A heterogeneous catalytic and solvent-free approach to 1,2-dihydroquinoline derivatives from aromatic amines and alkynes by tandem hydroarylation-hydroamination

Article abstract of DOI:10.1016/j.catcom.2019.105888

This study describes a mesoporous aluminosilicate (ASM) catalyst-induced one-step synthesis of substituted dihydroquinolines through a hydroarylation/hydroamination cascade reaction under solvent-free conditions. A sol-gel method was utilized to prepare t

Full text of DOI:10.1016/j.catcom.2019.105888

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A heterogeneous catalytic and solvent-free approach to
1
,2-dihydroquinoline derivatives from aromatic amines and
alkynes by tandem hydroarylation-hydroamination
Vasu Amrutham, Agliullin Marat Radikovich, Naresh Mameda,
Krishna Sai Gajula, Nellya Gennadievna Grigor'eva, Kutepov
Boris Ivanovich, Venugopal Akula, Narender Nama
PII:
S1566-7367(19)30349-8
DOI:
https://doi.org/10.1016/j.catcom.2019.105888
CATCOM 105888
Reference:
To appear in:
Catalysis Communications
Received date:
Revised date:
Accepted date:
27 August 2019
4 November 2019
5 November 2019
Please cite this article as: V. Amrutham, A.M. Radikovich, N. Mameda, et al., A
heterogeneous catalytic and solvent-free approach to 1,2-dihydroquinoline derivatives
from aromatic amines and alkynes by tandem hydroarylation-hydroamination, Catalysis
Communications (2018), https://doi.org/10.1016/j.catcom.2019.105888
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2018 Published by Elsevier.

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A heterogeneous catalytic and solvent-free approach to 1,2-
dihydroquinoline derivatives from aromatic amines and alkynes by tandem
hydroarylation-hydroamination
a,b
c
a,b
a,b
Vasu Amrutham, Agliullin Marat Radikovich, Naresh Mameda, Krishna Sai Gajula, Nellya
c
c
a,b
a,b
Gennadievna Grigor’eva, Kutepov Boris Ivanovich, Venugopal Akula, Narender Nama*
a
Catalysis and Fine Chemicals Division, CSIR-Indian Institute of Chemical Technology, Hyderabad,
Telangana, India-500 007.
b
Academy of Scientific and Innovative Research, CSIR-HRDC Campus, Sector 19, Kamala Nehru Nagar,
Ghaziabad, UP-201002, India.
IPC RAS, 141 prosp, Oktyabrya, 450075 Ufa, Russian Federation.
c
*
Corresponding authorE-Mail: nama.iict@gov.in, narendern33@yahoo.co.in.
Tel.: +91-40-27191703; Fax: +91-40-27160387/27160757
ABSTRACT
This study describes a mesoporous aluminosilicate (ASM) catalyst-induced one-step
synthesis of substituted dihydroquinolines through a hydroarylation/hydroamination cascade
reaction under solvent-free conditions. A sol-gel method was utilized to prepare the ASM
catalyst using tetraethyl orthosilicate (TEOS) and aluminum nitrate (Al(NO3)3.9H2O). The
catalytic protocol, utilizing simple starting materials and a heterogeneous catalyst in a clean
reaction environment, is considered an alternative and economically viable route to
synthesize a wide range of 1,2-dihydroquinoline derivatives.
Keywords: Dihydroquinolines, Mesoporous aluminosilicates, Sol-gel method, Solvent-free
conditions, Zeolites.
1
. Introduction

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The growth of novel approaches that offer high synthetic efficiency and atom
economy has been a vital assignment for synthetic chemists. Tandem reactions are considered
a suitable applicant for this objective and are a promptly developing area [1,2]. They
complete numerous chemical transformations in one pot and offer a robust method for the
construction of complex molecules by employing simple starting materials. The key
advantages of tandem reactions are a drop in overall stages by avoiding the separation of
often very reactive intermediates; minimizing waste generated by the stepwise reactions; and
decreasing the number of reagents, adsorbents, solvents, and energy. Thus, from the synthetic
and industrial point of view, eco-friendly tandem processes have gained increasing interest.
The 1,2-dihydroquinoline (1,2-DHQ) moiety is a valuable building block of numerous
natural products that hold a wide range of biological activities and potential pharmaceutical
applications [3-5]. 1,2-DHQs have also been employed as essential intermediates in the
synthesis of organic and natural products [6-8], and they have the surplus benefit of reducing
to 1,2,3,4-tetrahydroquinolines, which also have vital significance as pharmaceuticals and
agrochemicals [9,10]. Conventionally, Skraup and Bischler-Napieralski reactions, which
involve the use of aniline and a ketone or the intramolecular condensation of an aromatic
amide, were used to obtain 1,2-DHQ compounds [11-13]. Different synthetic routes using
transition metal catalysts have been developed for the synthesis of dihydroquinoline
derivatives [14-23]. However, the generation of undesirable by-products, use of expensive
catalysts and in situ-generated starting materials, and need for organic solvents are some of
the limitations of the existing approaches. Thus, a modest, effective, inexpensive
heterogeneous catalytic approach under solvent-free conditions would be prominently
desirable to produce this class of composites.
Solvent-free synthesis is an integral part of green chemistry because of the necessity
to eradicate the use of toxic organic solvents, which are the source for the mainstream of

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waste and pollution created by chemical methods. Additionally, there are separate benefits to
these solvent-free procedures, such as low cost, fewer energy supplies, quicker reaction rates,
and, consequently, decrease in reactor size and capital investment [24,25]. In the past few
years, use of zeolite catalysts has become an attractive research area in heterogeneous
catalysis because of their unique physical and chemical properties [26-28]. However, their
microporosity causes accessibility and diffusion problems, which considerably restricts their
broad catalytic applications. Thus, a mesoporous structure (mesoporous aluminosilicates
[
ASMs]) with surface acid sites is highly desirable to provide effective diffusion of
components in the liquid phase acid–base transformations with ever-increasing frequency
29-31]. The ASMs have a system of mesopores (pore size distributions from 2 to 50 nm),
[
which are similar to zeolite pores, and can accommodate large reactant and product
molecules that mitigate the diffusion and accessibility issues. In the extension of our
investigation to develop novel and eco-friendly synthetic routes for valuable compounds
using micro- and mesoporous materials, we aim to describe a proficient, straightforward, and
environmentally benign cascade methodology for the synthesis of substituted 1,2-DHQs
directly from alkynes and anilines in the presence of the ASM catalyst under solvent-free
conditions. The ASM catalyst (Si/Al ratio of 80) was prepared according to our previous
work [32]. To the best of our knowledge, ASMs have not been utilized as a heterogeneous
catalyst for the synthesis of 2,2,4-substituted 1,2-DHQs from alkynes and anilines.
2
. Results and Discussion
The surface analysis (pore structure) of the ASM catalyst was carried out, and the
results are presented in Fig. 1. The nitrogen adsorption–desorption isotherm results indicated
a type IV isotherm according to the IUPAC classification, which is characteristic of
mesoporous materials (Fig. 1a). The ASM catalyst exhibits a narrow pore size distribution in
3
the range of 2-5 nm (Fig. 1b); seemingly, the ASM has a microporous volume of 0.05 cm /g,

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3
a mesoporous volume of 0.5 cm /g, and Brunauer Emmett Teller (BET) specific surface area
2
of 670 m /g. Fig. 1c shows a transmission electron microscopic image of the ASM sample.
The porous structure of the ASM is formed by spherical particles of size 10-15 nm, which are
not densely packed together, and the voids formed between the particles are mesoporous.
According to the temperature programmed desorption of ammonia, the ASM has a total
acidity of 427 µmol/g. The IR spectra of adsorbed CO show the presence of both strong
Bronsted acid centers (28 µmol/g) and Lewis acid centers (119 µmol/g). More detailed
information on the characterization of ASM has been presented elsewhere [32,33].
Fig. 1. Porous structure of mesoporous aluminosilicate: (a) nitrogen sorption
isotherms, (b) pore size distribution by BJH, (c) TEM image.
First, we explored the proper reaction conditions for the cascade approach to the
synthesis of substituted 1,2-DHQs by the reaction of phenylacetylene (1a) with aniline (2a)
as a model reaction. The reaction was evaluated with various catalysts, their amounts (100-
2
00 mg), and reaction temperatures (120 to 140 ℃) in a sealed vial for 24 h under clean
conditions (Table 1). The main product of the reaction of aniline with phenylacetylene in the
presence of zeolite catalysts is ortho-hydroarylation product (4a) which is formed as a result
of the linear condensation of the starting compounds (Table 1, entries 1-3). The absence of
the desired compound (3a) in the reaction mass can be explained by the fact that the
dihydroquinoline molecule is bulkier than the molecule of product 4a and is difficult for it to
form inside the micropores of zeolite catalysts, in which the strongest acidic bridging OH-
groups are located. Among the studied microporous catalysts, the ones with the largest pores
are zeolite H-Y catalysts, for which the diameter of the large cavity (1.2 nm) is more than the

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diameter of the entrance windows (0.75 nm). Such a structure of zeolite HY can lead to rapid
blocking of acid sites in large cavities by the formed 1,2-DHQ bulky molecules (3a), which
will, consequently, cause the deactivation of the zeolite H-Y catalyst. This deactivation
apparently explains the lowest yield of the product 4a (23%) observed among zeolite
catalysts.
Why 1,2-DHQ (3a) is not formed on the external surface acid sites of zeolites, where
there is no steric hindrance for its synthesis? Perhaps this is because the surface acid groups
of zeolites are mainly formed by silanol groups, the strength of which is much lower than the
strength of the bridging OH-groups.
Notably, the ASM catalyst demonstrated better catalytic activity and selectivity
toward the desired product (3a, 24%) than the zeolites, which is attributed to the presence of
mesopores with strong acid sites (Table 1, entry 4) [32,33]. The presence of mesopores in the
aluminosilicate described above contributes to the reduction of steric hindrance for the
transport of reagents and development of conditions for the formation of compound 3а. In
addition, the concentration of the reacting molecules may be higher in mesopores, which
leads to an increase in the number of chemical interactions of reagents and an increase in the
degree of their conversion. In an attempt to improve the yield of 3a, various amounts of the
ASM catalyst and reaction temperatures were considered (Table 1, entries 6-10). The results
revealed that the amount of catalyst increases the yield of 3a (24-83%), but further increase in
reaction temperature (140 ℃) did not boost the yield (Table 1, entry 10), which implied that
increasing the catalyst amount increases the number of active sites on the surface of the
ASM. The findings of the optimization study showed that 200 mg of the ASM catalyst at 135
℃
achieves the highest yield of 3a from 1:2 mole ratio of 1a and 2a under solvent-free
conditions (Table 1, entry 7).
Table 1. Optimization of conditions for the cascade reaction (1a +2a → 3a)
a

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°
Entry
Catalyst
Amount (mg)
T ( C)
Isolated
yield of
Isolated
yield of 4a
(%)
3
a (%)
1
2
3
H-Mordenite
H-Y
100
100
100
135
135
135
-
-
44
23
60
H-Beta
-
4
100
135
24
20
ASM
5
6
7
Absence catalyst
ASM
ASM
-
135
135
135
-
43
83
-
17
4
150
200
8
ASM
200
120
62
8
9
10
ASM
ASM
200
200
130
140
70
82
5
4
a
Conditions: 1a (1 mmol), 2a (2 mmol), 24 h, sealed vial.
Having the optimized conditions, the generality of this catalytic method was
investigated for a variety of aromatic alkynes with aniline, and the results are presented in
Table 2. Most of the cases, particular ortho-hydroarylated products, were obtained as a minor
product that may be converted to the desired 1,2-DHQs upon prolonged reaction times. The
methyl-substituted phenyl acetylenes 2b-2c reacted smoothly and provided the 3b-3c in good
yields. Noticeably, meta-substituted aromatic alkyne (2c) displayed lower reactivity than
para-substituted alkyne (2b) under identical conditions because of steric hindrance, which
may affect the interaction with the catalyst surface (Table 2, entries 2 and 3). The higher
alkane chain bearing aromatic alkynes (2d and 2e) produced the desired dihydroquinolines
(3d and 3e) selectively in 89% and 90% yields (Table 2, entries 4 and 5), respectively. The
halo-substituted aromatic alkynes (2f-2i) showed diverse reactivity with aniline to their
respective products under similar conditions (Table 2 entries 6-9). The F-substituted alkynes
2
f and 2g furnished the respective dihydroquinoline products 3f and 3g in 73% and 87%
yields (Table 2, entry 6), respectively, whereas Br- and Cl-substituted phenylacetylenes (2h
and 2i) yielded

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Table 2: Substituted dihydroquinolines from aniline and aryl acetylenes in the presence of
a
the ASM catalyst
Entry Ar (aromatic alkyne, 2a-2j)
Isolated yield of
a-3j (%)
3
b
1
2
3
4
5
6
7
8
9
Ph
83 (4)
84
68 (16)
89
CH3-4-C6H4
CH3-3-C6H4
b
CH3-CH2-CH2-CH2-4-C6H4
CH3-CH2-CH2-CH2-CH2-4-C6H4
F-4-C6H4
F-4-CH3-3-C6H3
Br-4-C6H4
90
73 (21)
87 (12)
- (47)
b
b
b
b
Cl-3-C6H4
- (20)
1
0
C4H4S
75
a
°
Conditions: 1a (1 mmol), 2a-2j (2 mmol), ASM (200 mg), 135 C, 24 h, sealed
vial. ortho-alkenylated product was obtained.
b
the corresponding ortho-hydroarylated products instead of the preferred products (Table 2
entries 8 and 9). Interestingly, the electron-rich heterocyclic alkyne (2j) also generated the
selectively desired product 3j in 75% yield (Table 2, entry 10). Unfortunately, aromatic
alkynes having strong electron-withdrawing groups (-NO2, -COOMe, and -CF3) were not
active to react with aniline and recovered without any change, which is not included in Table
2
.
We explored this cascade reaction by reacting a variety of anilines with
phenylacetylene (2a) to extend more possibilities of this catalytic process and observed the
longer reaction time (72 h) required to provide dihydroquinoline compounds with good yields
(
Table 3). The ortho- and meta-methoxy-substituted anilines 1b and 1c produced the
respective dihydroquinolines 3ab and 3ac in 63% and 58% yields, respectively, along with
6% and 42% of ortho-hydroarylated products (Table 3, entries 1 and 2). On the other hand,
the para-methoxy-substituted aniline 1d furnished the ortho-hydroarylated and di-ortho-
3

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hydroarylated products in 23% and 69% yields, respectively, instead of the desired
dihydroquinoline product 3ad (Table 3, entry 3). Alkyl-substituted anilines 1e and 1f
transformed into the corresponding dihydroquinolines 3ae and 3af in 60% and 62% yields
along with their ortho-hydroarylated products (Table 3, entries 4 and 5). Particularly, longer
alkyl chain-bearing anilines (1g and 1h) did not provide selectivity toward the desired
products, and substantial amounts of ortho-hydroarylated products were also obtained (Table
3
, entries 6 and 7). Halo-substituted anilines 1i-1l contributed well to this catalytic reaction to
give the respective dihydroquinoline derivatives in good yields (54-76%) irrespective of the
position of halogen (Cl) groups on the phenyl ring (Table 3, entries 8-11). 2-Benzylaniline
also showed good reactivity with phenylacetylene to give 3am (Table 3, entry 12).
Regrettably, the synthetic potential of this reaction is limited to substrates containing electron-
withdrawing groups (-NO2, -CN, and -COOH) and substrates were recovered without change
even longer reaction time.
Table 3: Dihydroquinoline derivatives from substituted anilines with phenylacetylene in the
a
presence of the ASM catalyst
Entry
R (Aniline, 1b-1m)
Isolated yield of

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3
ab-3am (%)
b
1
2
3
4
5
6
7
8
9
2-MeO
63 (36)
b
3-MeO
4-MeO
4-Me
4-tert-Butyl
4-n-Butyl
4-n-Pentyl
2-F
58 (42)
b
c
-(23) (69)
b
60 (37)
b
62 (31)
b
c
22 (53) (25)
16 (56) (27)
b
c
54
76 (18)
b
3-Cl
1
1
1
0
1
2
2-Cl
3,4-Cl
Benzyl (Ph-CH2)
67
75 (16)
75(25)
b
b
a
Conditions: 1b-1j (1 mmol), 2a (2 mmol), ASM catalyst (200 mg),
35 °C, 72 h, sealed vial. ortho-alkenylated product was obtained.
di-ortho alkenylated product was obtained.
b
1
c
The reaction of phenylacetylene (1a) with aniline (2a) was carried out at different
reaction intervals (6-24 h) using the ASM catalyst at 135 °C to determine the intermediates of
this cascade reaction, and the outcomes are included in Fig. S1. The ortho-hydroarylation
product (4a) was afforded as a significant (primary) product in 6 h; however, the yield of 4a
gradually decreased and the yield of the desired product (3a) increased with time. The results
suggest that the ortho-hydroarylation product (4a) underwent hydroamination reaction with
another mole of phenylacetylene (2a) transformed to the desired product (3a). On the basis of
the above results and literature reports [34,35], a reasonable mechanism for the synthesis of
substituted 1,2-DHQs from anilines with alkynes in the presence of the ASM catalyst is
anticipated as outlined in
Scheme 1.
It is predicted that aromatic terminal alkyne (II) adsorbs onto the acid sites of ASMs
that successively reacts with aniline (I) to offer the ortho-hydroarylation product (III). The
ortho-hydroarylation product (III) underwent hydroamination with another terminal alkyne
(II) to generate an enamine (IV), followed by a 6π-electrocyclic rearrangement and [1,5]-H

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shift [35] to yield the respective 1,2-DHQ product (V) in the presence of acidic sites of the
ASM catalyst.
Scheme 1. A plausible reaction mechanism to generate
dihydroquinoline derivatives from anilines and aromatic
alkynes using the ASM catalyst.
3
. Conclusions
In summary, the ASM catalyst was successfully prepared by the sol-gel method and
utilized for the synthesis of substituted 1,2-DHQs by tandem ortho-hydroarylation-
hydroamination under solvent-free conditions. Comparison of the catalytic properties of
microporous zeolites and ASM shows that the porosity of the catalyst, along with acidity,
plays an important role in the implementation of the studied reaction. The main product of the
reaction of aniline with phenylacetylene in the presence of zeolite catalysts is ortho-
hydroarylation product (4a), which is due to the manifestation of the molecular sieve effect of
the microporous zeolite lattice. The presence of mesopores in the aluminosilicate contributes
to the reduction in steric hindrance for the transport of reagents and development of
conditions for the formation of 1,2-DHQs. The probability and limitations of the catalytic
route are presented with a variety of aromatic amines and alkynes. Conversely, deactivated
substrates (having strong electron-withdrawing groups) failed to give the desired products.
Noticeable benefits of this protocol are the user of a nonhazardous heterogeneous catalyst,

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absence of solvent, single-step approach, ready availability of starting materials, and easy
setup and work-up procedure.
Acknowledgments
We thank the DST, New Delhi, for financial support under the Indo-Russia (DST-
RSF) (No. INT/RUS/RSF/P-7) program. M. N. and G. K. acknowledge the CSIR, India, for
financial support in the form of fellowship. We thank the Director of CSIR-IICT
(IICT/Pubs./2019/135).
Appendix A. Supplementary material
Supplementary data associated with this article can be found, in the online version, at
References
[1] J.-C. Wasilke, S. J. Obrey, R. T. Baker, G. C. Bazan, Chem. Rev. 105 (2005) 1001-1020.
https://doi.org/10.1021/cr020018n.
[2] L. F. Tietz, Chem. Rev. 96 (1996) 115-136.
https://doi.org/10.1021/cr950027e.
[
3] N. B. Perry, J. W. Blunt, J. D. Mc Combs, M. H. G. Munro, J. Org. Chem. 51 (1986)
476-5478. https://doi.org/10.1021/jo00376a096.
4] J. V. Johnson, S. Rauckman, P. D. Baccanari, B. Roth, J. Med. Chem. 32 (1989) 1942-
949. https://doi.org/10.1021/jm00128a042.
5] R. W. Carling, P. D. Leeson, A. M. Moseley, R. Baker, A. C. Foster, S. Grimwood, J. A.
5
[
1
[
Kemp, G. R. Marshall, J. Med. Chem. 35 (1992) 1942-1953.
https://doi.org/10.1021/jm00089a003.
[6] P. Magnus, S. A. Eisenbeis, R. A. Fairhurst, T. Iliadis, N. A. Magnus, D. Parry, J. Am.
Chem. Soc. 119 (1997) 5591-5605. https://doi.org/10.1021/ja970435v.

Journal Pre-proof
[7] R. M. Kariba, P. J. Houghton, A. Yenesew, J. Nat. Prod. 65 (2002) 566-569.
https://doi.org/10.1021/np010298m.
[8] J. H. Rakotoson, N. Fabre, I. Jacquemond-Collect, S. Hannedouche, I. Fouraste, C.
Moulis, Planta Med. 64 (1998) 762-763. https://doi.org/10.1055/s-2006-957578.
[9] A. R. Katritzky, S. Rachwal, B. Rachwal, Tetrahedron 52 (1996) 15031-15070.
https://doi.org/10.1016/S0040-4020(96)00911-8.
[10] M. Anzini, A. Cappelli, S. Vomero, G. Giorgi, T. Langer, M. Hamon, N. Merahi, B. M.
Emerit, A. Cagnotto, M. Skorupska, T. Mennini, J. C. Pinto, J. Med. Chem. 38 (1995)
2
692-2704. https://doi.org/10.1021/jm00014a021.
11] Z. H. Skraup, Ber. Dtsch. Chem. Ges. 13 (1880) 2086-2087.
https://doi.org/ 10.1002/cber.188001302195.
12] M. Wahren, Tetrahedron 20 (1964) 2773-2780. https://doi.org/10.1016/S0040-
020(01)98495-9
13] A. Bischler, B. Napieralski, Ber. 26 (1893) 1903-1908.
https://doi.org/10.1002/cber.189302602143.
[
[
4
[
[14] E. C. Taylor, J. E. Macor, L. G. French, J. Org. Chem. 56 (1991) 1807-1812.
https://doi.org/10.1021/jo00005a027.
[15] A. Arduini, F. Bigi, G. Casiraghi, G. Casnati, G. Sartori, Synthesis 12 (1981) 975-977.
https://doi.org/10.1055/s-1981-29666.
[16] B. C. Ranu, A. Hajra, S. S. Dey, U. Jana, Tetrahedron 59 (2003) 813-819.
https://doi.org/10.1016/S0040-4020(02)01587-9.
[17] G. F. Hennion, R. S. Hanzel, J. Am. Chem. Soc. 82 (1960) 4908-4912.
https://doi.org/10.1021/ja01503a040.
[18] M. A. Cooper, M. A. Lucas, J. M.Taylor, A. D. Ward, N. M. Williamson, Synthesis 4
(2001) 621-625. https://doi.org/10.1055/s-2001-12349.

Journal Pre-proof
[
19] C. Theeraladanon, M. Arisawa, A. Nishida, M. Nakagawa, Tetrahedron 60 (2004) 3017-
035. https://doi.org/10.1016/j.tet.2004.01.084.
20] N. M. Williamson, A. D. Ward, Tetrahedron 61 (2005) 155-165.
https://doi.org/10.1016/j.tet.2004.10.035.
3
[
[21] C. S. Yi, S. Y. Yun, I. A. Guzei, J. Am. Chem. Soc. 127 (2005) 5782-5783.
https://doi.org/10.1021/ja042318n.
[22] C. S. Yi, S. Y. Yun, J. Am. Chem. Soc. 127 (2005) 17000-17006.
https://doi.org/10.1021/ja055608s.
[23] Y. Luo, Z. Li, C. J. Li, Org. Lett. 7 (2005) 2675-2678.
https://doi.org/10.1021/ol050826b.
[24] K. Tanaka, F. Toda, Solvent-free Organic Synthesis Wiley-VCH Weinheim, 2003.
[25] P. J. Walsh, H. Li, C. A. de Parrodi, Chem. Rev. 107 (2007) 2503-2545.
https://doi.org/10.1021/cr0509556.
[26] A. Dyer, An Introduction to Zeolite Molecular Sieves, Wiley, Chichester 1988.
[27] D. W. Breck, Zeolite Molecular Sieves, Wiley, New York 1974.
[28] W. E. Farneth, R. J. Gorte, Chem. Rev. 95 (1995) 615-635.
https://doi.org/10.1021/cr00035a007.
[29] E. G. Derouane, Catalysts for Fine Chemical Synthesis, Microporous and Mesoporous
Solid Catalysts, Wiley, Chichester, 2006.
[
30] D. Trong On, D. Desplantier-Giscard, C. Danumah, S. Kaliaguine, Appl. Catal. A Gen.
22 (2001) 299-357. https://doi.org/10.1016/s0926-860x(01)00842-0.
31] A. C. Carmo Jr, K. C. Luiz de Souza, E. F. Carlos da Costa, E. Longo, R. Jose Zamian,
2
[
N. Geraldo da Rocha Filho, Fuel 88 (2009) 461-468.
https://doi.org/10.1016/j.fuel.2008.10.007.

Journal Pre-proof
[
32] M. R. Agliullin, I. G. Danilova, A. V. Faizullin, S. V. Amarantov, S. V. Bubennov, T. R.
Prosochkina, N. G. Grigor’eva, E. A. Paukshtis, B. I. Kutepov, Microporous Mesoporous
Mater. 230 (2016) 118-127. https://doi.org/10.1016/j.micromeso.2016.05.007.
[33] M. R. Agliullin, V. P. Talzi, N. A. Filippova, R. B. Vera, S. V. Bubennov, T. R.
Prosochkina, N. G. Grigorieva, N. Narender, B. I. Kutepov, Applied Petrochemical Res.
8
(2018) 141-151. https://doi.org/10.1007/s13203-018-0202-0.
34] E. Kumaran, W. K. Leong, Organometallics 34 (2015) 1779-1782.
https://doi.org/10.1021/om501253v.
[
[35] H. Walet, Helv. Chim. Acta. 77 (1994) 608-614.
https://doi.org/10.1002/hlca.19940770303.

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Declaration of interests
☒
The authors declare that they have no known competingfinancialinterests orpersonal
relationships thatcould have appeared to influence the work reported in this paper.
☐
The authors declare the followingfinancial interests/personal relationships which may be
considered as potential competinginterests:

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A heterogeneous catalytic and solvent-free approach to 1,2-
dihydroquinoline derivatives from aromatic amines and alkynes
by tandem hydroarylation-hydroamination
Vasu Amrutham, Agliullin Marat Radikovich, Naresh Mameda, Krishna Sai Gajula, Nellya
Gennadievna Grigor’eva, Kutepov Boris Ivanovich, Venugopal Akula, Narender Nama*
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Solvent-free conditions
Cascade reaction (tandem)
Heterogeneous catalyst
19 entries, up to 90% yield
ASM
+
R = Alkyl, halo and Benzyl
1
R = Aromatic

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Mesoporous aluminosilicate (ASM) was well prepared by the sol-gel method.
ASM showed good activity to create 1,2-dihydroquinolines in solvent-free conditions.
Possibility of the catalytic way are presented with a range of amines and alkynes.
The desired products were obtained in decent yields.
A probable mechanism is anticipated for the production of 1,2-dihydroquinolines.