Aggregates of perylene bisimide stabilized superparamagnetic Fe3O4 nanoparticles: an efficient catalyst for the preparation of propargylamines and quinolines via C-H activation

Article abstract of DOI:10.1039/c5cc05752c

Aggregates of the perylene bisimide derivative 3 act as reactors and stabilizers for the preparation of superparamagnetic Fe₃O₄ nanoparticles (NPs) which exhibit excellent catalytic efficiency in (i) A³-coupling and aldehyde free coupling reactions for the preparation of propargylamines and (ii) tandem intramolecular cyclization reaction for the synthesis of quinolines via C-H activation.

Full text of DOI:10.1039/c5cc05752c

View Article Online
View Journal
ChemComm
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: S. kaur, M. Kumar
and V. Bhalla, Chem. Commun., 2015, DOI: 10.1039/C5CC05752C.
This is an Accepted Manuscript, which has been through the
Royal Society of Chemistry peer review process and has been
accepted for publication.
Accepted Manuscripts are published online shortly after
acceptance, before technical editing, formatting and proof reading.
Using this free service, authors can make their results available
to the community, in citable form, before we publish the edited
article. We will replace this Accepted Manuscript with the edited
and formatted Advance Article as soon as it is available.
You can find more information about Accepted Manuscripts in the
Information for Authors.
Please note that technical editing may introduce minor changes
to the text and/or graphics, which may alter content. The journal’s
standard Terms & Conditions and the Ethical guidelines still
apply. In no event shall the Royal Society of Chemistry be held
responsible for any errors or omissions in this Accepted Manuscript
or any consequences arising from the use of any information it
contains.
www.rsc.org/chemcomm

Please do not adjust margins
Page 1 of 4
ChemComm
View Article Online
DOI: 10.1039/C5CC05752C
Journal Name
COMMUNICATION
Aggregates of Perylene bisimide stabilized superparamagnetic
Fe3O4 nanoparticles: An efficient catalyst for the preparation of
propargylamines and quinolines via C-H activation
Received 00th January 20xx,
Accepted 00th January 20xx
Sandeep Kaur, Manoj Kumar and Vandana Bhalla*
DOI: 10.1039/x0xx00000x
www.rsc.org/
Aggregates of perylene bisimide derivative 3 act as reactors and where electron rich hexaphenylbenzene moiety played an
stabilizers for the preparation of superparamagnetic Fe3O4 nanoparticles important role in enhancing the efficiency of NPs by stabilizing
(NPs) which exhibit excellent catalytic efficiency in i) A3-coupling and the lower oxidation states of iron during the coupling reaction.
aldehyde free coupling reactions for the preparation of propargylamines In continuation of this work, we were then interested to develop
ii) tandem intramolecular cyclization reaction for the synthesis of supramolecular assemblies for the preparation of magnetic NPs
quinolines via C-H activation.
which could be used for selective C-H functionalization. It has
been reported that catalytic systems having stronger Lewis
acidity exhibit better efficiency in C-H functionalization.5
Keeping this in mind, we envisaged that if we use an electron
deficient perylene bisimide (PBI) as scaffold,6 it may contribute
in enhancing the Lewis acidity of in situ generated NPs which
could then influence the catalytic efficiency of the system in the
reactions involving C-H activation. Thus, we designed and
Metal catalysed functionalization of carbon-hydrogen (C-H)
bond for the formation of carbon-carbon (C-C) bond is a fast,
economical and eco-friendly approach for development of
biologically active compounds and natural products.1 Till now,
many costly transition metal catalysts such as gold, silver,
indium complexes have been extensively used in these C-H
activation reactions.2 Though these catalytic systems contribute
towards atom economy yet utilization of costly metal as major
component of catalytic system remains a big hurdle towards the
development of greener and sustainable chemical industry.
Thus, during the last few years, enormous efforts have been
made to develop recoverable catalytic system having
environmentally benign and less expensive metal ions as major
component.3 In this direction, a variety of recoverable hybrid
catalytic systems having iron as one of the component have
been developed for activation of C-H bonds, however, iron
component in these systems has no practical contribution
towards efficiency of catalytic system and its role is limited to
make the separation easy.3b Thus, development of an
economical, recoverable and efficient catalytic system for
carrying out C-H activation under mild condition is still a
challenge.
synthesized PBI derivative
groups. The presence of imino and hydroxyl groups is expected
to enhance the a nity of derivative toward di erent metal
ions. Interestingly, derivative formed aggregates in mixed
3 having imino and hydroxyl
ffi
3
ff
3
aqueous media and exhibited “turn-on” response towards Fe2+
ions and during the sensing process, these assemblies served as
“not quenched” reactors as well as stabilizers for the generation
of superparamagnetic Fe3O4 NPs. The preparation of stable
Fe3O4 NPs is not a simple process as these NPs have strong
tendency to form aggregates and undergo degradation when
directly exposed to severe environmental conditions.7 In this
context, work being reported in this manuscript presents a facile
and simple approach for the preparation of stable Fe3O4 NPs
(Table S1, ESI†). To our pleasure, these in situ generated
magnetic Fe3O4 NPs worked as recoverable catalyst in i) nearly
solvent-free (100 μl of H2O/THF) one pot reaction of aldehyde,
alkyne, amine (A3-coupling) and aldehyde free coupling
reaction for preparation of propargylamines ii) tandem reaction
of aldehyde, alkyne, amine for preparation of quinoline
derivatives. To the best of our knowledge, this is the first report
where the same catalytic system has been used for the
preparation of propargylamines and quinoline derivatives. The
catalytic efficiency of the Fe3O4 NPs was found to be better
than the other catalytic systems reported in the literature for the
Recently, we developed supramolecular aggregates of
a
hexaphenylbenzene derivative which served as reactors and
stabilizers for the preparation of ferromagnetic α-Fe2O3
nanoparticles (NPs). These in situ generated NPs exhibit high
catalytic efficiency in Sonogashira cross coupling reactions4
Department of Chemistry, UGC Sponsored Centre for Advanced Studies-1, Guru
Nanak
Dev
University,
Amritsar-143005,
Punjab,
India.
E-mail:
vanmanan@yahoo.co.in
Electronic Supplementary Information (ESI) available: [Experimental details,
NMR and Mass Spectra]. See DOI: 10.1039/x0xx00000x
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 1
Please do not adjust margins

Please do not adjust margins
ChemComm
Page 2 of 4
COMMUNICATION
Journal Name
preparation of propargylamines and quinoline derivatives via
C-H activation (Table S2, S3 and S4, ESI†).
3
are more selective towards Fe2+ ions as compared to Fe3+ ions.
View Article Online
DOI: 10.1039/C5CC05752C
This selectivity may be due to more affinity of soft imino
The condensation of derivative 18 with β-hydroxy moiety towards relatively soft Fe2+ ions in comparison to hard
salicylaldehyde,
2
furnished derivative
was confirmed from its
3
in 88% yield (Scheme Fe3+ ions.10
1). The structure of derivative
3
spectroscopic and analytical data (Fig. S32-S34, ESI†).
(A)
Fe2+ (Equiv.)
35
(B)
0.47 nm
(111)
0
Fig. 1 (A) Fluorescence spectra of compound 3 (5 µM) showing the response to the Fe2+
ion (0-35 equiv.) in H2O/THF (3:7, v/v) mixture buffered with HEPES; pH = 7.05, λex
=
485 nm. (B) HRTEM image of Fe3O4 NPs showing the interplanar spacing.
Scheme 1 Synthesis of PBI based derivative 3; condition dry THF:MeOH (4:6), 80°C
We also carried out time-resolved fluorescence studies of
derivative
in the presence and absence of Fe2+ ions. In the
The photophysical behaviour of derivative
3 in THF and in
3
THF/H2O mixture with varying amounts of water fraction was
studied by UV-vis and fluorescence spectroscopy. It was
observed that on increasing the water fraction upto 30%, the
absorption and emission bands were red shifted (~5 nm) (Fig.
S1-S2, ESI†). These studies indicate the formation of J-
aggregates. The formation of J- aggregates was further
absence of ferrous ions major fraction of molecules decay
through faster pathway while in the presence of ferrous ions,
major fraction of molecules decay through slower pathway
which suggests the formation of ordered aggregated species
(Fig. S11, Table S5, ESI†).
The transmission electron microscopic (TEM) images of
confirmed by temperature dependent UV-vis and concentration
3
in presence of Fe2+ ions revealed the presence of
1
derivative
dependent H NMR studies (Fig. S3-S4, ESI†)
.
The scanning
3 in H2O/THF
nanorods (S12A-B, ESI†). The selected area diffraction
pattern11 (Fig. S12C, ESI†) and high resolution transmission
electron microscopic images (Fig. 1B and Fig. S12 D-G, ESI†)
confirm the presence of crystalline nanorods of Fe3O4 NPs.12
The powder X-ray diffraction and Raman-scattering studies of
the precipitates showed the presence of diffraction peaks
corresponding to Fe3O4 NPs12 (Fig. S13 and S14, ESI†). The
DLS studies showed the presence of NPs with average size of
20-40 nm (Fig. S15A, ESI†). The POM image of the derivative
electron microscopic (SEM) image of derivative
(3:7, v/v) showed the presence of spherical aggregates (Fig. S5,
ESI†).
The presence of imine and hydroxyl moieties in the derivative
prompted us to investigate its sensing behaviour toward
di
erent metal ions (Cd2+, Ba2+, Hg2+, Fe2+, Fe3+, Ni2+, Zn2+,
3
ff
Cu2+, Pd2+, Ca2+, Co2+, Ag+, Cr3+ and Al3+) as their
perchlorate/chloride/or both perchlorate and chloride salts by
UV-Vis and fluorescence spectroscopy in H2O/THF (3:7, v/v)
(Fig. S6A-B, ESI†). On gradual addition of Fe2+ ions (0-35
3
containing Fe3O4 NPs showed ordered morphology (Fig.
S15B, ESI†). The magnetic hysteresis measurements indicate
the superparamagnetic nature of Fe3O4 nanorods (Fig. S16,
ESI†).13
We believe that upon addition of ferrous ions to the solution of
aggregates of derivative 3, the ferrous ions interact with imine
equiv. within 270 minutes) to the solution of
3 (5 µM), a broad
absorption band in the near infrared (NIR) region was observed
which may be attributed to the intervalence charge transfer
(IVCT) transition, thus, indicating the coexistence of Fe3+ and
Fe2+ ions. The appearance of NIR band suggests the formation
of Fe3O4 NPs9 (Fig. S7, ESI†).
and hydroxyl moieties and get reduced to Fe (0) NPs which
were further oxidized to stable Fe3O4 NPs by taking up oxygen
Upon addition of Fe2+ ions (0-35 equiv.) to the solution of
from water. During this process aggregates of derivative
themselves get oxidised. The emission spectrum of derivative
3
3
derivative
534 nm (Ф = 0.85) and 575 nm (Ф = 0.42) was observed (Fig.
1A). Further, the excitation spectrum of compound in the
3, enhancement in the emission intensity of bands at
obtained in the presence of Fe2+ ions has the contribution of
3
presence of Fe2+ ions showed broad band in the near NIR
region which suggests that Fe3O4 NPs are also contributing
towards the emission enhancement at 534 nm (Fig. S8, ESI†).
Thus, the system being reported here shows Fe3O4 NPs induced
emission enhancement characteristics. The detection limit of
oxidised species of aggregates of derivative
3. To confirm the
oxidation of aggregates of derivative , we carried out their
3
fluorescence studies in the presence of tert-butyl hydroperoxide
a strong oxidizing agent. The fluorescence spectrum exhibited
the emission bands at 534 and 575 nm as observed in the
presence of Fe2+ ions (Fig. S17, ESI†). This result supports our
assumption regarding the formation of oxidised species of
aggregates of
S9, ESI†). We also tested the binding behaviour of aggregates
of derivative
toward other metal ions such as Fe3+, Cd2+, Ba2+,
3
for Fe2+ ions was found to be 28×10-8 M (Fig.
aggregates of derivative
prove the formation of Fe (0) NPs in the reaction, we studied
the reaction between aggregates of derivative and FeCl2 under
3 during the reduction process. To
3
Hg2+, Ni2+, Zn2+, Cu2+, Pb2+, Pd2+, Co2+, Ag+, Cr3+, and Al3+
ions but no significant change in fluorescence intensity was
observed (Fig. S10A-B, ESI†). However, in case of Fe3+ ions
15% enhancement was observed. Thus, aggregates of derivative
3
inert atmosphere by UV-Vis-NIR spectroscopy. The UV-Vis-
NIR spectrum of the solution showed the presence of bands at
2 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Please do not adjust margins
Page 3 of 4
ChemComm
Journal Name
COMMUNICATION
262 and 357 nm corresponding to Fe (0) NPs14 (Fig. S18, groups and aliphatic aldehydes reacted smoothly to furnish the
View Article Online
DOI: 10.1039/C5CC05752C
ESI†). After keeping the sample under air, absorption band desired products in excellent yields. The reaction condition is
corresponding to Fe3O4 NPs appeared. This study indicates the also tolerant to nitro functionality. It has been reported that
oxidation of Fe (0) NPs to Fe3O4 NPs. Further, we slowly reaction involving nitro benzaldehyde requires much longer
evaporated the solution of aggregates of derivative
3 containing time and high temperature to form 1-(1-(4-Nitrophenyl)-3-
NPs. After two days, precipitates were observed which were phenylprop-2-ynyl)piperidine in lower yield.18 Interestingly,
1
filtered and washed with THF. The H NMR of the residue so A3-coupling
of
4-nitrobenzaldehyde,
piperidine
and
obtained after evaporation of THF solution showed the phenylacetylene in toluene at 50°C in the presence of Fe3O4
disappearance of signal corresponding to hydroxyl group with NPs went smoothly to give the desired product (7d) in
upfield shifting of signals corresponding to imino and aromatic moderate yield. Furthermore, the nature of amines affected the
protons (Fig. S19 and Table S6, ESI).
Further, we studied the effect of temperature, concentration of time. The reactions involving pyrrolidine were faster and
rate of A3-coupling reactions in terms of yield and reaction
aggregates of derivative
3 and presence of additional reducing furnished the desired products in higher yields in comparison to
agent such as sodium hydroxide and methanol15 on the rate of those of piperidine and morpholine. Furthermore, we also
formation, size and shape of iron NPs. It was observed that at studied the effect of aromatic vs aliphatic alkynes and it was
high temperature, higher concentration of aggregates of found that aromatic alkyne is more reactive than aliphatic
derivative
3 and in the presence of additional reducing agents, alkyne.
Fe3O4
NPs
the NPs of bigger size were obtained but there was no change in
the shape of NPs (Fig. S20-25, ESI†). These results indicate
that under above mentioned conditions, Fe2+ ions undergo
reduction at faster rate, hence, higher number of reduced NPs
are generated which are responsible for furnishing nanorods of
bigger size. Interestingly, on switching the solvent from
H2O/THF (3:7, v/v) to THF, the formation of Fe3O4 NPs was
not observed (Fig. S26, ESI†). This study indicates the
importance of aggregates in the formation of NPs.
Solvent-free
r.t.
6a-
7a-j
4a-g
5a-c
4a, R1= -C6H5; 4b, R1= p- Cl C6H4; R1= 4c p- Br C6H4; R1= 4d, p- NO2 C6H4; R1= 4e, p- OMe
C6H4; 4f = p- Me C6H4; R1= 4g.-H.
5a: (n=2, X=CH2 piperidine), 5b: (n=1, X=CH2 pyrrolidine), 5c: (n=2, X=O morpholine)
6a, R2= -C6H5; 6b, R2 = -C (Me)2OH.
Scheme 2. Catalytic activity of in situ generated Fe3O4 NPs in synthesis of
propargylamine synthesis with reaction of various aldehyde, amines and alkynes
1
Having done all this, we then planned to examine the catalytic All the products were isolated and characterized by H NMR
efficiency of these in situ generated Fe3O4 NPs in A3-coupling spectroscopy (Fig. S35-S46, ESI). A tentative mechanism is
reaction via C-H activation for the preparation of proposed on the basis of our findings (Scheme S1, ESI†).
propargylamine derivatives which are important building Further, Fe3O4 NPs were separated from reaction mixture by
blocks for the preparation of various nitrogen-containing simple magnetic decantation (Fig. S27, ESI†) and could be
biologically active compounds and natural products.16 To reused for nine times without significant loss of catalytic
elaborate the catalytic efficiency of in situ generated Fe3O4 activity (Fig. S28, ESI†). The efficiency of the in situ generated
NPs, we chose three component coupling reaction between Fe3O4 NPs was also tested for model reaction. When the
benzaldehyde (1 mmol), piperidine (1.2 mmol) and amount of Fe3O4 NPs is 0.5 mole %, the yield is 89% in 3.5h
phenylacetylene (1.2 mmol) as the model reaction. We carried against 0% when the reaction is conducted without Fe3O4 NPs
out A3-coupling of model substrates by using 0.5 mol % of (Table S9, ESI†). Such an extremely low quantity of catalyst
Fe3O4 NPs as catalyst in the presence of different solvents such has never been successfully utilized for A3-coupling reactions
as tetrahydrofuran, acetonitrile, ethanol, and toluene. at room temperature before the present study.
Interestingly, in the presence of toluene and under solvent-free To evaluate the practical applicability of the in situ generated
conditions, desired products were obtained in excellent yields Fe3O4 NPs, we also carried out the A3-coupling reaction of
(Table S7, ESI†). Thus, we carried out further reactions either hexaphenylbenzene derivative 4h
,
pyrrolidine 5b and
under solvent-free conditions or in toluene. We also studied the phenylacetylene 6a. The reaction went smoothly to furnish the
model reaction using in situ generated nanorods of bigger size desired product 7k in 58% yield (Scheme 3). This study
(80-100 nm) as catalyst. The reaction was complete in 16 h and demonstrates the practical utility of in situ generated Fe3O4 NPs
desired product was obtained in 82 % yield (Table S8, ESI†). for carrying out A3-coupling reactions.
Thus, catalytic efficiency of in situ generated Fe3O4 nanorods
depend on the size of nanorods. Further, we studied the model
reaction in presence of bare Fe3O4 NPs.17 The reaction was
Fe3O4
NPS
complete in 24 h to furnish the desired product in 40 % yield
(Table S8, ESI†). This result highlights the importance of
6a
5b
4h
7k yield 58%
aggregates of derivative
3 in enhancing the catalytic efficiency
Scheme 3 Synthesis of compound 7k by A3-coupling reaction in the presence of in situ
of in situ generated NPs.
To expand the scope of this A3-coupling, various aldehydes,
generated Fe3O4 NPs (1 mol%)
alkynes and amines were used as substrates under the optimized In the next part of our work, we planned to examine the
reaction conditions (Scheme 2, Table S8). It was found that, catalytic efficiency of in situ generated Fe3O4 NPs in aldehyde
aryl aldehydes bearing electron-withdrawing and electron-rich free synthesis of propargylamines using aromatic amines. The
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 3
Please do not adjust margins

Please do not adjust margins
ChemComm
Page 4 of 4
COMMUNICATION
Journal Name
1
scope of reactions was further explored by using different p- reaction after 1.5 h and after usual workup, its H NMR was
View Article Online
substituted N, N-dimethyl aniline derivatives bearing electron recorded (Fig. S31, ESI†). The 1H NMR DofOtI:h1e0.r1e0a3c9t/iCo5nCCm0i5x7t5u2rCe
donating or electron withdrawing groups (Scheme 4, Table showed the signals corresponding to the quinoline derivative as
1
S10). All the products were isolated and characterized by H well as propargylamine derivative which confirms the presence
NMR spectroscopy (Fig. S47-S51, ESI†). Furthermore, the in of propargylamine intermediate in the reaction involving
situ generated Fe3O4 NPs could be reused upto six times in case synthesis of quinoline derivative (11b)
.
of reaction involving synthesis of derivative 9a without In conclusion, we utilized aggregates of derivative
3
as reactors
significant loss of their catalytic activity (Fig. S29, ESI†). A and stabilizers for the preparation of Fe3O4 NPs at room
plausible mechanism for aldehyde free propargylamine temperature. Further, in situ generated Fe3O4 NPs acted as
synthesis3b is given in scheme S2, ESI†.
efficient and reusable catalyst for i) one pot A3-coupling
reaction/aldehyde free coupling reaction for preparation of
propargylamines ii) for preparation of quinoline derivatives via
Fe3O4
NPS
C-H activation.
6a
Solvent-free
r.t.
We are thankful to SERB, New Delhi (ref. no.
EMR/2014/000149) for financial support and UGC, New Delhi
8a-e
9a-e
8a/9a, R = -H; 8b/9b, R = -Cl; 8c/9c, R = -Br; 8d/9d, R = -Me; 8e/9e, R = -OMe.
for UPE project. S.K. is thankful to DST INSPIRE for SRF.
Scheme 4. Catalytic activity of in situ generated Fe3O4 NPs in synthesis of
propargylamine (9a-e) under aldehyde free conditions.
Notes and References
Encouraged by these results, we planned to carry out tandem
three component coupling/hydroarylation/dehydrogenation
reactions of aldehyde, alkyne and aromatic amine for
construction of quinoline derivatives. The quinoline derivatives
are important due to their antibacterial, anti inflammatory,
antifungal and analgesic properties.19 Earlier, transition metal
mediated synthesis of quinolines has been reported using
various transition metals.20 However, most of these systems
suffer from prerequisite of strongly acidic or basic conditions
and high reaction temperature. Interestingly, the reaction
between benzaldehyde, aniline derivatives (10a-e) and
phenylacetylene in the presence of in situ generated Fe3O4 NPs
(200 μl, H2O/THF, 3:7, v/v) in toluene at 110°C resulted in the
formation of quinoline derivatives (11a-e) (Scheme 5, Table
S11).
1
J. Yamaguchi, A. D. Yamaguchi, and K. Itami, Angew.
Chem. Int. Ed., 2012, 51, 8960.
(a) C. Wei and C.-J. Li, J. Am. Chem. Soc., 2003, 125, 9584;
(b) C. Wei, Z. Li and C.-J. Li, Org. Lett., 2003, 5, 4473; (c)
Y. Zhang, P. Li, M. Wang, and L. Wang, J. Org. Chem.,
2009, 74, 4364.
(a) T. Zeng,W.-W. Chen, C. M. Cirtiu, A. Moores, G. Song
and C.-J. Li, Green Chem., 2010, 12, 570; (b) A. T. Nguyen,
L. T. Pham, N. T. S. Phan and T. Truong, Catal. Sci.
Technol., 2014, 4, 4281.
S. Pramanik, V. Bhalla and M. Kumar, Chem. Commun.,
2014, 50, 13533.
S. A. Girard, T. Knauber, and C.-J. Li; Angew. Chem. Int.
Ed., 2014, 53, 74.
T. Maeda and F.Wurthner, Chem. Commun., 2015, 51, 7661.
X. Huo, J. Liu, B. Wang, H. Zhang, Z. Yang, X. She and P.
Xi, J. Mater. Chem. A, 2013, 1, 651.
S. Kaur, M. Kumar and V. Bhalla, Chem. Commun., 2015,
51, 4085.
H. Yao and Y. Ishikawa, J. Phys. Chem. C, 2015, 119, 13224.
2
3
4
5
6
7
8
9
Fe3O4
NPs
10 S. Sen, S. Sarkar, B. Chattopadhyay, A. Moirangthem, A.
Basu, K. Dhara and P. Chattopadhyay, Analyst, 2012, 137
3335.
,
11a-e
6a
10a-e
4a
11 X. Shi, T. P. Thomas, L. A. Myc, A. Kotlyar and J. R. Baker
Jr, Phys. Chem. Chem. Phys., 2007, , 5712.
12 X. Zhang, Y. Niu, X. d. Meng, Y. Li and J. Zhao,
10a/11a, R = -H; 10b/11b, R = -Cl; 10c/11c, R = -Br; 10d/11d, R = -Me; 10e/11e, R = -OMe.
9
Scheme 5. Catalytic activity of in situ generated Fe3O4 NPs in quinoline synthesis
In the presence of both electron-withdrawing and electron-
donating groups on aniline, the reactions proceeded smoothly to
furnish the corresponding products in excellent yields. All the
products were isolated and characterized by 1H NMR
spectroscopy (Fig. S52-S56, ESI†). The in situ generated Fe3O4
CrystEngComm., 2013, 15, 8166.
13 P. Zhang, J. Guo and C. Wang. J. Mater. Chem., 2012, 22
,
21426.
14 K. Klačanová, P. Fodran, P. Šimon, P. Rapta, R. Boča, V.
Jorík, M. Miglierini, E. Kolek, and L’. Čaplovič, Journal of
Chemistry, 2013, 2013, Article ID 961629.
NPs could be magnetically separated and reused upto five times 15 D. Li and S. Komarneni, Z. Naturforsch, 2006, 61b, 1566.
16 M. Konishi, H. Ohkuma, T. Tsuno and T. Oki, J. Am. Chem.
Soc., 1990, 112, 3715.
17 H. E. Ghandoor, H. M. Zidan, M. H. Khalil and M. I. M.
Ismail, Int. J. Electrochem. Sci., 2012, 7, 5734
18 S. D. Dindulkar, B. Kwan, K. T. Lim and Y. T. Jeong, J.
Chem. Sci., 2013, 125, 101.
in case of 11a without significant loss of their catalytic activity
(Fig. S30, ESI†). Based upon these results, we propose that
Fe3O4 NPs interact with alkyne which on reaction with in situ
generated imine derivative (I) furnished propargylamine
intermediate (II), Intramolecular hydroarylation followed by air
oxidation of propargylamine intermediate (III) generated the
quinoline derivative (Scheme S3, ESI†). We believe that
19 R. Kharb and H. Kaur, Int. Res. J. Pharm., 2013, 4, 63.
20 (a) X. Zhang, B. Liu, X. Shu, Y. Gao, H. Lv, and J. Zhu, J.
Org. Chem., 2012, 77, 501; (b) Y. Wang, C. Chen, J. Peng,
and M. Li, Angew. Chem. Int. Ed., 2013, 52, 5323.
formation
of
propargylamine
intermediate
and
hydroarylation/oxidation reaction is a cooperative process. We
investigated the reaction between benzaldehyde, 4-chloro-
aniline (10b) and phenylacetylene (6a). We stopped the
4 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins