with a reux condenser and
afford 1a; white solid; yield: (182 mg, 76%).
DDQ (125 mg, 0.55 mmol) was added. The reaction mixture was
Synthesis of 1-(indolin-1-yl)ethanone (1b).14 Acetyl chloride heated to reux under an argon atmosphere for 12 hours. The
(237 mg, 3.0 mmol) was added to a solution of indoline (240 mg, reaction was then cooled to RT, diluted with EtOAc, washed
2.0 mmol) in acetic acid (5 mL), and the reaction mixture was with water and brine and dried over anhydrous MgSO4. The
reuxed for 3 h. Aer removing the solvent afforded N-acetyl solvent was removed in vacuo and purication of the crude
indoline 1b; yield: (216 mg, 90%).
reaction mixture by ash chromatography to afford the
Synthesis of N-(2-pyridyl) carbonyl indoline (1c).15 The product.
indoline (119 mg, 1 mmol) were added to pyridine-2-carboxylic
Removing the directing group.4 A suspension of indoline or
acid (111 mg, 0.9 mmol), triethylamine (0.16 mL) and TBTU indole derivative (36 mg, 0.1 mmol) and activated Zn powder
(312 mg, 0.97 mmol) in THF(10 mL). The reaction mixture was (327 mg, 5 mmol, 50 equiv.) in a 1 : 1 mixture of THF and sat aq.
stirred for 3 h at RT, diluted with EtOAc and washed with 15% NH4Cl solution (5 mL) was stirred at room temperature until
potassium carbonate solution, saturated sodium chloride consumption of the starting material (TLC monitoring). The
solution and 1 M hydrochloric acid. The organic phase was mixture was diluted with EtOAc (15 mL) and ltered over a pad
dried over MgSO4 and the volatiles were removed under reduced of Celite to remove the Zn. The ltrate was washed with a
pressure. The residue was puried by ash chromatography to saturated aqueous solution of ammonium chloride and brine.
afford 1c. yield: (67 mg, 56%). The combined organic phase was dried over MgSO4 and
Synthesis of starting materials (N-(2-pyridyl)sulfonylindo- concentrated to dryness. The residue was puried by ash
line) derivatives
chromatography to afford the product.
2-Pyridylsulfonyl chloride.16. To a solution of 2-mercaptopyr-
idine (1.5 g, 13.5 mmol) in conc. H2SO4 (40 mL) was added
Product characterization data
3-Methylindoline.6 1H NMR (400 MHz, CDCl3) d 7.05 (d, J ¼ 8.0
dropwise a commercially available bleach solution (roughly 5% Hz, 1H), 7.00 (t, J ¼ 8.0 Hz, 1H), 6.71 (t, J ¼ 8.0 Hz, 1H), 6.59 (d, J
ꢀ
NaClO, 150 mL). The resulting mixture was stirred at 0 C for ¼ 8.0 Hz, 1H), 3.65–3.58 (m, 2H), 3.34–3.29 (m, 1H), 3.04 (t, J ¼
15 min before it was extracted with CH2Cl2 (3 ꢁ 25 mL). The 8.0 Hz, 1H), 1.29 (d, J ¼ 8.0 Hz, 3H); 13C NMR (100 MHz, CDCl3)
combined organic phase was dried (Na2SO4) and concentrated d 151.2, 134.2, 127.2, 123.3, 118.6, 109.4, 55.3, 36.5, 18.6.
under reduced pressure at 20 ꢀC (caution: in a fume hood
5-Methylindoline.6 1H NMR (400 MHz, CDCl3) d 6.94 (s, 1H),
because of the presence of Cl2) to afford the 2-pyridylsulfonyl 6.82 (d, J ¼ 4.0 Hz, 1H), 6.55 (d, J ¼ 8.0 Hz, 1H), 3.52–3.48 (m,
chloride as a colorless oil. This compound is relatively unstable 3H), 2.97 (t, J ¼ 8.0 Hz, 2H), 2.24 (s, 3H); 13C NMR (100 MHz,
at room temperature and it was immediately used without CDCl3) d 149.2, 129.3, 128.1, 127.5, 125.4, 109.5, 47.6, 30.0, 20.8.
1
further purication.
5-Methoxyindoline. H NMR (400 MHz, CDCl3) d 6.74 (s, 1H),
N-(2-Pyridyl)sulfonylindoline derivatives.17 A mixture of indo- 6.56 (s, 2H), 3.71 (s, 4H), 3.48 (t, J ¼ 8.0 Hz, 2H), 2.97 (t, J ¼ 8.0
line (2.2 g, 18.0 mmol) and sodium hydride (860 mg, 36.0 mmol) Hz, 2H); 13C NMR (100 MHz, CDCl3) d 153.4, 145.2, 131.11,
was stirred in dry THF at 0 ꢀC for 30 min. To the resulting 112.0, 111.4, 110.1, 55.8, 47.7, 30.4.
solution was slowly added at 0 ꢀC 2-pyridylsulfonyl chloride
5-Chloroindoline.6 1H NMR (400 MHz, CDCl3) d 7.17 (s, 1H),
(6.4 g, 36.0 mmol) and the resulting mixture was stirred at room 7.07 (d, J ¼ 8.0 Hz, 1H), 6.47 (d, J ¼ 8.0 Hz, 1H), 3.58–3.51 (m,
temperature overnight. The mixture was quenched with satu- 3H), 2.99 (t, J ¼ 8.0 Hz, 2H); 13C NMR (100 MHz, CDCl3) d 150.7,
rated aqueous NH4Cl solution and extracted with EtOAc. The 131.8, 129.8, 127.6, 110.6, 110.1, 47.6, 29.7.
combined organic phase was dried (Na2SO4) and concentrated
5-Bromoindoline.6 1H NMR (400 MHz, CDCl3) d 7.15 (s, 1H),
under reduced pressure. The residue was puried by ash 7.06 (d, J ¼ 8.0 Hz, 1H), 6.44 (d, J ¼ 8.0 Hz, 1H), 3.73 (s, 1H), 3.50
chromatography.
(t, J ¼ 8.0 Hz, 2H), 2.96 (t, J ¼ 8.0 Hz, 2H); 13C NMR (100 MHz,
Synthesis of the C-7 alkenylation of indolines. A seal tube CDCl3) d 150.6, 131.7, 129.7, 127.5, 110.5, 109.98, 47.5, 29.6.
containing the N-(2-pyridyl)sulfonylindoline derivative
1
1-Tosylindoline (1a).13 1H NMR (400 MHz, CDCl3) d 7.67–7.63
(0.2 mmol), Pd(OAc)2 (6.0 mg, 10 mol%) was evacuated and (m, 3H), 7.22–7.16 (m, 3H), 7.06 (d, J ¼ 8.0 Hz, 1H), 6.96 (t, J ¼
lled with dioxygen gas using an oxygen containing balloon. 8.0 Hz, 1H), 3.89 (t, J ¼ 8.0 Hz, 2H), 2.86 (t, J ¼ 8.0 Hz, 2H), 2.35
Then, anisole/AcOH (10 : 1, 1 mL), alkene 2 (0.4 mmol) and (s, 3H); 13C NMR (100 MHz, CDCl3) d 144.2, 141.9, 133.8, 131.8,
triuoroacetic acid (TFA, 0.4 mmol) were sequentially added to 129.6, 127.7, 127.3, 125.1, 123.7, 114.9, 49.9, 27.8, 21.5.
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1-(Indolin-1-yl)ethanone (1b).14 1H NMR (400 MHz, CDCl3) d
8.20 (d, J ¼ 8.0 Hz, 1H), 7.19–7.14 (m, 2H), 7.00 (d, J ¼ 8.0 Hz,
1H), 3.99 (t, J ¼ 8.0 Hz, 2H), 3.15 (t, J ¼ 8.0 Hz, 2H), 2.19 (s, 3H);
13C NMR (100 MHz, CDCl3) d 168.7, 142.8, 131.1, 127.4, 124.5,
123.5, 116.8, 48.7, 27.9, 24.2.
d 156.6, 156.0, 150.0, 137.7, 134.7, 133.9, 126.9, 123.0, 115.7,
112.3, 111.0, 55.4, 51.6, 28.4; HRMS (ESI): exact mass calcd for
C
14H14N2NaO3S+ [M + Na]+: 313.0617. Found: 313.0634.
5-Chloro-1-(pyridin-2-ylsulfonyl)indoline (1i).18 Pale yellow oil;
IR (KBr, cmꢂ1): 3056, 2920, 2851, 1603, 1574, 1472, 1426, 1355,
1176, 876, 817, 776, 745; H NMR (400 MHz, CDCl3) d 8.61 (s,
1
N-(2-Pyridyl) carbonyl indoline (1c).15 1H NMR (400 MHz,
CDCl3) d 8.62 (d, J ¼ 4.0 Hz, 1H), 8.32 (d, J ¼ 4.0 Hz, 1H), 7.84 (d,
J ¼ 8.0 Hz, 2H), 7.38 (s, 1H), 7.27–7.21 (m, 2H), 7.09–7.07 (m,
1H), 4.33 (t, J ¼ 8.0 Hz, 2H), 3.13 (t, J ¼ 8.0 Hz, 2H); 13C NMR
(100 MHz, CDCl3) d 166.1, 154.5, 148.0, 143.2, 137.1, 132.2,
127.4, 125.0, 124.6, 124.3, 124.1, 117.9, 50.1, 28.6.
1H), 7.94–7.85 (m, 2H), 7.47–7.37 (m, 2H), 7.05 (s, 2H), 4.32 (t, J
¼ 8.0 Hz, 2H), 3.04 (d, J ¼ 8.0 Hz, 2H); 13C NMR (100 MHz,
CDCl3) d 155.8, 150.2, 140.3, 137.9, 133.9, 128.7, 127.4, 127.2,
125.2, 123.0, 115.3, 51.5, 27.8; HRMS (ESI): exact mass calcd for
C
13H12ClN2O2S+ [M + H]+: 295.0303. Found: 295.0308.
N-(2-Pyridyl)sulfonylindoline (1d).17 IR (KBr, cmꢂ1): 3056,
5-Bromo-1-(pyridin-2-ylsulfonyl)indoline (1j).18 Pale yellow oil;
IR (KBr, cmꢂ1): 3089, 2918, 2849, 1604, 1526, 1458, 1423, 1350,
1174, 867, 807, 775, 744; H NMR (400 MHz, CDCl3) d 8.61 (s,
1
2969, 2927, 2857, 1599, 1570, 1481, 1454, 1350, 1178, 752; H
1
NMR (400 MHz, CDCl3) d 8.61 (d, J ¼ 4.0 Hz, 1H), 7.97 (d, J ¼ 8.0
Hz, 1H), 7.82 (t, J ¼ 8.0 Hz, 1H), 7.47–7.43 (m, 2H), 7.10–7.08 (m,
2H), 6.93 (t, J ¼ 8.0 Hz, 1H), 4.33 (t, J ¼ 8.0 Hz, 2H), 3.05 (t, J ¼
8.0 Hz, 2H); 13C NMR (100 MHz, CDCl3) d 156.2, 150.2, 141.5,
137.8, 132.0, 127.5, 127.0, 125.2, 123.7, 123.1, 114.5, 51.4, 28.1;
HRMS (ESI): exact mass calcd for C13H12N2NaO2S+ [M + Na]+:
283.0517. Found: 283.0513.
1H), 7.96 (d, J ¼ 8.0 Hz, 1H), 7.89–7.87 (m, 1H), 7.46 (s, 1H), 7.34
(d, J ¼ 8.0 Hz, 1H), 7.21 (s, 2H), 4.33 (t, J ¼ 8.0 Hz, 2H), 3.05 (t, J
¼ 8.0 Hz, 2H); 13C NMR (100 MHz, CDCl3) d 155.9, 150.3, 140.9,
137.9, 134.3, 130.4, 128.2, 127.2, 123.1, 116.3, 115.9, 51.6, 27.9;
HRMS (ESI): exact mass calcd for C13H12BrN2O2S+ [M + H]+:
338.9797. Found: 338.9795.
(E)-Ethyl 3-(1-(pyridin-2-ylsulfonyl)indolin-7-yl)acrylate (3da).
White solid; yield: 95%; mp ¼ 113–115 ꢀC; IR (KBr, cmꢂ1): 3093,
3054, 2975, 2919, 1707, 1638, 1578, 1512, 1450, 1428, 1360,
1177, 846, 786, 744; H NMR (400 MHz, CDCl3) d 8.65 (d, J ¼
2-Methyl-1-(pyridin-2-ylsulfonyl)indoline (1e). White solid; mp
¼ 96–97 ꢀC; IR (KBr, cmꢂ1): 3023, 2961, 2919, 1576, 1474, 1347,
1175, 763; 1H NMR (400 MHz, CDCl3) d 8.57 (d, J ¼ 4.0 Hz, 1H),
7.87 (d, J ¼ 4.0 Hz, 1H), 7.77 (t, J ¼ 8.0 Hz, 1H), 7.50 (d, J ¼ 8.0
Hz, 1H), 7.40–7.37 (m, 1H), 7.12–7.06 (m, 2H), 6.95 (t, J ¼ 8.0 Hz,
1H), 5.01–4.98 (m, 1H), 3.31–3.25 (m, 1H), 2.57 (d, J ¼ 16.0 Hz,
1H), 1.45 (d, J ¼ 4.0 Hz, 3H); 13C NMR (100 MHz, CDCl3) d 156.6,
150.0, 140.3, 137.7, 131.6, 127.4, 126.8, 125.3, 124.2, 122.8,
116.0, 59.9, 36.3, 23.6; HRMS (ESI): exact mass calcd for
1
4.0 Hz, 1H), 8.16 (d, J ¼ 16.0 Hz, 1H), 7.77 (t, J ¼ 8.0 Hz, 1H), 7.59
(d, J ¼ 8.0 Hz, 1H), 7.49 (d, J ¼ 4.0 Hz, 2H), 7.14–7.09 (m, 2H),
6.42 (d, J ¼ 16.0 Hz, 1H), 4.28 (t, J ¼ 8.0 Hz, 4H), 2.53 (t, J ¼
6.0 Hz, 2H), 1.34 (t, J ¼ 8.0 Hz, 3H); 13C NMR (100 MHz, CDCl3) d
166.9, 155.8, 150.1, 141.9, 141.4, 137.8, 137.7, 127.7, 127.2,
126.8, 126.0, 125.4, 123.3, 117.8, 60.4, 53.2, 29.2, 14.3; HRMS
(ESI): exact mass calcd for C18H18N2NaO4S+ [M + Na]+: 381.0879.
Found: 381.0880.
C
14H15N2O2S+ [M + H]+: 275.0849. Found: 275.0860.
3-Methyl-1-(pyridin-2-ylsulfonyl)indoline (1f).18 Pale yellow oil;
IR (KBr, cmꢂ1): 3053, 2963, 2927, 2875, 1507, 1477, 1454, 1354,
1177, 752; 1H NMR (400 MHz, CDCl3) d 8.60 (d, J ¼ 4.0 Hz, 1H),
7.97 (d, J ¼ 8.0 Hz, 1H), 7.83 (t, J ¼ 8.0 Hz, 1H), 7.48–7.41 (m,
2H), 7.13–7.06 (m, 2H), 6.96 (t, J ¼ 8.0 Hz, 1H), 4.47 (t, J ¼ 8.0 Hz,
1H), 3.85–3.80 (m, 1H), 3.39–3.34 (m, 1H), 1.22 (d, J ¼ 8.0 Hz,
3H); 13C NMR (100 MHz, CDCl3) d 155.9, 150.1, 140.9, 137.8,
136.8, 127.6, 127.0, 123.9, 123.7, 122.9, 114.1, 58.7, 34.7, 19.3;
HRMS (ESI): exact mass calcd for C14H14N2NaO2S+ [M + Na]+:
297.0668. Found: 297.0674.
(E)-Butyl 3-(1-(pyridin-2-ylsulfonyl)indolin-7-yl)acrylate (3db).4
White solid; yield: 88%; mp ¼ 108–110 ꢀC; IR (KBr, cmꢂ1): 3064,
2957, 2922, 2851, 1706, 1636, 1570, 1464, 1428, 1363, 1337,
1
1176, 849, 782, 743; H NMR (400 MHz, CDCl3) d 8.65 (d, J ¼
4.0 Hz, 1H), 8.16 (d, J ¼ 16.0 Hz, 1H), 7.76 (t, J ¼ 8.0 Hz, 1H), 7.60
(d, J ¼ 8.0 Hz, 1H), 7.48 (t, J ¼ 6.0 Hz, 2H), 7.12–7.09 (m, 2H),
6.42 (d, J ¼ 16.0 Hz, 1H), 4.28 (t, J ¼ 8.0 Hz, 2H), 4.22 (t, J ¼ 6.0
Hz, 2H), 2.53 (t, J ¼ 8.0 Hz, 2H), 1.70 (t, J ¼ 6.0 Hz, 2H), 1.46–1.44
(m, 2H), 0.97 (t, J ¼ 8.0 Hz, 3H); 13C NMR (100 MHz, CDCl3) d
167.1, 155.9, 150.1, 141.9, 141.5, 137.8, 137.7, 127.8, 127.2,
126.8, 126.0, 125.5, 123.3, 117.9, 64.3, 53.3, 30.8, 29.2, 19.2, 13.8;
HRMS (ESI): exact mass calcd for C20H22N2NaO4S+ [M + Na]+:
409.1192. Found: 409.1204.
5-Methyl-1-(pyridin-2-ylsulfonyl)indoline (1g). White solid; mp
¼ 95–96 ꢀC; IR (KBr, cmꢂ1): 3088, 2956, 2921, 2855, 1615, 1576,
1484, 1453, 1352, 1178, 815, 782, 744; 1H NMR (400 MHz,
CDCl3) d 8.58 (d, J ¼ 4.0 Hz, 1H), 7.92 (d, J ¼ 8.0 Hz, 1H),
7.82–7.80 (m, 1H), 7.40–7.33 (m, 2H), 6.89 (s, 2H), 4.29 (t, J ¼
8.0 Hz, 2H), 2.97 (t, J ¼ 8.0 Hz, 2H), 2.20 (s, 3H); 13C NMR
(100 MHz, CDCl3) d 155.9, 150.0, 138.9, 137.7, 133.3, 132.1,
127.8, 126.9, 125.7, 122.9, 114.2, 51.4, 27.9, 20.7; HRMS (ESI):
exact mass calcd for C14H14N2NaO2S+ [M + Na]+: 297.0668.
Found: 297.0682.
(E)-2-Acetoxyethyl 3-(1-(pyridin-2-ylsulfonyl)indolin-7-yl)acrylate
(3dc). White solid; yield: 91%; mp ¼ 116–119 ꢀC; IR (KBr, cmꢂ1):
3064, 2957, 2923, 1735, 1709, 1660, 1633, 1570, 1514, 1450,
1428, 1355, 1253, 1187, 849, 784, 745; 1H NMR (400 MHz,
CDCl3) d 8.65 (d, J ¼ 4.0 Hz, 1H), 8.21 (d, J ¼ 16.0 Hz, 1H), 7.77 (t,
J ¼ 8.0 Hz, 1H), 7.60 (d, J ¼ 8.0 Hz, 1H), 7.48 (d, J ¼ 8.0 Hz, 2H),
7.13–7.09 (m, 2H), 6.45 (d, J ¼ 16.0 Hz, 1H), 4.42–4.27 (m, 6H),
2.53 (t, J ¼ 6.0 Hz, 2H), 2.12 (s, 3H); 13C NMR (100 MHz, CDCl3) d
171.0, 166.6, 155.8, 150.2, 142.8, 141.6, 137.8, 137.7, 127.5,
127.2, 126.8, 126.2, 125.5, 123.3, 117.0, 62.3, 62.1, 53.2, 29.2,
20.9; HRMS (ESI): exact mass calcd for C20H20N2NaO6S+ [M +
Na]+: 439.0934. Found: 439.0941.
5-Methoxy-1-(pyridin-2-ylsulfonyl)indoline (1h).18 White solid;
mp ¼ 92–94 C; IR (KBr, cmꢂ1): 3097, 2954, 2838, 1601, 1574,
ꢀ
1486, 1429, 1351, 1241, 1177, 857, 815, 780, 745; 1H NMR
(400 MHz, CDCl3) d 8.60 (d, J ¼ 4.0 Hz, 1H), 7.89–7.81 (m, 2H),
7.42–7.37 (m, 2H), 6.64–6.62 (m, 2H), 4.30 (t, J ¼ 8.0 Hz, 2H),
3.70 (s, 3H), 2.96 (t, J ¼ 12.0 Hz, 2H); 13C NMR (100 MHz, CDCl3)
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124.6, 124.0, 123.6, 53.6, 29.3; HRMS (ESI): exact mass calcd for
C
(E)-7-(3-Chlorostyryl)-1-(pyridin-2-ylsulfonyl)indoline (3di).
(E)-1-(1-(Pyridin-2-ylsulfonyl)indolin-7-yl)pent-1-en-3-one (3dd).
21H17ClN2NaO2S+ [M + Na]+: 419.0591. Found: 419.0605.
White solid; yield: 79%; mp ¼ 112–114 ꢀC; IR (KBr, cmꢂ1): 3026,
2973, 2927, 1775, 1660, 1623, 1580, 1477, 1446, 1422, 1352,
White solid; yield: 82%; mp ¼ 132–134 ꢀC; IR (KBr, cmꢂ1): 3057,
2958, 2919, 1643, 1590, 1567, 1427, 1357, 1178, 848, 782, 739; 1H
NMR (400 MHz, CDCl3) d 8.66 (s, 1H), 7.72–7.68 (m, 2H), 7.88–
7.53 (m, 3H), 7.47–7.40 (m, 2H), 7.27 (t, J ¼ 6.0 Hz, 1H), 7.21 (d, J
¼ 8.0 Hz, 1H), 7.09 (t, J ¼ 8.0 Hz, 1H), 6.97 (t, J ¼ 8.0 Hz, 2H),
4.29 (t, J ¼ 8.0 Hz, 2H), 2.53 (t, J ¼ 8.0 Hz, 2H); 13C NMR
(100 MHz, CDCl3) d 156.0, 150.2, 140.3, 139.6, 137.7, 137.6,
134.5, 130.1, 129.9, 127.8, 127.4, 127.1, 126.9, 126.7, 125.1,
124.3, 124.0, 123.5, 53.6, 29.5; HRMS (ESI): exact mass calcd for
1
1191, 845, 789, 744; H NMR (400 MHz, CDCl3) d 8.65 (d, J ¼
4.0 Hz, 1H), 8.10 (d, J ¼ 16.0 Hz, 1H), 7.77 (t, J ¼ 8.0 Hz, 1H), 7.59
(d, J ¼ 8.0 Hz, 1H), 7.54–7.46 (m, 3H), 7.14–7.08 (m, 2H), 6.64 (d,
J ¼ 16.0 Hz, 1H), 4.31 (t, J ¼ 8.0 Hz, 2H), 2.90–2.85 (m, 2H), 2.56
(t, J ¼ 6.0 Hz, 2H), 1.20 (t, J ¼ 6.0 Hz, 3H); 13C NMR (100 MHz,
CDCl3) d 202.4, 155.7, 150.2, 141.5, 140.5, 137.9, 137.8, 127.9,
127.3, 127.0, 126.7, 126.1, 125.3, 123.5, 53.5, 32.0, 29.2, 8.3;
HRMS (ESI): exact mass calcd for C18H18N2NaO3S+ [M + Na]+:
365.0930. Found: 365.0944.
C
21H17ClN2NaO2S+ [M + Na]+: 419.0591. Found: 419.0606.
(E)-N,N-Diethyl-3-(1-(pyridin-2-ylsulfonyl)indolin-7-yl) acrylamide
(3de). White solid; yield: 92%; mp ¼ 118–120 ꢀC; IR (KBr, cmꢂ1):
3069, 2971, 2931, 1647, 1603, 1480, 1452, 1424, 1356, 1178, 828,
(E)-Diethyl2-(1-(pyridin-2-ylsulfonyl)indolin-7-yl)vinylphos-phonate
(3dj). Yellow oil; yield: 94%; IR (KBr, cmꢂ1): 3056, 2982, 2907,
1619, 1579, 1429, 1392, 1359, 1178, 856, 781, 744; 1H NMR (400
MHz, CDCl3) d 8.65 (d, J ¼ 4.0 Hz, 1H), 7.87–7.76 (m, 1H), 7.61
(d, J ¼ 8.0 Hz, 1H), 7.48 (d, J ¼ 8.0 Hz, 2H), 7.15–7.07 (m, 2H),
6.29 (t, J ¼ 18.0 Hz, 1H), 4.27–4.17 (m, 6H), 2.50 (t, J ¼ 8.0 Hz,
2H), 1.38 (t, J ¼ 8.0 Hz, 6H); 13C NMR (100 MHz, CDCl3) d 155.8,
150.2, 145.4 (d, J ¼ 8 Hz), 141.2, 137.9, 137.70, 128.3 (d, J ¼ 24
Hz), 127.2, 126.9, 125.9, 125.4, 123.5, 113.4 (d, J ¼ 190 Hz), 62.1
(d, J ¼ 5 Hz), 53.2, 29.2, 16.5 (d, J ¼ 6 Hz); HRMS (ESI): exact
mass calcd for C19H23N2NaO5PS+ [M + Na]+: 445.0958. Found:
445.0972.
1
784, 743; H NMR (400 MHz, CDCl3) d 8.65 (d, J ¼ 4.0 Hz, 1H),
7.95 (d, J ¼ 16.0 Hz, 1H), 7.80 (t, J ¼ 6.0 Hz, 1H), 7.67 (d, J ¼ 8.0
Hz, 1H), 7.50–7.45 (m, 2H), 7.11–7.04 (m, 2H), 6.84 (d, J ¼ 16.0
Hz, 1H), 4.24 (t, J ¼ 6.0 Hz, 2H), 3.50 (d, J ¼ 8.0 Hz, 4H), 2.53 (t, J
¼ 6.0 Hz, 2H), 1.28–1.19 (m, 6H); 13C NMR (100 MHz, CDCl3) d
166.0, 155.9, 150.0, 141.2, 138.8, 137.9, 137.6, 128.9, 127.1,
126.6, 125.6, 125.1, 123.3, 118.4, 53.0, 42.3, 40.7, 29.3, 15.0, 13.2;
HRMS (ESI): exact mass calcd for C20H24N3O3S+ [M + H]+:
386.1533. Found: 386.1549.
(E)-1-(Pyridin-2-ylsulfonyl)-7-styrylindoline (3df). White solid;
yield: 83%; mp ¼ 150–152 ꢀC; IR (KBr, cmꢂ1): 3056, 2956, 2921,
1715, 1572, 1495, 1451, 1425, 1355, 1178, 846, 778, 738; 1H NMR
(400 MHz, CDCl3) d 8.63 (d, J ¼ 4.0 Hz, 1H), 7.72 (d, J ¼ 16.0 Hz,
1H), 7.64–7.53 (m, 4H), 7.42–7.35 (m, 3H), 7.26 (d, J ¼ 4.0 Hz,
1H), 7.10–7.06 (m, 2H), 6.93 (d, J ¼ 8.0 Hz, 1H), 4.29 (t, J ¼
8.0 Hz, 2H), 2.47 (t, J ¼ 8.0 Hz, 2H); 13C NMR (100 MHz, CDCl3) d
155.8, 150.1, 134.0, 137.6, 130.7, 128.6, 128.2, 127.6, 127.1,
126.9, 126.8, 126.3, 124.2, 123.5, 53.5, 29.3; HRMS (ESI): exact
mass calcd for C21H18N2NaO2S+ [M + Na]+: 385.0981. Found:
385.0986.
Methyl 2-((1-(pyridin-2-ylsulfonyl)indolin-7-yl)methyl)-acrylate
(3dk). White solid; yield: 80%; mp ¼ 144–146 ꢀC; IR (KBr,
cmꢂ1): 3015, 2954, 2922, 2849, 1710, 1630, 1570, 1430, 1350,
1
1284, 1178, 843, 781, 743; H NMR (400 MHz, CDCl3) d 8.66 (s,
1H), 7.74 (t, J ¼ 8.0 Hz, 1H), 7.59 (d, J ¼ 8.0 Hz, 1H), 7.47 (t, J ¼
8.0 Hz, 1H), 7.28 (s, 1H), 7.03 (d, J ¼ 12.0 Hz, 2H), 6.91 (d, J ¼
4.0 Hz, 1H), 6.28 (s, 1H), 5.58 (s, 1H), 4.22 (t, J ¼ 8.0 Hz, 2H), 4.07
(s, 2H), 3.69 (s, 3H), 2.41 (t, J ¼ 6.0 Hz, 2H); 13C NMR (100 MHz,
CDCl3) d 167.5, 156.0, 150.2, 141.0, 139.4, 137.7, 137.5, 132.6,
129.1, 127.1, 126.9, 123.5, 122.8, 53.5, 51.9, 35.0, 29.5; HRMS
(ESI): exact mass calcd for C18H18N2NaO4S+ [M + Na]+: 381.0879.
Found: 381.0888.
(E)-7-(4-Fluorostyryl)-1-(pyridin-2-ylsulfonyl)indoline (3dg).
Brown solid; yield: 72%; mp ¼ 123–125 ꢀC; IR (KBr, cmꢂ1): 3056,
2956, 2921, 1734, 1682, 1643, 1594, 1507, 1426, 1355, 1226,
(E)-Methyl 3-(1-(pyridin-2-ylsulfonyl)indolin-7-yl)but-2-enoate (3dl).
Colorless oil; yield: 85%; IR (KBr, cmꢂ1): 3055, 2951, 2849, 1715,
1
1177, 824, 778, 741; H NMR (400 MHz, CDCl3) d 8.65 (d, J ¼
1
1634, 1573, 1431, 1356, 1263, 1176, 840, 784, 742; H NMR (400
4.0 Hz, 1H), 7.79–7.48 (m, 6H), 7.49–7.37 (m, 1H), 7.17–6.99 (m,
4H), 6.94 (d, J ¼ 8.0 Hz, 1H), 4.30 (t, J ¼ 8.0 Hz, 2H), 2.48 (t, J ¼
8.0 Hz, 2H); 13C NMR (100 MHz, CDCl3) d 162.4 (d, J ¼ 245 Hz),
155.9, 150.2, 140.0, 137.6, 133.9, 130.6, 128.4 (d, J ¼ 8 Hz), 127.2,
127.0, 126.9, 126.2, 124.1, 123.6, 115.6 (d, J ¼ 22 Hz), 53.6, 29.4;
HRMS (ESI): exact mass calcd for C21H17FN2NaO2S+ [M + Na]+:
403.0887. Found: 403.0901.
MHz, CDCl3) d 8.63 (s, 1H), 7.71 (t, J ¼ 4.0 Hz, 1H), 7.54 (d, J ¼ 8.0
Hz, 1H), 7.44 (d, J ¼ 4.0 Hz, 1H), 7.10–7.06 (m, 3H), 5.96 (s, 1H),
4.33 (t, J ¼ 6.0 Hz, 2H), 3.72 (d, J ¼ 4.0 Hz, 3H), 2.64–2.61 (m, 5H);
13C NMR (100 MHz, CDCl3) d 167.2, 157.4, 156.3, 150.1, 138.8,
137.6, 136.3, 127.9, 127.0, 126.6, 124.8, 123.1, 117.9, 52.9, 51.0,
29.4, 19.1; HRMS (ESI): exact mass calcd for C18H18N2NaO4S+
[M + Na]+: 381.0879. Found: 381.0885.
(E)-Dimethyl 2-(1-(pyridin-2-ylsulfonyl)indolin-7-yl)maleate (3dm).
White solid; yield: 95%; mp ¼ 114–116 ꢀC; IR (KBr, cmꢂ1):
3013, 2958, 2921, 1722, 1716, 1645, 1574, 1433, 1351, 1263,
1174, 837, 780, 744; 1H NMR (400 MHz, CDCl3) d 8.65 (d, J ¼ 4.0
Hz, 1H), 7.70 (t, J ¼ 8.0 Hz, 1H), 7.54 (d, J ¼ 8.0 Hz, 1H), 7.45–
7.42 (m, 1H), 7.12–7.02 (m, 2H), 7.01 (d, J ¼ 8.0 Hz, 2H), 4.46 (s,
1H), 4.12 (d, J ¼ 8.0 Hz, 1H), 3.88 (s, 3H), 3.60 (s, 3H), 2.58 (d, J
¼ 8.0 Hz, 2H); 13C NMR (100 MHz, CDCl3) d 166.1, 165.1, 155.9,
149.9, 143.5, 140.0, 137.6, 136.7, 129.0, 127.0, 127.0, 126.3,
125.8, 125.1, 123.6, 53.0, 52.8, 51.7, 29.3; HRMS (ESI): exact
(E)-7-(2-Chlorostyryl)-1-(pyridin-2-ylsulfonyl)indoline (3dh).
White solid; yield: 86%; mp ¼ 155–157 ꢀC; IR (KBr, cmꢂ1): 3058,
2955, 2921, 1653, 1566, 1426, 1352, 1176, 846, 777, 744; 1H NMR
(400 MHz, CDCl3) d 8.65 (d, J ¼ 4.0 Hz, 1H), 7.91 (d, J ¼ 8.0 Hz,
1H), 7.69–7.64 (m, 3H), 7.55 (d, J ¼ 8.0 Hz, 1H), 7.50 (s, 1H),
7.44–7.41 (m, 1H), 7.37 (d, J ¼ 8.0 Hz, 1H), 7.29–7.26 (m, 1H),
7.19 (t, J ¼ 8.0 Hz, 1H), 7.10 (t, J ¼ 8.0 Hz, 1H), 6.96 (d, J ¼ 8.0 Hz,
1H), 4.32 (t, J ¼ 8.0 Hz, 2H), 2.50 (t, J ¼ 8.0 Hz, 2H); 13C NMR
(100 MHz, CDCl3) d 155.8, 150.1, 140.1, 137.6, 137.6, 135.7,
133.3, 130.4, 129.6, 128.8, 128.5, 127.3, 127.2, 127.1, 126.9,
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mass calcd for C19H18N2NaO6S+ [M + Na]+: 425.0778. Found: (d, J ¼ 4.0 Hz, 1H), 8.15 (d, J ¼ 16.0 Hz, 1H), 7.78 (t, J ¼ 8.0 Hz,
425.0784.
1H), 7.58 (d, J ¼ 8.0 Hz, 1H), 7.51–7.49 (m, 1H), 7.29 (s, 1H), 6.90
(E)-Butyl 3-(2-methyl-1-(pyridin-2-ylsulfonyl)indolin-7-yl)acrylate (s, 1H), 6.41 (d, J ¼ 16.0 Hz, 1H), 4.27–4.20 (m, 4H), 2.45 (t, J ¼
(3eb). White solid; yield: 80%; mp ¼ 113–115 ꢀC; IR (KBr, 8.0 Hz, 2H), 2.29 (s, 3H), 1.72–1.70 (m, 2H), 1.46–1.43 (m, 2H),
cmꢂ1): 3056, 2922, 1704, 1634, 1570, 1513, 1427, 1361, 1279, 0.97 (t, J ¼ 8.0 Hz, 3H); 13C NMR (100 MHz, CDCl3) d 167.0,
1176, 854, 776, 739; 1H NMR (400 MHz, CDCl3) d 8.64 (d, J ¼ 4.0 155.7, 150.0, 141.9, 139.1, 137.8, 136.6, 127.2, 126.9, 125.7,
Hz, 1H), 8.15 (d, J ¼ 16.0 Hz, 1H), 7.81–7.70 (m, 1H), 7.58 (d, J ¼ 123.3, 117.5, 64.2, 53.3, 30.7, 29.0, 21.0, 19.1, 13.7; HRMS (ESI):
8.0 Hz, 1H), 7.51 (d, J ¼ 8.0 Hz, 1H), 7.47 (d, J ¼ 4.0 Hz, 1H), exact mass calcd for C21H24N2NaO4S+ [M + Na]+: 423.1349.
7.12–7.08 (m, 2H), 6.43 (d, J ¼ 16.0 Hz, 1H), 4.99–4.96 (m, 1H), Found: 423.1330.
4.23 (t, J ¼ 6.0 Hz, 2H), 2.68–2.63 (m, 1H), 2.26 (d, J ¼ 16.0 Hz,
(E)-7-(4-Fluorostyryl)-5-methyl-1-(pyridin-2-ylsulfonyl)-indoline
1H), 1.73–1.70 (m, 2H), 1.48–1.45 (m, 2H), 1.27 (d, J ¼ 6.0 Hz, (3gg). Brown oil; yield: 72%; IR (KBr, cmꢂ1): 3050, 2955, 2921,
3H), 0.98 (t, J ¼ 6.0 Hz, 3H); 13C NMR (100 MHz, CDCl3) d 167.2, 1597, 1507, 1458, 1426, 1355, 1178, 853, 823, 781, 740; 1H NMR
156.0, 150.1, 142.2, 140.0, 137.8, 136.7, 128.3, 127.1, 126.7, (400 MHz, CDCl3) d 8.65 (s, 1H), 7.70–7.64 (m, 2H), 7.60–7.53
126.5, 125.6, 123.3, 117.6, 64.4, 60.8, 36.1, 30.8, 21.8, 19.2, 13.8; (m, 3H), 7.44 (d, J ¼ 4.0 Hz, 1H), 7.36 (s, 1H), 7.05–7.01 (m, 3H),
HRMS (ESI): exact mass calcd for C21H24N2NaO4S+ [M + Na]+: 6.75 (s, 1H), 4.27 (t, J ¼ 8.0 Hz, 2H), 2.42 (t, J ¼ 6.0 Hz, 2H), 2.30
423.1349. Found: 423.1349.
(E)-7-(4-Fluorostyryl)-2-methyl-1-(pyridin-2-ylsulfonyl)-indoline
(s, 3H); 13C NMR (100 MHz, CDCl3) d 162.3 (d, J ¼ 246 Hz), 155.9,
150.1, 137.7, 137.6, 136.7, 134.0, 130.1, 128.4 (d, J ¼ 8 Hz), 127.1,
(3eg). Brown oil; yield: 70%; IR (KBr, cmꢂ1): 3032, 2924, 1648, 126.7, 126.2, 124.6, 124.5, 123.7, 115.5 (d, J ¼ 21 Hz), 53.7, 29.3,
1597, 1493, 1452, 1357, 1172, 814, 759, 720; 1H NMR (400 MHz, 21.3; HRMS (ESI): exact mass calcd for C22H19FN2NaO2S+ [M +
CDCl3) d 8.64 (s, 1H), 7.67–7.51 (m, 6H), 7.43 (d, J ¼ 12.0 Hz, Na]+: 417.1043. Found: 417.1056.
1H), 7.12–7.03 (m, 4H), 6.93 (d, J ¼ 8.0 Hz, 1H), 5.03–4.96 (m,
(E)-Butyl 3-(5-methoxy-1-(pyridin-2-ylsulfonyl)indolin-7-yl)acrylate
1H), 2.61–2.55 (m, 1H), 2.21 (d, J ¼ 16.0 Hz, 1H), 1.29 (d, J ¼ (3hb). Brown oil; yield: 55%; IR (KBr, cmꢂ1): 3053, 2956, 2923,
8.0 Hz, 3H); 13C NMR (100 MHz, CDCl3) d 162.4 (d, J ¼ 246 Hz), 1707, 1636, 1604, 1466, 1427, 1355, 1172, 855, 820, 778, 741; 1H
155.9, 150.1, 138.4, 137.6, 136.6, 134.0, 131.1, 128.4 (d, J ¼ 8 Hz), NMR (400 MHz, CDCl3) d 8.66 (d, J ¼ 4.0 Hz, 1H), 8.15 (d, J ¼
127.0, 126.7, 127.6, 126.4, 124.2, 124.1, 123.5, 115.6 (d, J ¼ 16.0 Hz, 1H), 7.76–7.74 (m, 1H), 7.58 (d, J ¼ 8.0 Hz, 1H), 7.48 (t, J
21 Hz), 60.9, 36.1, 21.9; HRMS (ESI): exact mass calcd for C22
H19FN2NaO2S+ [M + Na]+: 417.1043. Found: 417.1050.
-
¼ 6.0 Hz, 1H), 6.90 (s, 1H), 6.64 (s, 1H), 6.41 (d, J ¼ 16.0 Hz, 1H),
4.28–4.21 (m, 4H), 3.78 (s, 3H), 2.45 (t, J ¼ 6.0 Hz, 2H), 1.71 (t, J
(E)-Butyl 3-(3-methyl-1-(pyridin-2-ylsulfonyl)indolin-7-yl)acrylate ¼ 8.0 Hz, 2H), 1.49–1.43 (m, 2H), 0.96 (t, J ¼ 6.0 Hz, 3H); 13C
(3). White solid; yield: 80%; mp ¼ 132–133 ꢀC; IR (KBr, cmꢂ1): NMR (100 MHz, CDCl3) d 167.0, 158.5, 155.9, 150.2, 141.8, 139.4,
3061, 2956, 2924, 1706, 1637, 1572, 1513, 1458, 1427, 1358, 137.8, 135.0, 128.4, 127.2, 123.5, 118.2, 112.9, 109.0, 64.4, 55.6,
1
1281, 1177, 875, 785, 749; H NMR (400 MHz, CDCl3) d 8.66 (s, 53.5, 30.8, 29.5, 19.2, 13.8; HRMS (ESI): exact mass calcd for
1H), 8.13 (d, J ¼ 16.0 Hz, 1H), 7.79 (t, J ¼ 8.0 Hz, 1H), 7.68 (d, J ¼
C
21H24N2NaO5S+ [M + Na]+: 439.1298. Found: 439.1326.
(E)-7-(4-Fluorostyryl)-5-methoxy-1-(pyridin-2-ylsulfonyl) indoline
8.0 Hz, 1H), 7.49 (d, J ¼ 8.0 Hz, 2H), 7.17 (t, J ¼ 8.0 Hz, 1H), 7.03
(d, J ¼ 8.0 Hz, 1H), 6.42 (d, J ¼ 16.0 Hz, 1H), 4.67–4.62 (m, 1H), (3hg). Brown oil; yield: 75%; IR (KBr, cmꢂ1): 3053, 2938, 2927,
4.20 (t, J ¼ 6.0 Hz, 2H), 3.54 (t, J ¼ 12.0 Hz, 1H), 2.85–2.83 (m, 1598, 1507, 1466, 1427, 1353, 1225, 1171, 847, 823, 781, 740; 1H
1H), 1.72–1.68 (m, 2H), 1.48–1.42 (m, 2H), 1.13 (d, J ¼ 8.0 Hz, NMR (400 MHz, CDCl3) d 8.66 (s, 1H), 7.69–7.61 (m, 2H), 7.56–
3H), 0.97 (t, J ¼ 6.0 Hz, 3H); 13C NMR (100 MHz, CDCl3) d 167.0, 7.53 (m, 3H), 7.53–7.44 (m, 1H), 7.05–7.01 (m, 4H), 6.51 (s, 1H),
156.0, 150.1, 142.3, 141.9, 141.3, 137.9, 127.3, 127.2, 126.8, 4.28 (t, J ¼ 6.0 Hz, 2H), 3.80 (s, 3H), 2.41 (t, J ¼ 6.0 Hz, 2H); 13
C
125.5, 124.7, 123.2, 117.9, 64.3, 60.6, 35.5, 30.7, 19.1, 17.0, 13.8; NMR (100 MHz, CDCl3) d 162.4 (d, J ¼ 246 Hz), 158.6, 155.9,
HRMS (ESI): exact mass calcd for C21H24N2NaO4S+ [M + Na]+: 150.2, 139.3, 137.6, 133.8, 133.7, 131.3, 128.5 (d, J ¼ 8 Hz), 127.2,
423.1349. Found: 423.1373.
127.1, 126.1, 123.8, 115.6 (d, J ¼ 21 Hz), 110.3, 108.0, 55.7, 53.8,
(E)-7-(4-Fluorostyryl)-3-methyl-1-(pyridin-2-ylsulfonyl)-indoline
29.6; HRMS (ESI): exact mass calcd for C22H19FN2NaO3S+ [M +
(3fg). Yellow solid; yield: 70%; mp ¼ 119–120 ꢀC; IR (KBr, cmꢂ1): Na]+: 433.0993. Found: 433.1013.
3053, 2962, 2928, 1634, 1596, 1507, 1455, 1427, 1355, 1178, 870,
(E)-Butyl 3-(5-chloro-1-(pyridin-2-ylsulfonyl)indolin-7-yl)acrylate
781, 751; 1H NMR (400 MHz, CDCl3) d 8.65 (s, 1H), 7.75–7.54 (m, (3ib). Yellow oil; yield: 70%; IR (KBr, cmꢂ1): 3071, 2959, 2928,
6H), 7.43 (d, J ¼ 4.0 Hz, 1H), 7.18–7.11 (m, 1H), 7.05–7.01 (m, 1710, 1638, 1580, 1453, 1424, 1361, 1251, 1177, 862, 806, 779,
3H), 6.89 (d, J ¼ 8.0 Hz, 1H), 4.70–4.66 (m, 1H), 3.52 (t, J ¼ 742; 1H NMR (400 MHz, CDCl3) d 8.66 (s, 1H), 8.07 (d, J ¼
12.0 Hz, 1H), 2.79 (s, 1H), 1.12 (d, J ¼ 4.0 Hz, 3H); 13C NMR 16.0 Hz, 1H), 7.89–7.79 (m, 1H), 7.69 (d, J ¼ 8.0 Hz, 1H), 7.52–
(100 MHz, CDCl3) d 162.4 (d, J ¼ 246 Hz), 156.0, 150.1, 142.4, 7.45 (m, 2H), 7.06 (s, 1H), 6.40 (d, J ¼ 16.0 Hz, 1H), 4.31–4.20 (m,
139.9, 137.7, 133.9, 130.2, 128.4 (d, J ¼ 8 Hz), 127.1, 127.0, 126.2, 4H), 2.57–2.54 (m, 2H), 1.72–1.68 (m, 2H), 1.46–1.42 (m, 2H),
124.3, 123.5, 122.3, 115.5 (d, J ¼ 21 Hz), 61.0, 35.5, 17.1; HRMS 0.97 (t, J ¼ 8.0 Hz, 3H); 13C NMR (100 MHz, CDCl3) d 166.7,
(ESI): exact mass calcd for C22H19FN2NaO2S+ [M + Na]+: 155.8, 150.3, 140.7, 140.2, 139.7, 138.1, 132.2, 128.8, 127.4,
417.1043. Found: 417.1060.
125.9, 125.3, 123.4, 119.0, 64.5, 53.5, 30.7, 29.3, 19.2, 13.8;
(E)-Butyl-3-(5-methyl-1-(pyridin-2-ylsulfonyl)indolin-7-yl)-acrylate HRMS (ESI): exact mass calcd for C20H21ClN2NaO4S+ [M + Na]+:
(3gb). White solid; yield: 83%; mp ¼ 122–123 ꢀC; IR (KBr, cmꢂ1): 443.0803. Found: 443.0807.
3056, 2956, 2926, 1707, 1634, 1570, 1509, 1462, 1425, 1359,
(E)-5-Chloro-7-(4-uorostyryl)-1-(pyridin-2-ylsulfonyl) indoline
1278, 1178, 851, 824, 780, 739; 1H NMR (400 MHz, CDCl3) d 8.65 (3ig). Colorless oil; yield: 50%; IR (KBr, cmꢂ1): 3062, 2956, 2922,
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1641, 1589, 1507, 1426, 1356, 1178, 857, 820, 777, 737; 1H NMR
(400 MHz, CDCl3) d 8.65 (d, J ¼ 4.0 Hz, 1H), 7.74 (t, J ¼ 8.0 Hz,
1H), 7.66–7.45 (m, 6H), 7.07–6.99 (m, 3H), 6.90 (s, 1H), 4.30 (t,
J ¼ 8.0 Hz, 2H), 2.49–2.48 (m, 2H); 13C NMR (100 MHz, CDCl3) d
162.5 (d, J ¼ 246 Hz), 155.7, 150.2, 139.5, 138.7, 137.9, 133.4,
132.3, 131.7, 128.6 (d, J ¼ 8 Hz), 128.1, 127.3, 125.0, 123.9, 123.6,
123.5, 115.6 (d, J ¼ 21 Hz), 53.8, 29.3; HRMS (ESI): exact mass
calcd for C21H16ClFN2NaO2S+ [M + Na]+: 437.0497. Found:
437.0503.
(E)-Ethyl 3-(indolin-7-yl)acrylate (5da). Yellow oil; yield: 82%;
IR (KBr, cmꢂ1) 3364, 2923, 2853, 1692, 1649, 1608, 1462, 1361,
1
1304, 1240, 1176, 1049, 992, 855, 742, 591; H NMR (400 MHz,
CDCl3) d 7.73 (d, J ¼ 16.0 Hz, 1H), 7.19–7.13 (m, 2H), 6.70 (t, J ¼
8.0 Hz, 1H), 6.30 (d, J ¼ 16.0 Hz, 1H), 4.31–4.26 (m, 2H), 3.65 (t,
J ¼ 8.0 Hz, 2H), 3.10 (t, J ¼ 8.0 Hz, 2H), 1.36 (t, J ¼ 8.0 Hz, 3H),
1.29 (s, 1H); 13C NMR (100 MHz, CDCl3) d 167.7, 151.4, 141.8,
130.7, 127.1, 126.4, 118.8, 116.7, 116.0, 60.5, 47.3, 29.5, 14.5;
HRMS (ESI): exact mass calcd for C13H16NO2 [M + H]+:
+
(E)-Butyl 3-(5-bromo-1-(pyridin-2-ylsulfonyl)indolin-7-yl)acrylate
(3jb). Brown oil; yield: 70%; IR (KBr, cmꢂ1): 3065, 2958, 2928,
1710, 1638, 1578, 1542, 1425, 1362, 1334, 1251, 1177, 861, 821,
784, 743; 1H NMR (400 MHz, CDCl3) d 8.66 (s, 1H), 8.05 (d, J ¼
16.0 Hz, 1H), 7.83–7.81 (m, 1H), 7.70 (d, J ¼ 8.0 Hz, 1H), 7.61 (s,
1H), 7.50 (d, J ¼ 4.0 Hz, 1H), 7.21 (s, 1H), 6.39 (d, J ¼ 16.0 Hz,
1H), 4.30 (t, J ¼ 6.0 Hz, 2H), 4.22 (t, J ¼ 8.0 Hz, 2H), 2.58 (t, J ¼
8.0 Hz, 2H), 1.72–1.68 (m, 2H), 1.46–1.43 (m, 2H), 0.97 (t, J ¼
8.0 Hz, 3H); 13C NMR (100 MHz, CDCl3) d 166.7, 156.0, 150.3,
140.8, 140.6, 139.9, 138.1, 129.3, 128.8, 128.4, 127.4, 123.4,
120.0, 119.2, 64.6, 53.5, 30.8, 29.3, 19.2, 13.8; HRMS (ESI): exact
mass calcd for C20H21BrN2NaO4S+ [M + Na]+: 487.0298. Found:
487.0299.
(E)-5-Bromo-7-(4-uorostyryl)-1-(pyridin-2-ylsulfonyl)-indoline
(3jg). Yellow oil; yield: 50%; IR (KBr, cmꢂ1): 3068, 2956, 2923,
1633, 1583, 1507, 1450, 1426, 1359, 1179, 854, 821, 775, 737; 1H
NMR (400 MHz, CDCl3) d 8.65 (s, 1H), 7.75–7.72 (m, 1H), 7.67–
7.63 (m, 2H), 7.60–7.51 (m, 3H), 7.48 (d, J ¼ 4.0 Hz, 1H), 7.11–
6.97 (m, 4H), 4.30 (s, 2H), 2.51 (s, 2H); 13C NMR (100 MHz,
CDCl3) d 162.6 (d, J ¼ 246 Hz), 155.8, 150.3, 139.8, 139.2, 137.9,
133.4, 132.2, 128.6 (d, J ¼ 8 Hz), 128.2, 127.3, 127.0, 126.4, 124.9,
123.6, 120.2, 115.7 (d, J ¼ 21 Hz), 53.8, 29.3; HRMS (ESI): exact
mass calcd for C21H17BrFN2O2S+ [M + H]+: 459.0173. Found:
459.0175.
218.1176. Found: 218.1174.
(E)-7-Styrylindoline (5df). Colorless oil; yield: 80%; IR (KBr,
cmꢂ1) 3337, 3268, 2921, 2856, 1006, 1508, 1452, 1245, 1110, 956,
831, 769, 696, 617; 1H NMR (400 MHz, CDCl3) d 7.49 (d, J ¼
8.0 Hz, 2H), 7.36 (t, J ¼ 8.0 Hz, 2H), 7.26–7.10 (m, 2H), 7.10–6.97
(m, 3H), 6.75 (t, J ¼ 8.0 Hz, 1H), 3.62 (t, J ¼ 12.0 Hz, 2H), 3.08 (t,
J ¼ 8.0 Hz, 2H), 1.25 (s, 1H); 13C NMR (100 MHz, CDCl3) d 149.4,
137.8, 130.2, 128.7, 127.4, 126.3, 125.5, 125.4, 123.8, 119.8,
119.2, 47.4, 29.8; HRMS (ESI): exact mass calcd for C16H16N+ [M
+ H]+: 222.1277. Found: 222.1268.
(E)-Ethyl 3-(1H-indol-7-yl)acrylate (6da). Yellow oil; yield: 80%;
IR (KBr, cmꢂ1) 3373, 3018, 2921, 2905, 1691, 1636, 1509, 1472,
1435, 1336, 1274, 1187, 858, 792, 714; 1H NMR (400 MHz,
CDCl3) d 8.79 (s, 1H), 8.07 (d, J ¼ 16.0 Hz, 1H), 7.70 (d, J ¼
8.0 Hz, 1H), 7.42 (d, J ¼ 8.0 Hz, 1H), 7.25 (s, 1H), 7.13 (t, J ¼
8.0 Hz, 1H), 6.61–6.51 (m, 2H), 4.33–4.28 (m, 2H), 1.36 (t, J ¼
8.0 Hz, 3H); 13C NMR (100 MHz, CDCl3) d 167.5, 141.2, 134.4,
129.0, 124.9, 123.4, 122.3, 120.2, 118.3, 118.0, 103.3, 60.7, 14.4;
+
HRMS (ESI): exact mass calcd for C13H13NNaO2 [M + Na]+:
238.0838. Found: 238.0847.
(E)-7-Styryl-1H-indole (6df).6 White solid; yield: 82%; mp ¼
160–162 ꢀC; IR (KBr, cmꢂ1) 3739, 3407, 2923, 2852, 2495, 1600,
1
1456, 1390, 1268, 1064, 958, 788, 723, 472; H NMR (400 MHz,
CDCl3) d 8.47 (s, 1H), 7.60–7.54 (m, 3H), 7.40–7.36 (m, 4H), 7.30–
7.24 (m, 2H), 7.17–7.13 (m, 2H), 6.61–6.60 (m, 1H); 13C NMR
(100 MHz, CDCl3) d 137.6, 133.9, 129.9, 128.9, 128.6, 127.9,
126.5, 125.2, 124.4, 121.5, 120.6, 120.4, 103.4; HRMS (ESI): exact
mass calcd for C16H13NNa+ [M + Na]+: 242.0940. Found:
242.0943.
(E)-Ethyl
3-(1-(pyridin-2-ylsulfonyl)-1H-indol-7-yl)acrylate
(4da).19 White solid; yield: 75%; mp ¼ 160–161 ꢀC; IR (KBr,
cmꢂ1): 3045, 2974, 2923, 1710, 1645, 1638, 1575, 1508, 1461,
1423, 1359, 1255, 1178, 871, 786, 744; 1H NMR (400 MHz,
CDCl3) d 8.58–8.54 (m, 2H), 8.32 (d, J ¼ 8.0 Hz, 1H), 7.91–7.88
(m, 2H), 7.60 (d, J ¼ 8.0 Hz, 1H), 7.46–7.44 (m, 1H), 7.32 (d, J ¼
8.0 Hz, 1H), 7.24–7.21 (m, 1H), 6.75 (d, J ¼ 4.0 Hz, 1H), 6.08 (d, J
¼ 16.0 Hz, 1H), 4.31–4.26 (m, 2H), 1.37 (t, J ¼ 8.0 Hz, 3H); 13C
NMR (100 MHz, CDCl3) d 166.7, 155.9, 150.4, 144.2, 138.2, 133.0,
133.0, 130.5, 127.8, 124.8, 123.8, 123.4, 123.2, 122.8, 120.2,
108.2, 60.5, 14.5; HRMS (ESI): exact mass calcd for C18H16N2-
NaO4S+ [M + Na]+: 379.0723. Found: 379.0737.
Conclusions
We have developed a general and efficient method for the
intermolecular direct C-7-selective C–H alkenylation of indo-
lines using palladium(II) as the catalyst and molecular oxygen as
the sole oxidant. The reaction showed complete regio- and
stereoselectivity. All products were E-isomers at C-7 position,
and no Z-isomers or other position substituted product could be
detected. The approach also presented an efficient route for
synthesis of C-7 alkenylation of indoles. The method should
have many applications in organic and medical chemistry.
Detailed mechanistic investigations and application to other
types of heteroaromatic compounds are currently underway.
(E)-1-(Pyridin-2-ylsulfonyl)-7-styryl-1H-indole (4df).19 White
solid; yield: 74%; mp ¼ 163–165 ꢀC IR (KBr, cmꢂ1): 3428, 3158,
1
2921, 1577, 1342, 1249, 1178, 1128, 958, 794, 730, 661, 576; H
NMR (400 MHz, CDCl3) d 8.37 (d, J ¼ 6.0 Hz, 1H), 8.08 (d, J ¼
16.0 Hz, 1H), 7.90 (d, J ¼ 4.0 Hz, 1H), 7.80 (d, J ¼ 8.0 Hz, 1H),
7.51 (d, J ¼ 8.0 Hz, 1H), 7.44–7.43 (m, 2H), 7.41–7.28 (m, 5H),
7.25–7.20 (m, 2H), 6.75 (d, J ¼ 4.0 Hz, 1H), 6.44 (d, J ¼ 16.0 Hz,
1H); 13C NMR (100 MHz, CDCl3) d 156.0, 150.1, 137.7, 137.5,
133.0, 132.8, 131.7, 130.3, 128.8, 128.2, 127.9, 127.4, 126.9,
126.2, 124.6, 124.0, 123.0, 121.2, 108.3; HRMS (ESI): exact mass
Acknowledgements
calcd for
383.0800.
C
21H16N2NaO2S+ [M
+
Na]+: 383.0825. Found: We are grateful for nancial support from National Natural
Science Foundation of China (NSFC-20972126, 21272185), the
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