Synthesis, characterization, and biological evaluation of new heterocyclic systems 1, 2, 3-triazole-isoxazoline from eugenol by the mixed condensation reactions

Article abstract of DOI:10.1080/00397911.2020.1762224

We report the synthesis of new series of heterocyclic systems eugenol 1 derivatives by the mixed condensation reaction of 1,3-dipolar azide and the oxide of p-chlorophenylnitrile on the 4-allyl-2-methoxy-1-(prop-2-yn-1-yloxy)benzene 2. The mono and bicycloadducts, whose structure is homologous to compounds having a broad spectrum of activity, were obtained in good yields. The monocondensation reaction of azides on 4-allyl-2-methoxy-1-(prop-2-yn-1-yloxy)benzene 2 is completely chemoselective, regioselective and stereospecific. The condensation of nitrile oxide on 1,2,3-triazole monocycloadducts prepared was chemoselective and regioselective. The structure of all cycloadducts were characterized and confirmed by the ¹H, ¹³C, 2D nuclear magnetic resonance and mass spectrometry analysis. All the newly synthesized mono and bis-heterocyclic compounds have been selected for their antiproliferative activity against HT-1080 fibrosarcoma, A549 lung carcinoma, and MCF-7 and MDA-MB-231 breast carcinoma cell lines. Among the derivatives, only the compounds 4a, 4b, 5a, 5b, 5d, 5e and 5g showed significant cytotoxicity with IC₅₀ values ranging from 15.31 to 18.81 μM against HT-1080 cells, and 17.32 to 25.94 μM against the other cell lines.

Full text of DOI:10.1080/00397911.2020.1762224

Synthetic Communications
An International Journal for Rapid Communication of Synthetic Organic
Chemistry
ISSN: 0039-7911 (Print) 1532-2432 (Online) Journal homepage: https://www.tandfonline.com/loi/lsyc20
Synthesis, characterization, and biological
evaluation of new heterocyclic systems 1, 2, 3-
triazole-isoxazoline from eugenol by the mixed
condensation reactions
Abdelmaoujoud Taia, Mohamed Essaber, Ali Oubella, Abdeljalil Aatif,
Jacques Bodiguel, Brigitte Jamart-Grégoire, My Youssef Ait Itto & Hamid
Morjani
To cite this article: Abdelmaoujoud Taia, Mohamed Essaber, Ali Oubella, Abdeljalil Aatif,
Jacques Bodiguel, Brigitte Jamart-Grégoire, My Youssef Ait Itto & Hamid Morjani (2020):
Synthesis, characterization, and biological evaluation of new heterocyclic systems 1, 2, 3-triazole-
isoxazoline from eugenol by the mixed condensation reactions, Synthetic Communications, DOI:
10.1080/00397911.2020.1762224
To link to this article: https://doi.org/10.1080/00397911.2020.1762224
Published online: 06 May 2020.
Submit your article to this journal
Article views: 15
View related articles
View Crossmark data
Full Terms & Conditions of access and use can be found at
https://www.tandfonline.com/action/journalInformation?journalCode=lsyc20

V
R
SYNTHETIC COMMUNICATIONS
https://doi.org/10.1080/00397911.2020.1762224
Synthesis, characterization, and biological evaluation of
new heterocyclic systems 1, 2, 3-triazole-isoxazoline from
eugenol by the mixed condensation reactions
a
a
b
a
Abdelmaoujoud Taia , Mohamed Essaber , Ali Oubella , Abdeljalil Aatif , Jacques
c
c
b
d
Bodiguel , Brigitte Jamart-Gr eꢀ goire , My Youssef Ait Itto , and Hamid Morjani
a
Laboratory of Molecular Chemistry, Department of Chemistry, Faculty of Sciences Semlalia, University
b
of Cadi Ayyad, Marrakech, Morocco; D ꢀe partement de Chimie, Facult ꢀe des Sciences, Laboratoire de
c
Synth ꢁe se Organique et Physico-Chimie Mol ꢀe culaire, Marrakech, Morocco; Laboratoire de Chimie
Physique Macromol ꢀe culaire, UMR CNRS-Universit ꢀe de Lorraine 7375, Nancy Cedex, France;
d
BioSpectroscopie Translationnelle, BioSpecT - EA7506, UFR de Pharmacie, Universit ꢀe de Reims
Champagne-Ardenne, Reims Cedex, France
ABSTRACT
ARTICLE HISTORY
We report the synthesis of new series of heterocyclic systems
eugenol 1 derivatives by the mixed condensation reaction of 1,3-
dipolar azide and the oxide of p-chlorophenylnitrile on the 4-allyl-2-
methoxy-1-(prop-2-yn-1-yloxy)benzene 2. The mono and bicycload-
ducts, whose structure is homologous to compounds having a broad
spectrum of activity, were obtained in good yields. The monocon-
densation reaction of azides on 4-allyl-2-methoxy-1-(prop-2-yn-1-yloxy)
benzene 2 is completely chemoselective, regioselective and stereospe-
cific. The condensation of nitrile oxide on 1,2,3-triazole monocycload-
ducts prepared was chemoselective and regioselective. The structure
Received 2 February 2020
KEYWORDS
Cancer; cloves; cytotoxicity;
essential oil; eugenol; 123-
triazole; isoxazoline
1
13
of all cycloadducts were characterized and confirmed by the H, C,
D nuclear magnetic resonance and mass spectrometry analysis. All
2
the newly synthesized mono and bis-heterocyclic compounds have
been selected for their antiproliferative activity against HT-1080 fibro-
sarcoma, A549 lung carcinoma, and MCF-7 and MDA-MB-231 breast
carcinoma cell lines. Among the derivatives, only the compounds 4a,
4
b, 5a, 5b, 5d, 5e and 5g showed significant cytotoxicity with IC50
values ranging from 15.31 to 18.81 mM against HT-1080 cells, and
7.32 to 25.94 mM against the other cell lines.
1
GRAPHICAL ABSTRACT
CONTACT Abdelmaoujoud Taia
tatamajid@gmail.com
Laboratory of Molecular Chemistry, Department of
Chemistry, Faculty of Sciences Semlalia, University of Cadi Ayyad, PB. 2390, 40001, Marrakech, Morocco.
ß 2020 Taylor & Francis Group, LLC

2
A. TAIA ET AL.
Introduction
Eugenol [4-allyl-2-methoxyphenol] 1 is the main active component of clove oil (75-
[
1,2]
[3]
[3–7]
9
0%).
Eugenol 1 has several activities such as antimicrobials, antioxidants,
[
8,9]
[10]
[11]
antiviral,
anti-inflammatory,
antidiabetes and anti-leishmania.
This compound
is used in several domains such as pharmacology, agro alimentary, agricultural and
[
12,13]
cosmetics.
Previous studies have shown that several isoxazoline systems (Fig. 1), have a
[
14,15]
wide range of activities such as anti-HIV,
b-adrenergic receptor antagonistic
[
16]
[17]
[18]
properties,
fungal,
glycoprotein IIb/IIIa receptor antagonists,
anti-influenza virus,
anti-
[
19]
[20]
[21]
PTP1B inhibitory activity
and antimicrobial.
In another hand, many
[
22]
[23]
1
,2,3-triazole compounds, have shown various activities as antifungal,
anti-VIH,
[
24]
[25]
[26]
[27]
antiviral,
antibacterial
and anticancer.
Rakesh Maurya and al.
have synthe-
sized a serial of novel isoxazolines via 1,3-dipolar cycloaddition reaction of the nitrile
oxides on eugenol 1. The synthesized isoxazoline systems have important therapeutic
implications in neuropathological states induced by stress. Recently, Robson Ricardo
[
28]
Teixeira and al
have prepared 1,2,3-triazole systems derived from eugenol 1 (Fig. 2).
These compounds showed significant antileishmanial activity and selectivity index
[
28]
superior to those of pentamidine and glucantime.
In order to synthesize new heterocyclic systems similar to the potentially active prod-
[
22,28]
ucts described in the literature,
we were interested in the synthesis of their analogs
[
29,30]
by the reaction of the 1,3-dipolar mixed condensation.
This condensation involves
grafting firstly a triazole ring on one of two sites dipolarophiles of the 4-allyl-2-
methoxy-1-(prop-2-yn-1-yloxy)benzene 2, initially prepared by a simple O-alkylation
reaction of eugenol 1, then integrate the isoxazoline ring on the second dipolarophile
site (Fig. 3).
The synthesized compound 2 is chosen as a base skeleton for the preparation of
[
27,28]
some derivatives analogous to the active compounds previously described.
It has
two dipolarophilic sites, double and triple carbon-carbon bonds, intended to be targeted
for 1,3-dipolar cycloaddition reactions.
For the biological activity, all the 1,2,3-triazole derivatives and the hybrid compounds
(triazole-isoxazoline) newly synthesized from natural compound eugenol 1 have been
Figure 1. isoxazoline system.
Figure 2. 1,2,3-triazole system.

V
R
SYNTHETIC COMMUNICATIONS
3
Figure 3. 1,2,3-Triazolo-isoxazolinic system derived from eugenol 1.
Scheme 1. O-alkylation procedure of eugenol 1.
developed for their in vitro anticancer activities against HT-1080 fibrosarcoma, A549
lung carcinoma, and MCF-7 and MDA-MB-231 breast carcinoma cell lines.
Results and discussion
To synthesize new 1,2,3-triazole-isoxazoline biheterocyclic systems, we first extracted
the eugenol 1 from the cloves by hydrodistillation via a cleavinger apparatus. The
eugenol 1 obtained was purified by silica gel column chromatography and identified by
1
13
H and C NMR spectroscopies. Then, the purified eugenol 1 was subjected to an O-
alkylation reaction using the phase transfer catalysis (PTC) in the presence of propargyl
bromide and tetrabutylammonium bromide as a catalyst. The reaction residue was puri-
fied by column chromatography on silica gel using hexane-ethyl acetate (94:6) as eluent
and the 4-Allyl-2-methoxy-1-(prop-2-yn-1-yloxy)benzene 2 was obtained in an excellent
yield of 90% (Scheme 1).
The 1,3-dipolar monocondensation of 3a–g azides, initially prepared by the proce-
[
9]
dures used in the literature depending on the nature of the halide compound and the
[
31]
amine,
on the 4-allyl-2-methoxy-1-(prop-2-yn-1yloxy)benzene 2 at reflux in aceto-
[
32–36]
nitrile in the presence of copper iodide
as a catalyst leads to the formation with a
good yield (78–90%) of a single type of monocycloadduct 4a–g (Scheme 2) (Table 1). It
results from the condensation of the dipole azide on the carbon-carbon triple bond of
the propargyl moiety. Note that, in all cases, we did not detect the formation of a cyclo-
adduct resulting from the condensation on the carbon-carbon double bond of the vinyl
group regardless of the amount of dipole used. The cycloaddition 1,3-dipolar reaction
of azides on the dipolarophile 2 is then chemoselective because only the carbon-carbon
triple bond is affected by the azides 3a–g.
1
13
This monocondensation was confirmed by the spectral analysis of NMR ( H & C)
1
and mass spectroscopy. Indeed, the H NMR of the product 4a revealed the disappear-
ance of signals at around 2.5 ppm attributed to the acetylenic proton and the appear-
ance of a peak at around 7.55 ppm corresponding to the proton of the ethylenically

4
A. TAIA ET AL.
Scheme 2. 1,3-dipolar cycloaddition of azides 3a–g on compound 2.
Table 1. Yields of 1,3-dipolar monocondensation of azides 3a–g on compound 2.
Compound
4a
4b
4c
4d
4e
4f
4g
R
PhCH
86
2
EtO
2
CCH
90
2
C
8
H
82
17
Ph
80
p-MeC
78
H
6 4
p-MeOC
88
H
6 4
p-O
2
NC
86
6 4
H
Yield(%)
Scheme 3. Structures of the regioisomers 4a–g I and II.
13
triazole ring. The appearance of peaks at around 123.62 ppm and 145.41 ppm in the
NMR spectrum are allocated respectively to the HC–N and the quaternary carbon of
,2,3-triazole ring. The molecular peaks of mass spectra of the various synthesized
C
1
monocycloadducts are in perfect agreement with their theoretical molecular weights.
The 1,3-dipolar cycloaddition reaction of the azides dipole 3a–g on the dipolarophile
site carbon-carbon triple bond of compound 2 can theoretically be done according to
two opposite approaches leading to the formation of two possible regioisomers I and/or
II of 4a–g products (Scheme 3).
To elucidate this regioselectivity problem, a 2 D nuclear magnetic resonance analysis
is essential to study the remote coupling between different protons. Indeed, the analysis
of the NOESY NMR spectrum of the product 4a (Fig. 4) shows the existence of a
through space correlation between H4 (7.55 ppm) and 2H1’ (5.50 ppm). A HMBC
experiment (Fig. 5) could also give this information by providing three bonds cross-
peak between the H4 and the carbon CH2 of the benzyl group or from the hydrogens
of the benzyl CH2 and the C4, for the structure I, while the structure II could only
have cross-peak between the hydrogens of the CH2 and the quaternary carbon of the
triazole ring thus confirming the regioselective formation of a single regioisomer I
(Fig. 6).

V
R
SYNTHETIC COMMUNICATIONS
5
Figure 4. NOESY NMR spectrum of the product 4a.
Figure 5. HMBC NMR spectrum of the product 4a.
The 1,3-dipolar monocondensation reactions of azides 3a–g on the dipolarophilic
site of the 4-allyl-2-methoxy-1-(prop-2-yn-1-yloxy)benzene 2 are highly chemoselec-
tive because only the carbon-carbon triple bond is affected by these dipoles. The car-
bon-carbon double bond appears unreactive. The 1,3-dipolar cycloaddition
[
32–36]
reaction of azide catalyzed by copper (I)
on the dipolarophilic site of the

6
A. TAIA ET AL.
Figure 6. Regioisomer I of compound 4a.
Scheme 4. 1,2,3-triazole-isoxazoline compounds 5a–g.
Table 2. Yields of compounds 1,2,3-triazol-isoxazoline 5a–g.
Compound
5a
5b
5c
5d
5e
5f
5g
R
CH
64
2
Ph
CH
2
CO
72
2
Et
C
8
H
62
17
Ph
58
p-C
6
H
54
4
Me
p-C
6
H
70
4
OMe
6 4 2
p-C H NO
Yield (%)
60
alkyne is regio and stereoselective. This result is in perfect agreement with the
[
37]
literature.
To synthesize new biheterocyclic systems such 1,2,3-triazole-isoxazoline homologous
to active compounds derived from eugenol 1, we examined the 1,3 dipolar reactions of
monocycloadducts 4a–g with nitrile oxide in situ generated from its precursor 4-chloro-
N-hydroxybenzimidoyl chloride. These reactions were carried out in the chloroform
ꢀ
solvent in the presence of sodium hypochlorite (24 ) (bleach) at low temperature
ꢀ
[38]
(0 C).
In all cases, we obtained a series of mixed cycloadducts which consist of two het-
erocycles 1,2,3-triazole and 4,5-dihydroisoxazole 5a–g. These new compounds result
from the condensation of the nitrile oxide in the dipolarophile site carbon-carbon,
vinyl group, of monocycloadducts 4a–g with good yields (54–72%) (Scheme 4)
(
Table 2).
The structures of all the new prepared compounds 5a–g were established by spectral
1
13
analysis of their H, C NMR and mass spectra.
1
The H NMR spectrum of the product 5a shows the disappearance of peaks assigned
to allylic protons and the appearance of two multiplets at about 2.80 and 3.25 ppm

V
R
SYNTHETIC COMMUNICATIONS
7
Figure 7. Possibles regioisomers III and IV of compounds 5a–g.
13
assigned to the two protons nonequivalent of the isoxazoline ring. The C NMR spec-
trum mainly shows the appearance of three peaks at about 41.24 and 82.80 ppm which
are respectively assigned to the carbon atom –CH and –CH–O of the isoxazoline sys-
2
tem. In addition, the peak at about 156.26 ppm corresponds to the quaternary carbon
atom –C¼N.
The 1,3-dipolar cycloaddition reaction of nitrile oxide on dipolarophile 4a–g is che-
moselective because only the carbon-carbon double bond of the vinyl group is affected,
the carbon-carbon and nitrogen-nitrogen double bonds of the triazole ring appear unre-
active toward the nitrile oxide. However, the condensation of the nitrile oxide com-
pound on the monocycloadducts 4a–g may lead to the formation of two regioisomers
III and/or IV (Fig. 7).
To determine the exact regioselectivity of these 1,3-dipolar condensations, we per-
formed a spectral analysis of NOESY NMR and HMBC NMR. Indeed, the 2 D NOESY
NMR analysis of the product 5a (Fig. 8) shows a correlation between 2H2
0
0
,6
(
7.54–7.57 ppm) and 2H (3.01–3.33 ppm).
4
Similarly, the HMBC NMR spectrum analysis of the product 5a (Fig. 9) shows a cor-
relation between the carbon C (156.26 ppm) with the protons 2H (7.54–7.57 ppm)
0
2’,6
1
’
and 2H (3.01–3.33 ppm).
4
These results confirmed that the structure of the bicycloadduct 5a is identical to that
of the isomer III (Fig. 10) which results from a regioselective condensation of the nitrile
oxide on the carbon-carbon dipolarophilic site of the double bond. This result is in per-
[
39]
fect agreement with the literature.
In vitro anticancer activity
In an attempt to determine the structure-activity relationship, we first have synthesized
a series of 1,2,3-triazole derivatives 4a–g. Then we have introduced a fixed function of
3
-(4-chlorophenyl)isoxazoline which has been reported to be important for the anti-
[
40]
cancer activity,
in order to verify whether this will increase the antitumor growth
inhibitory effect of the targeted hybrid products 5a–g. The in vitro anticancer activities

8
A. TAIA ET AL.
Figure 8. NOESY NMR spectrum of product 5a.
Figure 9. HMBC spectrum of product 5a.

V
R
SYNTHETIC COMMUNICATIONS
9
Figure 10. Regioisomer III of compound 5a.
Table 3. In vitro antiproliferative activity of the compounds 5a–g and 6a–g.
IC50 (mM)
Compound
HT1080
A549
MCF-7
MDA-MB-231
4
4
4
4
4
4
4
5
5
5
5
5
5
5
a
b
c
d
e
f
g
a
b
c
d
e
f
18.61
18.81
35.21
45.85
31.55
25.48
35.92
15.31
17.83
>50
16.93
18.64
21.09
18.03
4.96
21.15
22.64
41.20
31.50
27.02
21.87
30.21
17.32
21.08
29.51
18.02
22.15
29.34
21.62
6.36
25.91
25.32
30.25
34.31
38.09
35.92
27.92
20.92
18.93
>50
19.30
17.02
25.61
25.16
5.46
20.55
17.64
43.19
40.06
>50
29.33
36.51
23.51
23.92
45.15
22.64
25.94
23.19
20.99
5.13
g
Dox
of 4a–g and 5a–g were evaluated against HT-1080 fibrosarcoma, A549 lung carcinoma,
and MCF-7 and MDA-MB-231 breast carcinoma cell lines using MTT assay after 24 h
[
41]
treatment.
Doxorubicine (Dox) was used as a positive control and the IC50 values
were calculated and are presented in Table 3.
The cytotoxicity profile of the different compounds presented in Table 3 shows that
the majority of the tested molecules exhibited average growth inhibitory effects on all
cancer cells lines with IC50 values ranging from 15 to 45 mM. Among the synthesized
series (4a–g & 5a–g), monoadducts (4a & 4b) and bis-heterocyclic (5a, 5b, 5d, 5e, and
5
g) exhibited promising cytotoxicity effects with IC50 values ranging from 15.31 and
18.81 mM against HT-1080 cells. The same groups of molecules were less active with
IC50 values ranging from 17.32 to 25.94 mM against the A-549, MCF-7 and MDA-MB-
31 cell lines. There was an exception in cases of products 4a and 5a, that were the
2
most cytotoxic with identical an IC50 value corresponding to 17 mM against A549 and
MDA-MB-231 cell lines. Finally, the (4d, 4e, 4g and 5c) compounds were the less cyto-
toxic among all tested molecules with IC50 values over 35 mM.
Conclusion
In this work, we have described the synthesis and characterization of novel 1,2,3-triazole
and 1,2,3-triazole-isoxazoline systems derived from eugenol 1 similar to the active mole-
cules described in the literature. These heterocyclic compounds are obtained in good
yield by the mixed 1,3-dipolar condensation reaction. We show that the reaction of the
monocycloadadition of azides on 4-Allyl-2-methoxy-1- (prop-2-yn-1-yloxy) benzene 2 is

1
0
A. TAIA ET AL.
a regio and stereospecific reaction. However, the double condensation of nitrile oxide
was regioselective. These data are in agreement with the previous published data related
to 1,2,3-triazoles systems and isoxazolines derived from eugenol 1. The analytic data
allowed us to confirm the structures of the synthesized mono and bicycloadducts.
Concerning the biological activity, the mono and bis-heterocyclic derivatives (4a–g &
5
a–g) were active against fibrosarcoma cell line, and lung and breast carcinoma cell
lines. Only the hybrid compound 5a showed the highest anticancer activity against all
tumor cell lines with IC50 values between 15.31 and 23.51 mM.
Experimental section
All chemicals were used as obtained from commercial sources (Aldrich and Acros).
Melting points (m.p.) were determined using a capillary apparatus and are inaccurate.
Analytical thin-layer chromatography (TLC) was performed on plates precoated with E.
Merck silica gel 60 F254 to a thickness of 0.25 mm. HRMS were obtained on a Q-TOF
1
micromass spectrometer. All spectra were taken in CDCl operating at 300 MHz for H
3
1
3
and 75 MHz for C except 5g which was recorded in DMSO-d with Bruker Avance III
6
spectrometer with a BBFO þ probe. Chemical shifts (d) are expressed in parts per mil-
lion (ppm). They were recorded relative to the solvent CDCl signal (7.26 ppm and 77.
3
69 ppm). 5 g was recorded relative to the solvent DMSO-d6 signal (2.50 ppm
and 39.52 ppm).
Cell culture
The human fibrosarcoma cell line HT-1080 (CCL 121) was purchased from Sigma
Aldrich (ECACC collection, SaintQuentin Fallavier, France). The human breast adeno-
carcinoma MCF-7 (HTB-22) and MDA-MB-231(HTB-26); and lung carcinoma A549
(
(
CCL-185) cell lines were purchased from the American Type Culture Collection
ATCC). Cells were cultured in MEM (HT-1080) and DMEM (A549, MCF-7 and
MDA-MB-231) with Earle salts and Glutamax I (Invitrogen, Cergy-Pontoise, France)
supplemented with 10% fetal bovine serum, (Invitrogen) and 1% penicillin-streptomycin
ꢀ
(
Invitrogen). Cultures were maintained at 37 C in a humidified atmosphere containing
5
% CO (v/v). Cells were routinely passaged at preconfluency using 0.05% trypsin,
2
0.53 mM EDTA (Invitrogen) and screened for the absence of mycoplasma using
PCR method.
Isolation and identification of eugenol (1)
Dried cloves were ground into fine particles. The vegetable powder (100 g) is mixed
with 800 ml of water and then subjected for 4 h to hydrodistillation extraction using a
Clevenger apparatus. The obtained hydrosol was transferred to a separatory funnel and
the aqueous extract was extracted with dichloromethane (4 ꢁ 25 ml). The organic
extracts were combined, dried over anhydrous sodium sulfate, filtered and concentrated
under reduced pressure. 11 g (11%) of essential oil is obtained. 3 g of the resulting oil
was subjected to silica gel column chromatography eluted with hexane-ethyl acetate (6:
1) by volume. 2.2 g (73.3%) of eugenol 1 is obtained in pure form. Eugenol (1) has been

V
R
SYNTHETIC COMMUNICATIONS
11
1
13
identified by NMR spectral analyzes of H and C and which are perfectly similar to
those of commercial eugenol.
1
Yield: 90%; colorless oil. H NMR (300 MHz, CDCl ), d: 3.27 (d, 2H,J ¼ 6.6 Hz, CH ),
3
2
3
.76 (s, 3H, CH ), 5.01–5.07 (m, 2H, CH ), 5.88 (s, 1H, OH), 5.90–5.93 (m, 1H, CH),
3 2
6
.62–6.64 (m, 2H, ArH), 6.82 (d, 1H, J ¼ 4.5 Hz, ArH).
1
3
C NMR (75 MHz, CDCl ), d: 39.97 (CH ), 55.87 (CH ), 111.37 (CH), 114.58
3
2
3
(
(
CHarom), 115.56 (CH ), 121.29 (CHarom), 131.98 (Carom), 138.03 (CHarom),144.05
Carom), 146, 69 (Carom).
2
Synthesis of 4-allyl-2-methoxy-1-(prop-2-ynyloxy) benzene (2)
In a flask equipped with a magnetic stirrer, (0.5 g,3.04 mmol) of eugenol 1 and (15 mg)
of tetrabutylammonium chloride and sodium hydroxide solution (5%) are introduced.
(20 mL) of benzene as the solvent and (0.25 mL, 3.30 mmol) propargyl bromide are
added. The mixture was stirred at room temperature for 6 h. The mixture is extracted
three times with 15 mL of dichloromethane, The residue was purified by column chro-
matography on silica gel, eluent hexane-ethyl acetate (v/v ¼ 94/6). Coloress oil was iso-
lated (yield: 90%).
1
Yield: 90%; colorless oil. H NMR (300 MHz, CDCl ), d: 2.50 (t, 1H, J ¼ 2.4 Hz, CH),
3
3
5
.35 (d, 2H, J ¼ 6.3 Hz, CH ), 3.86 (s, 3H, OCH ), 4.73 (d, 2H, J ¼ 2.1 Hz, CH ),
2
3
2
.12–5.06 (m, 2H, CH ), 6.02–5.93 (m, 2H, CH), 6.75–6.74 (m, 2H, ArH), 6.99–6.96
2
13
(m, 1H, ArH). C NMR (75 MHz, CDCl ), d: 39.84 (CH ), 55.82 (CH ), 56.99 (CH ),
3 2 3 2
7
5.60 (C), 112.46 (CHarom), 114.90 (CHarom), 115.75 (CH ), 120.37 (CHarom), 134.28
2
(
Carom), 137.51 (CH), 145.19 (Carom), 149.76. (Carom). HRMS-ESI (m/z): calcd for
þ
C H NaO [M þ Na] : 225.0891, found: 225.0910.
1
3
14
2
General procedure for the preparation of the new 1,2,3-triazole (4a-g)
To a solution of the compound 2 (2.5 mmol) in anhydrous acetonitrile, azides 3a–g
(2.5 mmol) and 10 mg Copper (I) iodide (CuI) are added. The mixture was refluxed for
2
h. After cooling, the reaction mixture was extracted three times with dichloromethane.
The organic phase was dried with sodium sulfate and purified by column chromatog-
raphy on silica gel, eluent hexane-ethyl acetate (80:20). The resulting monocycloadducts
4
a–g are obtained with excellent yield.
4-(4-Allyl-2-methoxy-phenoxymethyl)-1-benzyl-1H-[1,2,3]triazole (4a)
ꢀ
1
Yield: 86%; white solid, mp: 89–91 C. H NMR (300 MHz, CDCl ), d: 3.31 (d, 2H,
3
J ¼ 6.6 Hz, CH ), 3.80 (s, 3H, OCH ), 5.03–5.10 (m, 2H, CH ), 5.24 (s, 2H, CH ), 5.50
2
3
2
2
(
7
(
s, 2H, CH ), 5.87–6.00 (m, 1H, CH), 6.66 (s, 1H, ArH), 6.68 (d, 2H, J ¼ 7.5 Hz, ArH),
2
13
.23–7.26 (d, 2H, J ¼ 9.3, ArH), 7.35–7.37 (m, 3H, ArH), 7.55 (s, 1H, CH). C NMR
75 MHz, CDCl ), d: 40.4 (CH ), 55.0 (CH ), 56.4 (CH ) 64.1 (CH ), 113.0 (CHarom),
3 2 2 3 2
1
15.5 (CHarom), 116.4 (CH ), 121.2 (CHarom), 123.6 (CHN), 128.8 (CHarom), 129.5
2
(
(
2CHarom), 129.8 (2CHarom), 134.7 (Carom), 134.9 (Carom), 138.1 (CH), 145.4 (C), 146.5
þ
Carom), 150.3 (Carom).HRMS-ESI (m/z): calcd for C H N NaO [M þ Na] : 358.1531,
20
21
3
2
found: 358.1560.

1
2
A. TAIA ET AL.
General procedure for the preparation of the new 1,2,3-triazole-
isoxazoline (5a–g)
In a flask equipped with a dropping funnel, (1.6 mmol) of p-chlorobenzaldoxime and
(
1.6 mmol) of the product 4a–g are dissolved in 10 ml of chloroform. The mixture is
ꢀ
stirred at 0 C with stirring for 10 min. 15 ml of a solution of sodium hypochlorite are
added dropwise. The mixture is allowed to stir magnetically at 0 C. Thereafter, 140 ml
of concentrated bleach (24 ) is added dropwise to the reaction mixture. After stirring
ꢀ
ꢀ
for 6 h, the reaction mixture is treated three times with 10 ml of dichloromethane and
then washed twice with 10 ml of water. The organic phase is dried with sodium sulfate
and the solvent is then evaporated off under reduced pressure. The residue is then puri-
fied by column chromatography on silica gel, eluent hexane-ethyl acetate (74:26).
5
-[4-(1-Benzyl-1H-[1,2,3]triazol-4-ylmethoxy)-3-methoxy-benzyl]-3-(4-chloro-
phenyl)-4,5-dihydro-isoxazole (5a)
ꢀ
1
Yield: 64%; white solid, mp: 124–126 C. H NMR (300 MHz, CDCl ), d: 2.83–3.05 (m,
3
2
2
7
H, CH ), 3.01–3.33 (m, 2H, CH ), 3.82 (s, 3H, CH ), 4.93–4.99 (m, 1H, CH), 5.24 (s,
2 2 3
H, CH ), 5.51 (s, 2H, CH2), 6.71–6.80 (m, 2H, ArH), 6.96 (d, 1H, J ¼ 8.1 Hz, ArH),
2
.24–7.27 (m, 2H, ArH),7.33–7.63(m, 5H, ArH), 7.54 (s, 1H, CH), 7.54–7.57 (m, 2H,
1
3
CH). C NMR (75 MHz, CDCl ), d: 39.88 (CH ), 41.24 (CH ), 55.12 (CH ), 56.58
3
2
2
2
(
CH ), 63.93 (CH ), 82.82 (CH), 113.77 (CHarom), 115.44 (CHarom), 122.10 (CHarom),
3 2
1
1
28.49 (CHN), 128.87 (CHarom), 129.56 (2 CHarom), 129.62 (CHarom), 129.83 (CHarom),
31.37 (Carom), 134.84 (Carom), 136.62 (CN), 147.12 (Carom), 150.36 (Carom), 156.26
þ
(CN). HRMS-ESI (m/z): calcd for C H ClN O [M þ H] : 489.1693, found: 489.1709.
2
7
26
4 3
Cytotoxicity assay
Cytotoxicity of the synthesized compounds was assessed by the CellTiter 96VR Non-
Radioactive Cell Proliferation Assay (MTT) (Promega, Charbonnieres les Bain, France).
Briefly, the cells were plated at a density of 2500 cells/well in a 96-well plates with
100 mL culture medium, containing different concentrations of the previously cited mol-
ecules (6.25, 12.5, 25 and 50 mM). After 24 h, 15 mL of MTT dye solution was added in
each well. The plates were further incubated for 4 h. Then, 100 mL of the solubilization/
stop solution was added into each well and the plate was incubated 1 h at room tem-
perature. The optical density of each well was measured at 570 nm using the microplate
reader Revelation 96-well multiscanner (Dynex Technologies, Chantilly, VA). Data were
represented as a percentage of cell growth relative to untreated cells. The IC50 was
defined as the drug concentration required for inhibition of cell growth by 50%.
References
[
1] Patra, A. K.; Saxena, J. Phytochemistry 2010, 71, 1198–1222. DOI: 10.1016/j.phytochem.
010.05.010.
2
[
2] Mailhebiau, P. La nouvelle aromath ꢀe rapie: caract ꢀe rologie des essences et temp ꢀe raments
humains: [biochimie aromatique et influence psychosensorielle des odeurs.], Jakin Ed.,
Lausanne, 1994.

V
R
SYNTHETIC COMMUNICATIONS
13
[
[
[
3] Eyambe, G.; Canales, L.; Banik, B. K. Heterocycl. Lett. 2011, 1, 154–157.
4] Hyang, N.; Moon-Moo, K. Food Chem. Toxicol. 2013, 55, 106–112.
5] Mahapatra, S. K.; Chakraborty, S. P.; Majumdar, S.; Bag, B. G.; Roy, S. Eur. J. Pharmacol.
009, 623, 132–140. DOI: 10.1016/j.ejphar.2009.09.019.
2
[6] Hidalgo, M. E.; De la Rosa, C.; Carrasco, H.; Cardona, W.; Gallardo, C.; Espinoza, L.
Quꢀım. Nova. 2009, 32, 1467–1470. DOI: 10.1590/S0100-40422009000600020.
7] Awasthi, P. K.; Dixit, S. C.; Dixit, N.; Sinha, A. K. J. Pharm. Res. 2008, 1, 215–220.
8] Sun, W. J.; Lv, W. J.; Li, L. N.; Yin, G.; Hang, X.; Xue, Y.; Chen, J.; Shi, Z. N. Biotechnol.
[
[
2
016, 33, 345–354. DOI: 10.1016/j.nbt.2016.01.001.
[9] Wang, C.-W.; Chan, C. H. Y.; Ho, R. T. H.; Chan, J. S. M.; Ng, S.-M.; Chan, C. L. W.
BMC Complement. Altern. Med. 2014, 14, 8–11. DOI: 10.1186/1472-6882-14-8.
[
10] Fons ^e ca, D. V.; Salgado, P. R. R.; Arag ~a o Neto, H. d C.; Golzio, A. M. F. O.; Caldas Filho,
M. R. D.; Melo, C. G. F.; Leite, F. C.; Piuvezam, M. R.; Pordeus, L. C. d M.; Barbosa
Filho, J. M.; et al. Int. Immunopharmacol. 2016, 38, 402–408. DOI: 10.1016/j.intimp.2016.
06.005.
[
11] de Morais, S. M.; Vila-Nova, N. S.; Bevilaqua, C. M. L.; Rondon, F. C.; Lobo, C. H.;
Moura, A. A. A. N.; Sales, A. D.; Rodrigues, A. P. R.; Figuereido, J. R.; Campello, C. C.;
et al. Bioorg. Med. Chem. 2014, 22, 6250–6255. DOI: 10.1016/j.bmc.2014.08.020.
12] Esp ꢀı ndola, J. W. P.; Silva, L. O.; Silva, D. R. C.; Nunes, V. H.; Costa, S.; Almeida, A. F.;
Melo, C. M. L.; Soares, E. C. L.; Ara uꢀ jo, J. M.; Pereira, V. R. A.; Brondani, D. J. Rev. Bras.
Farm. 2011, 92, 171–175.
[
[
[
[
[
[
[
[
[
13] Larghi, E. L.; Kaufman, T. S. J. Braz. Chem. Soc. 2006, 17, 599–1085. DOI: 10.1590/S0103-
5
0532006000300026.
14] Ichiba, T.; Scheuer, P. J.; Borges, M. K. M. J. Org. Chem. 1993, 58, 4149–4150. DOI: 10.
021/jo00067a062.
1
15] Srivastava, S.; Bajpai, L. K.; Batra, S.; Bhaduri, A. P.; Maikhuri, J. P.; Gupta, G.; Dhar,
J. D. Bioorg. Med. Chem. 1999, 7, 2607–2613. DOI: 10.1016/S0968-0896(99)00188-1.
16] Conti, P.; Dallanoce, C.; Amici, M. D.; Micheli, C. D.; Klotz, K. N. Bioorg. Med. Chem.
1
998, 6, 401–408. DOI: 10.1016/S0968-0896(97)10051-7.
17] Sielecki, T. M.; Liu, J.; Mousa, S. A.; Racanelli, A. L.; Hausner, E. A.; Wexler, R. R.; Olson,
R. E. Bioorg. Med. Chem. Lett. 2001, 11, 2201–2204. DOI: 10.1016/S0960-894X(01)00406-1.
18] Kai, H.; Matsumoto, H.; Hattori, N.; Takase, A.; Fujiwara, T.; Sugimoto, H. Bioorg. Med.
Chem. Lett. 2001, 11, 1997–2000. DOI: 10.1016/S0960-894X(01)00362-6.
19] Basappa, M.; Sadashiva, P.; Mantelingu, K.; Nanjunda, S. S.; Rangappa, K. S. Bioorg. Med.
Chem. Lett. 2003, 11, 4539–4544. DOI: 10.1016/j.bmc.2003.08.007.
20] Ahmad, G.; Mishra, P. K.; Gupta, P.; Yadav, P. P.; Tiwari, P.; Tamrakar, A. K.; Srivastava,
A. K.; Maurya, R. Bioorg. Med. Chem. Lett. 2006, 16, 2139–2143. DOI: 10.1016/j.bmcl.
2
006.01.062.
21] Gaonkar, S. L.; Rai, L.; Prabhuswamy, B. Med. Chem. Res. 2007, 15, 407–417. DOI: 10.
007/s00044-006-0015-z.
22] Aher, N. G.; Pore, V. S.; Mishra, N. N.; Kumar, A.; Shukla, P. K.; Sharma, A.; Bhat, M. K.
Bioorg. Med. Chem. Lett. 2009, 19, 759–763. DOI: 10.1016/j.bmcl.2008.12.026.
23] Vel ꢀa zquez, S.; Alvarez, R.; P ꢀe rez, C.; Gago, F.; De Clercq, E.; Balzarini, J.; Camarasa, M.-J.
Antivir. Chem. Chemother. 1998, 9, 481–489. DOI: 10.1177/095632029800900604.
24] Alvarez, R.; Velazquez, S.; San-Felix, A.; Aquaro, S.; De Clercq, E.; Perno, C.-F.; Karlsson,
A.; Balzarini, J.; Camarasa, M. J. J. Med. Chem. 1994, 37, 4185–4194. DOI: 10.1021/
jm00050a015.
[
[
[
[
1
[
[
[
25] Wang, X.-L.; Wan, K.; Zhou, C.-H. Eur. J. Med. Chem. 2010, 45, 4631–4639. DOI: 10.
1016/j.ejmech.2010.07.031.
26] Kamal, A.; Shankaraiah, N.; Devaiah, V.; Laxma Reddy, K.; Juvekar, A.; Sen, S.; Kurian, N.;
Zingde, S. Bioorg. Med. Chem. Lett. 2008, 18, 1468–1473. DOI: 10.1016/j.bmcl.2007.12.063.
27] Maurya, R.; Ausaf, A.; Gupta, P.; Chand, K.; Kumar, M.; Jayendra, P.; Rawat, P.; Rasheed,
N.; Palit, G. Med. Chem. Res. 2011, 20, 139–145. DOI: 10.1007/s00044-010-9299-0.

1
4
A. TAIA ET AL.
[
28] Teixeira, R. R.; Gazolla, P. A. R.; da Silva, A. M.; Borsodi, M. P. G.; Bergmann, B. R.;
Ferreira, R. S.; Vaz, B. G.; Vasconcelos, G. A.; Lima, W. P. Eur. J. Med. Chem. 2018, 146,
2
74–286. DOI: 10.1016/j.ejmech.2018.01.046.
29] Essaber, M.; Baouid, A.; Hasnaoui, A.; Benharref, A.; Lavergne, J.-P. Commun. 1998, 28,
097–4104. DOI: 10.1080/00397919809458689.
30] Boudina, A.; Baouid, A.; Hasnaoui, A.; Essaber, M. Synthetic Commun. 2006, 36, 573–579.
DOI: 10.1080/00397910500406443.
[
[
[
4
31] Melhado, L. L.; Leonard, N. J. J. Org. Chem. 1983, 48, 5130–5133. DOI: 10.1021/
jo00173a071.
[
[
32] Hein, J. E.; Fokin, V. V. Chem. Soc. Rev. 2010, 39, 1302–1315. DOI: 10.1039/b904091a.
33] Moses, J. E.; Moorhouse, A. D. Chem. Soc. Rev 2007, 36, 1249–1262. DOI: 10.1039/
B613014N.
[
34] Kolb, H. C.; Finn, M. G.; Sharpless, K. B. Angew. Chem. Int. Ed. 2001, 40, 2004–2021.
DOI: 10.1002/1521-3773(20010601)40:11<2004::AID-ANIE2004>3.0.CO;2-5.
35] Worrell, B. T.; Malik, J. A.; Fokin, V. V. Science. 2013, 340, 457–460. DOI: 10.1126/sci-
ence.1229506.
[
[
[
36] Wu, P.; Fokin, V. V. Aldrichimica Acta. 2007, 40, 7–17.
37] Rostovtsev, V. V.; Green, L. G.; Fokin, V. V.; Sharpless, K. B. Angew. Chem. Int. Ed. 2002,
4
1, 2596–2599. DOI: 10.1002/1521-3773(20020715)41:14<2596::AID-ANIE2596>3.0.CO;2-4.
[
[
[
[
38] Liu, K.-C.; Shelton, B. R.; Howe, R. K. J. Org. Chem. 1980, 45, 3916–3918. DOI: 10.1021/
jo01307a039.
39] Lahouar, G.; Bahy, A.; Touati, R.; Ben Hassine, B. JAC. 2016, 12, 4333–4337. DOI: 10.
2
4297/jac.v12i4.2173.
40] Husain, A.; Rashid, M.; Shaharyar, M.; Siddiqui, A. A.; Mishra, R. Eur. J. Med. Chem.
013, 62, 785–798. DOI: 10.1016/j.ejmech.2012.07.011.
2
41] Oubella, A.; Ait Itto, M. Y.; Auhmani, A.; Riahi, A.; Robert, A.; Daran, J.-C.; Morjani, H.;
Parish, C. A.; Esseffar, M. J. Mol. Struct. 2019, 1198, 126924. DOI: 10.1016/j.molstruc.
2019.126924.