Assembly of Diversely Substituted Quinolines via Aerobic Oxidative Aromatization from Simple Alcohols and Anilines

Article abstract of DOI:10.1021/acs.joc.6b03064

An aerobic oxidative aromatization of simple aliphatic alcohols and anilines under the Pd(OAc)₂/2,4,6-Collidine/Br?nsted acid catalytic system has been established, providing a direct approach for the preparation of diverse substituted quinoline derivatives in high yields with wide functional group tolerance. Practically, the protocol can be easily scaled up to gram-scale and was utilized in the concise formal synthesis of a promising herbicide candidate.

Full text of DOI:10.1021/acs.joc.6b03064

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Note
Assembly of Diversely Substituted Quinolines via Aerobic
Oxidative Aromatization from Simple Alcohols and Anilines
Jixing Li, Jinlong Zhang, Huameng Yang, and Gaoxi Jiang
J. Org. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.joc.6b03064 • Publication Date (Web): 22 Feb 2017
Downloaded from http://pubs.acs.org on February 22, 2017
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Assembly of Diversely Substituted Quinolines via Aerobic Oxidative
Aromatization from Simple Alcohols and Anilines
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Jixing Li,ab Jinlong Zhang,a Huameng Yanga and Gaoxi Jiang*a
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a. State Key Laboratory for Oxo Synthesis and Selective Oxidation, Suzhou Research Institute of
LICP, Lanzhou Institute of Chemical Physics (LICP), Chinese Academy of Sciences, Lanzhou 730000,
P. R. China. E-mail: gxjiang@licp.cas.cn
b. University of Chinese Academy of Sciences, Beijing 100049, P. R. China.
gxjiang@licp.cas.cn
Abstract: An aerobic oxidative aromatization of simple aliphatic alcohols and anilines under the
Pd(OAc)2/2,4,6-Collidine/Brønsted acid catalytic system has been established, providing a direct
approach for the preparation of diverse substituted quinoline derivatives in high yields with wide
functional-group tolerance. Practically, the protocol can be easily scaled up to gram-scale and was
utilized in the concise formal synthesis of a promising herbicide candidate.
The quinoline skeleton represents a privileged structural component that occurs ubiquitously
in medicine,1 organo,2 and material chemistry.3 Consequently, the development of new practical
and efficient methods for the quinolines synthesis is of very importance to the pharmaceutical and
chemical industries. Traditionally, different classical transformations have been developed through
the condensation between carbonyl substrates with anilines in strong acidic conditions, like the
Skraup reaction, Gould−Jacobs reaction, Combes reaction, and others.4 Although modifications
have been realized to improve the aforementioned condensation processes to date, a major drawback
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still existed in the use of expensive raw materials, mostly limited substrate scope and low substrates
utilization efficiency.4 The further excavation of direct and efficient access from simple starting
materials to quinolines is still in strong demand yet challenging.5 Primary alcohols that can be
readily obtained by industrial processes via catalytic transformation or fermentation of
lignocellulosic biomass have been regarded as sustainable synthetic reagents.6 In principle, the
direct assemblage of abundantly available primary alcohols and anilines to synthesize quinolines
should be regarded as one of the most ideal methodologies. This kind of transformation between
arylamines and diols or aminoalcohols goes back at least to the 80’s of the last century, in which
cross-dehydrogenative coupling process occurred with another (over)stoichiometric amounts of
alkene as the hydrogen acceptors to deliver the target products.7 In 2012, Khusnutdinov and co-
workers demonstrated the possibilities of oxidative process for the synthesis of quinolines by
FeCl3•6H2O or Ni(OAc)2·4H2O catalysis while the transformation suffered from the use of toxic
CCl4 as the oxidant8 (Scheme 1, 1). Another heterogeneous attempt about photocatalytic process
with Au-doped TiO2 nanoparticles was reported by Swaminathan. However, the limited substrate
scope prevents its further application to some extent9 (Scheme 1, 1). Recently, surge of interest to
develop practical aerobic oxidation reactions has been engaged,10 especially the aerobic oxidation
of alcohols for concise synthesis of various useful chemicals.11 To the best of our knowledge, it is
still unprecedented for synthesis of quinolines to use dioxygen (O2) as the sole oxidant, along with
simple aliphatic alcohols and anilines as starting materials. Nevertheless, the difficult challenges
facing this transformation are: i) to control the definite chemoselectivity of the
cyclization/aromatization cascade process from the intrinsically competitive N-alkylation,12 ii) to
suppress the side-oxidation of starting materials, and iii) to overcome the coordination of the
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structural similar quinoline products with transition-metal that might interdict the more reactive
transition-metal catalyst. Enlightened by the pioneering achievements in aerobic oxidation of
alcohols,10,11 we envisioned that a Brønsted acid catalysis might facilitate the formation of aldimine
with simple anilines and promote the successive cyclization/aerobic oxidative aromatization to final
quinolines. Herein, we present an aerobic oxidative aromatization of simple aliphatic alcohols and
anilines enabled by a Pd(OAc)2/Brønsted acid catalysis, which provides a concise and readily
scalable approach for the synthesis of versatile quinolines in high yields with wide functional-group
tolerance (Scheme 1, 2). The process features the use of abundantly available starting materials,
environmental benign dioxygen molecule as the sole oxidant, which would make it particularly
attractive.
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1: Previous studies (Oxidative Povarov/aromatization tandem reaction)
R1
homogeneous: [Fe]/CCl4, [Ni]/CCl4
R1
OH
R'
+
R2
NH2
heterogeneous: Au-TiO2/UV
N
2: This work: aerobic oxidative aromatization
R1
Pd(OAc)2/Brønsted Acid Catalysis
R1
OH
R'
+
R2
O2
-H2O
NH2
N
Challenges:
Advantages:
i) chemoselectivity vs N-alkylation
ii) side-oxidation of starting materials
iii) coordination effect of quinoline products
i) cheap starting substrates
ii) wide functional-group tolerance
iii) O2 as the sole oxidant
Scheme 1 Oxidative aromatization strategy for quinolines construction.
Initially, we chose the reaction of phenylamine 1a in ethanol 2a solvent with a
concentration of 0.2 M as the model reaction to optimize the conditions at 150 oC for 12 h
under O2 atmosphere (Table 1). Only a trace amount of the desired quinoline 3aa was
detected using Pd(PPh3)4 as the catalyst without or with TsOH (entries 1-2). Pleasingly, the
yield of 3aa was increased to 20% with the addition of pyridine (entry 3). Next, the catalytic
activity investigation of different palladium salts demonstrated that Pd(OAc)2 is the better
catalyst than others and a 33% yield was obtained (entries 3-8). After extensive screening of
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the reaction conditions in terms of metal catalysts, such as Fe, Cu, Ni, and Co compounds,
ligands (25 ligands) and additives, it was found that Pd(OAc)2/2,4,6-Collidine/CF3CO2H
remains the suitable catalytic system and 75% of 3aa was obtained (entry 9, for details,
please see the Electronic Supplementary Information, ESI). Lowering the concentration of
1a from 0.2 M to 0.1 M led to a noticeable performance, providing 3aa in 93% isolated yield
(entry 10). Palladium and acid was indispensable for this reaction and a trace amount of
products detected in the absence of them, respectively (entries 11-12). Also, the existence of
the ligand 2,4,6-collidine was valuable for this transformation to gain excellent results and a
sharp decrease of yield to 32% was obtained (entry 13). The reaction proceeded smoothly in
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air and resulted in 68% yield for a prolonged time (entry 14).
Table 1 Optimization of the reaction conditions.a
Entry
[Pd]-Cat.
Ligand
Acid
Yieldb
1
Pd(PPh3)4
Pd(PPh3)4
Pd(PPh3)4
Pd2(dba)3
Pd(OAc)2
Pd(TFA)2
PdCl2
Trace
Trace
20%
20%
33%
7%
2
TsOH
3
Pyridine
TsOH
4
Pyridine
TsOH
5
Pyridine
TsOH
6
Pyridine
TsOH
7
Pyridine
TsOH
16%
20%
75%c
93%c
trace
trace
32%
72%c
8
[Pd(allyl)Cl]2
Pd(OAc)2
Pd(OAc)2
Pyridine
TsOH
9
2,4,6-Collidine
2,4,6-Collidine
2,4,6-Collidine
2,4,6-Collidine
CF3CO2H
CF3CO2H
CF3CO2H
10d
11d
12d
13d
14de
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
CF3CO2H
CF3CO2H
2,4,6-Collidine
a Reaction conditions: 1a (0.3 mmol), [Pd] (5 mol%), Ligand (10 mol%), Acid (20 mol%), ethanol 2a (1.5 mL), O2 (1 atm), 12 h. b The yield
was determined by GC. c Yield of isolated product. d 3.0 mL ethanol used ([1a]: 0.1 M). e In air for 72 h.
Under the standard reaction conditions (Table 1, entry 10), we next investigated the
substrate scope with respect to both anilines and aliphatic alcohols to evaluate the generality
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of the reaction. First, a wide range of aromatic amines were employed to react with ethanol
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2a. As shown in Scheme 2, the reactions proceeded smoothly with anilines bearing mono-
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substituent at ortho-, para-, or meta-position to afford the corresponding quinolines 3ba-3wa
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in 55-90% yields regardless of the electronic characteristics. 8-hydroxy quinoline is a well-
known ligand for abstraction of many metal ions (Cu2+, Co2+, Zn2+, etc.).13 Surprisingly, its
2-methyl analog 3wa can be concisely prepared by the approach in a moderate yield.
Disubstituted anilines were also compatible with this transformation and readily gave rise to
3aaa
-afa in 66-84% yields. Benzoquinolines 3aga and 3aha were obtained in more than 90%
Scheme 2 Scope of anilines
yields and 15:1 regioselectivity for 3aha (1-/3-position). It is noteworthy that 1H-pyrazol-5-
amines 1ai and 1aj be successfully converted into the corresponding 1H-pyrazolo[3,4-
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b
b
]pyridines 3aia and 3aja in 70% and 67% yield, respectively. Recently, 1H-pyrazolo[3,4-
]pyridine derivatives were discovered to be promising lead compounds as potent and
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selective FGFR kinase inhibitors.14 Undoubtedly, this protocol might streamline the
synthesis of such useful compounds.
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Scheme 3 Scope of primary aliphatic alcohols
Next the scope of the aliphatic alcohols was investigated in scheme 3. The treatment of
long-chain alcohols 2b
-
f
with 1a to the standard reaction conditions produced 2,3-
af in 85-90% yields.
disubstituted quinolines 3ab
-
Significantly, the developed Pd(OAc)2/2,4,6-Collidine/ CF3COOH catalysis successfully
extended to prepare another class of 2-nonsubstituted quinolines with propane-1,3-diol 2g
as the starting material.7a As shown in Scheme 4, alkyl and methoxyl groups worked well to
afford the desired products 3bg-eg and 3hg in yields ranging from 72% to 75%. The use of
1q and 1r gave 3qg and 3rg in 70% and 75% yield for 36 hours, respectively. Dimethyl
quinoline 3aag was obtained in 82% with a 14:1 regioselectivity (2-/6-position).
Benzoquinolines 3agg and 3ahg were readily produced in 82-80%. Importantly, the more
challenging 2-aminophenol 1w is also suitable for the process and laconically assembled the
useful ligand 8-hydroxy quinoline 3wg13 in an acceptable yield.
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Scheme 4 Scope of anilines for the reaction with 2g
To highlight the practicability of the method, the gram-scale synthesis was conducted in
scheme 5. Consequently, one gram-scale synthesis of 3aa was executed and 90% yield
obtained (Scheme 5, i). Interestingly, a slightly decreased yield of 85% was received by the
direct use of the product 3aa itself as the ligand instead of 2,4,6-collidine, intrinsically
Scheme 5 Gram-scale reactions and formal synthesis of the promising herbicide candidate
obviating the difficulties in separation of the desired product 3aa from extra pyridine-type
ligand (Scheme 5, ii). Remarkably, the transformation of 1x under the standard reaction
conditions took place well in 2.3 gram-scale and effectively provided 3xa in 75% yield. The
synthetic block 3xa is a useful motif for the concise synthesis of the herbicide candidate
developed by BASF16 (Scheme 5).
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Scheme 6 Controlled reactions to verify hypothesis
Finally, several controlled reactions were performed to probe the possible reaction
mechanism (Scheme 6). Aldehyde
alcohol 2f to the Pd(OAc)2-catalysis in toluene for 4 h (eq. 1). Quinoline 3ab was formed
effectively in 89% by the reaction of 1a with 2.5 equiv. of propionaldehyde in toluene (eq.
2, i). The similar yield was obtained only with CF3CO2H as catalyst (eq. 2, ii). Additionally,
the subjection of imine to the oxidative reaction conditions in EtOH gave rise to a mixed
products of benzaldehyde 3ah, and 3aa in ratio of 7:79:14 (eq. 3). Aldehyde should
come from the hydrolysis of with the simultaneous release of aniline 1a that produced 3aa
4 can be detected in about 10% yield by treatment of
5
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7
,
7
6
.
Based on the pioneering works on the oxidation of alcohols with oxygen10,11 and the
cyclization routes for quinoline synthesis,8,9,15 the above observation suggested that the
aldehyde synthesized in situ by Stahl oxidation was the high reactive intermediate for the
aldimine formation, followed by cycloaddition with its enamine tautomer to form 2-Methyl-
1,2,3,4-tetrahydroquinolin-4-yl(phenyl)amine, which resulted in the desired product via the
elimination of an aniline molecule and subsequent aerobic oxidative aromatization (Scheme
7). 9b,15a,15c
O2
PhNH2
+
OH
- H2O
N
2a
1a
3aa
H+
concerted catalysis
[Pd]/O2
NHPh
[Pd]/O2
Stahl Oxidation
H+
H+
PhHN
O
PhN
Brønsted Acid Catalysis
N
H
2a'
Scheme 7 Proposed reaction mechanism
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In conclusion, we have realized the first example of aerobic oxidative synthesis of
diverse quinolines from simple primary alcohols and anilines by a designed Pd/Brønsted acid
catalysis, which streamlines efficiently the construction of quinoline and 1H-pyrazolo[3,4-
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b
]pyridine derivatives with wide functional-group tolerance. Importantly, the new protocol
can be easily scaled up to gram-scale and was utilized in the concise formal synthesis of a
promising herbicide candidate. The use of abundantly available starting materials,
environmental benign dioxygen molecule as oxidant, and cheap 2,4,6-collidine as ligand
instead of traditional P-ligand should make this method particularly attractive.
Experimental Section
General Information: All non-aqueous manipulations were using standard Schlenk techniques.
Reactions were monitored using thin-layer chromatography (TLC) on Silica Gel plates.
Visualization of the developed plates was performed under UV light (254 nm) or KMnO4 stain.
Silica Gel Flash Column Chromatography was performed on SYNTHWARE 40-63μm silica gel.
Unless otherwise indicated, starting catalysts and materials were obtained from Sigma Aldrich, TCI,
Alfa Aesar, or Acros Co. Ltd. Moreover, commercially available reagents were used without
additional purification. All NMR spectra were run at 400 MHz (1H NMR) or 100 MHz (13C NMR)
or 377 MHz (19F NMR) in CDCl3 or d6-DMSO solution. 1H NMR spectra were internally referenced
to TMS. 13C NMR spectra were internally referenced to the residual solvent signal. High resolution
mass spectra (HRMS) were recorded on Bruker MicrOTOF-Q II mass instrument (ESI).
a
a
a
a
a
a
a
a
a
a
b
Compounds 3aa17 , 3ba17 , 3ha17 , 3ma17 , 3na17 , 3oa17 , 3ag17 , 3bg17 , 3hg17 , 3ta17 , 3agg17
,
p
c
c
c
c
c
c
c
c
c
d
e
f
3an17 , 3wa7 , 3aca7 , 3ada7 , 3aga7 , 3ab17 , 3ac17 , 3ad17 , 3ae17 , 3af17 , 3ua17 , 3pa17 , 3aha17 ,
3ahg17 , 3wg17 , 3ra8b, 3qg17 , 3aba9b, 3aca9b, 3pg17 , 3da17 , 3dg17 , 3ca17 , 3ea17 , 3aaa17 , 3cg17
,
g
h
i
j
k
k
l
m
n
o
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p
q
3aag17 and 3eg17 have previously been reported and their structure has been confirmed by
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comparison with the published spectral data.
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9
General procedures for the products 3aa-wa and 3aaa-aja: Anilines 1 (0.3 mmol), Pd(OAc)2 (5
mol %), 2,4,6-collidine (10 mol %) and CF3COOH (20 mol %) was added to a flame-dried Schlenk
tube which charged with a magnetic stir bar in 3.0 mL ethanol. The resulting suspension was stirred
at 150℃ under O2 for appropriate time. After celite filtration and evaporation of the solvents in
vacuo, the crude product was purified by column chromatography on silica gel (petroleum/ethyl
acetate=100/1) to yield products.
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1
2-Methylquinoline (3aa): A yellow oil. Yield: 39.9 mg (93%). H NMR (400 MHz, CDCl3) δ =
8.00 (d, J = 8.4 Hz, 1H), 7.86 (d, J = 8.4 Hz, 1H), 7.66-7.54 (m, 2H), 7.36 (dd, J = 11.0, 4.0 Hz,
1H), 7.10 (d, J =8.4 Hz, 1H), 2.65 (s, 3H). 13C NMR (101 MHz, CDCl3) δ = 158.8, 147.8, 136.0,
129.3, 129.3, 128.5, 127.4, 127.4, 127.4, 126.4, 125.6, 125.5, 125.5, 121.9, 121.8, 25.3.
1
2,6-Dimethylquinoline (3ba): A light yellow oil. Yield: 43.8 mg (89%). H NMR (CDCl3, 400
MHz) δ= 8.01-8.04 (m, 2H), 7.60 (d, J = 8.0 Hz, 2H), 7.32 (s, 1H), 2.81 (s, 3H), 2.60 (s, 3H). 13
C
NMR (CDCl3, 100 MHz) δ = 158.0, 146.4, 135.6, 135.4, 131.7, 128.3, 126.5, 126.4, 122.0, 29.7,
25.2, 21.5.
6-Ethyl-2-methylquinoline (3ca): A light yellow oil. Yield: 46.2 mg (90%). 1H NMR (400 MHz,
CDCl3) δ= 7.94 (t, J = 8.0 Hz, 2H), 7.54 (d, J = 8.0 Hz, 1H), 7.52 (s, 1H), 7.22 (s, 1), 2.80 (q, J =
8.0 Hz, 2H), 2.71 (s ,3H), 1.31(t, J = 8.0 Hz, 3H). 13C NMR (100 MHz, CDCl3) δ= 158.0, 146.6,
141.6, 135.7, 130.6, 128.4, 126.5, 125.1, 125.1, 125.1, 125.0, 121.9, 121.9, 28.8, 25.3, 15.4.
6-iso-Propyl-2-methylquinoline (3da): A light yellow oil. Yield: 45.5 mg (82%). 1H NMR (CDCl3,
400 MHz) δ= 8.01 (t, J = 8.0 Hz, 2H), 7.63 (d, J = 8.0 Hz, 1H), 7.59 (s,1H), 7.28 (d, J = 8.0 Hz,
1H), 3.08-3.15 (m, 1H), 2.76 (s, 3H), 1.38 (d, J = 8.0 Hz, 6H). 13C NMR (CDCl3, 100 MHz) δ =
158.0, 146.7, 146.2, 135.9, 129.3, 128.4, 126.5, 123.6, 121.9, 34.0, 25.2, 23.9. HRMS (ESI) calcd.
For C13H16N [M+H]: 186.1283, found: 186.1277.
1
6-(tert-Butyl)-2-methylquinoline (3ea): A light yellow oil. Yield: 49.6 mg (83%). H NMR
(CDCl3, 400 MHz) δ= 8.01-8.05 (m, 2H), 7.82 (d, J = 8.0 Hz, 1H), 7.72 (s, 1H), 7.29 (s, 1H), 2.77
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(s, 3H ), 1.46 (s, 9H). 13C NMR (CDCl3, 100 MHz) δ = 158.2, 148.4, 146.3, 136.2, 128.3, 128.1,
126.1, 126.0, 122.5, 121.9, 112.5, 34.8, 31.2, 25.2.
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6-Cyclohexyl-2-methylquinoline (3fa): A light yellow oil. Yield: 56.7 mg (84%).1H NMR (CDCl3,
400 MHz) δ= 7.96 (m, dd, J1 = 1.2 Hz, J2 = 8.0 Hz 2H), 7.55 (t, J = 8.0 Hz, 2H), 7.22(d, J = 8.0
Hz,1H), 2.71 (s, 3H), 2.62 -2.68 (m, 1H), 1.97 (d, J = 8.0 Hz, 2H), 1.95 (d, J = 8.0 Hz, 2H), 1.38-
1.51 (m,4H),1.28-1.34 (m,2H). 13C NMR (CDCl3, 100 MHz) δ= 158.0, 145.5, 136.1, 129.8, 128.1,
126.5, 124.0, 121.9, 44.4, 34.4, 26.9, 26.2, 25.0. HRMS (ESI) calcd. For C16H20N [M+H]: 226.1596,
found: 226.1589.
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2-Methyl-6-phenylquinoline (3ga): A light yellow oil. Yield: 53.9 mg (84%). 1H NMR
(CDCl3 ,400 MHz) δ= 8.14 (d, J = 8.0 Hz, 1H), 8.10 (d, J = 8.0 Hz, 1H), 7.99 (d, J = 8.0 Hz, 2H),
7.74 (d, J = 8 Hz, 2H), 7.52 (t, J = 8.0 Hz ,2H), 7.44 (m 1H),7.32(d, J = 8.0 Hz, 1H), 2.80 (s, 3H).
13C NMR (CDCl3, 100 MHz) δ= 159.0, 147.3, 140.4, 138.4, 136.4, 129.1, 129.1, 128.9, 127.6, 127.4,
126.7, 125.2, 122.4, 25.4. HRMS (ESI) calcd. For C16H14N [M+H]: 220.1126, found: 220.1133.
6-Methoxy-2-methylquinoline (3ha): A light yellow oil. Yield: 43.1 mg (83%). 1H NMR (CDCl3,
400 MHz) δ= 7.91 (d, J = 8.0 Hz, 2H), 7.32 (dd, J1 = 1.2 Hz, J2 = 8.0 Hz, 1H), 7.21 (d, J = 8.0 Hz,
1H), 7.01 (d, J = 8.0 Hz, 1H), 3.89 (s, 3H), 2.69 (s, 3H). 13C NMR (CDCl3, 100 MHz) δ= 157.1,
156.3, 143.8, 135.1, 129.9, 127.3, 122.3, 121.9, 105.2, 55.5, 24.9.
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2-Methylquinolin-6-ol (3ia): A light yellow oil. Yield: 24.0 mg (55%). H NMR (400 MHz,
DMSO-d6) δ= 8.03 (d, J = 8.0 Hz, 1H), 7.79 (d, J = 8.0 Hz, 1H), 7.29 (t, J = 8.0 Hz, 2H), 7.12 (s, J
= 1.0 Hz, 1H), 2.60 (s, 3H). 13C NMR (101 MHz, CDCl3) δ =156.9, 151.7, 137.7, 136.1, 126.6,
126.6, 122.7, 117.6, 109.8, 24.9. HRMS (ESI) calcd. For C10H10NO [M+H]: 160.0762, found:
160.0756.
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N-(2-methylquinolin-6-yl)acetamide (3ja): A light yellow oil. Yield: 43.2 mg (72%). H NMR
(CDCl3, 400 MHz) δ= 9.22 (s, 1H), 8.31 (s, 1H), 7.88 (dd, J1 = 1.2 Hz, J2 = 8.0 Hz, 2H), 7.56 (d, J
= 8.0 Hz, 1H), 7.30 (m, 1H), 2.66 (s, 3H), 2.17 (s, 3H). 13C NMR (CDCl3, 100 MHz) δ = 169.4,
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157.8, 144.7, 136.2, 135.8, 128.6, 126.9, 123.4, 122.5, 116.2, 24.9, 24.4. For C12H13N2O [M+H]:
201.1028, found: 201.1020.
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4-(2-Methylquinolin-6-yl)morpholine (3ka): A light yellow oil. Yield: 39.7 mg (58%). 1H NMR
(400 MHz, CDCl3) δ= 7.89 (t, J = 8.0 Hz 2H), 7.42 (dd, J1 = 8 Hz, J2 = 3.6, 1H), 7.19 (s, J = 8.0 Hz,
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1H), 6.99 (d, J = 8.0 Hz, 1H), 3.89 (t, J = 8.0 Hz, 4H), 3.24 (t, J = 8.0 Hz, 4H), 2.68 (s, 3H). 13
C
NMR (100 MHz, CDCl3) δ = 156.2, 148.7, 143.5, 135.1, 129.3, 127.4, 122.3, 122.0, 109.2, 66.9,
49.6, 25.0. HRMS (ESI) calcd. For C14H17N2O [M+H]: 229.1341, found: 229.1338.
(E)-Ethyl 3-(2-methylquinolin-6-yl)acrylate (3la): A light yellow oil. Yield: 52.1 mg (72%). 1H
NMR (400 MHz, CDCl3) δ 8.01-8.05 (m, 2H), 7.85 (t, J = 8.0 Hz, 3H), 7.31 (d, J = 8.0 Hz, 1H),
6.55 (d, J = 8.0 Hz, 1H), 4.31 (q, 2H), 2.76 (s,3H),1.37 (s, 3H). 13C NMR (100 MHz, CDCl3) δ =
166.9, 160.2, 148.6, 143.8, 136.6, 136.5, 136.4, 131.8, 129.4, 129.0, 127.2, 126.4, 119.0, 119.0,
119.0, 60.6, 29.7, 29.7, 25.5, 25.4, 25.4, 14.4. HRMS (ESI) calcd. For C15H16NO 2 [M+H]: 242.1181,
found: 242.1173.
6-Fluoro-2-methylquinoline (3ma): A light yellow oil. Yield: 36.2 mg (75%). 1H NMR (400 MHz,
CDCl3) δ= 7.97-8.05 (m, 2H), 7.47 (t, J = 4.0 Hz, 1H), 7.40 (d, J = 8.0 Hz, 1H), 7.31 (m, 1H), 2.76
(s, 3H). 13C NMR (100 MHz) δ= 161.1, 158.7, 158.3, 158.3, 144.9, 135.5, 135.5, 131.0, 130.9, 127.0,
126.9, 122.7, 119.6, 119.3, 110.6, 110.4, 25.2. 19F NMR (CDCl3, 376 MHz): δ= -114.5 ppm.
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6-Chloro-2-methylquinoline (3na): A white solid. Yield: 30.6 mg (56%). H NMR (400 MHz,
CDCl3) δ= 7.99 (d, J = 8.0 Hz, 2H), 7.79 (s, 1H), 7.65 (d, J = 8.0 Hz , 1H), 7.34 (d, J = 8.0 Hz ,1H),
2.77 (s, 3H). 13C NMR (100 MHz, CDCl3) δ= 159.4, 146.2, 135.2, 131.3, 130.3, 130.2, 127.1, 126.2,
122.9, 25.3.
6-trifluoromethyl-2-methylquinoline (3oa) : A white solid (47.5 mg , 75%) .1H NMR (400 MHz,
CDCl3) δ= 8.16 (t , J = 8.0Hz, 3H), 7.90 (d, J = 8.0 Hz, 1H), 7.43(d, J = 8.0Hz, 1H) , 2.83 (s, 3H);
13C NMR (100 MHz, CDCl3) δ = 161.5, 148.8, 136.8, 129.8, 125.5, 125.4, 125.2, 125.1, 123.2, 25.5.
19F NMR (CDCl3, 376 MHz): δ= -62.13 ppm .
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1-(2-Methylquinolin-6-yl)ethanone (3pa): A white solid. Yield: 41.6 mg (75%). H NMR (400
MHz, CDCl3) δ= 8.35 (s, 1H), 8.18 (d, J = 8.0 Hz, 1H), 8.10 (d, J = 8.0 Hz, 1H), 8.01 (d, J = 8.0
Hz, 1H), 7.31 (d, J = 8.0 Hz, 1H), 2.73 (s, 3H), 2.65 (s, 3H). 13C NMR (101 MHz, CDCl3) δ = 169.4,
158.0, 144.7, 136.2, 135.8, 128.6, 126.9, 123.4, 122.5, 116.2, 24.9, 24.4.
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Ethyl 2-methylquinoline-6-carboxylate (3qa): A white solid. Yield: 41.9 mg (65%). H NMR
(400 MHz, CDCl3) δ= 8.51 (s, 1H), 8.25 (d, J = 8.0 Hz, 1H), 8.11 (d, J = 8.0 Hz, 1H), 8.02 (d, J =
8.0 Hz, 1H), 7.31 (d, J = 8.0 Hz, 1H), 4.42 (q, 2H), 2.74 (s, 3H), 1.42 (t, 3H). 13C NMR (101 MHz,
CDCl3) δ = 197.4, 161.8, 149.8, 137.5, 134.1, 129.6, 129.1, 127.8, 125.6, 122.9, 26.7, 25.6. HRMS
(ESI) calcd. For C13H14NO2 [M+H]: 216.1025, found: 216.1018.
2,7-Dimethylquinoline (3ra): A yellow oil. Yield: 41.9 mg (89%). 1H NMR (400 MHz, CDCl3) δ=
7.93 (d, J = 8.0 Hz, 2H), 7.50 (d, J = 8.0 Hz, 2H), 7.22 (d, J = 8.0 Hz, 1H), 2.72 (s, 3H) , 2.50 (s,
3H). 13C NMR (100 MHz, CDCl3) δ = 158.0, 135.7, 135.4, 131.7, 128.1, 126.5, 126.4, 122.0, 25.1,
21.5.
7-Isopropyl-2-methylquinoline (3sa): A yellow oil. Yield: 48.8 mg (88%). 1H NMR (CDCl3, 400
MHz) δ= 7.97 (d, J = 8.0 Hz,1H), 7.87 (s, 1H), 7.67 (d, J = 8.0 Hz, 1H), 7.37 (d, J = 8.0 Hz, 1H),
7.19 (d, J = 8.0 Hz, 1H), 3.09 (m, 1H), 2.71 (s, 3H), 1.34 (d, J = 8.0 Hz, 6H). 13C NMR (CDCl3,
100 MHz) δ = 158.8, 150.6, 148.0, 136.0, 127.2, 125.8, 124.9, 124.7, 121.3, 34.3, 25.2, 23.8, 23.8.
HRMS (ESI) calcd. For C13H16N [M+H]: 186.1283, found: 186.1276.
7-Methoxy-2-methylquinoline (3ta): A yellow oil. Yield: 40.5 mg (78%). 1H NMR (CDCl3, 400
MHz) δ= 7.93 (d, J =8.0 Hz, 1H), 7.62 (d, J = 8.0 Hz, 1H), 7.37 (s, 1H), 7.11-7.14 (m, 2H), 3.92 (s,
3H), 2.70 (s, 3H). 13C NMR (CDCl3, 100 MHz) δ = 160.8, 159.2, 149. 5, 135.9, 128.5, 121.6, 119.8,
118.7, 106.7, 55.5, 25.2.
2,8-dimethylquinoline (3ua): A yellow oil. Yield: 33.9 mg (72%). 1H NMR (CDCl3, 400 MHz) δ=
8.04 (d, J = 8.0 Hz, 1H), 7.66 (d, J = 8.0 Hz, 1H), 7.58 (d, J = 8.0 Hz, 1H), 7.41(t , J = 8.0 Hz, 1H),
7.31 (d, J = 8.0 Hz, 1H), 2.87 (s, 3H), 2.82 (s, 3H). 13C NMR (100 MHz, CDCl3) δ = 157.9, 147.0,
136.5, 136.2, 129.5, 126.4, 125.5, 125.3, 121.6, 25.7, 18.0.
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2-Methyl-8-phenylquinoline (3va): A yellow oil. Yield: 44.7 mg (68%). H NMR (CDCl3, 400
MHz) δ= 8.14 (d, J = 8.0 Hz, 1H), 7.88 (d, J = 8.0 Hz, 2H), 7.80- 7.85 (m, 2H), 7.56-7.63 (m, 3H),
7.50 (d, J = 8.0 Hz, 1H), 7.36 (d, J = 8.0 Hz 1H), 2.77 (s, 3H); 13C NMR (CDCl3, 100 MHz) δ=
158.8, 145.5, 139.9, 139.6, 136.3, 131.1, 130.3, 127.8, 127.3, 127.1, 127.0, 125.4, 121.8, 25.8.
HRMS (ESI) calcd. For C16H14N [M+H]: 220.1126, found: 220.1133.
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2-methylquinolin-8-ol (3wa) : A white solid (27.7 mg , 58%) . 1H NMR (CDCl3,400 MHz):δ=
8.07 (d, J = 8.0Hz,1H), 7.42 (t, J = 8.0 Hz, 1H), 7.33 (t, J = 8.0 Hz, 2H), 7.19 (d, J = 8.0 Hz, 1H),2.77
(s, 3H); 13C NMR (100 MHz, CDCl3) δ = 156.9, 151. 7, 137.7, 136.1, 126.6, 126.6, 122.7, 117.6,
109.8, 24.9. ppm. HRMS (ESI) calcd. For C10H10NO [M+H]: 160.0762 , found: 160.0755 .
2,6,7-Trimethylquinoline (3aaa): A yellow oil. Yield: 27.7 mg (84%).1H NMR (CDCl3,400 MHz)
δ= 7.92 (d, J = 8.0 Hz, 1H), 7.81 (s, 1H), 7.50 (s, 1H), 7.19 (d, J = 8.0 Hz, 1H), 2.73 (s, 3H), 2.47
(s, 3H), 2.43 (s, 3H). 13C NMR (100 MHz, CDCl3) δ = 157.9, 147.0, 139.5, 135.3, 135.1, 128.0,
126.7, 125.0, 121.1, 25.2, 20.4, 19.9.
2,5,7-Trimethylquinoline (3aba): A yellow oil. Yield: 27.7 mg (84%).The title compound was
prepared according to the general procedure as a yellow oil (27.7 mg, 84%). 1H NMR (CDCl3, 400
MHz) δ= 8.10 (d, J = 8.0 Hz, 1H), 7.65 (s, 1H), 7.19 (d, J = 8.0 Hz, 1H) 7.12 (s,1H), 2.70 (s, 3H),
2.59 (s, 3H), 2.48 (s, 3H). 13C NMR (100 MHz, CDCl3) δ = 158.3, 148.4, 139.2, 133.9, 132.4, 128.5,
128.5, 125.9, 123.8, 120.7, 25.1, 21.8, 18.5.
5,7-Dimethoxy-2-methylquinoline (3aca): A yellow oil. Yield: 48.7 mg (80%). 1H NMR (CDCl3,
400 MHz) δ= 8.32 (d, J = 8.0 Hz, 1H), 7.12 (d, J = 8.0 Hz, 1H), 7.01 (s, 1H), 6.47(s, 1H), 3.95 (d,
6H), 2.71 (s, 3H). 13C NMR (100 MHz, CDCl3) δ = 161.3, 159.5, 156.0, 150.0, 130.9, 118.8, 114.7,
99.1, 97.3, 55.7, 55.5, 25.1.
6,7-Dimethoxy-2-methylquinoline (3ada): A yellow oil. Yield: 49.9 mg (82%). 1H NMR (CDCl3,
400 MHz) δ= 7.82 (d, J = 8.0 Hz, 1H), 7.32 (s, 1H), 7.08 (d, J = 8.0 Hz, 1H), 6.94 (s, 1H), 3.96 (d,
3H), 3.93 (s, 3H), 2.63 (s, 3H). 13C NMR (100 MHz, CDCl3) δ = 156.5, 152.2, 149.0, 144.6, 134.5,
121.7, 120.1, 107.4, 105.0, 56.0, 55.9, 24.9.
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6-Methyl-[1,3]dioxolo[4,5-g]quinoline (3aea): A white solid. Yield: 47.1 mg (84%). 1H NMR
(CDCl3, 400 MHz) δ= 7.87 (d, J = 8.0 Hz, 1H), 7.35 (s, 1H), 7.15 (d, J = 8.0 Hz, 1H), 7.03 (s, 1H),
6.10 (s, 2H), 2.70 (s, 3H). 13C NMR (100 MHz, CDCl3) δ = 156.5, 150.6, 145.9, 135.1, 123.1,
120.2, 105.3, 102.7, 101.5, 101.3, 29.7, 24.9. HRMS (ESI) calcd. For C11H10NO2 [M+H]: 188.0712,
found: 188.0718.
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2,6-Dimethylquinolin-8-ol (3afa): A white solid. Yield: 34.3 mg (66%). 1H NMR (CDCl3, 400
MHz) δ= 8.18 (d, J = 8.0 Hz, 1H), 7.35 (d, J = 8.0 Hz, 1H), 7.22 (d, J = 8.0 Hz, 1H), 7.08 (d, J =
8.0 Hz, 1H) , 2.76 (s, 3H), 2.60 (s, 3H). 13C NMR (100 MHz, CDCl3) δ = 156.3, 145.0, 137.9, 133.1,
126.5, 125.7, 124.1, 122.2, 109.1, 24.8, 17.8. HRMS (ESI) calcd. For C11H12NO [M+H]: 174.0919,
found: 174.0926.
2-Methylbenzo[h]quinoline (3aga): A white solid. Yield: 52.1 mg (90%). 1H NMR (CDCl3, 400
MHz) δ= 9.38 (d, J = 8.0 Hz,1H), 8.03 (d, J = 8.0 Hz, 1H), 7.90 (d, J = 8.0 Hz, 1H ), 7.63-7.77(m ,
4H), 7.38 (d, J = 8.0 Hz, 1H), 2.82 (s, 3H). 13C NMR (100 MHz, CDCl3) δ = 157.8, 146.0, 136.1,
136.0, 135.8, 133.7, 131.4, 127.9, 127.7, 127.0, 126.8, 126.7, 125.2, 25.5.
2-Methylbenzo[g]quinoline (3aha): A white solid. Yield: 53.3 mg (90%). 1H NMR (CDCl3, 400
MHz) δ= 8.80 (d, J = 8.0 Hz, 1H), 8.57 (d, J = 8.0 Hz, 1H), 7.98 (s, 2H), 7.94(d, J = 8.0 Hz, 1H),
7.61-7.69 (m, 2H), 7.42 (d, J = 8.0 Hz, 1H), 2.82 (s, 3H). 13C NMR (100 MHz, CDCl3) δ = 158.4,
147.7, 131.3, 130.9, 130.7, 129.7, 128.6, 127.8, 127.0, 126.8, 126.8, 25.0.
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3,6-Dimethyl-1-phenyl-1H-indazole (3aia): A white solid. Yield: 46.6 mg (70%). H NMR
(CDCl3, 400 MHz) δ= 8.44 (d, J = 8.0 Hz, 1H), 8.25 (d, J = 8.0 Hz, 2H), 7.54 (t, J = 8.0 Hz, 2H),
7.31 (t, J = 8.0 Hz, 1H), 6.93 (d, J = 8.0 Hz, 1H), 2.79 (s, 3H), 2.74 (s, 3H). 13C NMR (100 MHz,
CDCl3) δ = 151.1, 149.2, 149.0, 148.9, 143.1, 142.6, 139.5, 129.1, 129.0, 129.0, 125.5, 121.3, 121.2,
118.4, 116.6, 29.7, 19.1, 15.5. HRMS (ESI) calcd. For C15H15N2 [M+H]: 224.1188, found: 224.1180.
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1,3,6-Trimethyl-1H-pyrazolo[3,4-b]pyridine (3aja): A light yellow solid. Yield: 31.4 mg (66%).
1H NMR (CDCl3, 400 MHz) δ= 8.31 (d, J = 8.0 Hz, 1H), 6.77 (d, J = 8.0 Hz, 2H), 4.03 (s, 3H), 2.65
(d, 6H). 13C NMR (100 MHz, CDCl3) δ = 151.3, 148.7, 148.6, 148.5, 143.0, 140.4, 117.0, 114.8,
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33.5, 19.0, 15.1. HRMS (ESI) calcd. For C9H12N3 [M+H]: 162.1031, found: 162.1024.
General procedures for the products 3ab-f: Anilines 1a (0.3 mmol), Pd(OAc)2 (5 mol%), 2,4,6-
Collidine (10 mol%) and CF3COOH (20 mol%) was added to a flame-dried Schlenk tube which
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charged with a magnetic stir bar in 3 mL solvent. The resulting suspension was stirred at 150 C
under O2 for appropriate time. Then the reaction was quenched with 10 mL of distilled water and
extracted with EtOAc (10×3 mL), then dried over with Na2SO4. The organic liquid was then
removed in vacuo and the resulting mixture was purified by column chromatography on silica gel
(petroleum/ethyl acetate=100/1) to yield products.
2-ethyl-3-methylquinoline (3ab) : A yellow oil ( 42.1 mg, 85%) . 1H NMR (CDCl3, 400 MHz)δ
= 8.07 (d, J = 8.0 Hz, 1H), 7.87(s, 1H), 7.74 (d, J= 8.0 Hz, 1H), 7.66 (m, 1H), 7.45(t, J = 8.0Hz,
1H) , 3.04 (t, J = 8.0 Hz, 2H), 2.52 (s, 3H), 1.42 (q, 3H) ppm.
3-Ethyl-2-propylquinoline (3ac): A yellow oil. Yield: 52.5 mg (88%). 1H NMR (CDCl3, 400 MHz)
δ= 8.07 (d, J = 8.0 Hz, 1H), 7.87 (s, 1H), 7.75 (d, J = 8.0 Hz, 1H), 7.64 (t, J = 8.0 Hz, 1H), 7.47 (t,
J = 8.0 Hz, 1H), 3.01 (t, J = 8.0 Hz, 2H), 2.88 (t, J = 8.0 Hz, 2H), 1.74-1.84 (m, 2H), 1.03 (t, J = 8.0
Hz, 3H), 1.09 (t, J = 8.0 Hz, 3H). 13C NMR (100 MHz, CDCl3) δ = 162.0, 146.4, 135.4, 133.9, 128.7,
128.4, 127.4, 126.9, 125.6, 37.8, 25.2, 23.0, 14.5, 14.4.
2-Butyl-3-propylquinoline (3ad): A yellow oil. Yield: 60.6 mg (90%). 1H NMR (CDCl3, 400 MHz)
δ= 8.07 (d, J = 8.0 Hz, 1H), 7.90 (s, 1H), 7.77 (d, J = 8.0 Hz, 1H), 7.66 (t, J = 8.0 Hz, 1H), 7.50 (d,
J = 8.0 Hz, 1H), 3.02 (t, J = 8.0 Hz, 2H), 2.80 (t, J = 8.0 Hz, 2H), 1.74-1.84 (m, 4H), 1.52-1.57 (m,
2H), 1.03 (t, J = 8.0 Hz, 3H), 1.09 (t, J = 8.0 Hz, 3H). 13C NMR (100 MHz, CDCl3) δ = 162.3, 146.5,
134.9, 133.9, 128.4, 128.3, 127.2, 126.9, 125.5, 35.7, 34.4, 31.9, 23.6, 23.1, 14.10, 14.07.
3-Butyl-2-pentylquinoline (3ae): A yellow oil. Yield: 68.9 mg (90%).1H NMR (CDCl3, 400 MHz)
δ= 8.07 (d, J = 8.0 Hz, 1H), 7.89 (s, 1H), 7.76 (d, J = 8.0 Hz, 1H), 7.65 (t, J = 8.0 Hz, 1H), 7.49 (t ,
J = 8.0 Hz, 1H), 3.03 (t, J = 8.0 Hz, 2H), 2.94 (t, J = 8.0 Hz, 2H), 1.84- 1.87 (m, 2H), 1.75-1.17 (m,
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2H), 1.41-1.52 (m, 6H), 0.97-1.05 (m, 6H). 13C NMR (100 MHz, CDCl3) δ = 162.3, 146.50, 134.9,
133.9, 128.4, 128.3, 127.2, 126.9, 125.5, 35.7, 34.4, 31.9, 31.4, 30.2, 23.6, 23.1, 14.10, 14.07.
2-Hexyl-3-pentylquinoline (3af): A yellow oil. Yield: 74.7 mg (88%).1H NMR (CDCl3, 400 MHz)
δ= 8.06 (d, J = 8.0 Hz, 1H), 7.88 (s, 1H), 7.76 (d, J = 8.0 Hz, 1H), 7.65 (t, J = 8.0 Hz, 1H), 7.49 (t,
J = 8.0 Hz, 1H), 3.02 (t, J = 8.0 Hz, 2H), 2.82 (t, J = 8.0 Hz, 2H), 1.74-1.85 (m, 4H), 1.31-1.52 (m,
16H). 13C NMR (100 MHz, CDCl3) δ = 162.3, 146.5, 134.8, 134.2, 128.4, 128.3, 127.2, 126.9, 125.5,
36.0, 32.4, 31.8, 30.2, 29.8, 29.7, 29.2, 22.7, 22.6, 14.11, 14.06.
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General procedures for the products 3ag-3wg: Anilines 1 (0.3 mmol), Pd(OAc)2 (5 mol%), 2,4,6-
Collidine (10 mol%) and CF3COOH (20 mol%) was added to a flame-dried Schlenk tube which
charged with a magnetic stir bar in 3.0 mL propan-1,3-diol. The resulting suspension was stirred at
150 oC under O2 for appropriate time. Then the reaction was quenched with 10 mL of distilled water
and extracted with EtOAc (10×3 mL), then dried over with Na2SO4. The organic liquid was then
removed in vacuo and the resulting mixture was purified by column chromatography on silica gel
(petroleum/ethyl acetate=100/1) to yield products.
Quinoline (3ag): A yellow oil. Yield: 29.4 mg (76%). 1H NMR (CDCl3, 400 MHz) δ= 8.74 (s, 1H),
8.00 (d, J = 8.0 Hz, 1H), 7.84 (d, J = 8.0 Hz, 1H), 7.48-7.55 (m, 2H), 7.30 (t, J = 8.0 Hz, 1H), 7.10
(t, J = 8.0 Hz, 1H).13C NMR (100 MHz, CDCl3) δ = 150.2, 148.1, 135.8, 129.3, 128.1, 127.7, 126.3,
120.9
6-Methylquinoline (3bg): A yellow oil. Yield: (32.6 mg (75%). 1H NMR (CDCl3, 400 MHz) δ=
8.94 (s, 1H), 8.05 (d, J = 8.0 Hz, 1H), 8.00 (d, J = 8.0 Hz, 1H), 7.51- 7.57(m, 2H), 7.34-7.37 (m,
1H), 2.54 (s, 3H).
6-Ethylquinoline (3cg): A yellow oil. Yield: 34.9 mg (73%). 1H NMR (CDCl3, 400 MHz) δ= 8.85
(s, 1H), 8.09 (d, J = 8.0 Hz, 1H), 8.03 (d, J = 8.0 Hz, 1H), 7.58-7.65 (m, 2H), 7.34-7.38 (m, 1H),
2.94 (q, 2H), 1.34 (t, 3H). 13C NMR (100 MHz, CDCl3) δ = 149.6, 147.1, 142.6, 135.6, 130.7, 129.2,
128.4, 125.3, 121.0, 28.9, 15.4.
6-iso-Propylquinoline (3dg): A yellow oil. Yield: 37.4 mg (73%). 1H NMR (CDCl3, 400 MHz) δ=
8.89 (s, 1H), 8.15 (d, J = 8.0 Hz, 1H), 8.09 (d, J = 8.0 Hz, 1H), 7.58-7.66 (m, 2H), 7.37-7.43 (m,
1H), 3.11-3.31 (m, 1H), 1.39 (d, 6H).
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6-(tert-Butyl)quinoline (3eg): A yellow oil. Yield: 40.5 mg (73%). 1H NMR (CDCl3, 400 MHz)
δ= 8.85 (d, J = 8.0 Hz, 1H), 8.11 (d, J = 8.0 Hz, 1H), 8.05 (d, J = 8.0 Hz, 1H), 7.80-7.82 (m, 1H),
7.72 (d, J = 8.0 Hz, 1H), 7.34-7.37 (m, 1H), 1.42(s, 9H).
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6-Methoxyquinoline (3hg): A yellow oil. Yield: 34.3 mg (72%). 1H NMR (CDCl3, 400 MHz) δ=
8.78 (d, J = 8.0 Hz, 1H), 8.02-8.07 (m, 2H), 7.35- 7.41 (m, 2H), 7.08 (d, J = 8.0 Hz, 1H), 3.94 (s,
3H).
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1-(Quinolin-6-yl)ethanone (3pg): A white solid. Yield: 35.9 mg (70%). 1H NMR (CDCl3, 400
MHz) δ= 9.01 (d, J = 8.0 Hz, 1H), 8.45 (s, 1H), 8.25-8.30 (m, 2H), 8.16 ( d, J = 8.0 Hz, 1H), 7.47-
7.50 (m, 1H), 2.74 (s, 3H). 13C NMR (100 MHz, CDCl3) δ = 197.4, 152.6, 150.1, 137.6, 134.9,
130.1, 129.9, 127.7, 127.5, 122.0, 26.8.
Ethyl quinoline-6-carboxylate (3qg): A yellow solid. Yield: 45.2 mg (75%). 1H NMR (CDCl3,
400 MHz) δ= 9.00 (d, J = 8.0 Hz, 1H), 8.59 (s, 2H), 8.25-8.32 (m, 2H), 8.14 (d, J = 8.0 Hz, 1H),
7.46-7.49 (m, 1H), 4.45 (q, 2H), 1.45 (t, 3H). 13C NMR (100 MHz, CDCl3) δ =166.1, 152.4, 150.0,
137.3, 130.9, 129.7, 129.0, 127.4, 121.8, 61.4, 14.4.
6,7-Dimethylquinoline (3aag): A yellow solid. Yield: 38.6 mg (82%). 1H NMR (CDCl3, 400 MHz)
δ= 8.93-8.95 (m, 1H), 8.05 (d, J = 8.0 Hz, 1H), 7.56 (s, 1H), 8.14 (d, J = 8.0 Hz, 1H), 7.30-7.33 (m,
1H), 2.50 (t, 3H), 2.45 (s, 3H).
Benzo[h]quinoline (3agg): A yellow solid. Yield: 44 mg (82%). 1H NMR (CDCl3, 400 MHz) δ=
9.35 (d, J = 8.0 Hz, 1H), 9.00-9.02 (m, 1H), 8.07-8.10 (m, 1H), 7.99 (d, J = 8.0 Hz, 1H), 7.75-7.79
(m, 2H), 7.68-7.72 (m, 1H), 7.61 (d, J = 8.0 Hz, 1H), 7.44-7.47 (m, 1H). 13C NMR (100 MHz,
CDCl3) δ = 148.8, 146.6, 135.8, 133.6, 131.5, 128.2, 127.9, 127.8, 127.1, 126.4, 125.4, 124.4, 121.8.
Benzo[f]quinolone (3ahg): A yellow solid. Yield: 43 mg (80%). 1H NMR (CDCl3, 400 MHz) δ=
8.99-9.03 (m ,1H), 8.94 (d, J = 8.0 Hz, 1H), 6.62 (d, J = 8.0 Hz, 1H), 7.94-8.05 (m, 3H), 7.65-7.73
(m, 2H), 7.55-7.58 (m, 1H). 13C NMR (100 MHz, CDCl3) δ = 149.7, 148.2, 131.7, 130.9, 130.7,
129.6, 128.7, 128.2, 127.3, 127.1, 125.4, 122.6, 121.3.
Quinolin-8-ol (3wg): A white solid. Yield: 23.9 mg (55%). 1H NMR (CDCl3, 400 MHz) δ= 8.84-
8.86 (m, 1H), 8.15-8.18 (m, 1H), 7.51 (t, J = 8.0 Hz, 1H), 7.42-7.45 (m, 1H), 7.38-7.35 (m, 1H),
7.27-7.29 (m, 1H). 13C NMR (100 MHz, CDCl3) δ = 152.4, 148.0, 138.3, 136.2, 128.6, 127.8, 121.8,
118.0, 110.4.
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2-Methyl-6-(4-nitrophenoxy)quinoline (3xa): 2.3 g aniline in this gram-scale synthesis. A light
yellow solid. Yield: 2.1 g (75%). 1H NMR (CDCl3, 400 MHz) δ= 8.23 (d, J = 8.0 Hz, 2H), 8.11 (d,
J = 8.0 Hz, 1H), 8.02 (t, J = 8.0 Hz, 1H), 7.46 (d, J = 8.0 Hz, 2H), 7.35 (d, J = 8.0 Hz, 1H), 7.09 (d,
J = 8.0 Hz, 2H), 2.78 (s, 3H). 13C NMR (100 MHz, CDCl3) δ = 163.0, 158.9, 152.0, 145.5, 142.9,
135.8, 135.6, 131.4, 127.2, 126.1, 125.9, 123.8, 122.8, 117.8, 117.6, 25.3. HRMS (ESI) calcd. For
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C16H13N2O3 [M+H]: 281.0926, found: 281.0915.
2-Phenylquinoline (3ah): A light yellow solid. 1H NMR (CDCl3, 400 MHz) δ= 8.18-8.23 (m, 4H),
7.88 (d, J = 8.0 Hz, 1H), 7.83 (d, J = 8.0 Hz, 1H), 7.74 (t, J = 8.0 Hz, 1H), 7.46-7.63 (m, 4H). 13
C
NMR (100 MHz, CDCl3) δ = 157.4, 148.3, 139.7, 136.8, 129.8, 129.7, 129.3, 128.9, 127.6, 127.5,
127.2, 126.3, 119.0.
Acknowledgment: Financial support from the Hundred Talent Program of Chinese Academy of
Sciences (CAS), the National Natural Science Foundation of China (21602231) and the Natural
Science Foundation of Jiangsu (Grant No. BK20151235 and BK20160396) are gratefully
acknowledged.
Supporting Information: Copy of 1H and 13C NMR spectra of all compounds were presented on
supporting information.
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