An Efficient Mesoporous Cu-Organic Nanorod for Friedl?nder Synthesis of Quinoline and Click Reactions

Article abstract of DOI:10.1002/cctc.201900860

Within the green chemistry context, heterogeneous catalysis for the synthesis of N-heterocycles from renewable resources using non-precious metals has garnered great interest in terms of economic and environmental perspectives. Herein, we present a triazine functional hierarchical mesoporous organic polymer (HMOP) with nanorod morphology together with large BET surface area ～1218 m² g^?1, huge pore volumeγτ“;6 mL g^?1 and dual micro/mesopore architectures. Subsequent Cu-coordination with nitrogen atoms of the HMOP provides a robust catalyst (Cu-HMOP) to accomplish multi-step cascade reactions for preparation of N-heterocycles by different routes. For instance, the Cu-HMOP efficiently catalyzes one-pot sequential multi-step oxidative dehydrogenative coupling of 2-aminobenzyl alcohol with diverse aromatic ketones to afford corresponding quinolines in excellent isolated yields (up to 97 %). Secondly, the present catalyst exhibits good aerobic oxidative dehydrogenation activity of amines to imines. Thirdly, for “click” reaction involving azides-alkynes, the Cu-HMOP produced quantitative yield for 1,4-disubstituted 1,2,3-triazole derivatives at room temperature using water as solvent. Verification of active metal leaching by a hot filtration test as well as reusability of the retrieved Cu-HMOP catalysts shows a consistent activity in the multi-component quinoline synthesis as model reaction.

Full text of DOI:10.1002/cctc.201900860

Accepted Article
Title: An efficient Cu−mesoporous organic nanorod for Frieldländer
quinoline synthesis, aerobic oxidative dehydrogenation, and click
reactions
Authors: Elavarasan Samaraj, Asim Bhaumik, and Sasidharan
Manickam
This manuscript has been accepted after peer review and appears as an
Accepted Article online prior to editing, proofing, and formal publication
of the final Version of Record (VoR). This work is currently citable by
using the Digital Object Identifier (DOI) given below. The VoR will be
published online in Early View as soon as possible and may be different
to this Accepted Article as a result of editing. Readers should obtain
the VoR from the journal website shown below when it is published
to ensure accuracy of information. The authors are responsible for the
content of this Accepted Article.
To be cited as: ChemCatChem 10.1002/cctc.201900860
Link to VoR: http://dx.doi.org/10.1002/cctc.201900860
A Journal of
www.chemcatchem.org

10.1002/cctc.201900860
ChemCatChem
FULL PAPER
An efficient Cumesoporous organic nanorod for Frieldländer
quinoline synthesis, and click reactions
Samaraj Elavarasan,[a] Asim Bhaumik,[b] and Manickam Sasidharan*[a]
Abstract: Within the green chemistry context, heterogeneous
catalysis for the synthesis of N-heterocycles from renewable
resources using non-precious metals has garnered great interest in
terms of economic and environmental perspectives. Herein, we
material chemistry.[2] In recent past, the tandem CC and CN
bond forming reactions using cheap, abundant alcohols as
coupling reagents have been effected with borrowing hydrogen
or hydrogen autotransfer (BH/HA) approach.[3] In this context,
Milstein and co-workers reported acceptorless dehydrogenative
coupling of alcohols and amines to prepare imines.[4] Since then,
several precious-metals based catalytic systems have been
investigated extensively under homogeneous conditions.[5]
Recently, intensive efforts were also devoted to replace noble
metal catalysts by affordable, environmentally friendly earth-
abundant base metals to accomplish N-heterocycles.[6] To
synthesis N-heterocyclic compounds, several research groups
including Beller, Kempe, Milstein, and Sato have demonstrated
efficient Ir, and Ru based organometallic complexes by coupling
the secondary alcohols, diols, and primary alcohols.[7] Initially,
noble-metal supported mesoporous silica like MCM-41, SBA-15,
porous zeolitic Cu-based metal organic frameworks (MOF) with
2-aminoaryl ketones were investigated for Friedländer
reaction.[8a-c] Later on, Ru-complex mediated quinoline synthesis
was reported by the group of Shim, Yus, and Verpoort via
indirect Friedländer protocol involving oxidative cyclization of
2aminobenzyl alcohol with either ketone or alcohols.[8d-f]
Recently in 2016, Yan, Barta, Milstein and co-workers have
introduced Fe, Co, and Mn based homogeneous catalysts to
improve the sustainability by using inexpensive and widely
abundant first row transition metals (Scheme 1).[9]
present
a triazine functional hierarchical mesoporous organic
polymer (HMOP) with nanorod morphology together with large BET
1
1
surface area 1218 m2g , huge pore volume  6 mL.g and dual
micro/mesopore architectures. Subsequent Cu-coordination with
nitrogen atoms of the HMOP provides a robust catalyst (Cu-HMOP)
to accomplish multi-step cascade reactions for preparation of N-
heterocycles by different routes. For instance, the Cu-HMOP
efficiently catalyzes one-pot sequential multi-step oxidative
dehydrogenative coupling of 2-aminobenzyl alcohol with diverse
aromatic ketones to afford corresponding quinolines in excellent
isolated yields (up to 97%). Secondly, the present catalyst exhibits
good aerobic oxidative dehydrogenation activity of amines to imines.
Thirdly, for “click” reaction involving azides-alkynes, the Cu-HMOP
produced quantitative yield for 1,4-disubstituted 1,2,3-triazole
derivatives at room temperature using water as solvent. Verification
of active metal leaching by a hot filtration test as well as reusability
of the retrieved Cu-HMOP catalysts shows a consistent activity in
the multi-component quinoline synthesis as model reaction.
Introduction
The surge in the development of sustainable and atom-
economical synthetic methodologies involving cascade organic
synthesis is a fundamental challenge in chemical research.[1]
Even more demanding is the advancement of heterogeneous
catalysts based on base metals or metal oxide due to its facile
product/catalyst separation, prospects of catalyst reusability, and
environmental benignity. Accordingly, tremendous research
efforts have been focused on new synthetic methodologies to
design specific catalysts that enable the preparation of highly
valuable N-heterocycles preferably in an atom-economical and
sustainable
fashion.
Amines
and
nitrogen-containing
heterocycles such as pyridines, quinolines, and pyrimidines are
ubiquitous in biologically active core structures of many naturally
occurring and biologically active molecules which are
extensively used in pharmaceuticals, agrochemicals, and
[a]
[b]
Mr. S. Elavarasan, Prof. Dr. M. Sasidharan
SRM Research Institute and Department of Chemistry, SRM
Institute of Science and Technology, Kattankulathur, Chennai,
603203, India.
E-mail: sasidharan.m@res.srmuniv.ac.in
Prof. Dr. A. Bhaumik
Scheme 1. Comparison of our work with recent reports on the synthesis of N-
heterocycles and imines using different catalysts
School of Materials Science, Indian Association for the Cultivation of
Science, Jadavpur, Kolkata-700032, India.
In an alternate approach for achieving N-heterocyclic
compounds, aerobic dehydrogenation of amines to imines via
homocoupling, cross-coupling as well as (partially) saturated N-
heterocyclic compounds as a complementary atom economical
route was explored. In this strategy, several homogeneous
Supporting information for this article is given via a link at the end of
the document.
This article is protected by copyright. All rights reserved.

10.1002/cctc.201900860
ChemCatChem
FULL PAPER
catalysts
such
as
[Rh2(caprolactamate)4],
[Cp*Ir(2-
nanoparticles also displayed good catalytic activity in alkyne–
azide click cycloaddition reaction under mild conditions.[18]
Herein, we report a new triazine functional hierarchical
mesoporous organic polymer (HMOP) platform through the
polymerization of cyanuric chloride and melamines with nanorod
morphology possessing high BET surface area 1218 m2g1 and
hydroxypyridine)], Fe(NO3)3/TEMPO, Fe/Co-pincer complexes,
and FeCl2/DMSO have been investigated to obtain quinolines
albeit with moderate yield under homogeneous conditions.[10]
The oxidative dehydrogenation has also been reported with
Ru/Al2O3, Ru/Co3O4, Rh/MWCNT, and FeOx@N-rGO under
heterogeneous conditions to prove their efficacy.[11] Similarly, for
aerobic dehydrogenation of amines to imines, precious metal
based catalysts such as Pd, Pt, Au,[12a-f] Ru,[12g] metal organic
frameworks,[12h], α-MnO2[12i] and photocatalysts like TiO2[12j] were
investigated. However, most of these catalytic systems rely on
noble metals, or either have cumbersome preparation methods
or require the use of harsh reaction conditions like high
pressure/temperature, light irradiation, and use of oxidative
promoters. Therefore, development of inexpensive and facile
catalytic system for dehydrogenative transformations is highly
desirable. Yet another strategy to achieve N-heterocyclic
compounds, is the “click” chemistry pioneered by Sharpless and
Meldal, which involves the Cu(I) catalyzed [3+2] cycloadditon
between terminal alkynes and azides.[13] Apart from the Cu-
catalysts, other transition metals like Ag, Ru, Ir, etc. have also
been extensively investigated to obtain 1,2,3-triazoles and its
derivatives.[14] In order to improve the catalytic activity, a co-
catalyst such as bases, auxillary ligands, and oxidizing or
reducing agents depending on the Cu sources is often employed.
Hence, the development of novel heterogeneous catalysts with
improved catalytic activity devoid of any additives or ligands is
quite important to meet the sustainability. In this context,
immobilization of homogeneous Cu ions onto various
heterogeneous supports like hyper-crosslinked polystyrene,
zeolites, activated carbons, N-heterocyclic carbene (NHC)-
modified silica, and MOFs has been reported.[15]
Recently, porous organic polymers (POP) have garnered
considerable attention because of their potential applications in
catalysis, gas separation, and sensors.[16] Owing to their high
surface area, robust organic framework, and viability for
functional group modification, porous polymers received great
attention as a versatile platform in the field of heterogeneous
catalysis. Despite of these advantages, the design of porous
organic networks is often challenging and requires special
ligands such as benzylamine, 2,2'-bipyridine or 4-
diphenylphosphinostyrene etc. which limits the scope of these
class of materials. Hence, exploration of a simple but facile
protocol to create active sites on the solid support is quite critical.
These POPs have outstanding properties over the already well-
established inorganic silicate polymer with respect to molecular
design flexibility to form various architectures, high surface area,
and their stability against polar solvents. In this context,
chemical process involving condensation of primary amine with
carbonyl group of the aldehydes to form an imine or Schiff base
is known to be beneficial for the interaction of polar gases or
metal ions. In this perspective, Cu(I) supported over styrene-
huge pore volume
 6
mL.g1 with dual micro/mesopore
architectures. The present new Schiff base network serves as
an efficient support due to abundance N sites for effective Cu-
chelation (Cu-HMOP) that provides a ligand-free catalyst system
to be used in diverse organic catalysis. Herein, we demonstrate
for the first time, Cu-HMOP effectively catalyze multi-step
cascade reaction of 2-aminobenzyl alcohol and aromatic
ketones to diverse quinolines and aerobic dehydrogenation of
partially (saturated) N-heterocyclic compounds to the
corresponding heteroaromatics as well as aerobic oxidation of
amines to imines (Scheme 1). The efficacy of the present Cu-
HMOP also scrutinized for “click” chemistry to synthesize 1,2,3-
triazole derivatives using water as green solvent at room
temperature.
Results and Discussion
3.1. Catalyst characterization.
The triazine-based polymer was synthesized by modified
literature report.[19] The cyanuric chloride effectively condenses
with melamine monomer in a three dimensional network in
presence of KOH to give polymer network comprising of
exclusive triazine units connected through NH functionality.
Fig.1 exhibits the powder XRD patterns of Cu-HMOP and the
appearance of diffraction peaks at 24.3° and 43.9° corresponds
to (002) and (101) planes, respectively, similar to amorphous
carbon materials. The prominent reflection at 43.9° of HMOP
confirms the hexagonal C3N3 structure similar to the literature
report.[20]
based
polymeric
beads,
dimethylaminomethyl
grafted
polystyrene/divinylbenene resin (Amberlyst 21), melamine and
tetraphathalaldehyde have been explored for “click reaction”
under heterogeneous conditions.[17] Supported cuprous oxide
Fig. 1. X-ray diffractogram of hierarchical mesoporous organic polymer
(HMOP) and Cu-loaded HMOP (Cu-HMOP).
This article is protected by copyright. All rights reserved.

10.1002/cctc.201900860
ChemCatChem
FULL PAPER
The presence of a rather broad XRD peak feature at
A relatively sharp distribution curve centered at 2.2 nm and a
rather broad peak at 5.0 nm in diameters are obvious. The
narrow pores of 2.2 nm could have originated from the
intermolecular condensation between cyanuric chloride and
melamine units to form micropores in short range order;
whereas mesopores could have originated from the cross-linking
of interlayers, interparticle’s voids as well as incomplete
condensation between the triazine subunits. The Brunner-
Emmet-Teller (BET) surface area was found to be 1218 m2g1
with huge pore volume  6 mLg1 as evaluated from N2 sorption
isotherms at P/P0 = 0.99. These dual pore architecture and
robust textural properties are expected to promote facile
diffusion of reactants and products during the catalytic reactions.
Fig. 3B exhibits sorption measurements of Cu-HMOP (after Cu-
24.3° is attributed to the amorphous nature of polymer with
exclusive hexagonal benzene-like triazine (C3N3) network.[21]
The occurance of sharp reflections at 15.9, 17.0, 32.3, 33.1, and
40.3° suggest the existence of Cu species in the Cu-HMOP
polymer (Fig.1). Fig.S1 (electronic supplementary, ESI†) shows
a typical magnified TEM image of HMOP with nanorod or plate
like morphological features with 100 nm length and 30 nm
breath. High-resolution TEM micrograph of Cu-HMOP (Fig.2a-b)
clearly confirms a sheet-like or nanotube-like morphology with
plenty of mesopores in the range of 3‒7 nm in diameter. Fig.
2c-d confirms the presence of lattice fringes corresponding Cu
metal with high degree of Cu dispersion in the triazine
constructed polymer (Fig. 2c). The appearance of concentric
bright spots against smooth background in the electron
diffraction pattern (ED) further correlate the high crystallinity of
Cu in the amorphous polymer network. To confirm the
mesopores observed in TEM micrographs, we further employed
N2 adsorption/desorption measurements of HMOP and Cu-
HMOP.
complexation); a Type IV isotherm is clearly evident at P/P0

0.4 and the mesopores become poly-dispersed in the range of
3-8 nm but the micropores located at 2.2 nm is relatively
unchanged. Besides, the BET surface area and pore volumes
were reduced to 550 m2g1 and 0.52 mL.g1, respectively. All
these textural properties involving reduction in the pore volume
and BET surface area clearly confirms the presence of Cu inside
the pores as well as channels of polymer networks.
Notably, N2 isotherm plots shown in Fig. 3A of HMOP
obviously exhibits a characteristic Type I plateau up to P/P0

0.3 indicating the presence of micropores of size below 2 nm. In
depth inspection of adsorption/desorption isotherms revealed a
narrow hysteresis loop at partial pressure P/P0  0.3 and a
prominent hysteresis loop (Type IV) is appeared at P/P0 0.8-0.9
suggesting the presence of large mesopores in the polymer
networks. The pore size features (Fig.3A, inset) were further
obtained using the desorption branch of the isotherm employing
Barret-Joyner-Halenda (BJH) model.[22]
Figure 3. N2 adsorption/desorption isotherms and BJH pore size distributions
(inset figure) of pristine HMOP (A) and (B) Cu-HMOP.
The X-ray photoelectron spectroscopy (XPS) was
employed to investigate the composition of various elements
present in the pristine HMOP (Fig. S2A, ESI†). The survey
spectrum of pristine HMOP material shows the presence of C, N,
and O; the C 1s spectrum can be deconvoluted into two peaks,
where the signal at 283.6 eV is ascribed to the sp2-hybrized C-N
bond present in the aromatic rings. The second high energy
peak located at 286 eV that stem from the sp2-hybridized C in an
aromatic ring attached to side arm –NHR groups (Fig. S2B,
ESI†).[23,24] The N 1s signal exhibits a single broad peak which
can be deconvoluted into two signals located at 397.5 and 398.6
eV caused by pyridinic and urotropine-like N in a nitrogen-rich
environment[23] which represent a nitrogen in triazine unit and
bridging –NH‒, respectively (Fig. S2c, ESI†). The full XPS
survey spectrum of Cu-HMOP (Fig. 4A) displays the presence of
C, N, Cu, O, and Cl elements in the Cu-HMOP. After Cu loading,
the intensity of the signal at 286 eV corresponding to sp2-
hybridized C of aromatic ring attached to –NHR is just reversed
(Fig. 4B) unlike pristine polymer indicating that the –NHR‒
interacts effectively with Cu(II) ions.
Figure 2. TEM micrographs of Cu-HMOP: (A) Nanorods at low magnification,
(B) Magnified single strand, (C) HRTEM image showing lattice fringe of Cu-
complex, and (D) Electron diffraction pattern.
This article is protected by copyright. All rights reserved.

10.1002/cctc.201900860
ChemCatChem
FULL PAPER
Similar to pristine HMOP, the Cu-loaded counterpart
was an effective base for oxidative cyclization in presence of O2
(Table 1, entries 25). Among the different solvents scrutinized
(Table 1, entries 2, 69), the multistep cascade reaction
proceeds smoothly with non-polar solvent like toluene and thus,
toluene was used for further investigation. Screening of reaction
temperatures (Table 1, entries 2,1012) indicated that 130 °C is
the optimal temperature to attain high reactant conversion and
product selectivity. By lowering the reaction time (entries 13 &
14) or catalyst loading (entries 15 & 16) under identical reaction
conditions decreased the yield of the quinoline. Further,
optimization for Cu-grafted catalyst was achieved with 15 wt%
(entry 2). The reactions performed without base or catalyst
shows N 1s XPS signals corresponding to pyridinic and –NH‒
bridging group in the polymer (Fig. 4C). The XPS signals at
932.0 eV, and 952.4 eV are due to the two types of Cu species
assigned to the strong spin-orbit coupling of Cu 2p3/2 and Cu
2p1/2 which are in good agreement with the literature report.[25]
Table 1. Reaction optimization using Cu-HMOPa
Base /
Entry
Catalyst Wt.%
solvents /
temperature
no base
t-BuOK
KOH
K2CO3
Et3N
DMF
ethanol
H2O
acetonitrile
120 °C
110 °C
90 °C
t-BuOK
t-BuOK
t-BuOK
t-BuOK
t-BuOK
t-BuOK
t-BuOK
t-BuOK
Time, h
Yield, %
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19b
20c
15
15
15
15
15
15
15
15
15
15
15
15
15
15
10
24
24
24
24
24
24
24
24
24
24
24
24
18
12
24
24
24
24
24
24
Nil
96
77
21
trace
68
42
23
28
79
54
23
76
73
84
30
21
29
26
44
Figure 4. XPS spectra of Cu-HMOP: (A) Survey spectrum, (B) C 1s spectrum,
(C) N 1s spectrum and (D) Cu 2p spectrum.
The other two low intensity peaks at 939.8 and 960.6 eV (Fig.
4D) might be due to newly formed Cu–N and Cu–Cl bonds on
the polymer surface.[26] The survey spectrum also clearly
indicates the presence of Cl atom from the appearance of a
signal at 200 eV, which is mainly due to the strong spin-orbit
coupling of Cl 2p3/2 and Cl 2p1/2. Thus the XPS studies clearly
reflect that –NHR- and triazine network effectively complexes
with Cu(II) chloride on the polymer surface, which could serve as
an efficient catalyst for organic transformation. The amount of
Cu estimated by XPS analysis was found to be 1.1 wt% and
further analysis for trace metals by ICP showed 1.24 wt%
copper in the Cu-HMOP material.
5
No catalyst
Pristine polymer
15
15
[a]Reaction conditions: 2-aminobenzyl alcohol, (1, 1.0 mmol),
acetophenone, (2a, 1.10 mmol), Base (0.25 mmol) and toluene (2.0 mL)
were stirred at 130 °C unless otherwise noted. [b]Under Argon. [c]Under
air.
3.2. Activity of Cu-HMOP in quinoline synthesis
did not afford the desired product (Table 1, entries 1 & 17),
whereas 29% of quinoline was obtained using the HMOP
polymer (entry 18). The yield of quinoline was reduced when the
reactions was performed in argon or air atmosphere (Table 1,
entries 19 & 20).
With the optimized reaction conditions in hand for the
cascade synthesis of quinoline, we next examined the substrate
scope of various substituted ketones (2ao) having electron-
donating and electron-withdrawing groups with 2-amino benzyl
alcohol 1 as summarized in Table 2. When the R2‒, R3‒, and
R4‒ functionalities on the aromatic ring was appended with
electron-donating groups such as 4-Et-Ph (2c), 4-Me-Ph (2d), 4-
MeO-Ph (2e), 4-EtO-Ph (2f), 3,4-di-MeO-Ph (2g), 2,5-di-MeO-Ph
(2h) and 3,4,5-tri-MeO-Ph (2i) the reaction underwent smooth
conversion to afford the desired quinoline derivatives 3c-3i in
We first examined the efficacy of Cu-HMOP catalytic
system for dehydrogenative oxidative coupling to synthesize
quinoline derivatives, an alternative to conventional
homogeneous Frieldländer quinoline synthesis.[27] Elena Pérez-
Mayoral and Miroslav Polozij have synthesized quinoline using
Cu-catalyst from 2-aminoaryl ketones and aldehydes with 41 -
99% yield[28] Inspired by the catalytic activity of Cu-species, we
have investigated 2-aminobenzyl alcohols as precursor to afford
quinolines by aerobic oxidation of alcohols followed by
cyclization. Treatment of 1 (1.0 mmol) with slight excess of 2
(1.1 mmol) in presence of catalytic Cu-HMOP and tBuOK as
base in toluene (2.0 mL) at 130 °C resulted in 96% isolated yield
of quinoline after 24 h without any traces of side products (Table
1, entry 2). Screening of different bases indicated that t-BuOK
This article is protected by copyright. All rights reserved.

10.1002/cctc.201900860
ChemCatChem
FULL PAPER
89%-95% yields. On the other hand, When the R2‒ and R3‒
functionalities on the aromatic ring was appended with halogen
derivatives such as 4-Cl-Ph (2j), 4-Br-Ph (2k), 4-F-Ph (2l), 4-F-2-
Me-Ph (2m) and 2,3-di-Cl-Ph (2n), the reaction proceeded
smoothly to produce the desired quinolines in 65%-82% yields.
pathway A, the reaction proceed through three step sequence (i)
Schiff base formation 16a; (ii) amine-enamine tautomerization
17a; (iii) intramolecular annulation 18 and dehydration. In
pathway B, the reaction proceeds through a base catalyzed
intermolecular aldol adduct 17b followed by water elimination
The electronic nature of the substitutents such as ethyl, methoxy, and intramolecular condensation reaction. Based on previous
ethoxy, and halides on the aromatic ring of ketones had less
effect over the quinoline formation (Table 2, 3a-i). The potential
steric nature of di- or trisubstituted groups on aryl ketones did
not hamper the oxidative cyclization to the corresponding
quinoline derivatives (Table 2, 3g-3i). Noteworthy feature of this
theoretical studies, aldolic condensation is quite feasible than
the initial imine formation, hence pathway B would be more
favorable to form quinolines from the intermediate 15.[27,28]
Table 2. Quinoline synthesis using various aryl ketones and 2-aminobenzyl
alcohol over Cu-HMOP[a]
Scheme 2. Plausible reaction pathway for formation of quinoline by oxidative
dehydrogenation using Cu-HMOP.
3.3. Cu-HMOP catalyzed aerobic dehydrogenative coupling
The coupling reaction was first surveyed with different
solvents of varying polarity and the toluene emerged as the best
solvent (Table S1, ESI†, entries 1-4). A series of experiments
with different temperatures ranging from 110-140 °C (Table S1,
ESI†, entries 1, 5-7) revealed that 130 °C as critical temperature
for achieving a maximum yield of imines (94% isolated yield).
Using toluene solvent at 130 °C, the optimal reaction time was
found to be 30 h to attain maximum conversion and selectivity
(Table S1, ESI†, entries 1, 8-11). The gradual increase in
activity with catalyst loading (Table S1, ESI†, entries 1, 12,13)
suggests that the present catalyst system is not suffering from
adsorption/desorption governed mass transfer limitation. Both
the pristine polymer (HMOP) and absence of catalysts, led to
lower yields signifying the importance of catalysts in the aerobic
dehydrogenative coupling (Table S1, ESI†, entries 14, 15). To
probe the role of oxidant, the reaction was carried out under
argon atmosphere instead of O2. Interestingly, decreased
conversion was observed, indicating the importance of oxygen in
the reactions (Table S1, ESI†, entry 16). However, the air
ambience shows moderate activity (Table S1, ESI†, entry 17)
than that of pure O2 (entry 1). Therefore, after extensive
screening of various reaction parameters, we chose aerobic
conditions using toluene at 130 °C as the optimal reaction
conditions for further investigation. With the above optimized
reaction conditions for N-benzylidene benzylamine (5a, Table 3,
reaction A), the substrate scope was verified for reactions
involving homo-coupling, cross-coupling, and unsaturated
[a] Reaction conditions: 2-aminobenzyl alcohol (1, 1.0 mmol), aryl ketones
(2a-o, 1.10 mmol), base (0.25 mmol) and toluene (2.0 mL) was stirred at 130
oC.
methodology is that the sterically hindered, m,pdimethoxy,
o,m,ptrimethoxy, o,pdichloro, and o,pdimethoxy derivatives
gave excellent yields (82-96%). To our delight, propiophenone
(2b) and 1,3dioxalone-substituted arylmethyl ketones (2o) also
gave complete conversion to generate the corresponding
products in 91-97% (Table 2, 3b and 3o).
Based on the previous literature reports, a plausible
reaction mechanism is proposed as depicted in Scheme 2. The
initial oxidation of o-aminobenyl alcohol 1 with catalytic Cu-
HMOP in the presence of oxygen gave the o-amino
benzaldehyde intermediate 15. Subsequent reaction of
intermediate 15 with acetophenone 2a generated the desired
Friedlander product 3a in two possible pathways (A & B). In the
This article is protected by copyright. All rights reserved.

10.1002/cctc.201900860
ChemCatChem
FULL PAPER
heterocyclic compounds. Table 3, runs 5a‒5d show the catalytic
aerobic oxidation of various benzylamines bearing 4-Me-Bn (4b),
4-F-Bn (4c) and 4-Cl-Bn (4d) substituents with excellent yields
(90%-94%). The electron withdrawing as well as donating
groups had marginal impact ( 5% conversion under otherwise
identical conditions).
With the excellent activities of Cu-HMOP mediated homo-
coupling, we further scrutinized the feasibility of this present
protocol in the synthesis of un-symmetrical imines synthesis
(Table 3, reaction B). Reactions between benzylamine and
different substituted anilines were carried out to achieve
unsymmetrical imines (Table 3, runs 8aa-8ae). The presence of
electron-donating groups such as 4-MeO-Ph (7b), 3-MeO-Ph
(7c) and 4-n-Bu-Ph (7d) had less impact on the product
selectivity (83-93%, 8ab-8ad). When the functionality was
electron withdrawing group like 3,4-di-Cl-Ph (7e), the reaction
produced 80% yield. Further varying benzylamine functionalities
1,2,3,4-tetrahydroquinoline
readily
underwent
smooth
conversion with excellent isolated yield (84%, 10a). Similarly,
indoline leads to high yield (78%, 10b) under identical conditions
indicating the robustness of present catalytic protocol. More
importantly, the catalyst is highly suitable for compounds
containing electron lone pairs on oxygen atom like ‒OMe which
gives impressive yield of 81% (10c) that can be interpreted as a
measure of the susceptibility of the catalytic efficiency to
substitutent effects.
Based on the preceding literature reports for
dehydrogenative imine formation over the metal-complexes and
metal-oxides,[12h,j] herein, a plausible reaction mechanism is
proposed as shown in Scheme 3. Initial oxidation of compound
4a in the presence of Cu-HOMP followed by the benzylic proton
elimination gave the zwitterion intermediate 20. Then the
oxidation of the intermediate 20 and a proton elimination
resulted in the key imine intermediate 22. Subsequent hydrolysis
of intermediate 22 produced the oxidation compound 23. Next,
the coupling of aldehyde 23 with another molecule of benzyl
amine obtained the desired homo-coupled imine compound 5a.
Table 3. Aerobic oxidative dehydrogenation of amines by homocoupling, and
cross-coupling over Cu-HMOPa.
Scheme 3. (A,B) Aerobic oxidative dehydrogenative homo- and cross-
coupling and (C) dehydrogenative aromatization of heterocycles.
[a] Reaction conditions: Amines (4a-d, 9a-c 1.0 mmol) and Toluene (2.0 mL)
was stirred at 130 °C for 30 h. bDMF (2.0 mL)
On the other hand, when a two-component reaction was
introduced with aniline as a substrate under the same reaction
conditions, the cross-coupled imine was obtained through the
intermediate 24. A similar oxidative strategy was employed for
the synthesis of quinoline 10a from tetrahyroquinoline as the
substrate under the standard reaction conditions.
like electron-donating groups such as 4-Me-Bn (4b), 2-MeO-Bn
(4e) and halogen group like 2-Cl-Bn (4f) in cross-coupling
reaction produced good yields 92%, 85% and 90%, respectively.
The present Cu-HMOP catalyst protocol is even better than the
mesporous Cs/MnOx (77% maximum yield) catalysts.[29]
The scope of current methodology is also extended to N-
containing aromatic heterocycles (Table 3, reaction C). The
This article is protected by copyright. All rights reserved.

10.1002/cctc.201900860
ChemCatChem
FULL PAPER
3.4. Cu-HMOP catalyzed [3+2] cycloaddition of terminal alkynes
and azides
Electron withdrawing functionalities like 3-F-Ph (11b) and
4-Cl-Ph (11c) afforded slightly lower yields 86% & 88% (14ba &
14ca) as compared to 99% (14aa) without any substituents.
Similarly, 4-MeO-Ph (11d), 4-Me-Ph (11e), and 4-t-Bu-Ph (11f)
also led to good yields in the range of 77-91% (14da-14fa). More
importantly, aliphatic derivative such as propargyl alcohol
reacted under optimized reaction condition to give the
corresponding product in 63% selectivity (14ga). Entries 14ab-
14af show the effect of various substitutents present on the
aromatic ring of benzyl halide and exhibit pronounced decrease
in the yield (65-78%) unlike influence of substituents on terminal
alkynes as mentioned above. For instance, the 4-F-Bn (13b), 4-
NO2-Ph (13c), and 4-CF3-Ph (13d) afford moderate yield 69-78%
(14ab-14ad), attributed to the electronic effect of strongly
electron withdrawing nature. Similarly, the electron donating 4-
Me-Ph (13e), and 4-PhO-Ph (13f) substituents (14ae, 14af) also
led to lower yield despite its electron-donating nature and the
lower yield is partly ascribed to the steric nature of aromatic
rings. More importantly, the aliphatic substrates like iso-propyl
(13g), n-propyl (13h) derivative, and simple sodium azide (12)
gave the corresponding 1,2,3-triazole derivatives (14ag-14ai) in
good to excellent yields.
A plausible reaction pathway for the Cu-HOMP-catalysed
three-component click chemistry was proposed as shown in
Scheme 4.[30] In-situ reduction of Cu(II)-HOMP using
trimethylamine gave the active Cu(I) species, which on further
reaction with phenyl acetylene produced the copper acetylide
intermediate 29. Reaction of intermediate 29 with in-situ
generated azide (from benzyl halide) afford the 1,4-
regioselective vinyl copper species 32 via alkyne-azide click
cyclization. Protolysis of intermediate 32 resulted in the desired
triazole 14aa and the active catalyst was regenerated for the
next catalytic cycle.
Encouraged with the catalytic performance of previous
reactions, we have also extended the utility of present Cu-
HMOP catalytic protocol for synthesis of 1,2,3-triazole (14aa) by
three component system comprising terminal alkynes, sodium
azides, and benzyl halides involving in-situ alkyl/arylazide
generation followed by [3+2] cycloaddition (Table S2, ESI†).
Preliminary control experiments with
a mixture of phenyl
acetylene (1.0 mmol), benzyl halides (1.10 mmol), and sodium
azide (1.50 mmol) in presence of triethylamine base (0.10 mmol)
and water at room temperature resulted in 99% yield for 14aa
(run 3). Further optimization with various bases and solvents,
proved water as the best solvent at room temperature in
presence of triethylamine as an ideal base (runs 2-8). Next,
screening of reaction duration as well as catalyst loading under
standard conditions (runs 9-12) indicated 10 wt% critical catalyst
loading with 18 h reaction time to achieve high conversion and
good product selectivity. Notably, the absence of base as well as
pristine HMOP polymer under identical conditions lead to poor
yield, (35 & 8% for runs 1 & 14) and no reaction was observed in
the absence of catalyst (run, 13). Next, using the above
optimized reaction conditions involving water as green solvent at
room temperature, we have explored the scope of this protocol
for the synthesis of 1,4-disubstituted-1,2,3-triazoles. As shown in
Table 4, compounds 14aa-14ga show influence of substitutents
on phenyl-ring of alkynes over the [3+2] cycloaddition. Electron-
donating as well as electron withdrawing groups gave good to
excellent isolated yields (typically 63-99%).
Table 4. Click reactions of various substituted benzyl halides with different
alkynes over Cu-HMOP.[a]
Scheme 4. Proposed reaction pathway [3+2] cycloaddition of terminal alkynes
and azides using Cu-HMOP.
[a]Reaction conditions: Phenyl acetylene (11a-g, 1.0 mmol), benzyl halides (13a-
i), 1.1 mmol, sodium azide (12, 1.50 mmol), base (0.10 mmol) and H2O (5.0
mL) was stirred at room temperature for 18 h. bAlkyl halide (13a, 2.0 mmol),
sodium azide (12, 2.50 mmol). cReaction was stirred at 80 °C. dReaction carried
out only with sodium azide (12, 2.0 mmol).
3.5. Catalyst leaching test and recyclability
Catalyst deactivation possibly due to primary particles
agglomeration and leaching of active metals from solid matrix
into solution under operating conditions is often a challenge for
heterogeneous catalytic systems. Investigation of active metal
leaching was carried out from the reaction system involving
This article is protected by copyright. All rights reserved.

10.1002/cctc.201900860
ChemCatChem
FULL PAPER
2aminobenzyl alcohols (1) and acetophenone (2) to form
quinoline as model system under identical conditions (Fig. S3,
ESI†). In a typical hot-filtration leaching test reaction, the Cu-
HMOP solid catalyst was removed from the reaction system
after 10 h (35% conversion) and the reaction was continued
with filtrate under the same reaction conditions for another 14 h.
Analysis of the filtrate revealed no further progress in the
reaction. Furthermore, trace metal analysis of the filtrate by ICP
technique confirmed the absence of Cu in the solution phase
and therefore, catalysis by Cu-species in solution phase is safely
ruled out. To evaluate the reusability of Cu-HMOP for quinoline
synthesis as model reaction, the catalyst was separated from
the reaction mixture by centrifugation, washed thoroughly with
toluene and ethanol. Prior to each recycle runs, the catalyst was
reactivated at 100 °C in a vacuum oven for 6 h to remove any
surface adsorbed reactants/product molecules. It is seen from
Fig. S4, ESI†, the catalyst can be reused for a minimum of 5
trials albeit with a minor loss of 6% activity from its initial
performance. Furthermore, the re-used Cu-HMOP catalyst
retained a rod like morphology (Fig. S5, ESI†) after the liquid-
phase reaction. Hence, the present Cu-loaded triazine based
porous polymer serves as truly heterogeneous catalyst with high
active site stability.
Experimental Section
Materials and Methods
Cyanuric chloride, melamine, dimethyl sulfoxide (DMF) CuCl2.2H2O,
NaN3, triethylamine, KOH, K2CO3, and t-BuOK+ with AR grade were
purchased from Sigma-Aldrich and used without any further purification.
All solvents like hexane, ethylacetate, ethanol, and methanol were
obtained from Fisher scientific and used as received. Reaction progress
was monitored by thin-layer chromatography (TLC) using Merck 60 F254
pre-coated silica gel plate. Column chromatography separations were
performed using 100-200 mesh silica gel and ethylacetate/hexane
1
solvents as mobile phase. H and 13C NMR spectral data were acquired
on Bruker 500 MHz instrument. Powder X-ray diffraction (XRD) pattern
was recorded with a Bruker diffractometer (D8 Advance, Davinci) with
CuK rays (λ = 1.5418 Å). The morphology was explored using
transmission electron microscopic (HRTEM) images acquired with a
JEOL (JEM-2100 Plus) operating at 200 kV by coating test samples on a
copper grid. Specific surface area, pore size distribution, and pore
volume details were obtained from N2 sorption isotherms using autosorb
IQ series (Quantachrome Instruments).
Synthesis of hierarchical mesoporous organic polymer (HMOP) and Cu-
HMOP
In a typical synthesis of HMOP, melamine (5.0 mmol) dissolved in 100
mL DMSO was magnetically stirred using a 250 mL round bottom flask.
To the above content, cyanuric chloride (5.0 mmol) dissolved in DMSO
(100 mL) was added drop wise followed by the addition of KOH (10.0
mmol). The reaction mixture was heated to 160 °C for 24 h under a
refluxing condenser. After the completion of reaction, the precipitate was
filtered off, washed thoroughly with water and methanol to remove
solvent as well as unreacted precursors. The polymer was dried at 80 °C
for 24 h to obtain a hierarchical mesoporous organic polymer (HMOP).
For the synthesis of Cu-HMOP, an appropriate amount of CuCl2.2H2O
was dissolved in ethanol (10 mL) and 1.0 g HMOP was added to the
above solution and stirred vigorously for an hour. The resultant turbid
mixture was sonicated for 10 min followed by overnight stirring. Finally
the material was filtered off and washed thoroughly with water, ethanol,
and dried at 80 °C to obtain Cu-HMOP.
Conclusions
In summary, we have successfully demonstrated a nanoporous
hierarchical Cu-chelated porous organic polymer consisting of
exclusive triazine units (C3N3) connected through –NH groups as
robust catalysts for the synthesis of N-heterocycles by different
synthetic strategies. The robust textural properties, high BET
surface area ~1218 m2g1, huge pore volume  6 mL.g1 and
multimodal micro/mesopore architectures are expected to favor
high catalytic activity for the synthesis of N-heterocycles. The
Cu-HMOP efficiently catalyzed one-pot sequential multi-step
oxidative dehydrogenative coupling of 2-aminobenzyl alcohol
with diverse aromatic ketones to afford quinolines in excellent
yields (up to 97%). The Cu-HMOP/O2 catalyst system also
furnished excellent oxidative dehydrogenation activity of
(partially) saturated N-heterocycles to the corresponding
aromatic analogues and amines to imines. Scrutinization of Cu-
HMOP for “click” chemistry produced quantitative yield for
diverse 1,2,3-triazole derivatives at room temperature using
water as green solvent without any additives or ligands.
Verification of leaching of the active metal by a hot filtration test
as well as reusability of the retrieved Cu-HMOP catalysts
suggested its sustainable catalytic activity in the multi-step
quinoline synthesis. All experimental results demonstrated the
robustness of present Cu-HMOP catalyst in terms of versatility,
Synthesis of quinoline
A 60 mL pressure tube was charged with a magnetic bar, Cu-HMOP (15
wt%), t-BuOK (0.12 mmol), toluene (2.0 mL), 2-aminobenzylalcohol (1.0
mmol), and arylketones (1.10 mmol). Then the tube was purged with O2,
and stirred at 130 °C in a preheated oil bath for a period of 24 h. The
reaction mixture was diluted with ethylacetate (5.0 mL), filtered through
celite material, and washed with solvent. The combined solvent was
evaporated and the crude product was purified by column
chromatography technique using ethylacetate/hexane as an eluent
system.
Aerobic dehydrogenative coupling of amines
recovery/reusability,
heterogeneous catalysis.
and
potential
impact
in
green
A 60 mL pressure tube was charged with magnetic bar, Cu-HMOP (10
wt%), saturated amines (1.0 mmol), and Toluene (2.0 mL). Finally, the
tube was purged with O2, followed by stirring at 130 °C in a preheated oil
bath for 24 h. The reaction mixture was diluted with ethylacetate (5.0 mL)
filtered through celite bed and washed thoroughly. The collected solvents
were evaporated and the crude product was purified using column
chromatography technique with ethylacetate/hexane solvent system.
This article is protected by copyright. All rights reserved.

10.1002/cctc.201900860
ChemCatChem
FULL PAPER
Protocol for 1,2,3-triazole synthesis (Click chemistry)
A. Espinosa Jalapa, D. Milstein, J. Am. Chem. Soc. 2016, 138, 4298–
4301.
[6]
a) P. Daw, Y. Ben-David, D. Milstein, ACS Catal., 2017, 7, 7456–7460;
b) M. Mastalir, M. Glatz, N. Gorgas, B. Stöger, E. Pittenauer, G.
Allmaier, L. Veiros and K. Kirchner, Chem. - A Eur. J. 2016, 22, 12316–
12320.
In a typical synthesis, a 15 mL tube was charged with a magnetic bar,
Cu-HMOP (10 wt%), phenyl acetylene (1.0 mmol), benzyl chloride (1.10
mmol), sodium azide (1.50 mmol), and triethylamine (0.10 mmol) and
stirred at room temperature for 18 h using water as a solvent. After the
completion, ethylacetate (5.0 mL) was added to the reaction mixture and
the aqueous layer was separated and partitioned again with ethylacetate
(5mL x 2). Then the combined organic layer were dried over Na2SO4 and
evaporated, the resultant crude product was purified using column
chromatography with ethylacetate/hexane as the solvent system.
[7]
[8]
a) N. Deibl, K. Ament, R. Kempe, J. Am. Chem. Soc. 2015, 137,
12804–12807; b) S. Michlik, R. Kempe, Nat. Chem. 2013, 5, 140–144;
c) K. Iida, T. Miura, J. Ando, S. Saito, Org. Lett. 2013, 15, 1436–1439.
a) . Marco- ontelles, E. P rez-Mayoral, A. Samadi, M. do C. Carreiras,
E. Soriano, Chem. Rev., 2009, 109, 2652–2671; b) F. Domínguez-
Fernández, J. López-Sanz, E. Pérez-Mayoral, D. ek, R. M. Mart n-
Aranda, A. . pez-Peinado, . e ka, ChemCatChem, 2009, 1, 241–
243; c) E. Pérez-Mayoral, . e ka, ChemCatChem, 2011, 3, 157–159;
d) C. S. Cho, B. T. Kim, T.-J. Kim, S. C. Shim, Chem. Commun., 2002,
2576–2577; e) R. Martínez, D. J. Ramón, M. Yus, Eur. J. Org. Chem.
2007, 2007, 10, 1599–1605; f) H. Vander Mierde, P. Van Der Voort, D.
De Vos, F. Verpoort, Eur. J. Org. Chem. 2008, 2008, 9, 1625–1631.
a) T. Yan, K. Barta, ChemSusChem. 2016, 9, 2321–2325; b) D. Srimani,
Y. Ben-David, D. Milstein, Chem. Commun. 2013, 49, 6632-6634; c) B.
Pan, B. Liu, E. Yue, Q. Liu, X. Yang, Z. Wang, W. H. Sun, ACS Catal.
2016, 6, 1247–1253.
Leaching and recycling test
To study leaching of any active copper metal into solution, hot filtration
test was performed considering quinoline synthesis as a test reaction. As
described in section 2.3, an identical experiment was performed between
2-aminobenzylalcohol (1 mmol), and arylketones (1.1 mmol) for inital
period of 10 h by maintaining all other reaction parameters identical. The
catalyst was recovered from the reaction system and the filtrate was kept
under the same reaction conditions to further continue for 14 h. The
course of reaction was followed by monitoring conversion and product
formation using gas chromatography (GC). For catalyst recyclability test,
the catalyst recovered from the first reaction run between 2-
aminobenzylalcohol (1 mmol), and arylketones (1.1 mmol) was separated
by centrifugation, washed thoroughly with ethanol and acetone, dried in a
vacuum oven at 100 °C for overnight to remove any occluded organics
on the catalyst surface. The activated catalyst was reused for quinoline
synthesis as a model reaction for another 5 successive cycles under
identical conditions as described above experimental details.
[9]
[10] a) H. Choi, M. P. Doyle, Chem. Commun. 2007, 745-747; b) R.
Yamaguchi, C. Ikeda, Y. Takahashi, K. Fujita, J. Am. Chem. Soc. 2009,
131, 8410-8412; c) S. Chakraborty, W. W. Brennessel, W. D. Jones, J.
Am. Chem. Soc. 2014, 136, 8564-8567; d) E. Zhang, H. W. Tian, S. D.
Xu, X. Xx. Yu, Q. Xu, Org. Lett. 2013, 15, 2704-2707.
[11] a) F. Li, J. Chen, Q. H. Zhang, Y. Wang, Green Chem. 2008, 10, 553-
562; b) K. Kamata, J. Kasai, K. Yamaguchi, N. Mizuno, Org. Lett. 2004,
6, 3577-3580; c) D. V. Jawale, E. Gravel, N. Shah, V. Dauvois, H. Li, I.
N. N. Namboothiri, E. Doris, Chem. Eur. J. 2015, 21, 7039-7042; d) X. J.
Cui, Y. H. Li, S. Bachmann, M. Scalone, A. E. Surkus, K. Junge, C.
Topf, M. Beller, J. Am. Chem. Soc. 2015, 137, 10652-10658; e) K.
Mullick, S. Biswas, A. M. Angeles-Boza, S. L. Suib, Chem. Commun.
2017, 53, 2256-2259.
Acknowledgements
[12] a) J. R. Wang, Y. Fu, B. B. Zhang, X. Cui, L. Liu, Q. X. Guo,
Tetrahedron Lett. 2006, 47, 8293-8297; b) B. Zhu, M. Lazar, B. G.
Trewyn, R. J. Angelici, J. Catal. 2008, 260, 1-6; c) A. Grirrane, A.
Corma, H. Garcia, J. Catal. 2009, 264, 138-144; d) B. Zhu, R. J.
Angelici, Chem. Commun. 2007, 2157-2159; e) H. Yuan, W. J. Yoo, H.
Miyamura, S. Kobayashi, J. Am. Chem. Soc. 2012, 134, 13970-13973;
f) H. Yuan, W. J. Yoo, H. Miyamura, S. Kobayashi, Adv. Synth. Catal.
2012, 354, 2899-2904; g) A. Taketoshi, T. A. Koizumi, T. Kanbara,
Tetrahedron Lett. 2010, 51, 6457-6459; h) H. Huang, J. Huang, Y. M.
Liu, H. Y. He, Y. Cao, K. N. Fan, Green Chem. 2012, 14, 930-934; i) A.
Dhakshinamoorthy, M. Alvaro, H. Garcia, ChemCatChem. 2010, 2,
1438-1443; j) Z. Zhang, F. Wang, M. Wang, S. Xu, H. Chen, C. Zhang,
J. Xu, Green Chem. 2014, 16, 2523-2527; k) X. Lang, H. Ji, C. Chen, W.
Ma and J. Zhao, Angew. Chem. Int. Ed. 2011, 50, 3934-3937.
M. S. thanks Science & Engineering Research Board for their
research support (No. SB/S1/PC-043/2013).
Keywords: Click reaction • Dehydrogenation • Hierarchical
structures • Porous organic polymer • Quinoline synthesis
[1]
[2]
M. Butters, D. Catterick, A. Craig, A. Curzons, D. Dale, A. Gillmore, S.
P. Green, I. Marziano, J.-P. Sherlock, W. White, Chem. Rev. 2006, 106,
3002–3027.
a) A. R. Katritzky, C. A. Ramsden, E. F. V. Scriven, R. J. K. Taylor,
Comprehensive Heterocyclic Chemistry III; Elsevier, 2008; b) J. L.
McGuire, Pharmaceuticals: Classes, Therapeutic Agents, Areas of
Application; Wiley-VCH, 2000; c) J. A. Joule, K. Mills, Heterocyclic
Chemistry. In Heterocyclic Chemistry, 2010.
[13] a) H. C. Kolb, M. G. Finn, K. B. Sharpless, Angew. Chem. Int. Ed. 2001,
40, 2004-2021; b) V. V. Rostovtsev, L. G. Green, V. V. Fokin, K. B.
Sharpless, Angew. Chem. Int. Ed. 2002, 41, 2596-2599; c) C. W.
Tornoe, C. Christensen, M. Meldal, J. Org. Chem. 2002, 67, 3057-3064.
[14] a) J. McNulty, K. Keskar, Eur. J. Org. Chem. 2012, 2012, 5462-5470; b)
L Zhang, X. Chen, P. Xue, H. H. Y. Sun, I. D. Williams, K. B. Sharpless,
V. V. Fokin, G. C. Jia, J. Am. Chem. Soc. 2005, 127, 15998-15999; c)
M. M. Majreck, S. M. Weinreb, J. Org. Chem. 2006, 71, 8680-8683; d)
S. Ding, G. Jia, J. Sun, Angew. Chem. Int. Ed. 2014, 53, 1877-1880.
[15] a) N. L. Rosi, J. Eckert, M. Eddaoudi, D. T. Vodak, . Kim, M. O’Keeffe,
O. M. Yaghi, Science 2003, 300, 1127-1129; b) M. G. Schwab, B.
Fassbender, H. W. Spiess, A. Thomas, X. L. Feng, K. Mullen, J. Am.
Chem. Soc. 2009, 131, 7216-7217; c) I. Luz, F. X. Llabres ixamena, A.
Corma, J. Catal. 2010, 276, 6692-6702; d) S. Kaur, V. Bhalla, M.
Kumar, Chem. Commun. 2015, 51, 526-529; e) M. Susec, S. C. Ligon,
[3]
a) R. Grigg, T. R. B. Mitchell, S. Sutthivaiyakit, N. Tongpenyai, J. Chem.
Soc. Chem. Commun. 1981, 611-612; b) Y. Watanabe, Y. Tsuji, Y.
Ohsugi, Teterahedron Lett. 1981, 22, 2667-2670; c) K. Barta, P. C.
Ford, Acc. Chem. Res. 2014, 47, 1503-1512.
[4]
[5]
B. Gnanaprakasam, J. Zhang, D. Milstein, Angew. Chemie Int. Ed.
2010, 49, 1468–1471.
a) B. Saha, S. M. Wahidurrahaman, P. Daw, G. Sengupta, J. K. Bera,
Chem. - A Eur. J. 2014, 20, 6542–6551; b) J. Bain, P. Cho, A.
Voutchkova-Kostal, Green Chem. 2015, 17, 2271–2280; c) S. Wöckel,
P. Plessow, M. Schelwies, M. K. Brinks, F. Rominger, P. Hofmann M.
Limbach, ACS Catal. 2014, 4, 152–161; d) S. Ruch, T. Irrgang, R.
Kempe, Chem. - A Eur. J. 2014, 20, 13279–13285; e) D. Srimani, Y.
Ben-David, D. Milstein, Angew. Chemie Int. Ed. 2013, 52, 4012–4015;
f) A. Mukherjee, A. Nerush, G. Leitus, L. J. W. Shimon, Y. Ben David, N.
This article is protected by copyright. All rights reserved.

10.1002/cctc.201900860
ChemCatChem
FULL PAPER
J. Stampfl, R. Liska, P. Krajnc, Macromol. Rapid Commun. 2013, 34,
[23] P. Hammer, F. Alverez, Thin Solid Films, 2001, 398, 116-123.
938-943.
[24] E. Riedo, F. Comin, J. Chevrier, A. Bonnot, J. Appl. Phys. 2000, 88,
4365-4370.
[16] a) B. P. Biswal, H. D. Chaudhari, R. Banerjee, U. K. Kharul, Chem. Eur.
J. 2016, 22, 4695-4699; b) P. Kaur, J. T. Hupp, S. T. Nguyen, ACS
Catal. 2011, 1, 819-835; c) A. Modak, M. Nandi, J. Mondal, A. Bhaumik,
Chem. Commun. 2012, 48, 248-250; d) B. P. Biswal, H. D. Chaudhari,
R. Banerjee, U. K. Kharul, Chem. Eur. J. 2016, 26, 4695-4699; e) C.
Xie, J. L. Song, H. R. Wu, Y. Hu, H. Z. Liu, Y. D. Yang, Z. R. Zhang, B.
F. Chen B. X. Han, Green Chem. 2018, 20, 4655-4661.
[25] N. Fredj, T. D. Burleigh, J. Electrochem. Soc. 2011, 158, C104-C110.
[26] S. Payra, A. Saha, S. Banerjee, ChemCatChem. 2018, 10, 5468-5474.
[27] a) C.-C. Cheng, S.-J. Yan, Friendländer synthesis of quinoline in
Organic Reactions, John Wiley & Sons, Inc., Hoboken, NJ, USA, 1982,
37–201; b) C. S. Cho, W. X. Renb, S. C. Shim, Tetrahedron Lett. 2006,
47, 6781–6785.
[17] a) C. Girard, E. Onen, M. Aufort, S. Beauviere, E. Samson, J.
Herscovici, Org. Lett. 2006, 8, 1689-1692; b) Y. Kitamura, K. Taniguchi,
T. Maegawa, Y. Monguchi, Y, Kitade, H. Sajiki, Heterocyles 2007, 77,
521-532; c) O. S. Taskin, S. D. Silab, B. Kiskan, J. Weber, Y. Yagci,
Macromol. Chem. Phys. 2015, 216, 1746-1753.
[28] a) E. Pérez-Mayoral, Z. Musilová, . Gil, . Marszalek, M. Položi , P.
Nachtigall. . e ka, Dalt. Trans. 2012, 41, 4036-4044; b) M. Položi , E.
Pérez-Mayoral, . e ka, . Hermann and P. Nachtigall, Catal. Today,
2013, 204, 101–107.
[29] S. Biswas, B. Dutta, K. Mullick, C.-H. Kuo, A. S. Poyraz, S. L. Suib,
ACS Catal. 2015, 5, 4394–4403.
[18] D. Clarisse, P. Prakash, V. Geertsen, F. Miserque, E. Gravel, E. Doris,
Green Chem. 2017, 19, 3112-3115.
[30] a) S. Chassaing, A. S. S. Sido, A. Alix, M. Kumarraja, P. Pale, J.
Sommer, Chem. Eur. J. 2008, 14, 6713-6721; b) R. Kamat, S.
Yamaguchi, M. Kotani, K. Yamaguchi, N. Mizuno, Angew. Chem. Int.
Ed. 2008, 47, 2407-2410; c) V. V. Rostovtsev, L. G. Green, V. V. Fokin,
K. B. Sharpless, Angew. Chem. Int. Ed. 2002, 41, 2708-2711; d) F.
Himo, T. Lovell, R. Hilgral, V. V. Rostovtsev, L. Noodleman, K. B.
Sharpless, V. V. Fokin, J. Am. Chem. Soc. 2005, 127, 210-216.
[19] J. Zhang, Z. Wang, L. Li, J. Zhao, J. Zheng, H. Cui, Z. Zhu, J. Mater.
Chem. 2014, 2, 8179-8183.
[20] M. A. Hossain, Am. J. Nanosci. Nanotechnol. 2013, 1, 52-56.
[21] A. D. Faisal, A. A. Aljubouri, Int. J. Adv. Mater. Res. 2016, 2, 86–91.
[22] a) K.S.W. King, D.H. Everett, R.A.W. Haul, L. Moscow, R.A. Pierotti, J.
Rouquerol, T. Siemieniewska, Pure Appl. Chem. 1985. 57, 603-619; b)
S.J. Gregg, K.S.W. Sing, Adsorption, Surface Area and Porosity,
Academic Press, New York, 1982; c) S. K. Kundu, A. Bhaumik, ACS
Sustainable Chem. Eng. 2016, 4, 3697-3703.
This article is protected by copyright. All rights reserved.

10.1002/cctc.201900860
ChemCatChem
FULL PAPER
Entry for the Table of Contents
Layout 1:
FULL PAPER
Cu-hierarchical mesoporous organic
polymer (Cu-HMOP) with nanorod
morphology serves as an efficient
catalyst for Frieldländer quinoline
synthesis by one-pot sequential multi-
Samaraj Elavarasan, Asim
Bhaumik, and Manickam
Sasidharan*
Page No. – Page No.
step
oxidative
dehydrogenative
coupling of 2-aminobenzyl alcohol with
diverse aromatic ketones. The Cu-
HMOP also catalyze aerobic oxidative
dehydrogenation of amines to imines
and “click” reaction involving azides-
alkynes. Active metal leaching by a
hot filtration confirmed heterogeneous
nature of catalysts.
Title
This article is protected by copyright. All rights reserved.