Microwave-assisted synthesis, anti-inflammatory and anti-proliferative activities of new maslinic acid derivatives bearing 1,5- and 1,4-disubstituted triazoles

Article abstract of DOI:10.1080/14756366.2016.1193733

In this work, 40 analogs with a natural maslinic acid core (from Olea europaea L.) and various aromatic azides were synthesized. A regiospecific, facile and practical synthesis of 1,5-triazolyl derivatives by Ru(II)-catalyzed azide-alkyne cycloaddition (R

Full text of DOI:10.1080/14756366.2016.1193733

Journal of Enzyme Inhibition and Medicinal Chemistry
ISSN: 1475-6366 (Print) 1475-6374 (Online) Journal homepage: http://www.tandfonline.com/loi/ienz20
Microwave-assisted synthesis, anti-inflammatory
and anti-proliferative activities of new maslinic
acid derivatives bearing 1,5- and 1,4-disubstituted
triazoles
Karim Chouaïb, Stéphanie Delemasure, Patrick Dutartre & Hichem Ben
Jannet
To cite this article: Karim Chouaïb, Stéphanie Delemasure, Patrick Dutartre & Hichem Ben
Jannet (2016): Microwave-assisted synthesis, anti-inflammatory and anti-proliferative activities
of new maslinic acid derivatives bearing 1,5- and 1,4-disubstituted triazoles, Journal of Enzyme
Inhibition and Medicinal Chemistry, DOI: 10.1080/14756366.2016.1193733
To link to this article: http://dx.doi.org/10.1080/14756366.2016.1193733
Published online: 19 Jul 2016.
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ISSN: 1475-6366 (print), 1475-6374 (electronic)
J Enzyme Inhib Med Chem, Early Online: 1–18
2016 Informa UK Limited, trading as Taylor & Francis Group. DOI: 10.1080/14756366.2016.1193733
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RESEARCH ARTICLE
Microwave-assisted synthesis, anti-inflammatory and anti-proliferative
activities of new maslinic acid derivatives bearing 1,5- and
1,4-disubstituted triazoles
1
Karim Choua¨ıb , Stephanie Delemasure , Patrick Dutartre , and Hichem Ben Jannet
2
2
1
´
1
´ ´
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Laboratoire de Chimie Heterocyclique, Produits Naturels et Reactivite. Equipe: Chimie Medicinale et Produits Naturels, Departement de Chimie,
2
Faculte des Sciences de Monastir, Universite de Monastir, Avenue de l’Environnement, Monastir, Tunisie and COHIRO Biotechnology, Facultes de
´
´
´
´
Medecine et Pharmacie, Dijon, France
Abstract
Keywords
In this work, 40 analogs with a natural maslinic acid core (from Olea europaea L.) and various
aromatic azides were synthesized. A regiospecific, facile and practical synthesis of 1,5-triazolyl
derivatives by Ru(II)-catalyzed azide-alkyne cycloaddition (RuAAC), and mono-, bis- and tri-
1,4-triazolyl derivatives by Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) was described.
All the reactions were assisted by microwave irradiation avoiding toxic reagents and solvents.
The new products were obtained from the reaction mixture by simple purification in almost
quantitative yields and the reaction times were in general shorter than those reported in the
literature. Their chemical structures were elucidated on the basis of extensive spectroscopic
methods including ESI-HRMS, 1D and 2D-NMR. Most of the compounds were evaluated for their
anti-inflammatory activity using LPS-stimulated human peripheral blood mononuclear cells
(PBMCs) and antiproliferative effects towards cultured murine EMT-6 (Breast) and human
SW480 (colon) cancer cell lines.
Anti-inflammatory, anti-proliferative, maslinic
acid, Olea europaea L., triazoles
History
Received 10 February 2016
Revised 16 May 2016
Accepted 19 May 2016
Published online 19 July 2016
Introduction
reduction of pro-inflammatory cytokine generation in murine19,20
.
Furthermore, interesting reports from Reyes-Zurita et al.21,22
suggest that compound 1 is able to induce cell death by apoptosis
in the colon cancer cell lines HT29 and in Caco-2. Among others,
Allouche et al.23 demonstrate that maslinic acid 1 was reported to
be cytotoxic for the breast cancer cell line MCF7. Thus, maslinic
acid 1 exhibited some selectivity between malignant and
nonmalignant cell lines24 and selective parasitostatic activities
in mice25. Recent research results correlate the low rate of cancer
Recently, 1,2,3-triazoles have gained special attention in the field
of drug discovery due to the growing use of ‘‘click’’ reaction such
as ruthenium-catalyzed azide-alkyne cycloaddition (RuAAC)1–3
and copper-catalyzed azide-alkyne cycloaddition (CuAAC)4–6
.
Moreover, compounds containing a 1,2,3-triazole display a wide
range of biological capacities such as anti-HIV7, cytotoxic8 and
anti-inflammatory9 activities. On the other hand, natural products
and their synthetic derivatives are very important in drug
design10,11. Among these, natural pentacyclic triterpenoids and
their derivatives are present in several classes of natural and
mortality in Mediterranean countries to a diet rich in olives26,27
.
In this context, maslinic acid 1 (Figure 1) which isolated from
pomace olive (Olea europaea L.) cultivar: Chemlali, under ultra-
sonication conditions with high quantities (17 g (8.5 mg/g DW))
was used herein as a starting material to synthesize new 1,5-
disubstituted-1,2,3-triazolo-maslinic acid derivatives through
well-established Ru(II)-catalyzed azide-alkyne cycloaddition
(RuAAC) and to access to mono, bis- and tri-1,4-triazolyl
derivatives via the Cu(I)-catalyzed azide-alkyne cycloaddition
(CuAAC) conducted under microwave conditions. Most obtained
compounds were evaluated for their anti-inflammatory and
anti-proliferative activities in vitro.
synthetic biologically active compounds12,13
. In particular,
maslinic acid (1, Figure 1) and its derivatives are of interest
because of their wide spectrum of biological activities. Thus, for
natural compound 1 an inhibitory activity for glycogen phosphor-
ylases14, protein tyrosine phosphatase 1B15, anti-inflammatory16,
anti-tumor17 as well as an anti-HIV-1 activities18 was reported.
However, the natural pentacyclic triterpenoid 1 may have utility in
other pathological processes for its anti-inflammatory and anti-
cancer properties. It has been found to attenuate intracellular
oxidative stress via inhibition of NO and H2O2 production and
Materials and methods
Address for correspondence: Hichem Ben Jannet, Laboratoire de Chimie
´ ´
General experimental procedures
´
Heterocyclique, Produits Naturels et Reactivite. Equipe: Chimie
Medicinale et Produits Naturels, Departement de Chimie, Faculte des
´
´
´
´
Solvents were distilled and dried using standard methods. Melting
points were determined on a Bu¨chi 510 apparatus (Mount Holly,
NJ) using capillary tubes. Commercial TLC plates (Silica gel 60,
´
Sciences de Monastir, Universite de Monastir, Avenue de
L’Environnement, Monastir, Tunisia. Tel: +21673500279. Fax:
+21673500278. E-mail: hich.benjannet@yahoo.fr

¨
K. Chouaıb et al.
2
J Enzyme Inhib Med Chem, Early Online: 1–18
J ¼ 2.4 Hz), 2.05 (2H, m), 1.77–1.47 (8H, m), 1.37–1.23 (10H,
m), 1.14 (3H, s), 1.06 (3H, s), 0.99 (3H, s), 0.94 (3H, s), 0.92 (3H,
s), 0.85 (3H, s), 0.76 (3H, s); 13C NMR (75 MHz, CDCl3): ꢂ
183.3, 143.2, 121.7, 80.4, 79.7, 76.5, 73.9, 55.8, 54.5, 47.1, 46.0,
45.3, 42.0, 41.1, 40.4, 38.8, 38.6, 37.7, 33.2, 32.5, 32.1, 31.9,
30.1, 29.2, 28.1, 27.1, 25.4, 23.0, 22.3, 17.6, 16.6, 16.4, 16.0;
HRMS (ESI+): calculated for (C33H51O4)+ [M + H]+ 511.3787,
found 511.3794.
OH
HO
HO
O
Propargyl-(2ꢀro2-(propargyloxy)-(3ꢁro2-(propargolean-12-
en-28-oate (4). White solid; m.p.: 296–298 ꢁC; 1H NMR
(300 MHz, CDCl3): ꢂ 5.22 (1H, s), 4.67 (1H, dd, J ¼ 15.6;
2.4 Hz), 4.56 (1H, dd, J ¼ 15.3; 2.1 Hz), 4.26 (1H, dd, J ¼ 15.9;
Figure 1. Chemical structure of Maslinic acid 1.
F254, sds) were used to monitor the progress of the reaction. 2.4 Hz), 4.15 (1H, dd, J ¼ 15.9; 2.1 Hz), 3.54 (1H, td, J ¼ 11.1;
Column chromatography was performed with silica gel 60 4.2 Hz), 3.06 (1H, d, J ¼ 9.6 Hz), 2.86 (1H, dd, J ¼ 13.8; 3.9 Hz),
(particle size 40–63 mm, sds). HRMS were acquired with a LCT 2.44 (3H, m), 2.04–1.94 (2H, m), 1.92–1.89 (2H, m), 1.70–1.53
Premier XE (Waters, ESI technique, positive mode) mass (7H, m), 1.45–1.29 (4H, m), 1.24–1.16 (2H, m), 1.12 (3H, s), 1.04
spectrometer. For ESI experiments, leucine-enkephaline peptide (3H, s), 0.96 (3H, s), 0.92 (3H, s), 0.89 (3H, s), 0.83 (3H, s), 0.73
was employed as the LockSpray lockmass. H (300 MHz, 16–32 (3H, s); 13C NMR (75 MHz, CDCl3): ꢂ 176.2, 143.0, 121.8, 80.8,
1
scans) and BB-decoupled 13C (75 MHz, 256–2048 scans) NMR 79.8, 77.6, 76.6, 73.9, 73.9, 55.8, 54.5, 51.1, 47.0, 46.2, 45.3,
spectra were recorded at room temperature (rt) on a Bruker AM- 42.1, 41.2, 40.7, 38.9, 38.6, 37.7, 33.3, 32.5, 32.1, 31.6, 30.1,
300 Fourier Transform spectrometer (Fitchburg, MA) equipped 28.2, 27.1, 25.3, 23.1, 23.0, 22.4, 17.6, 16.6, 16.4, 16.0; HRMS
with a 10 mm probe in deuterated chloroform, acetone and (ESI+): calculated for (C36H53O4)+ [M + H]+ 549.3944, found
pyridine with all chemical shifts (d), reported in ppm, refereed to 549.3938.
residual non-deuterated solvent. Coupling constants were mea-
Propargyl-(3ꢀropargyl-(3e8-oate-(3den-28-oate aolean-12-
sured in Hz. and signals are using the following abbreviations: s, en-28-oate (5). White solid; m.p.: 296–298 ꢁC; 1H NMR
singlet; d, doublet; t, triplet; m, multiplet, etc.
(300 MHz, CDCl3): ꢂ 5.22 (1H, t, J ¼ 3.3 Hz), 4.60 (1H, dd,
J ¼ 15.6; 2.4 Hz), 4.49 (1H, dd, J ¼ 15.6; 2.4 Hz), 4.41 (1H, dd,
J ¼ 15.9; 2.4 Hz), 4.25 (1H, dd, J ¼ 15.9; 2.4 Hz), 3.72 (1H,
td, J ¼ 11.1; 4.2 Hz), 2.79 (1H, dd, J ¼ 13.8; 3.9 Hz), 2.74 (1H, d,
J ¼ 9.6 Hz), 2.42 (1H, t, J ¼ 2.4 Hz), 2.33 (1H, t, J ¼ 2.4 Hz), 2.07
Chemistry
Synthesis of dipolarophiles 2–6
Method I: To a solution of compound 1 (3 g, 6.3 mmol) in dry (2H, m), 1.91–1.83 (4H, m), 1.59–1.47 (8H, m), 1.34 (2H, m),
DMF (5 mL), sodium hydride (12.6 mmol) and propargyl 1.30–1.22 (4H, m), 1.10 (3H, s), 0.94 (3H, s), 0.88 (3H, s), 0.85
bromide (18.9 mmol) were added and the reaction mixture was (3H, s), 0.82 (3H, s), 0.73 (3H, s), 0.66 (3H, s); 13C NMR
stirred at room temperature for 2 h. Reaction was monitored by (75 MHz, CDCl3): ꢂ 176.2, 142.8, 121.9, 93.0, 80.3, 77.6, 74.1,
TLC. After the completion of the reaction, the residue was diluted 73.9, 68.0, 61.0, 54.8, 51.1, 47.1, 46.2, 45.3, 41.2, 40.7, 39.7,
with water (300 mL). The mixture was extracted with ethyl acetate 38.9, 37.5, 33.3, 32.5, 32.1, 31.7, 30.1, 28.4, 27.1, 26.4, 25.3,
(3 ꢀ 100 mL). The combined organic layer was dried over 23.1, 22.9, 22.4, 17.6, 16.6, 16.4, 16.0; HRMS (ESI+): calculated
anhydrous sodium sulfate and evaporated to dryness. The residue for (C36H53O4)+ [M + H]+ 549.3944, found 549.3940.
was chromatographed over silica gel and eluted with ethyl
Propargyl-(2ꢀ,3ꢁ) ꢂ 2,3 ꢂ ꢁꢃꢄ(propargyloxy)-olean-12-en-
1
acetate:petroleum ether (2:8 then 3:7) to obtain the alkyl 28-oate (6). White solid; m.p.: 296–298 ꢁC; H NMR (300 MHz,
derivatives 2–6 in 44, 5, 15, 11 and 7% yield, respectively. CDCl3): ꢂ 5.23 (1H, s), 4.60 (1H, dd, J ¼ 15.6; 2.4 Hz), 4.50 (1H,
Method II: With the aim to fully propargylate the maslinic acid 1 dd, J ¼ 15.6; 2.4 Hz), 4.41 (1H, dd, J ¼ 15.9; 2.4 Hz), 4.34 (1H,
in C-2, C-3 and C-28 positions, we increased the number of dd, J ¼ 15.9; 2.4 Hz), 4.17 (2H, d, J ¼ 2.1 Hz), 3.59 (1H, td,
equivalents of NaH (which goes from 2 to 4 equiv.) and propargyl J ¼ 11.1; 4.2 Hz), 2.82 (1H, d, J ¼ 9.6 Hz), 2.79 (1H, dd, J ¼ 13.8;
bromide (which goes from 3 to 4 equiv.) and we extended the 3.9 Hz), 2.33 (2H, m), 2.25 (1H, m), 1.96–1.83 (4H, m), 1.60–1.46
reaction time from 2 h to 8 h. The same protocol adopted in (8H, m), 1.34–1.20 (8H, m), 1.10 (3H, s), 0.94 (3H, s), 0.88 (3H,
method I was applied and only the alkyl derivatives 2 and 4–6 was s), 0.85 (3H, s), 0.81 (3H, s), 0.73 (3H, s), 0.66 (3H, s); 13C NMR
obtained in 25, 23, 20 and 31% yield, respectively.
(75 MHz, CDCl3): ꢂ 176.3, 142.9, 121.9, 89.2, 80.6, 77.7, 77.6,
Propargyl-(2ꢀ,3ꢁ)-2,3-dihydroxyolean-12-en-28-oate
(2). 73.8, 73.8, 73.2, 73.1, 60.2, 56.7, 54.8, 51.1, 47.1, 46.2, 45.3,
1
White solid; m.p.: 297–299 ꢁC; H NMR (300 MHz, CDCl3): ꢂ 44.2, 41.2, 40.7, 39.5, 38.9, 37.4, 33.5, 33.3, 32.1, 31.7, 30.1,
5.23 (1H, t, J ¼ 3.6 Hz), 4.61 (1H, dd, J ¼ 15.6; 2.4 Hz), 4.50 (1H, 29.1, 27.1, 26.4, 25.3, 23.1, 22.5, 17.8, 17.0, 16.5, 15.9; HRMS
dd, J ¼ 15.6; 2.7 Hz), 3.60 (1H, td, J ¼ 9.3; 2.7 Hz), 2.93 (1H, d, (ESI+): calculated for (C39H55O4)+ [M + H]+ 587.4100, found
J ¼ 9.6 Hz), 2.80 (1H, dd, J ¼ 13.8; 3.9 Hz), 2.34 (1H, 587.4092.
t, J ¼ 2.7 Hz), 1.99 (4H, m), 1.93–1.83 (4H, m), 1.62–1.46 (6H,
m), 1.45–1.21 (6H, m), 1.06 (3H, s), 0.96 (3H, s), 0.91 (3H, s),
General procedure for the RuAAC reaction
0.86 (3H, s), 0.83 (3H, s), 0.75 (3H, s), 0.67 (3H, s); 13C NMR
To a solution of alkyne 2 (0.1 g, 0.2 mmol) in DMF (1 mL),
Cp*RuCl(PPh3)2 (5 mol %) was added at room temperature. To
this mixture, aryl azide (0.4 mmol) was added and the reaction
mixture was subjected to microwave irradiations at 250 W
completed within 4–8 minutes. The crude mixture was diluted
with water (75 mL) then extracted with EtOAc (3 ꢀ 25 mL) and
the combined organic layer was dried over sodium sulfate,
concentrated in vacuo and purified through a column chroma-
tography to give pure the 1,5-triazolyl derivatives 8a–g in 83–98%
yields.
(75 MHz, CDCl3): ꢂ 176.3, 142.9, 121.9, 83.4, 77.6, 73.8, 68.4,
54.8, 51.1, 47.1, 46.2, 45.9, 45.3, 41.2, 40.7, 38.9, 38.6, 37.8,
36.5, 33.3, 32.5, 32.1, 31.7, 30.1, 28.1, 27.1, 26.7, 25.3, 23.0,
22.9, 22.5, 17.8, 16.6; HRMS (ESI+): calculated for
(C33H51O4)+ [M + H]+ 511.3787, found 511.3778.
(2ꢀ)-2-(Propargyloxy)-(3ꢁ)-3-hydroxy-olean-12-en-28-oic
acid (3). White solid; m.p.: 293–294 ꢁC; 1H NMR (300 MHz,
CDCl3): ꢂ 5.29 (1H, s), 4.30 (1H, dd, J ¼ 15.9; 2.4 Hz), 4.18 (1H,
dd, J ¼ 15.9; 2.4 Hz), 3.58 (1H, td, J ¼ 9.3; 2.7 Hz), 2.93 (1H, d,
J ¼ 9.6 Hz), 2.84 (1H, dd, J ¼ 13.8; 3.9 Hz), 2.47 (1H, t,

DOI: 10.1080/14756366.2016.1193733
Synthesis of 1,4-triazoles from maslinic acid
3
(1-Phenyl-1H-1,2,3-triazol-5-yl)methyl-(2ꢀ,3ꢁ)-2,3-dihydrox-
0.90 (3H, s), 0.79 (3H, s), 0.53 (3H, s); 13C NMR (75 MHz,
yolean-12-en-28-oate (8a). Yellowish gum; m.p.: 218–219 ꢁC; CDCl3): ꢂ 176.5, 144.5, 143.6, 142.9, 142.0, 131.8, 128.6, 128.6,
1H NMR (300 MHz, CDCl3): ꢂ 7.77 (1H, s), 7.53–7.42 (5H, m), 124.0, 124.0, 122.9, 83.6, 68.7, 54.8, 53.7, 47.0, 46.4, 45.8, 45.2,
5.19 (1H, t, J ¼ 3.3 Hz), 5.09 (1H, d, J ¼ 13.5 Hz), 5.01 (1H, d, 41.2, 40.8, 38.8, 38.6, 37.8, 33.2, 32.4, 32.0, 31.8, 30.1, 29.1,
J ¼ 13.5 Hz), 3.63 (1H, td, J ¼ 10.8; 4.2 Hz), 2.91 (1H, d, 28.1, 27.0, 27.1, 25.3, 22.9, 23.6, 18.0, 17.5, 16.0; HRMS
J ¼ 9.6 Hz), 2.76 (1H, dd, J ¼ 11.8; 3.8 Hz), 2.24 (2H, m), 1.93– (ESI+): calculated for (C39H55N4O6)+ [M + H]+ 675.4122, found
1.75 (6H, m), 1.61–1.24 (12H, m), 1.23 (3H, s), 1.03 (3H, s), 0.89 675.4125.
(3H, s), 0.86 (3H, s), 0.81 (3H, s), 0.74 (3H, s), 0.46 (3H, s); 13C
(1-(3-Methylphenyl)-1H-1,2,3-triazol-5-yl)methyl-(2ꢀ,3ꢁ)-2,3-
NMR (75 MHz, CDCl3): ꢂ 176.8, 143.4 136.7, 136.2, 131.4, dihydroxyolean-12-en-28-oate (8f). White solid; m.p.:
129.8, 129.6, 129.6, 124.7, 124.7, 122.6, 83.9, 68.9, 55.2, 53.7, 326–327 ꢁC; 1H NMR (300 MHz, CDCl3): ꢂ 7.84 (1H, s),
47.4, 46.9, 46.3, 45.7, 41.7, 41.2, 39.3, 39.1, 38.2, 33.7, 32.6, 7.47–7.34 (4H, m), 5.28 (1H, t, J ¼ 3.3 Hz), 5.16 (1H, d,
31.9, 30.6, 29.3, 28.6, 27.5, 25.8, 23.5, 23.4, 18.2, 16.8, 16.7, J ¼ 13.5 Hz), 5.10 (1H, d, J ¼ 13.5 Hz), 3.66 (1H, td, J ¼ 10.5;
16.5,
14.0;
HRMS
(ESI+):
calculated
for 3.9 Hz), 3.01 (1H, d, J ¼ 9.6 Hz), 2.87 (1H, dd, J ¼ 9.2;
3.8 Hz), 2.47 (3H, s), 2.04–7.86 (6H, m), 1.69–1.52 (8H, m),
1.50–1.33 (6H, m), 1.13 (3H, s), 1.04 (3H, s), 0.95 (3H, s),
(C39H56N3O4)+ [M + H]+ 630.4271, found 630.4274.
(1-(4-Methoxyphenyl)-1H-1,2,3-triazol-5-yl)methyl-(2ꢀ,3ꢁ)-
2,3-dihydroxyolean-12-en-28-oate (8b). Dark red solid; m.p.: 0.90 (6H, s), 0.83 (3H, m), 0.55 (3H, s); 13C NMR (75 MHz,
1
222–224 ꢁC; H NMR (300 MHz, CDCl3): ꢂ 7.83 (1H, s), 7.47 CDCl3): ꢂ 176.8, 143.4, 139.9, 135.8, 135.4, 132.3, 130.5,
(2H, dd, J ¼ 6.9; 2.1 Hz), 7.06 (2H, dd, J ¼ 6.9; 2.1 Hz), 5.27 129.3, 125.3, 122.5, 121.7, 83.9, 68.9, 55.2, 53.7, 47.5, 46.8,
(1H, t, J ¼ 3.3 Hz), 5.12 (1H, d, J ¼ 13.5 Hz), 5.06 (1H, d, 46.3, 45.7, 41.7, 41.2, 39.3, 39.1, 38.2, 33.7, 32.9, 32.5, 32.3,
J ¼ 13.8 Hz), 3.90 (3H, s), 3.71 (1H, td, J ¼ 10.8; 3.9 Hz), 3.01 31.9, 30.6, 29.6, 28.5, 27.5, 25.8, 23.5, 23.4, 23.0, 22.6, 21.3,
(1H, d, J ¼ 9.6 Hz), 2.86 (1H, dd, J ¼ 8.8; 3.4 Hz), 2.00–1.86 18.2; HRMS (ESI+): calculated for (C40H58N3O4)+
(4H, m), 1.69–1.56 (6H, m), 1.52–1.44 (6H, m), 1.29–1.22 [M + H]+ 644.4427, found 644.4431.
(4H, m), 1.27 (3H, s), 1.13 (3H, s), 1.04 (3H, s), 1.01 (3H, s),
(1-Naphthalen-1-yl-1H-1,2,3-triazol-5-yl)methyl-(2ꢀ,3ꢁ)-2,3-
0.96 (6H, s), 0.83 (3H, s), 0.55 (3H, s); 13C NMR (75 MHz, dihydroxyolean-12-en-28-oate (8 g). Eggplant solid; m.p.: 335–
1
CDCl3): ꢂ 176.3, 160.3, 142.9, 134.7, 132.0, 128.6, 125.7, 337 ꢁC; H NMR (300 MHz, CDCl3): ꢂ 8.09 (1H, d, J ¼ 7.6 Hz),
125.7, 122.0, 114.2, 114.2, 83.4, 68.4, 55.1, 54.7, 53.3, 47.0, 7.98 (1H, d, J ¼ 7.8 Hz), 7.94 (1H, s), 7.61–7.51 (4H, m), 7.24
46.3, 45.8, 45.2, 41.2, 40.7, 38.8, 38.6, 37.7, 33.8, 33.2, (1H, d, J ¼ 8.4 Hz), 5.18 (1H, t, J ¼ 2.7 Hz), 4.96 (1H, d,
32.4, 32.0, 31.8, 30.1, 29.1, 28.0, 27.0, 25.3, 24.4, 22.6, J ¼ 13.4 Hz), 4.91 (1H, d, J ¼ 13.8 Hz), 3.69 (1H, td, J ¼ 10.5;
17.7,
16.3,
15.2;
HRMS
(ESI+):
calculated
for 3.9 Hz), 2.99 (1H, d, J ¼ 9.6 Hz), 2.68 (1H, dd, J ¼ 13.5; 4.2 Hz),
2.04 (1H, m), 1.93 (3H, m), 1.77–1.60 (4H, m), 1.43–1.18 (12H,
m), 1.12 (3H, s), 1.05 (3H, s), 0.93 (3H, s), 0. 86 (3H, s), 0.84 (3H,
(C40H58N3O5)+ [M + H]+ 660.4376, found 660.4381.
(1-(4-Chlorophenyl)-1H-1,2,3-triazol-5-yl)methyl-(2ꢀ,3ꢁ)-
2,3-dihydroxyolean-12-en-28-oate (8c). Dark orange solid; m.p.: s), 0.83 (3H, s), 0.49 (3H, s); 13C NMR (75 MHz, CDCl3): ꢂ
1
235–237 ꢁC; H NMR (300 MHz, CDCl3): ꢂ 7.84 (1H, s), 7.51– 176.1, 143.2, 142.7, 133.6, 133.4, 131.1, 128.2, 128.1, 128.1,
7.44 (4H, m), 5.25 (1H, t, J ¼ 3.6 Hz), 5.14 (1H, d, J ¼ 13.2 Hz), 127.2, 126.2, 124.4, 124.4, 121.9, 121.6, 83.4, 68.5, 55.0, 53.4,
5.10 (1H, d, J ¼ 13.2 Hz), 3.67 (1H, td, J ¼ 10.8; 4.2 Hz), 2.98 47.0, 46.3, 45.3, 41.2, 40.8, 38.3, 38.2, 37.9, 36.4, 33.3,
(1H, d, J ¼ 9.6 Hz), 2.81 (1H, dd, J ¼ 11.2; 4.1 Hz), 2.08–1.82 32.5, 31.9, 30.1, 27.6, 27.1, 26.6, 25.2, 23.1, 22.8, 22.5,
(6H, m), 1.68–1.54 (8H, m), 1.51–1.37 (6H, m), 1.25 (3H, s), 1.01 17.7, 16.5, 16.2, 16.0; HRMS (ESI+): calculated for
(3H, s), 0.98 (3H, s), 0.93 (3H, s), 0.90 (3H, s), 0.79 (3H, s), 0.50 (C43H58N3O4)+ [M + H]+ 680.4427, found 680.4429.
(3H, s); 13C NMR (75 MHz, CDCl3): ꢂ 176.3, 142.8, 135.5, 135.2,
133.9, 131.9, 129.4, 129.4, 125.4, 125.4, 122.1, 83.4, 68.3, 54.7,
General procedure for the synthesis of mono-1,4-triazolyl
53.1, 46.9, 46.4, 45.4, 45.2, 41.2, 40.7, 38.8, 38.6, 37.7, 33.2,
derivatives 9a–g under CuAAC condition
32.4, 32.0, 31.8, 30.1, 29.1, 28.1, 27.0, 27.1, 25.3, 22.9, 23.3,
(ESI+):
calculated
for
Under solvent-free conditions, 0.1 g (0.2 mmol) of dipolarophile
18.1,
17.0,
16.7;
HRMS
(C39H55ClN3O4)+ [M + H]+ 664.3881, found 664.3885.
2, Copper(I) iodide (0.5 equiv.) and triethylamine (1 equiv.) were
added at room temperature. To this mixture, aryl- azide
(0.4 mmol) was added and the reaction mixture was subjected
to microwave irradiations at 200 W completed within 2–4 min-
utes. The crude mixture was extracted with EtOAc (3 ꢀ 25 mL)
and the combined organic layer was dried over sodium sulfate,
concentrated under reduced pressure and purified through a
column chromatography or by recrystallization, to give pure 9a–g
in 90–99% yields.
(1-(4-Bromophenyl)-1H-1,2,3-triazol-5-yl)methyl-(2ꢀ,3ꢁ)-2,3-
dihydroxyolean-12-en-28-oate (8d). White solid; m.p.: 276–
277 ꢁC; H NMR (300 MHz, CDCl3): ꢂ 7.86 (1H, s), 7.53–7.46
1
(4H, m), 5.23 (1H, t, J ¼ 3.3 Hz), 5.16 (1H, d, J ¼ 13.5 Hz), 5.08
(1H, d, J ¼ 13.5 Hz), 3.69 (1H, td, J ¼ 11.1; 4.2 Hz), 3.02 (1H, d,
J ¼ 9.6 Hz), 2.86 (1H, dd, J ¼ 11.2; 4.1 Hz), 2.05–1.83 (6H, m),
1.68–1.64 (6H, m), 1.58–1.50 (4H, m), 1.46–1.30 (4H, m), 1.25
(3H, s), 1.01 (3H, s), 0.98 (3H, s), 0.93 (3H, s), 0.90 (3H, s), 0.79
(3H, s), 0.51 (3H, s); 13C NMR (75 MHz, CDCl3): ꢂ 176.5, 142.9,
135.5, 135.3, 134.0, 132.0, 129.4, 129.4, 125.4, 125.4, 122.1,
83.3, 68.4, 54.8, 53.7, 47.0, 46.4, 45.8, 45.2, 41.2, 40.8, 38.8,
38.6, 37.8, 33.2, 32.4, 32.0, 31.8, 30.1, 29.1, 28.1, 27.0, 27.1,
25.3, 22.8, 23.5, 18.3, 17.2, 16.5; HRMS (ESI+): calculated for
(C39H55BrN3O4)+ [M + H]+ 708.3376, found 708.3379.
(1-(4-Nitrophenyl)-1H-1,2,3-triazol-5-yl)methyl-(2ꢀ,3ꢁ)-2,3-
dihydroxyolean-12-en-28-oate (8e). Yellow solid; m.p.: 308–
310 ꢁC; H NMR (300 MHz, CDCl3): ꢂ 7.81 (1H, s), 7.51–7.40
(4H, m), 5.22 (1H, t, J ¼ 3.0 Hz), 5.14 (1H, d, J ¼ 13.5 Hz), 5.06
(1H, d, J ¼ 13.5 Hz), 3.66 (1H, td, J ¼ 10.5; 3.9 Hz), 3.00 (1H, d,
J ¼ 9.6 Hz), 2.87 (1H, dd, J ¼ 11.2; 4.4 Hz), 2.09–1.87 (4H, m),
1.69–1.66 (4H, m), 1.63–1.58 (2H, m), 1.56–1.41 (6H, m), 1.39–
1.28 (4H, m), 1.25 (3H, s), 1.01 (3H, s), 0.98 (3H, s), 0.93 (3H, s),
(1-Phenyl-1H-1,2,3-triazol-4-yl)methyl-(2ꢀ,3ꢁ)-2,3-dihydrox-
1
yolean-12-en-28-oate (9a). Yellow paste; m.p.: 202–204 ꢁC; H
NMR (300 MHz, CDCl3): ꢂ 8.01 (1H, s), 7.70 (2H, dd, J ¼ 7.5;
1.5 Hz), 7.50 (2H, dd, J ¼ 7.2; 1.5 Hz), 7.42 (1H, m), 5.25 (3H,
m), 3.15 (1H, dd, J ¼ 11.2; 4.8 Hz), 2.87 (1H, dd, J ¼ 7.7; 3.8 Hz),
1.94 (2H, m), 1.80 (2H, dd, J ¼ 8.7; 3.5 Hz), 1.63–1.45 (12H, m),
1.34 (2H, m), 1.26 (4H, m), 1.08 (3H, s), 0.94 (3H, s), 0.89 (3H,
s), 0.86 (3H, s), 0.74 (3H, s), 0.72 (3H, s), 0.44 (3H, s); 13C NMR
(75 MHz, CDCl3): ꢂ 177.7, 143.7, 143.5, 136.5, 129.7, 129.7,
129.7, 128.8, 122.5, 120.5, 120.5, 78.9, 57.3, 55.2, 47.5, 46.7,
45.8, 41.6, 41.4, 39.2, 38.7, 38.4, 36.9, 33.6, 33.0, 32.6, 32.4,
30.6, 29.6, 28.0, 27.6, 27.1, 25.7, 23.9, 23.8, 22.9, 18.2, 16.7,
15.5, 15.1; HRMS (ESI+): calculated for (C39H56N3O4)+
[M + H]+ 630.4271, found 630.4274.
1

¨
K. Chouaıb et al.
4
J Enzyme Inhib Med Chem, Early Online: 1–18
(1-(4-Methoxyphenyl)-1H-1,2,3-triazol-4-yl)methyl-(2ꢀ,3ꢁ)- 129.4, 122.6, 122.4, 121.2, 117.6, 78.9, 57.3, 55.1, 47.5, 46.7,
2,3-dihydroxyolean-12-en-28-oate (9b). Dark purple solid; m.p.: 45.8, 41.6, 41.3, 39.2, 38.7, 38.4, 36.9, 33.8, 33.0, 32.6, 32.4,
1
280–281 ꢁC; H NMR (300 MHz, CDCl3): ꢂ 7.96 (1H, s), 7.62 31.8, 30.6, 29.6, 28.0, 27.6, 27.1, 25.7, 23.6, 23.3, 22.9, 18.2,
(2H, d, J ¼ 7.8 Hz), 7.02 (2H, d, J ¼ 8.1 Hz), 5.25 (3H, m), 3.87 16.7,
15.5;
HRMS
(ESI+):
calculated
for
(3H, s), 3.20 (1H, dd, J ¼ 10.2; 4.2 Hz), 2.84 (1H, dd, J ¼ 8.7; (C40H58N3O4)+ [M + H]+ 644.4427, found 644.4432.
3.8 Hz), 2.00 (2H, m), 1.80 (2H, dd, J ¼ 9.0; 3.0 Hz), 1.63–1.45
(1-Naphthalen-1-yl-1H-1,2,3-triazol-4-yl)methyl-(2ꢀ,3ꢁ)-2,3-
(10H, m), 1.33–1.19 (8H, m), 1.10 (3H, s), 0.97 (3H, s), 0.91 (3H, dihydroxyolean-12-en-28-oate (9 g). Eggplant solid; m.p.:
s), 0.89 (3H, s), 0.78 (3H, s), 0.75 (3H, s), 0.46 (3H, s); 13C NMR 286–287 ꢁC; H NMR (300 MHz, CDCl3): ꢂ 8.03–7.94 (3H, m),
1
(75 MHz, CDCl3): ꢂ 177.3, 159.3, 143.1, 143.0, 129.8, 122.2, 7.65–7.50 (5H, m), 5.38 (1H, d, J ¼ 12.9 Hz), 5.30 (1H, d,
122.9, 121.6, 121.6, 114.2, 114.2, 78.4, 56.8, 55.1, 46.9, 46.2, J ¼ 13.8 Hz), 5.26 (1H, s), 3.17 (1H, dd, J ¼ 10.8; 5.1 Hz), 2.88
45.3, 41.1, 40.8, 38.7, 38.2, 37.8, 36.4, 33.2, 32.6, 32.0, 31.8, (1H, dd, J ¼ 13.5; 4.2 Hz), 1.94 (1H, m), 1.80 (2H, m), 1.71–1.57
30.1, 29.2, 27.6, 27.1, 26.6, 25.2, 23.1, 22.8, 22.4, 17.7, 16.2, (3H, m), 1.60–1.47 (8H, m), 1.42–1.37 (2H, m), 1.28–1.19 (6H,
15.0, 14.7; HRMS (ESI+): calculated for (C40H58N3O5) m), 1.12 (3H, s), 0.96 (3H, s), 0.91 (3H, s), 0.88 (3H, s), 0.74 (3H,
+ [M + H]+ 660.4376, found 660.4378.
s), 0.73 (3H, s), 0.54 (3H, s); 13C NMR (75 MHz, CDCl3): ꢂ
(1-(4-Chlorophenyl)-1H-1,2,3-triazol-4-yl)methyl-(2ꢀ,3ꢁ)-
2,3-dihydroxyolean-12-en-28-oate (9c). Dark red solid; m.p.: 126.5, 126.2, 124.4, 122.9, 121.9, 121.8, 78.4, 59.8, 57.0, 54.6,
177.3, 143.1, 142.7, 133.7, 133.0, 129.9, 127.8, 127.8, 127.4,
1
286–287 ꢁC; H NMR (300 MHz, CDCl3): ꢂ 8.02 (1H, s), 7.69 47.0, 46.3, 45.3, 41.2, 40.8, 38.3, 38.2, 37.9, 36.4, 33.3, 32.5,
(2H, dd, J ¼ 6.9; 2.7 Hz), 7.51 (2H, dd, J ¼ 6.6; 3.0 Hz), 5.28 (3H, 31.9, 30.1, 27.6, 27.1, 26.6, 25.2, 23.1, 22.8, 22.5, 17.7, 16.5,
m), 3.21 (1H, dd, J ¼ 10.8; 4.2 Hz), 2.87 (1H, dd, J ¼ 9.2; 3.8 Hz), 15.0, 14.6; HRMS (ESI+): calculated for (C43H58N3O4)+
2.01 (1H, m), 1.80 (2H, dd, J ¼ 7.8; 2.4 Hz), 1.68–1.45 (12H, m), [M + H]+ 680.4427, found 680.4429.
1.29 (3H, m), 1.18 (4H, m), 1.11 (3H, s), 0.97 (3H, s), 0.92 (3H,
s), 0.90 (3H, s), 0.78 (3H, s), 0.76 (3H, s), 0.46 (3H, s); 13C NMR
General procedure for the synthesis of bis-1,4-triazolyl
(75 MHz, CDCl3): ꢂ 177.8, 143.5, 135.5, 134.6, 129.9, 129.9,
derivatives 10a–g and 11a–g under CuAAC condition
129.0, 122.5, 121.6, 121.6, 116.2, 78.9, 57.2, 55.1, 47.5, 46.7,
Under solvent-free conditions, 0.1 g of bis-alkynes 4 or 5,
Copper(I) iodide (0.8 equiv.) and triethylamine (2 equiv.) were
added at room temperature. To this mixture, aryl azide (4 equiv.)
was added and the reaction mixture was subjected to microwave
irradiations at 250 W completed within 4–7 minutes. The crude
mixture was extracted with EtOAc (3 ꢀ 25 mL) and the combined
organic layer was dried over sodium sulfate, concentrated under
reduced pressure and purified by recrystallization or silica gel
column chromatography and eluted with petroleum ether:ethyl
acetate (7:3) to obtain the desired new cycloadducts (10a–g and
11a–g).
45.8, 41.6, 41.3, 39.2, 38.7, 38.4, 36.9, 33.8, 33.0, 32.6, 32.4,
31.8, 30.6, 28.0, 27.6, 27.1, 25.7, 23.6, 23.3, 22.9, 18.2, 16.7,
15.5; HRMS (ESI+): calculated for (C39H55ClN3O4)
+ [M + H]+ 664.3881, found 664.3884.
(1-(4-Bromophenyl)-1H-1,2,3-triazol-4-yl)methyl-(2ꢀ,3ꢁ)-2,3-
dihydroxyolean-12-en-28-oate (9d). White solid; m.p.: 294–
1
296 ꢁC; H NMR (300 MHz, CDCl3): ꢂ 8.01 (1H, s), 7.65 (2H,
dd, J ¼ 8.1; 3.4 Hz), 7.50 (2H, dd, J ¼ 7.8; 3.2 Hz), 5.29 (3H, m),
3.21 (1H, dd, J ¼ 10.8; 4.2 Hz), 2.87 (1H, dd, J ¼ 9.2; 3.8 Hz),
1.99 (2H, m), 1.80 (2H, dd, J ¼ 7.9; 2.8 Hz), 1.71–1.55 (10H, m),
1.33–1.27 (4H, m), 1.18 (4H, m), 1.11 (3H, s), 0.97 (3H, s), 0.92
(3H, s), 0.90 (3H, s), 0.78 (3H, s), 0.76 (3H, s), 0.46 (3H, s); 13C
NMR (75 MHz, CDCl3): ꢂ 177.9, 143.7, 136.1, 133.9, 129.2,
129.2, 129.0, 122.5, 120.8, 120.8, 115.9, 78.7, 56.8, 55.5, 47.6,
46.7, 45.8, 41.9, 41.3, 39.4, 38.7, 38.8, 36.7, 33.9, 33.3, 32.9,
32.4, 31.8, 30.6, 28.7, 27.9, 27.4, 25.7, 23.6, 23.3, 22.9, 18.2,
16.8, 15.2; HRMS (ESI+): calculated for (C39H55BrN3O4)
+ [M + H]+ 708.3376, found 708.3379.
(1-Phenyl-1H-1,2,3-triazol-4-yl)methyl-(2ꢀ,3ꢁ)-2-((1-phenyl-
1H-1,2,3-triazol-4-yl)methoxy)-3-hydroxy-olean-12-en-28-oate
1
(10a). Yellowish solid; m.p.: 227–228 ꢁC; H NMR (300 MHz,
CDCl3): ꢂ 8.06 (1H, s), 8.00 (1H, s), 7.74 (2H, m), 7.71 (2H, m),
7.56–7.50 (3H, m), 7.48–7.43 (3H, m), 5.32–5.22 (3H, m), 4.88
(1H, d, J ¼ 12.3 Hz), 4.72 (1H, d, J ¼ 12.3 Hz), 3.56 (1H, td,
J ¼ 11.2; 4.8 Hz), 3.13 (1H, d, J ¼ 9.3 Hz), 2.87 (3H, m), 2.14–
1.85 (4H, m), 1.68–1.48 (8H, m), 1.34 (3H, m), 1.26 (3H, m), 1.09
(3H, s), 1.04 (3H, s), 0.92 (3H, s), 0.89 (3H, s), 0.84 (3H, s), 0.80
(3H, s), 0.44 (3H, s); 13C NMR (75 MHz, CDCl3): ꢂ 177.3, 143.3,
143.2, 143.2, 136.4, 136.3, 129.3, 129.3, 129.2, 129.2, 128.4,
128.4, 122.1, 121.7, 120.1, 120.1, 120.1, 120.0, 120.0, 81.0, 77.9,
61.8, 56.8, 54.5, 47.0, 46.2, 45.2, 42.3, 41.2, 40.1, 38.8, 38.5,
37.6, 33.2, 32.5, 31.9, 30.2, 29.2, 28.2, 27.0, 25.3, 23.1, 23.0,
22.4, 17.6, 16.4, 16.2, 15.9; HRMS (ESI+): calculated for
(C48H63N6O4)+ [M + H]+ 787.4911, found 787.4908.
(1-(4-Methoxyphenyl)-1H-1,2,3-triazol-4-yl)methyl-(2ꢀ,3ꢁ)-2-
((1-(4-methoxyphenyl)-1H-1,2,3-triazol-4-yl)methoxy)-3-hydroxy-
olean-12-en-28-oate (10b). Dark solid; m.p.: 235–237 ꢁC; 1H
NMR (300 MHz, CDCl3): ꢂ 7.94 (1H, s), 7.87 (1H, s), 7.60 (4H, d,
J ¼ 8.7 Hz), 7.03–7.00 (4H, m), 5.30–5.24 (3H, m), 4.86 (1H, d,
J ¼ 12.3 Hz), 4.70 (1H, d, J ¼ 12.3 Hz), 3.89 (6H, s), 3.53 (1H, td,
J ¼ 11.2; 4.8 Hz), 3.16 (1H, d, J ¼ 9.3 Hz), 2.88 (1H, dd, J ¼ 13.5;
4.2 Hz), 2.84 (2H, m), 2.16–1.88 (4H, m), 1.70–1.49 (6H, m), 1.37
(4H, m), 1.29–1.18(4H, m), 1.10 (3H, s), 1.04 (3H, s), 0.93 (3H,
s), 0.89 (3H, s), 0.85 (3H, s), 0.81 (3H, s), 0.47 (3H, s); 13C NMR
(75 MHz, CDCl3): ꢂ 177.6, 160.3, 158.9, 143.8, 143.8, 143.2,
136.4, 136.3, 134.8, 134.8, 125.8, 125.8, 125.7, 121.7, 121.6,
120.2, 114.3, 114.2, 114.0, 80.9, 77.8, 61.9, 55.1, 55.1, 55.0, 54.0,
47.0, 46.2, 45.2, 42.3, 41.2, 40.1, 38.8, 38.5, 37.6, 33.2, 32.5,
31.9, 30.2, 29.2, 28.2, 27.0, 25.3, 23.5, 23.2, 23.0, 16.4, 16.3,
(1-(4-Nitrophenyl)-1H-1,2,3-triazol-4-yl)methyl-(2ꢀ,3ꢁ)-2,3-
dihydroxyolean-12-en-28-oate (9e). Yellow solid; m.p.: 298–
300 ꢁC; 1H NMR (300 MHz, CDCl3): ꢂ 8.02 (1H, s), 7.60 (2H, d,
J ¼ 7.9 Hz), 7.00 (2H, d, J ¼ 8.1 Hz), 5.28 (3H, m), 3.23 (1H, dd,
J ¼ 10.8; 3.8 Hz), 2.87 (1H, dd, J ¼ 9.6; 4.0 Hz), 2.01 (1H, m),
1.83 (2H, dd, J ¼ 7.8; 2.6 Hz), 1.68–1.44 (12H, m), 1.29 (3H, m),
1.22 (4H, m), 1.10 (3H, s), 0.98 (3H, s), 0.92 (3H, s), 0.90 (3H, s),
0.79 (3H, s), 0.76 (3H, s), 0.49 (3H, s); 13C NMR (75 MHz,
CDCl3): ꢂ 177.6, 143.1, 135.0, 134.4, 129.6, 129.6, 129.0, 122.4,
121.4, 121.4, 116.8, 78.9, 56.8, 55.0, 47.2, 46.6, 45.5, 41.3, 41.0,
39.2, 38.7, 38.2, 36.9, 33.8, 33.0, 32.7, 32.4, 31.8, 30.9, 28.2,
27.6, 27.0, 25.7, 23.9, 23.3, 22.9, 18.2, 16.8, 15.9; HRMS (ESI+):
calculated
675.4124.
for
(C39H55N4O6)+ [M + H]+ 675.4122,
found
(1-(3-Methylphenyl)-1H-1,2,3-triazol-4-yl)methyl-(2ꢀ,3ꢁ)-2,3-
dihydroxyolean-12-en-28-oate (9f). Dark red solid; m.p.: 288–
290 ꢁC; 1H NMR (300 MHz, CDCl3): ꢂ 8.02 (1H, s), 7.55 (1H, s),
7.50 (1H, d, J ¼ 8.1 Hz), 7.39 (1H, t, J ¼ 7.5 Hz), 7.25 (1H, d,
J ¼ 7.5 Hz), 5.28 (3H, m), 3.23 (1H, dd, J ¼ 10.8; 4.2 Hz), 2.87
(1H, dd, J ¼ 9.2; 3.8 Hz), 2.44 (3H, s), 1.95 (1H, td, J ¼ 10.2;
3.8 Hz), 1.83 (2H, dd, J ¼ 8.7; 3.3 Hz), 1.67–1.43 (10H, m), 1.38
(8H, m), 1.12 (3H, s), 1.04 (3H, s), 0.97 (3H, s), 0.94 (3H, s), 0.78
(3H, s), 0.75 (3H, s), 0.67 (1H, m), 0.45 (3H, s); 13C NMR
(75 MHz, CDCl3): ꢂ 177.7, 143.6, 143.5, 139.9, 136.9, 129.5,

DOI: 10.1080/14756366.2016.1193733
Synthesis of 1,4-triazoles from maslinic acid
5
16.2,
16.0;
HRMS
(ESI+):
calculated
for 56.8, 54.5, 47.0, 46.2, 45.3, 42.4, 41.2, 40.8, 38.8, 38.5, 37.6,
33.2, 32.5, 32.0, 31.6, 29.2, 28.2, 27.0, 25.3, 23.5, 23.2, 23.0,
20.8, 20.8, 16.4, 16.3, 16.3, 16.1; HRMS (ESI+): calculated for
(C50H67N6O4)+ [M + H]+ 815.5224, found 815.5220.
(C50H67N6O6)+ [M + H]+ 847.5122, found 847.5120.
(1-(4-Chlorophenyl)-1H-1,2,3-triazol-4-yl)methyl-(2ꢀ,3ꢁ)-2-
((1-(4-chlorophenyl)-1H-1,2,3-triazol-4-yl)methoxy)-3-hydroxy-
olean-12-en-28-oate (10c). Dark solid; m.p.: 230–231 ꢁC; 1H
(1-Naphthalen-1-yl-1H-1,2,3-triazol-4-yl)methyl-(2ꢀ,3ꢁ)-2-
NMR (300 MHz, CDCl3): ꢂ 8.02 (1H, s), 7.95 (1H, s), 7.68 (4H, d, ((1-naphthalen-1-yl-1H-1,2,3-triazol-4-yl)methoxy)-3-hydroxy-
J ¼ 8.7 Hz), 7.50 (4H, dd, J ¼ 5.1; 3.3 Hz), 5.30 (1H, m), 5.26 olean-12-en-28-oate (10 g). dark purple solid; m.p.: 219–220 ꢁC;
(2H, m), 4.86 (1H, d, J ¼ 12.3 Hz), 4.70 (1H, d, J ¼ 12.3 Hz), 3.55 1H NMR (300 MHz, CDCl3): ꢂ 8.05–7.96 (4H, m), 8.02 (1H, s),
(1H, td, J ¼ 11.2; 4.8 Hz), 3.12 (1H, d, J ¼ 9.6 Hz), 2.86 (1H, dd, 7.91 (1H, s), 7.68–7.53 (10H, m), 5.40 (1H, d, J ¼ 12.6 Hz), 5.34
J ¼ 13.5; 4.2 Hz), 2.13–1.85 (6H, m), 1.67–1.44 (8H, m), 1.33 (1H, d, J ¼ 12.6 Hz), 5.31 (1H, t, J ¼ 3.6 Hz), 4.95 (1H, d,
(2H, m), 1.26 (4H, m), 1.10 (3H, s), 1.04 (3H, s), 0.90 (3H, s), J ¼ 12.3 Hz), 4.81 (1H, d, J ¼ 12.3 Hz), 3.61 (1H, td, J ¼ 11.2;
0.86 (3H, s), 0.81 (3H, s), 0.78 (3H, s), 0.46 (3H, s); 13C NMR 4.8 Hz), 3.17 (1H, d, J ¼ 9.3 Hz), 2.87 (1H, dd, J ¼ 13.5; 4.2 Hz),
(75 MHz, CDCl3): ꢂ 177.3, 144.8, 143.5, 143.2, 134.9, 134.9, 2.15–1.87 (4H, m), 1.75–1.43 (10H, m), 1.39–1.31 (3H, m), 1.25
134.1, 134.1, 129.4, 129.4, 129.4, 129.4, 122.4, 122.2, 121.7, (2H, m), 1.13 (3H, s), 1.06 (3H, s), 0.90 (3H, s), 0.87 (3H, s), 0.83
121.7, 121.6, 121.6, 120.3, 81.1, 77.9, 61.9, 55.0, 54.0, 47.0, 46.2, (3H, s), 0.80 (3H, s), 0.57 (3H, s); 13C NMR (75 MHz, CDCl3): ꢂ
45.2, 42.3, 41.2, 40.1, 38.8, 38.5, 37.6, 33.2, 32.5, 32.0, 31.6, 177.3, 143.9, 142.7, 143.2, 133.7, 133.6, 133.2, 133.0, 133.0,
29.2, 28.2, 27.0, 25.3, 23.5, 23.2, 23.0, 16.4, 16.3, 16.2, 16.0; 129.9, 129.9, 128.0, 127.8, 127.7, 127.7, 127.7, 127.7, 127.4,
HRMS (ESI+): calculated for (C48H61Cl2N6O4)+ [M + H]+ 126.6, 126.2, 124.4, 124.4, 123.0, 122.8, 121.8, 121.7, 81.0, 77.4,
855.4131, found 855.4127.
(1-(4-Bromophenyl)-1H-1,2,3-triazol-4-yl)methyl-(2ꢀ,3ꢁ)-2-
((1-(4-bromophenyl)-1H-1,2,3-triazol-4-yl)methoxy)-2-hydroxy-
62.0, 57.0, 54.5, 47.0, 46.2, 45.2, 42.3, 41.2, 40.1, 38.8, 38.5,
37.6, 33.2, 32.5, 32.0, 31.6, 29.2, 28.2, 27.0, 25.3, 23.5, 23.2,
17.6, 16.6, 16.6, 16.4, 16.0; HRMS (ESI+): calculated for
olean-12-en-28-oate (10d). White solid; m.p.: 227–229 ꢁC; 1H (C56H67N6O4)+ [M + H]+ 887.5224, found 887.5221.
NMR (300 MHz, CDCl3): ꢂ 8.02 (1H, s), 7.95 (1H, s), 7.70 (4H, d,
(1-Phenyl-1H-1,2,3-triazol-4-yl)methyl-(2ꢀ,3ꢁ)-2-hydroxy-3-
J ¼ 8.7 Hz), 7.52 (4H, m), 5.31 (1H, t, J ¼ 3.3 Hz), 5.28 (2H, m), ((1-phenyl-1H-1,2,3-triazol-4-yl)methoxy)-olean-12-en-28-oate
1
4.87 (1H, d, J ¼ 12.3 Hz), 4.71 (1H, d, J ¼ 12.3 Hz), 3.53 (1H, td, (11a). Yellowish solid; m.p.: 230–232 ꢁC; H NMR (300 MHz,
J ¼ 11.2; 4.8 Hz), 3.15 (1H, d, J ¼ 9.6 Hz), 2.83 (1H, dd, J ¼ 13.5; CDCl3): ꢂ 8.02 (1H, s), 7.94 (1H, s), 7.73–7.69 (4H, m), 7.54–
4.2 Hz), 2.11–1.81 (8H, m), 1.69–1.40 (4H, m), 1.33 (4H, m), 1.23 7.47 (4H, m), 7.45–7.39 (2H, m), 5.28–5.25 (3H, m), 4.98 (1H, d,
(4H, m), 1.11 (3H, s), 1.02 (3H, s), 0.90 (3H, s), 0.86 (3H, s), 0.80 J ¼ 12.0 Hz), 4.95 (1H, d, J ¼ 12.0 Hz), 3.88 (1H, td, J ¼ 11.2;
(3H, s), 0.75 (3H, s), 0.48 (3H, s); 13C NMR (75 MHz, CDCl3): ꢂ 4.8 Hz), 2.95 (1H, d, J ¼ 9.3 Hz), 2.87 (1H, dd, J ¼ 13.5; 4.2 Hz),
177.3, 144.8, 143.5, 143.2, 134.9, 134.9, 134.1, 134.1, 129.4, 2.02 (2H, m), 2.00–1.85 (4H, m), 1.70–1.61 (4H, m), 1.64–1.43
129.4, 129.4, 129.4, 122.4, 122.2, 121.7, 121.7, 121.6, 121.6, (4H, m), 1.34 (4H, m), 1.26 (4H, m), 1.14 (3H, s), 1.10 (3H, s),
120.3, 81.1, 77.9, 61.9, 55.0, 54.0, 47.0, 46.2, 45.2, 42.3, 41.2, 0.99 (3H, s), 0.89 (3H, s), 0.83 (3H, s), 0.79 (3H, s), 0.46 (3H, s);
40.1, 38.8, 38.5, 37.6, 33.2, 32.5, 32.0, 31.6, 29.2, 28.2, 27.0, 13C NMR (75 MHz, CDCl3): ꢂ 177.2, 143.3, 143.0, 143.0, 136.4,
25.3, 23.5, 23.2, 23.0, 16.4, 16.3, 16.2, 16.0; HRMS (ESI+): 136.4, 129.2, 129.2, 129.2, 129.2, 129.2, 129.2, 128.3, 128.2,
calculated for (C48H61Br2N6O4)+ [M + H]+ 943.3121, found 122.1, 120.1, 120.1, 119.9, 119.9, 94.6, 68.2, 67.2, 56.8, 54.8,
943.3118.
(1-(4-Nitrophenyl)-1H-1,2,3-triazol-4-yl)methyl-(2ꢀ,3ꢁ)-2-
((1-(4-nitrophenyl)-1H-1,2,3-triazol-4-yl)methoxy)-2-hydroxy-
47.0, 46.2, 46.1, 45.3, 41.2, 40.1, 38.8, 38.5, 37.6, 33.2, 32.5,
31.9, 30.2, 29.2, 28.2, 27.0, 25.3, 23.1, 23.0, 22.4, 17.6, 17.0,
16.2, 15.9; HRMS (ESI+): calculated for (C48H63N6O4)+
olean-12-en-28-oate (10e). Yellowish solid; m.p.: 251–253 ꢁC; 1H [M + H]+ 787.4911, found 787.4905.
NMR (300 MHz, CDCl3): ꢂ 8.00 (1H, s), 7.94 (1H, s), 7.77–7.68
(1-(4-Methoxyphenyl)-1H-1,2,3-triazol-4-yl)methyl-(2ꢀ,3ꢁ)-2-
(4H, m), 7.55–7.49 (4H, m), 5.31 (1H, t, J ¼ 3.6 Hz), 5.28 (2H, hydroxy-3-((1-(4-methoxyphenyl)-1H-1,2,3-triazol-4-yl)methoxy)-
m), 4.85 (1H, d, J ¼ 12.3 Hz), 4.73 (1H, d, J ¼ 12.3 Hz), 3.55 (1H, olean-12-en-28-oate (11b). Dark solid; m.p.: 269–270 ꢁC; 1H
td, J ¼ 11.2; 4.8 Hz), 3.17 (1H, d, J ¼ 9.6 Hz), 2.81 (1H, dd, NMR (300 MHz, CDCl3): ꢂ 7.94 (1H, s), 7.86 (1H, s), 7.60 (4H,
J ¼ 13.5; 4.2 Hz), 2.09–1.85 (6H, m), 1.71–1.45 (6H, m), 1.33 dd, J ¼ 6.9; 2.4 Hz), 7.00 (4H, dd, J ¼ 6.9; 2.4 Hz), 5.30 (1H, m),
(2H, m), 1.29–1.21 (6H, m), 1.11 (3H, s), 1.05 (3H, s), 0.90 (3H, 5.27 (1H, d, J ¼ 12.9 Hz), 5.25 (1H, d, J ¼ 12.9 Hz), 4.97 (1H, d,
s), 0.87 (3H, s), 0.81 (3H, s), 0.78 (3H, s), 0.44 (3H, s); 13C NMR J ¼ 12.3 Hz), 4.94 (1H, d, J ¼ 12.3 Hz), 3.86 (1H, td, J ¼ 11.2;
(75 MHz, CDCl3): ꢂ 177.3, 144.8, 143.5, 143.2, 134.9, 134.9, 4.8 Hz), 3.85 (6H, s), 3.16 (1H, d, J ¼ 9.3 Hz), 2.87 (1H, dd,
134.1, 134.1, 129.4, 129.4, 129.4, 129.4, 122.4, 122.2, 121.7, J ¼ 13.5; 4.2 Hz), 2.10–1.86 (4H, m), 1.66–1.48 (8H, m), 1.43
121.7, 121.6, 121.6, 120.3, 81.1, 77.9, 61.9, 55.0, 54.0, 47.0, 46.2, (4H, m), 1.35–1.19 (4H, m), 1.13 (3H, s), 1.03 (3H, s), 0.93 (3H,
45.2, 42.3, 41.2, 40.1, 38.8, 38.5, 37.6, 33.2, 32.5, 32.0, 31.6, s), 0.89 (3H, s), 0.85 (3H, s), 0.81 (3H, s), 0.46 (3H, s); 13C NMR
29.2, 28.2, 27.0, 25.3, 23.5, 23.2, 23.0, 16.4, 16.3, 16.2, 16.0; (75 MHz, CDCl3): ꢂ 177.2, 159.4, 159.3, 146.0, 143.1, 143.0,
HRMS (ESI+): calculated for (C48H61N8O8)+ [M + H]+ 877.4612, 129.9, 129.8, 122.1, 121.9, 121.7, 121.7, 121.5, 121.5, 119.8,
found 877.4610.
(1-(3-Methylphenyl)-1H-1,2,3-triazol-4-yl)methyl-(2ꢀ,3ꢁ)-2-
((1-(3-methylphenyl)-1H-1,2,3-triazol-4-yl)methoxy)-2-hydroxy-
114.2, 114.2, 114.2, 114.2, 94.6, 68.2, 67.3, 56.9, 55.1, 55.1, 54.8,
47.0, 46.2, 46.1, 45.2, 41.1, 40.6, 38.8, 38.5, 37.6, 33.2, 32.5,
31.9, 30.2, 29.2, 28.2, 27.0, 25.3, 23.5, 23.2, 22.9, 16.4, 16.3,
olean-12-en-28-oate (10f). White solid; m.p.: 211–213 ꢁC; 1H 16.2, 16.0; HRMS (ESI+): calculated for (C50H67N6O6)+
NMR (300 MHz, CDCl3): ꢂ 8.02 (1H, s), 7.96 (1H, s), 7.55 (2H, [M + H]+ 847.5122, found 847.5103.
m), 7.48 (2H, m), 7.41–7.36 (2H, m), 7.24 (2H, m), 5.32–5.21
(1-(4-Chlorophenyl)-1H-1,2,3-triazol-4-yl)methyl-(2ꢀ,3ꢁ)-2-
(3H, m), 4.86 (1H, d, J ¼ 12.3 Hz), 4.71 (1H, d, J ¼ 12.3 Hz), 3.57 hydroxy-3-((1-(4-chlorophenyl)-1H-1,2,3-triazol-4-yl)methoxy)-
(1H, td, J ¼ 11.2; 4.8 Hz), 3.17 (1H, d, J ¼ 9.3 Hz), 2.87 (1H, dd, olean-12-en-28-oate (11c). Yellowish solid; m.p.: 244–246 ꢁC; 1H
J ¼ 13.5; 4.2 Hz), 2.45 (3H, s), 2.44 (3H, s), 2.13–1.86 (4H, m), NMR (300 MHz, CDCl3): ꢂ 8.02 (1H, s), 7.94 (1H, s), 7.73 (4H,
1.67–1.43 (6H, m), 1.33 (4H, m), 1.29–1.21 (6H, m), 1.11 (3H, s), dd, J ¼ 6.9; 2.1 Hz), 7.50 (4H, dd, J ¼ 6.9; 2.4 Hz), 5.29 (1H, m),
1.05 (3H, s), 0.90 (3H, s), 0.86 (3H, s), 0.81 (3H, s), 0.78 (3H, s), 5.26 (2H, s), 4.98 (2H, s), 3.86 (1H, td, J ¼ 11.2; 4.8 Hz), 3.12
0.45 (3H, s); 13C NMR (75 MHz, CDCl3): ꢂ 177.2, 145.2, 143.2, (1H, d, J ¼ 9.3 Hz), 2.86 (1H, dd, J ¼ 13.5; 4.2 Hz), 2.13–1.85
139.4, 136.5, 136.4, 131.3, 129.0, 129.0, 128.5, 126.5, 122.2, (4H, m), 1.69–1.41 (10H, m), 1.36 (2H, m), 1.28 (4H, m), 1.10
121.7, 120.7, 120.6, 119.9, 117.0, 113.6, 111.7, 81.0, 77.4, 61.9, (3H, s), 1.04 (3H, s), 0.90 (3H, s), 0.86 (3H, s), 0.81 (3H, s), 0.78

¨
K. Chouaıb et al.
6
J Enzyme Inhib Med Chem, Early Online: 1–18
(3H, s), 0.46 (3H, s); 13C NMR (75 MHz, CDCl3): ꢂ 177.7, 145.1, 4.2 Hz), 2.15–1.87 (6H, m), 1.75–1.43 (8H, m), 1.35(3H, m), 1.26
144.0, 144.0, 139.9, 139.9, 134.6, 134.5, 129.9, 129.9, 129.9, (2H, m), 1.13 (3H, s), 1.06 (3H, s), 0.90 (3H, s), 0.87 (3H, s), 0.83
129.9, 122.4, 122.4, 121.7, 121.7, 121.6, 121.6, 120.0, 95.0, 68.8, (3H, s), 0.80 (3H, s), 0.57 (3H, s); 13C NMR (75 MHz, CDCl3): ꢂ
67.7, 57.2, 55.3, 47.0, 46.2, 45.2, 42.3, 41.2, 40.1, 38.8, 38.5, 177.7, 143.6, 142.7, 143.2, 133.7, 133.6, 133.2, 133.0, 133.0,
37.6, 33.2, 32.5, 32.0, 31.6, 29.2, 28.2, 27.0, 25.3, 23.5, 23.2, 129.9, 129.9, 128.0, 127.8, 127.7, 127.7, 127.7, 127.7, 127.4,
23.0, 18.1, 17.6, 16.7, 16.4; HRMS (ESI+): calculated for 126.6, 126.2, 124.4, 124.4, 123.0, 122.4, 122.3, 122.2, 95.2, 77.2,
(C48H61Cl2N6O4)+ [M + H]+ 855.4131, found 855.4123.
(1-(4-Bromophenyl)-1H-1,2,3-triazol-4-yl)methyl-(2ꢀ,3ꢁ)-2-
hydroxy-3-((1-(4-bromophenyl)-1H-1,2,3-triazol-4-yl)methoxy)-
68.8, 67.8, 57.6, 55.4, 47.6, 46.8, 45.8, 41.7, 40.1, 38.8, 38.5,
37.6, 33.2, 32.5, 32.0, 31.6, 29.2, 28.2, 27.0, 25.3, 23.5, 23.2,
17.6, 16.6, 16.6, 16.4, 16.0; HRMS (ESI+): calculated for
olean-12-en-28-oate (11d). White solid; m.p.: 256–258 ꢁC; 1H (C56H67N6O4)+ [M + H]+ 887.5224, found 887.5220.
NMR (300 MHz, CDCl3): ꢂ 8.01 (1H, s), 7.91 (1H, s), 7.76 (4H,
dd, J ¼ 6.6; 2.1 Hz), 7.52 (4H, dd, J ¼ 6.6; 2.1 Hz), 5.29 (3H, m),
General procedure for the synthesis of tri-1,4-triazolyl
4.99 (1H, d, J ¼ 12.3 Hz), 4.96 (1H, d, J ¼ 12.03 Hz), 3.89 (1H, td,
derivatives 12a–g under CuAAC condition
J ¼ 11.2; 4.8 Hz), 3.14 (1H, d, J ¼ 9.3 Hz), 2.89 (1H, dd, J ¼ 13.5;
Maslinic acid-tri-alkyne 6 (0.1 g, 0.17 mmol) and the appropriate
azide (1 mmol) were dissolved in 3 mL H2O. While the mixture
was being stirred, cuprous iodide (1 equiv) was added, followed
by Et3N (0.5 mmol) at room temperature. The reaction mixture
was then subjected to microwave irradiations at 300 W for 5–
10 min, after which it was diluted with water and then extracted
with ethyl acetate (3 ꢀ 50 mL). The organic layer was dried over
Na2SO4. After removal of solvent in vacuo, the resulting residue
was purified by recrystallization or silica gel column chromatog-
raphy and eluted with petroleum ether:ethyl acetate (8:2) to obtain
the desired new products (12a–g).
4.2 Hz), 2.17–1.89 (4H, m), 1.69–1.46 (8H, m), 1.39 (2H, m),
1.35–1.26 (6H, m), 1.11 (3H, s), 1.05 (3H, s), 0.90 (3H, s), 0.86
(3H, s), 0.82 (3H, s), 0.78 (3H, s), 0.47 (3H, s); 13C NMR
(75 MHz, CDCl3): ꢂ 177.6, 146.0, 144.2, 144.4, 139.4, 139.4,
134.6, 134.5, 129.9, 129.9, 129.8, 129.8, 122.9, 122.9, 121.5,
121.5, 121.5, 121.5, 119.5, 95.0, 68.8, 67.7, 57.2, 55.3, 47.0, 46.2,
45.2, 42.3, 41.2, 40.1, 38.8, 38.5, 37.6, 33.2, 32.5, 32.0, 31.6,
29.2, 28.2, 27.0, 25.3, 23.5, 23.2, 23.0, 18.1, 17.6, 16.7, 16.4;
HRMS (ESI+): calculated for (C48H61Br2N6O4)+ [M + H]+
943.3121, found 943.3115.
(1-(4-Nitrophenyl)-1H-1,2,3-triazol-4-yl)methyl-(2ꢀ,3ꢁ)-2-
hydroxy-3-((1-(4-nitrophenyl)-1H-1,2,3-triazol-4-yl)methoxy)-
olean-12-en-28-oate (11e). Yellowish solid; m.p.: 218–220 ꢁC; 1H
NMR (300 MHz, CDCl3): ꢂ 8.03 (1H, s), 7.95 (1H, s), 7.75–1.71
(4H, m), 7.52–7.49 (4H, m), 5.28 (3H, m), 4.98 (2H, s), 3.89 (1H,
td, J ¼ 11.2; 4.8 Hz), 3.12 (1H, d, J ¼ 9.3 Hz), 2.91 (1H, dd,
J ¼ 13.5; 4.2 Hz), 2.11–1.89 (6H, m), 1.71–1.55 (6H, m), 1.46
(4H, m), 1.31 (4H, m), 1.12 (3H, s), 1.04 (3H, s), 0.92 (3H, s),
0.86 (3H, s), 0.81 (3H, s), 0.75 (3H, s), 0.44 (3H, s); 13C NMR
(75 MHz, CDCl3): ꢂ 177.7, 145.1, 144.0, 144.0, 139.9, 139.9,
134.6, 134.5, 129.9, 129.9, 129.9, 129.9, 122.4, 122.4, 121.7,
121.7, 121.6, 121.6, 120.0, 95.0, 68.8, 67.7, 57.2, 55.3, 47.0, 46.2,
45.2, 42.3, 41.2, 40.1, 38.8, 38.5, 37.6, 33.2, 32.5, 32.0, 31.6,
29.2, 28.2, 27.0, 25.3, 23.5, 23.2, 23.0, 18.1, 17.6, 16.7, 16.4;
HRMS (ESI+): calculated for (C48H61N8O8)+ [M + H]+ 877.4612,
found 877.4604.
(1-(3-Methylphenyl)-1H-1,2,3-triazol-4-yl)methyl-(2ꢀ,3ꢁ)-2-
hydroxy-3-((1-(3-methylphenyl)-1H-1,2,3-triazol-4-yl)methoxy)-
olean-12-en-28-oate (11f). White solid; m.p.: 261–263 ꢁC; 1H
NMR (300 MHz, CDCl3): ꢂ 8.02 (1H, s), 7.93 (1H, s), 7.55 (2H,
s), 7.50 (2H, d, J ¼ 8.1 Hz), 7.42–7.36 (2H, td, J ¼ 7.8; 1.5 Hz),
7.25 (2H, d, J ¼ 8.1 Hz), 5.31 (1H, m), 5.29 (1H, d, J ¼ 12.6 Hz),
5.25 (1H, d, J ¼ 12.6 Hz), 5.01 (1H, d, J ¼ 12.3 Hz), 4.95 (1H, d,
J ¼ 12.3 Hz), 3.87 (1H, td, J ¼ 11.2; 4.8 Hz), 3.17 (1H, d,
J ¼ 9.3 Hz), 2.88 (1H, dd, J ¼ 13.5; 4.2 Hz), 2.45 (6H, s), 2.04
(2H, m), 1.89 (2H, m), 1.67–1.43 (10H, m), 1.36 (2H, m), 1.25–
1.17 (4H, m), 1.11 (3H, s), 1.05 (3H, s), 0.97 (3H, s), 0.93 (3H, s),
0.81 (3H, s), 0.78 (3H, s), 0.45 (3H, s); 13C NMR (75 MHz,
CDCl3): ꢂ 177.2, 143.7, 143.5, 143.5, 139.9, 139.9, 137.0, 136.9,
129.6, 129.6, 129.5, 129.5, 121.6, 122.4, 121.3, 121.2, 120.1,
117.6, 117.5, 95.1, 77.2, 68.7, 67.8, 57.3, 55.3, 47.1, 45.3, 42.4,
41.2, 40.8, 38.8, 38.5, 37.6, 33.2, 32.5, 32.0, 31.6, 29.2, 28.2,
27.0, 25.3, 23.6, 23.4, 22.9, 21.3, 21.3, 18.1, 17.6, 16.7, 16.5;
HRMS (ESI+): calculated for (C50H67N6O4)+ [M + H]+ 815.5224,
found 815.5218.
(1-Phenyl-1H-1,2,3-triazol-4-yl)methyl-(2ꢀ,3ꢁ)-2,3-bis((1-
phenyl-1H-1,2,3-triazol-4-yl)methoxy)-olean-12-en-28-oate
(12a). Purple solid; m.p.: 214–216 ꢁC; 1H NMR (300 MHz,
CDCl3): ꢂ 8.27 (1H, s), 8.07 (1H, s), 8.05 (1H, s), 7.77–7.71 (6H,
m), 7.57–7.36 (9H, m), 5.33–5.23 (5H, m), 4.90 (1H, d,
J ¼ 12.3 Hz), 4.81 (1H, d, J ¼ 12.3 Hz), 3.73 (1H, td, J ¼ 11.2;
4.8 Hz), 3.03 (1H, d, J ¼ 9.6 Hz), 2.91 (1H, dd, J ¼ 13.8; 4.2 Hz),
2.14–1.85 (6H, m), 1.78–1.48 (11H, m), 1.31 (2H, m), 1.20 (2H,
m), 1.12 (3H, s), 1.07 (3H, s), 1.00 (3H, s), 0.89 (3H, s), 0.84 (3H,
s), 0.80 (3H, s), 0.44 (3H, s); 13C NMR (75 MHz, CDCl3): ꢂ
177.3, 143.6, 137.1, 137.1, 137.1, 129.7, 129.7, 129.7, 129.6,
129.6, 129.6, 129.6, 129.6, 129.6, 128.8, 128.6, 128.4, 122.5,
122.3, 120.5, 120.4, 120.3, 120.3, 120.3, 120.3, 120.3, 120.3,
90.7, 77.9, 67.5, 63.3, 57.3, 47.5, 46.7, 45.8, 44.4, 44.3, 41.2,
40.1, 38.8, 38.5, 37.6, 33.2, 32.5, 31.9, 30.2, 29.2, 28.2, 27.0,
25.3, 23.1, 23.0, 22.4, 17.6, 16.4, 16.2, 15.9; HRMS (ESI+):
calculated
944.5573.
for
(C57H70N9O4)+ [M + H]+ 944.5551,
found
(1-(4-Methoxyphenyl)-1H-1,2,3-triazol-4-yl)methyl-(2ꢀ,3ꢁ)-
2,3-bis((1-(4-methoxyphenyl)-1H-1,2,3-triazol-4-yl)methoxy)-
olean-12-en-28-oate (12b). Red solid; m.p.: 255–257 ꢁC; 1H
NMR (300 MHz, CDCl3): ꢂ 8.16 (1H, s), 7.97 (1H, s), 7.95 (1H,
s), 7.65–7.58 (6H, m), 7.05–6.95 (6H, m), 5.32–5.20 (5H, m),
4.90–4.77 (2H, m), 3.87 (6H, s), 3.84 (3H, s), 3.79 (1H, td,
J ¼ 11.2; 4.8 Hz), 3.02 (1H, d, J ¼ 9.9 Hz), 2.92 (1H, dd, J ¼ 13.8;
4.2 Hz), 2.14–1.85 (5H, m), 1.78–1.48 (10H, m), 1.31 (4H, m),
1.20 (2H, m), 1.12 (3H, s), 1.07 (3H, s), 1.00 (3H, s), 0.89 (3H, s),
0.84 (3H, s), 0.80 (3H, s), 0.44 (3H, s); 13C NMR (75 MHz,
CDCl3): ꢂ 177.7, 159.9; 159.7, 159.6, 146.6, 146.5, 143.6, 143.5,
130.6, 130.4, 122.2, 122.1, 122.1, 121.9, 121.9, 121.9, 121.0,
120.9, 114.8, 114.8, 114.8, 114.7, 114.7, 114.7, 114.7, 114.7,
114.7, 90.7, 77.9, 67.5, 63.3, 57.3, 55.5, 55.6, 55.5, 47.5, 46.7,
45.8, 44.4, 44.3, 41.2, 40.1, 38.8, 38.5, 37.6, 33.2, 32.5, 31.9,
30.2, 29.2, 28.2, 27.0, 25.3, 23.1, 23.0, 22.6, 18.2, 17.5, 16.7,
16.4; HRMS (ESI+): calculated for (C60H76N9O4)+ [M + H]+
1034.5868, found 1034.5917.
(1-Naphthalen-1-yl-1H-1,2,3-triazol-4-yl)methyl-(2ꢀ,3ꢁ)-2-
hydroxy-3-((1 naphthalen-1-yl -1H-1,2,3-triazol-4-yl)methoxy)-
olean-12-en-28-oate (11 g). Dark purple solid; m.p.: 244–
(1-(4-Chlorophenyl)-1H-1,2,3-triazol-4-yl)methyl-(2ꢀ,3ꢁ)-
2,3-bis((1-(4-chlorophenyl)-1H-1,2,3-triazol-4-yl)methoxy)-
olean-12-en-28-oate (12c). Yellowish solid; m.p.: 234–235 ꢁC; 1H
NMR (300 MHz, CDCl3): ꢂ 8.20 (1H, s), 7.96 (1H, s), 7.93 (1H,
s), 7.65–7.57 (6H, m), 7.44–7.35 (6H, m), 5.23–5.10 (5H, m),
1
245 ꢁC; H NMR (300 MHz, CDCl3): ꢂ 8.05–7.91 (4H, m), 8.01
(1H, s), 7.97 (1H, s), 7.67–7.52 (10H, m), 5.41–531 (3H, m), 5.09
(1H, d, J ¼ 12.6 Hz), 5.03 (1H, d, J ¼ 12.6 Hz), 3.92 (1H, td,
J ¼ 11.2; 4.8 Hz), 3.04 (1H, d, J ¼ 9.6 Hz), 2.90 (1H, dd, J ¼ 13.5;

DOI: 10.1080/14756366.2016.1193733
Synthesis of 1,4-triazoles from maslinic acid
7
4.90–4.77 (2H, m), 3.67 (1H, td, J ¼ 11.2; 4.8 Hz), 2.95 (1H, d,
(1-Naphthalen-1-yl-1H-1,2,3-triazol-4-yl)methyl-(2ꢀ,3ꢁ)-2,3-
J ¼ 9.9 Hz), 2.87 (1H, dd, J ¼ 13.8; 4.2 Hz), 2.14–1.85 (5H, m), bis((1-naphthalen-1-yl-1H-1,2,3-triazol-4-yl)methoxy)-olean-12-
1.78–1.48 (10H, m), 1.31 (4H, m), 1.20 (2H, m), 1.12 (3H, s), en-28-oate (12 g). Dark purple solid; m.p.: 204–205 ꢁC; 1H NMR
1.07 (3H, s), 0.97 (3H, s), 0.81 (3H, s), 0.78 (3H, s), 0.74 (3H, s), (300 MHz, CDCl3): ꢂ 8.15–7.99 (12H, m), 7.77–7.64 (6H, m),
0.38 (3H, s); 13C NMR (75 MHz, CDCl3): ꢂ 177.7, 159.9; 159.7, 7.62–7.55 (6H, m), 5.41–531 (3H, m), 5.09 (2H, d, J ¼ 12.6 Hz),
159.6, 146.6, 146.5, 143.6, 143.5, 130.6, 130.4, 122.2, 122.1, 5.03 (2H, d, J ¼ 12.6 Hz), 3.92 (1H, td, J ¼ 11.2; 4.8 Hz), 3.04
122.1, 121.9, 121.9, 121.9, 121.0, 120.9, 114.8, 114.8, 114.8, (1H, d, J ¼ 9.6 Hz), 2.90 (1H, dd, J ¼ 13.5; 4.2 Hz), 2.15–1.87
114.7, 114.7, 114.7, 114.7, 114.7, 114.7, 90.7, 77.9, 67.5, 63.3, (6H, m), 1.75–1.43 (8H, m), 1.35(3H, m), 1.26 (4H, m), 1.13 (3H,
57.3, 47.5, 46.7, 45.8, 44.4, 44.3, 41.2, 40.1, 38.8, 38.5, 37.6, s), 1.06 (3H, s), 0.90 (3H, s), 0.87 (3H, s), 0.83 (3H, s), 0.80 (3H,
33.2, 32.5, 31.9, 30.2, 29.2, 28.2, 27.0, 25.3, 23.1, 23.0, 22.6, s), 0.57 (3H, s); 13C NMR (75 MHz, CDCl3): ꢂ 177.5, 143.6,
18.2, 17.5, 16.7, 16.4; HRMS (ESI+): calculated for 143.2, 143.2, 143.2, 142.7, 142.7, 133.7, 133.6, 133.2, 133.0,
(C57H67Cl3N9O4)+ [M + H]+ 1046.4382, found 1046.4411.
133.0, 129.9, 129.9, 129.9, 129.9, 129.9, 129.9, 128.0, 127.8,
(1-(4-Bromophenyl)-1H-1,2,3-triazol-4-yl)methyl-(2ꢀ,3ꢁ)-2,3- 127.7, 127.7, 127.7, 127.7, 127.4, 126.6, 126.2, 124.4, 124.4,
bis((1-(4-bromophenyl)-1H-1,2,3-triazol-4-yl)methoxy)-olean-12- 123.0, 122.4, 122.4, 122.4, 122.4, 122.3, 122.3, 122.3, 122.2,
en-28-oate (12d). White solid; m.p.: 221–223 ꢁC; 1H NMR 122.2, 122.2, 93.2, 77.2, 68.8, 67.8, 57.6, 55.4, 47.6, 46.8, 45.8,
(300 MHz, CDCl3): ꢂ 8.26 (1H, s), 8.01 (1H, s), 7.97 (1H, s), 41.7, 40.1, 38.8, 38.5, 37.6, 33.2, 32.5, 32.0, 31.6, 29.2, 28.2,
7.75–7.55 (6H, m), 7.41–7.29 (6H, m), 5.25 (4H, m), 5.21–5.12 27.0, 25.3, 23.5, 23.2, 17.6, 16.6, 16.6, 16.6, 16.2; HRMS
(4H, m), 4.93–4.79 (2H, m), 3.71 (1H, td, J ¼ 11.2; 4.8 Hz), 2.99 (ESI+): calculated for (C69H76N9O4)+ [M + H]+ 1094.6020, found
(1H, d, J ¼ 9.9 Hz), 2.87 (1H, dd, J ¼ 13.8; 4.2 Hz), 2.14–1.85 1094.6061.
(5H, m), 1.70–1.55 (6H, m), 1.48–1.38 (4H, m), 1.31 (2H, m),
1.25 (4H, m), 1.12 (3H, s), 1.07 (3H, s), 0.97 (3H, s), 0.81 (3H, s), Biological assay
0.78 (3H, s), 0.74 (3H, s), 0.49 (3H, s); 13C NMR (75 MHz,
Natural pentacyclic triterpenoid (Maslinic acid 1) and most of the
CDCl3): ꢂ 177.9, 159.6; 159.3, 159.3, 145.1, 145.1, 151.1, 143.5,
synthesized triazoles were dissolved in dimethyl sulfoxide
130.6, 130.4, 122.2, 122.1, 122.1, 121.9, 121.9, 121.9, 121.0,
(DMSO) and added into the medium at final concentrations of
120.9, 115.9, 115.8, 115.8, 1116.0, 116.0, 116.0, 116.2, 116.2,
10, 30 and 100 mM. The final concentration of DMSO was 0.33%
116.2, 90.7, 77.9, 67.5, 63.3, 57.3, 47.5, 46.7, 45.8, 44.4, 44.3,
and was determined to have no cytotoxicity.
41.2, 40.1, 38.8, 38.5, 37.6, 33.2, 32.5, 31.9, 30.2, 29.2, 28.2,
27.0, 25.3, 23.1, 23.0, 22.6, 18.2, 17.8, 16.2, 16.0; HRMS (ESI+):
Determination of pro-inflammatory IL-1b cytokine
calculated for (C57H67Br3N9O4)+ [M + H]+ 1178.2866, found
production in PBMCs
1178.2897.
(1-(4-Nitrophenyl)-1H-1,2,3-triazol-4-yl)methyl-(2ꢀ,3ꢁ)-2,3-
Human peripheral blood mononuclear cells (PBMCs) were
isolated from buffy coats from healthy donors by density gradient
bis((1-(4-nitrophenyl)-1H-1,2,3-triazol-4-yl)methoxy)-olean-12-
1
en-28-oate (12e). Yellowish solid; m.p.: 211–212 ꢁC; H NMR centrifugation (Pancoll human, d.1.077 g/mL). Recovered PBMCs
(300 MHz, CDCl3): ꢂ 8.17 (1H, s), 7.91 (1H, s), 7.90 (1H, s), were washed thrice in Dulbecco’s phosphate buffered saline,
7.68–7.55 (6H, m), 7.40–7.31 (6H, m), 5.24–5.16 (5H, m), 4.92– seeded in a 96-well microplate at 6.67 ꢀ 105 cells/mL in RPMI-
4.78 (2H, m), 3.69 (1H, td, J ¼ 11.2; 4.8 Hz), 2.95 (1H, d, 1640 containing 10% fetal bovine serum, penicillin (100 U/mL),
J ¼ 9.9 Hz), 2.87 (1H, dd, J ¼ 13.8; 4.2 Hz), 2.14–1.85 (5H, m), streptomycin (100 mg/mL), amphotericin B (250 ng/mL), and
1.78–1.48 (8H, m), 1.39 (4H, m), 1.22 (4H, m), 1.12 (3H, s), 1.07 incubated at 5% CO2 and 37 ꢁC. PBMCs were treated with
(3H, s), 0.97 (3H, s), 0.81 (3H, s), 0.78 (3H, s), 0.74 (3H, s), 0.44 compound 1 and the synthesized triazoles (8b–g; 9a–d,f,g;
(3H, s); 13C NMR (75 MHz, CDCl3): ꢂ 177.7, 159.9; 159.7, 159.6, 10a,c,f,g; 11a–c,f; 12b,c,f,g) (10, 30 and 100 mM) then were
146.6, 146.5, 143.6, 143.5, 130.6, 130.4, 122.2, 122.1, 122.1, stimulated for 24 h with LPS (E. coli, 0128:B12, Sigma)
121.6, 121.6, 121.6, 121.0, 120.9, 115.2, 115.2, 115.1, 114.9, (10 ng/mL)28,29. Three anti-inflammatory standards were tested
114.8, 114.8, 114.7, 114.7, 114.7, 90.7, 77.9, 67.5, 63.3, 57.3, in the same conditions: ZVAD (5 mM), dexamethasone (DEXA,
47.5, 46.7, 45.8, 44.4, 44.3, 41.2, 40.1, 38.8, 38.5, 37.6, 33.2, 1 mM) and prednisolone (PRED, 70 mM). After incubation, the
32.5, 31.9, 30.2, 29.2, 28.2, 27.0, 25.3, 23.1, 23.0, 22.6, 18.2, supernatants were harvested and kept at ꢂ20 ꢁC until use.
17.5,
16.7,
16.4;
HRMS
(ESI+):
calculated
for Viability of PBMCs was assessed by XTT assay. Secretion IL-
(C57H67N12O10)+ [M + H]+ 1046.5103, found 1072.5144.
1b was measured only in the culture supernatants of PBMCs
(1-(3-Methylphenyl)-1H-1,2,3-triazol-4-yl)methyl-(2ꢀ,3ꢁ)-2,3- treated with compounds that showed low toxicity, using a
bis((1-(3-methylphenyl)-1H-1,2,3-triazol-4-yl)methoxy)-olean-12- sandwich enzyme-linked immunosorbent assay (ELISA) method
en-28-oate (12f). White solid; m.p.: 211–213 ꢁC; 1H NMR (eBioscience, San Diego, CA), according to manufacturer
(300 MHz, CDCl3): ꢂ 8.12 (1H, s), 8.02 (1H, s), 7.97 (1H, s), instructions.
7.57 (3H, m), 7.51–7.36 (6H, m), 7.40–7.35 (3H, m), 5.33 (1H, s),
5.30 (2H, m), 5.27 (2H, m), 4.99 (2H, m), 3.89 (1H, td, J ¼ 11.2;
Determination of anti-proliferative activity in EMT-6 and
4.8 Hz), 3.17 (1H, d, J ¼ 9.3 Hz), 2.88 (1H, dd, J ¼ 13.5;
SW480 cancer cell lines
4.2 Hz), 2.46 (3H, s), 2.44 (6H, s), 2.06 (4H, m), 1.89 (4H, m),
Murine mammary carcinoma cell line EMT-6 and human
colorectal adenocarcinoma cell line SW480, purchased from
American Type Culture Collection (ATCC, Manassas, VA), were
cultured in DMEM supplemented with 10% of fetal bovine serum
and penicillin (100 U/mL), streptomycin (100 mg/mL), ampho-
tericin B (250 ng/mL) and placed in CO2 incubator with 5% of
CO2 at 37 ꢁC. Cells were seeded in a 96-well microplate at
3.125 ꢀ 104 cells/mL and treated with compounds (10, 30 and
100 mM) for 48 h. Doxorubicin, etoposide, 5-fluorouracil and
methotrexate (10 mM) were used as anti-cancer references. The
anti-proliferative activity of compounds and drug references were
1.67–1.43 (6H, m), 1.34 (2H, m), 1.25–1.19 (5H, m), 1.11 (3H,
s), 1.05 (3H, s), 0.97 (3H, s), 0.93 (3H, s), 0.81 (3H, s), 0.78 (3H,
s), 0.45 (3H, s); 13C NMR (75 MHz, CDCl3): ꢂ 177.3, 143.7,
143.5, 143.5, 143.4, 139.9, 139.9, 139.8, 137.0, 136.9, 129.6,
129.4, 122.2, 122.1, 122.1, 121.0, 120.9, 115.2, 115.2, 115.1,
114.9, 114.8, 114.8, 114.8, 115.8, 115.7, 115.7, 90.0, 77.8, 67.5,
63.3, 57.3, 47.5, 46.7, 46.5, 46.5, 46.3, 45.8, 44.4, 44.3, 41.2,
40.1, 38.8, 38.5, 37.6, 33.2, 32.5, 31.9, 30.2, 29.2, 28.2, 27.0,
25.3, 23.1, 23.0, 22.6, 18.2, 17.5, 16.7, 16.0; HRMS
(ESI+): calculated for (C60H76N9O4)+ [M + H]+ 986.6020, found
986.6053.

¨
K. Chouaıb et al.
8
J Enzyme Inhib Med Chem, Early Online: 1–18
determined using XTT assay30,31. This assay is based on the (99%). Chromatography on a silica-gel column of this mixture
conversion of the water-soluble XTT (sodium 2,3,-bis(2-methoxy- resulted only the alkyl derivatives 2 and 4–6 in 25, 23, 20 and 21%
4-nitro-5-sulfophenyl)-5-[(phenylamino)-carbonyl]-2H-tetrazo-
lium) inner salt) reagent, in the presence of the electron-coupling
yield, respectively (Table 1).
The structures of the propargylated compounds 2–6 were
reagent PMS (phenazine methylsulfate) to an orange formazan unambiguously confirmed by ESI-HRMS and NMR. Thus, the
product by metabolically active cells. The amount of formazan molecular formula of compounds 2 and 3 (C33H50O4) as
produced was detected by measurement of the absorbance at determined by ESI-HRMS (m/z 511.3778 and 511.3794, respect-
499 nm and a reference wavelength was used at 660 nm on a ively [M + H]+, calculated for 511.3787), was in agreement with a
¨
microplate reader Infinite M200 Pro TECAN (Mannedorf, monopropargylated structure of maslinc acid 1. While, the
Switzerland). Cell viability is expressed as a percentage of molecular formula of compounds 4 and 5 (C36H52O4) as
control, which was taken as 100%.
established by ESI-HRMS (m/z 549.3938 and 549.3940, respect-
ively [M + H]+, calculated for 549.3944), indicated that were they
derived from the dipropargylation of maslinic acid 1. Moreover,
the molecular formula of compound 6 (C39H54O4) as determined
by ESI-HRMS (m/z 587.4092 [M + H]+, calculated for 587.4100),
was found to be in concordance with the tripropargylation of
maslinic acid 1. The position of the alkylation in the obtained
derivatives was deduced by simple comparison of their NMR
spectral data (1H and 13C) with those of the starting substrate 1.
Results and discussion
Chemistry
Synthesis of maslinic acid-alkyne derivatives 2–6 as
dipolarophiles
Taking cue from the literature, we have undertaken a research
program directed toward the structural modifications of maslinic
acid 1 to fine tune its biological potential as anti-inflammatory
and anti-proliferative agent. The synthesis of maslinic acid-alkyne
derivatives 2–6 was done on maslinic acid (1) which isolated
RuAAC and CuAAC for the synthesis of 1,5- and
1,4-disubstituted triazoles
under green chemistry condition, from pomace olive (Olea Aromatic azides were synthesized from the appropriate anilines
europaea L.) cultivar: Chemlali with a large amount (17 g using a two-step procedure by diazotization with sodium nitrite in
(8.5 mg/g DW) using an ultrasonic bath. The compound 1 was acidic conditions followed by displacement with sodium azide.
subjected to a propargylation of the hydroxyl groups at C-2, C-3 The desired aromatic azides 7a–g were obtained in yields ranging
and carboxylic group at C-28. This reaction was tried under from 85 to 98%.
different conditions in dry N,N-dimethylformamide (DMF).
Method I: 2 equiv. of NaH was used in the presence of propargyl yields, side-reactions and poor regioselectivity32,33
The thermal [3 + 2] cycloaddition method can suffer from low
While
.
bromide (3 equiv.) in dry DMF for 2 h at room temperature ‘‘click’’ reaction mediated preparations of 1,4- and 1,5-disubsti-
yielded a mixture of compounds in 82% yield (Table 1). tuted triazoles have been reported to provide satisfactory
Chromatography on a silica-gel column of this mixture resulted yields34,35. The ruthenium-catalyzed version of the reaction
compounds 2 (44%), 3 (5%), 4 (15%), 5 (11%) and 6 (7%). (RuAAC), led mainly to 1,5-regioisomers36. Although the
Method II: When the amounts of NaH and propargyl bromide Ru(II)-catalyzed Hu¨isgen 1,3-dipolar cyclization usually proceeds
were increased to 4 equiv. of each in dry DMF at room in high yields, this type of reaction has been reported to be highly
temperature for 8 h, the yield of mixture has been improved dependent on the substrate and reaction conditions. At the outset
Table 1. Method I and II for the synthesis of dipolarophiles 2–6a.
OH
28
HO
HO
O
2
3
1
Method I or II
Dry DMF, rt
O
OH
O
O
O
O
HO
HO
O
O
HO
O
O
O
O
O
O
O
+
+
+
+
2
HO
4
3
HO
6
5
Compounds
Method I (82%)b
(%)c
Method II (99%)b
(%)c
2
3
4
5
6
44
5
15
11
7
25
0
23
20
31
NaH (2 equiv)d
propargyl bromide
(3 equiv)d
NaH (4 equiv)d
propargyl bromide
(4 equiv)d
2 h
8 h
aMaslinic acid (1) in dry DMF as solvent at room temperature.
byield of mixture, based on the starting material (compound 1).
cIsolated yield of compounds (2–6) after column chromatography (EP-EtOAc), based on the maslinicacid (1).
dReferred to the starting material (compound 1).

DOI: 10.1080/14756366.2016.1193733
Synthesis of 1,4-triazoles from maslinic acid
9
of our studies, we investigated the cyclo-addition reaction give the corresponding secondary amines37,38
between phenylazide 7a and maslinic acid-alkyne 2 with different investigated the Cu(I)-catalyzed azide-alkyne cycloaddition
.
We have then
concentrations of the catalyst Cp*RuCl(PPh3)2. The most relevant (CuAAC) under microwave conditions for the synthesis of 1,4-
results of this study are shown in Table 2.
regiomers 9a–g. The copper (I)-catalyzed of the reaction
At the beginning, the reaction conditions were optimized in (CuAAC) leading to the sole 1,4-regioisomers. Working under
heating at 110 ꢁC (reflux temperature of toluene) with different microwave conditions at 200 W, we first investigated the optimal
catalyst loading (Table 2, entries 1–3), and it was found that 5 mol conditions for the ‘‘click’’ reaction of dipolarophile 2 and
% Ru(II) was the optimum amount of catalyst for these conditions phenylazide 7a in presence of triethylamine with different solvent
(entry 2). When the temperature was decreased to room tempera- and copper(I) iodide loading (Table 4). A 92% conversion was
ture, the yield of reaction, decreased significantly (30%) after even obtained only after 2 min of reaction with 0.5 equiv. catalyst. The
48 h of reaction (entry 4). It should be noted that some catalyst total conversion of starting maslinic acid-alkyne 2 was obtained
deactivation has been encountered during long-heating times. only after 2 min under solvent-free conditions and in 5 min in
Thus, to circumvent this limitation, we decided to work under DMF for 0.5 equiv. catalyst loading. For lower CuI loading,
microwave activation. Interestingly, from the different solvents, conversion was not complete, even after 15 min reaction.
solvent/co-solvent mixtures and solvent-free tested under micro- Moreover, when we worked under H2O as solvent, the yield
wave conditions, DMF was found to be the most effective for this decreased (70%) even after 15 min reaction (entry 4). It may be
reaction (Table 2, compare entries 5–8). Thus, using 5 mol% due to the poor solubility of the maslinic acid-alkyne 2 or the
Cp*RuCl(PPh3)2 under microwave heating in DMF, the reaction of possible complexation of the copper species in water.
dipolarophile 2 with phenylazide 7a, gave (1-phenyl-1H-1,2,3-
Starting with the maslinic acid-alkyne 2 the synthesis of
triazol-5-yl)methyl-(2a,3b)-2,3-dihydroxyolean-12-en-28-oate 8a various 1,4-disubstituted-1,2,3-triazolyl-maslinic acid was per-
almost quantitatively in only 6 min of reaction time (Table 2, entry formed region-specifically using CuI as catalyst under microwave
5). It is interesting to note that anhydrous conditions are not and solvent-free conditions (Scheme 1). The desired new 1,2,3-
necessary. Indeed, undistilled DMF, or DMF-containing 0.5 equiv. triazoles 9a–g were obtained in yields ranging from 90 to 99%
of water can be used to run this RuAAC (entries 5 and 7). While the (Table 3). This method has the advantage of being simple, low-
use of water as solvent results in a significant reduction in yield cost and the products can be obtained from the reaction mixture
(Traces) even after 15 min reaction (entry 6). It may be due to the by simple purification. The new products can be obtained from
poor solubility of the starting dipolarophile 2.
Under the optimized conditions, a region-specific approach times were in general shorter than those reported in the literature6.
using Huisgen 1,3-dipolar cyclo-addition reaction (RuAAC) of The synthesized 1,5- and 1,4-disubstituted-1,2,3-triazolyl-
the reaction mixture in almost quantitative yields and the reaction
1
terminal alkyne 2 with various aromatic azides 7a–g in presence maslinic acid (8a–g, 9a–g) were characterized by H/13C NMR,
of Cp*RuCl(PPh3)2 as catalyst resulting into the formation of DEPT 135, NOESY and ESI-HRMS (Experimental section). The
regiospecific 1,5-substituted-triazolyl derivatives 8a–g in excel- absence of 1H NMR signals of terminal alkyne 2 at ꢂH 2.34 (1H, t,
lent yields (Scheme 1). All the reactions were carried under J ¼ 2.7 Hz), and emerging of a singlet at ꢂH 7.77–8.09 (H-4 of the
microwave irradiation (250 W) completed within 4–8 minutes triazole ring, for 1,5-isomers, 8a–g) and at ꢂH 7.96–8.03 (H-5 of
(Table 3). A similar reactivity was observed for most azides the triazole ring, for 1,4-isomers, 9a–g) provides a good support
(Table 3, entries 1–4, 6 and 7). In contrast, 4-nitrophenylazide for the cycloaddition to form 1,5- and 1,4-disubstituted-triazoles.
showed to be relatively less reactive under the same reaction The same features are reflected in 13C NMR spectra, where the
conditions (Table 3, entry 5), probably due to the presence of a signal belongs to the terminal carbon of alkyne was disappeared
group with a negative mesomeric effect at the 4-position of the and a new signal belongs to C–H ring carbon, was appeared at ꢂC
phenyl group, which could promote the dimerization of azides to ꢃ114.2–136.7 after cyclo-addition.
Table 2. Optimization of the 1,3-dipolar cyclization for the ruthenium-catalyzed click reactiona.
N
3
N
N
N
O
O
HO
HO
HO
HO
7a
O
O
8a
2
Entry
Mol% of Ru(II)b
Method
Time (h)
Yield (%)
1
2
3
4
5
6
7
8
2
5
10
5
5
5
110 ꢁC (Toluene)
110 ꢁC (Toluene)
110 ꢁC (Toluene)
rt (Toluene)
8
8
8
48
0.1
0.4
0.1
0.4
55
82
78
30
MWc (DMF)
98
MWc (H2O)
Traces
86
No reaction
5
5
MWc (DMF/H2O (2:1))
MWc (Solvent free)
Bold in entry highlight the optimal reaction condition.
aAlkyne 2 (2 mmol) and two equivalents of phenylazide (7a).
bReferred to the starting alkyne 2.
cThe reaction was performed at 250 W.

¨
10 K. Chouaıb et al.
J Enzyme Inhib Med Chem, Early Online: 1–18
N3
4
N 2
R–N3
5
O
1'
N1
7a-g
O
HO
HO
RuAAC, MW
R
O
HO
HO
O
a
8a-g
R–N3
7a-g
CuAAC, MW
Solvent free
b
Ru
Cl
Ph3P
PPh3
3
N
N2
N1
[Cp*RuCl(PPh3)3]
R
O
1'
4
5
HO
HO
O
9a-g
Scheme 1. Synthesis of the 1,5- and 1,4-triazolyl (8a–g, 9a–g) derivatives. Reagents and conditions: (a) [Cp*RuCl(PPh3)2], DMF, Microwave (250 W,
4–8 min), 83–98%. (b) Cuprous iodide (CuI), Et3N, solvent free, Microwave (200 W, 2–4 min), 90–99%.
Table 3. Maslinic acid-1,5- and 1,4-disubstituted triazolyl derivatives varying at aromatic ring.
3
N
N3
N2
4
5
N2
N1
R
O
O
1'
1'
N1
R
4
5
HO
HO
HO
HO
O
O
1,5-Regioisomers (8a–g)
1,4-Regioisomers (9a–g)
1,4-Regioisomers (CuAAC)
1,5-Regioisomers (RuAAC)
Entry
R
Time (min) Yield% (Compounds)
Time (min) Yield% (Compounds)
1
6
98 (8a)
98 (8b)
2
2
99 (9a)
98 (9b)
2
3
4
5
4
O
6
4
8
6
95 (8c)
96 (8d)
83 (8e)
95 (8f)
4
4
4
2
94 (9c)
94 (9d)
90 (9e)
96 (9f)
Cl
Br
NO
2
6
7
6
96 (8g)
2
95 (9g)

DOI: 10.1080/14756366.2016.1193733
Synthesis of 1,4-triazoles from maslinic acid 11
Table 4. Optimization of CuAAC under microwave conditions for 9aa.
N3
N
N
N
O
O
HO
HO
HO
HO
7a
O
O
9a
2
Irradiation timec
Entry
Catalyst loading CuI (equiv)b
Solvent
2 min
5 min
15 min
1
2
3
4
5
0.1
0.3
0.5
0.5
0.5
DMF
DMF
DMF
–
–
92%
–
–
78%
100%
–
45%
80%
–
70%
–
H2O
Solvent free
100%
–
aMaslinic acid-alkyne 2 (2 mmol), Et3N (2 mmol) and two equivalents of phenylazide (7a).
bReferred to the starting alkyne 2.
cThe reaction was performed at 200 W.
acid 10a–g were obtained in good yields (92–98%). The same
methodology was successfully applied to bis-alkyne 5. The latter
compound gave the desired new bis-1,4-disubstituted-1,2,3-
triazolyl-maslinic acid 11a–g with various aromatic azides. All
the reactions were carried under microwave irradiation (250 W)
completed within 4–7 minutes (Scheme 2). A similar reactivity
was observed for most azides. In contrast, with the electron-
deficient azides, reactivity was decreased slightly under the same
reaction conditions. Similarly the synthesized new bis-1,4-disub-
stituted triazoles 10a–g and 11 a–g were characterized by 1H/13C
NMR, DEPT 135, NOESY and ESI-HRMS (Experimental
section).
Table 5. Optimization of CuAAC under microwave and solvent free
conditions for 10aa.
Irradiation timec (min)
Catalyst loading CuI (equiv)b
4
6
12
0.5
0.6
0.7
0.8
–
–
–
–
55%
80%
–
85%
100%
100%
–
–
aMaslinic acid-bis-alkyne 4 (2 mmol), Et3N (4 mmol) and 4 equivalents
of phenylazide (7a).
bReferred to the starting bis-alkyne 4.
cThe reaction was performed at 250 W.
CuAAC for the synthesis of tri-1,4-disubstituted triazolyl
derivatives
The 1,5-regiochemistry thus adopted in compounds 8a–g was
confirmed by NOESY spectra showing NOEs between the H-
On the contrary of dipolarophiles 2–5, tri-alkyne 6 is fully soluble
in water. Interestingly the use of water as solvent, we investigated
the reactivity for the cyclo-addition of latter dipolarophile (6) and
phenylazide 7a in the presence of triethylamine (3 equiv. referred
to the starting tri-alkyne 6) with different catalyst (CuI) loading
under microwave heating in water. The addition of CuI as catalyst
(1 equiv. referred to the starting maslinic acid-tri-alkyne 6), was
essential to obtain the maximum yield of the desired tri-1,4-
disubstituted triazolyl 12a in minimum reaction time. For lower
catalyst loading (0.8 and 0.9 equiv.), conversion was not complete.
With the optimized condition in hand, the dipolarophile 6 was
reacted with various aromatic azides, 3 equiv. of triethylamine
and 1 equiv. of CuI catalyst. All the reactions were performed
at 300 W under microwave conditions in water completed within
5–10 minutes. A similar reactivity was observed for all azides
used. The desired new tri-triazoles 12a–g were obtained in yields
ranging from 92 to 96% (Scheme 3). All the synthesized new
tri-1,4-disubstituted triazoles were characterized by 1H/13C NMR,
DEPT 135, NOESY and ESI-HRMS (Experimental section).
0
4triazole/H1 and H1 /Harom, and the absence of any NOE between
H-4triazole/Harom, under RuAAC conditions. While The
NOESY spectra of regioisomers 9a–g showed NOEs between
0
H-5triazole/H1 and H-5triazole/Harom, and the absence of any NOE
0
between H1 /Harom, under CuAAC conditions. Such observations
0
are in perfect agreement with the proposed structures and with
that cited in the literature.
CuAAC for the synthesis of bis-1,4-disubstituted triazolyl
derivatives
Working under microwave and solvent-free conditions, we first
investigated the optimal conditions for the cyclo-addition of bis-
alkyne 4 and phenylazide 7a with different concentrations of
catalyst (Table 5). A 85% conversion into the desired cyclo-adduct
10a was obtained only after 4 min of reaction with 0.7 equiv.
catalyst. The total conversion of starting bis-alkyne 4 was
obtained after 6 min with 0.7 equiv. catalyst loading and in
4 min for 0.8 equiv. catalyst loading. For lower catalyst loading,
conversion was not complete, even after 12 min reaction
(Scheme 2). Thus, 0.8 equiv. catalyst, 2 equiv. Et3N and 4
equiv. of phenylazide 7a under microwave and solvent-free
conditions for 4 min allowed the formation of the desired cyclo-
adduct 10a. With this optimized condition, we probed the scope
of the condensation of bis-alkyne 4 with various aromatic azides.
The desired new bis-1,4-disubstituted-1,2,3-triazolyl-maslinic
Pharmacological screening
Anti-inflammatory activity
The anti-inflammatory activity of the tested compounds was
studied using LPS-stimulated human peripheral blood mono-
nuclear cells (PBMCs). Three anti-inflammatory references were

¨
12 K. Chouaıb et al.
J Enzyme Inhib Med Chem, Early Online: 1–18
N
N
N
Ar
N
N
N
O
O
Ar
N3
7a-g
Ar
O
R1O
O
O
CuAAC, MW
Solvent free
HO
R2O
10a-g
4: R1=
5: R1= H
; R2 = H
; R2 =
10
11
Ar
Ph
Comp.
T(min) Yield% T(min) Yield%
CuAAC, MW
Solvent free
4
96
4
96
Ar
N3
7a-g
a
( )
b
4
7
7
98
90
92
( ) p-MeOPh
3
6
6
98
94
94
c
( ) p-ClPh
N
N
N
d
( ) p-BrPh
Ar
O
e
5
6
92
96
( ) p-NO2Ph
4
6
92
94
HO
O
O
f
( ) m-MePh
Ar
N
N
g
( ) Naphthyl
5
98
6
94
N
11a-g
Scheme 2. Bis-1,4-disubstituted triazoles 10a–g and 11a–g prepared by the Cu(I)-catalyzed synthesis.
N
N
N
N
N
Ar
N
N
O
Ar N3
CuAAC, MW
O
Ar
Ar
O
O
O
O
O
O
H2O, Et3N
N
N
12a-g
6
Comp.
12a
Ph
12b
12c
12d
12e
12f
12g
p-MeOPh
p-ClPh
p-BrPh
p-NO2Ph
m-MePh
Ar
Naphthyl
T(min)
8
5
8
10
6
10
8
Yield%
98
98
95
94
92
98
96
Scheme 3. Tri-1,4-disubstituted triazoles 12a–g prepared by the Cu(I)-catalyzed synthesis.
tested in the same conditions: ZVAD (5 mM), dexamethasone compounds type 8 with those of the derivatives 9 substituted
(DEXA, 1 mM) and prednisolone (PRED, 70 mM). Secretion IL-1b identically at the triazole ring revealed that these latter are more
was measured only in the culture supernatants of PBMCs treated active (% IL-1b production ¼ 40–91 and 21–82, respectively;
with compounds that showed no or low toxicity, using a 100 mM). However, we found that the regiochemistry in two
sandwich enzyme-linked immunosorbent assay (ELISA) method analogs from the series 8 and 9 bearing the same substituent
(eBioscience, San Diego, CA), according to manufacturer intervenes to reverse the activity, we cite the example of
instructions.
compounds 8d (p-Br) (% IL-1b production ¼ 61 5; 100 mM)
As shown in Table 6, the % IL-1b production indicated that and 9d (p-Br) (% IL-1b production ¼ 21 1; 100 mM). This
most compounds exhibited a significant anti-inflammatory activ- finding showed the importance of both the regiochemistry of the
ity. It has been found that all the synthesized triazoles exhibited triazole and the nature of the aryl attached to it.
more potent inhibitory activities than the starting natural
Regarding the bis-1,4-disubstituted triazoles type 10, only
compound 1. This finding showed that the introduction of the compounds 10a (H), 10c (p-Cl), showed a relatively-important
triazoles moieties in compound 1 considerably improve its anti- activity (% IL-1b production ¼ 71 2 and 56 2, respectively;
inflammatory effect. In the series of 1,5-regioisomers, compounds 100 mM) compared to the remaining analogs and maslinic acid 1
8e (p-NO2) and 8f (m-C2H5) were found to be the most actives (% (% IL-1b production ¼ 109 3; 30 mM). However, the % IL-1b
IL-1b production ¼ 42 1 and 46 3 respectively; 100 mM). On production exhibited by the bis-1,4-disubstituted triazoles type 11
the other hand, our findings showed that most of the tested 1,4- revealed that compounds with electron donating groups at an
regioisomers 9a, 9b, 9d, 9f and 9 g displayed a significant anti- aromatic ring are generally more active than compounds without
inflammatory activity, the derivative 9d with (p-Br) was found to substitutions or substitutions with an electron withdrawing group.
be the most active (% IL-1b production ¼ 21 1; 100 mM). The In fact, compounds 11b and 11f, with p-OCH3 and m-Me
comparison of % IL-1b production values of the tested substitutions at the aromatic ring were the most promising

DOI: 10.1080/14756366.2016.1193733
Synthesis of 1,4-triazoles from maslinic acid 13
Table 6. Effect of natural pentacyclic triterpenoid (Maslinic acid 1) and the synthesized triazoles on viability and inflammatory cytokine (IL-1b)
production in LPS-stimulated PBMCs.
Conc. (mM)
% PBMCs viability (/Control)
% IL-1b production (/Control)
DMSO 0.33% + LPS (Control)
ZVAD + LPS
DEXA + LPS
100
110
81
4
4
7
8
100
42
32
43
2
2
2
4
5
1
70
PRED + LPS
67
Entry
1
Code
1
100
30
14
53
7
5
Nd
109
3
Mono-1,5-disubstituted triazoles
N
N
O
O
N
HO
HO
R
8
2
3
4
5
6
7
8b
8c
8d
8e
8f
100
30
100
30
100
30
100
30
100
30
100
30
87
93
76
74
94
87
75
93
51
99
93
95
4
5
3
5
3
4
4
3
7
9
2
7
91
Nd
60
Nd
61
Nd
42
Nd
46
Nd
76
Nd
3
2
5
1
3
1
8g
Mono-1,4-disubstituted triazoles
N
N
N
R
O
HO
HO
O
9
8
9a
9b
9c
9d
9f
100
30
100
30
100
30
100
30
100
30
100
30
92
91
71
75
83
55
92
74
6
6
5
9
4
1
8
2
62
Nd
65
Nd
82
Nd
21
Nd
59
Nd
53
Nd
1
2
4
1
3
3
9
10
11
12
13
88 10
97
97
88
3
2
7
9g
Bis-1,4-disubstituted triazoles
N
N
N
N
N
R
N
N
N
R
O
O
N
R
O
HO
O
O
HO
O
11
R
N
10
N
N
14
15
10a
10c
100
30
100
30
92
92
98
94
5
3
4
2
71
Nd
56
Nd
2
2
(continued )

¨
14 K. Chouaıb et al.
J Enzyme Inhib Med Chem, Early Online: 1–18
Table 6. Continued
Conc. (mM) % PBMCs viability (/Control)
% IL-1b production (/Control)
16
17
18
19
20
21
22
10f
10g
11a
11b
11c
11f
100
30
100
30
100
30
100
30
100
30
100
30
100
30
66
93
97
80
88
82
74
88
71
91
81
83
95
93
2
5
3
5
5
4
5
2
2
5
5
5
5
5
100
Nd
95
Nd
82
Nd
34
Nd
74
Nd
52
Nd
91
Nd
4
2
1
2
2
1
3
11g
Tri-1,4-disubstituted triazoles
N
N
N
N
N
R
N
N
O
N
N
R
O
O
O
R
12
23
24
25
26
12b
100
30
100
30
100
30
100
30
73
96
83
85
40
63
31
72
1
2
5
3
5
4
1
5
43
Nd
47
Nd
Nd
23
Nd
34
3
2
12c
12f
12g
3
3
Table 7. Effect of natural pentacyclic triterpenoid 1 and the synthesized triazoles on viability of EMT-6 and SW480 cell lines.
Viability (%/Control)
Tissue:
Cell line:
Breast
EMT-6
Colon
SW480
Conc. (mM)
DMSO 0.33% (Control)
Doxorubicin
Etoposide
5-fluorouracil
Methotrexate
Entry
14
6
41
26
14
2
0
2
1
2
100
25
70
92
68
2
10
10
10
10
1
5
2
0
Code
1
1
100
5
0
9
0
30
10
5
100
0
2
11
123
1
2
1,5-disubstituted triazoles
N
N
N
O
HO
H
R
O
8
2
3
8b
8c
100
30
10
100
30
103
97
96
24
54
1
0
2
0
0
122
108
106
51
1
1
6
1
3
61
(continued )

DOI: 10.1080/14756366.2016.1193733
Synthesis of 1,4-triazoles from maslinic acid 15
Viability (%/Control)
Tissue:
Cell line:
Breast
EMT-6
Colon
SW480
Conc. (mM)
10
100
30
10
100
30
10
100
30
10
100
30
96
13
108
105
40
110
108
43
62
104
47
102
110
1
1
2
2
0
3
1
1
2
3
4
0
0
75
34 11
0
4
5
6
7
8d
8e
8f
128
118
99
3
4
2
2
0
3
3
0
1
0
0
117
110
56
73
108
59
8g
99
120
10
Mono-1,4-disubstituted triazoles
N
N
N
R
O
HO
HO
O
9
9
10
11
12
13
14
9a
9b
9c
9d
9f
100
30
10
100
30
10
100
30
10
100
30
10
100
30
10
100
15
1
1
3
0
1
0
0
0
1
0
0
0
3
0
0
4
0
3
45
74
102
59
86
96
13
10
1
0
1
3
9
5
0
0
2
0
9
33
92
40
66
109
9
6
87
7
92
108
39
70
98
76
87
102
19
13
113
112 11
64
77
94
73
87
93
2
1
4
0
0
3
9g
30
10
Bis-1,4-disubstituted triazoles
N
N
N
N
N
N
N
N
R
R
O
O
N
R
O
HO
O
O
HO
O
11
R
10
N
N
N
15
16
17
18
19
10a
10c
10f
10g
11a
100
30
10
100
30
10
100
30
10
100
30
10
116
114
113
118
115
111
123
117
113
117
111
112
115
110
109
0
0
1
0
0
4
0
1
1
1
2
2
1
0
1
103
114
119
117
115
117
112
112
111
116
111
115
103
100
102
1
1
0
0
1
1
1
2
1
4
3
1
1
1
0
100
30
10
(continued )

¨
16 K. Chouaıb et al.
J Enzyme Inhib Med Chem, Early Online: 1–18
Table 7. Continued
Viability (%/Control)
Tissue:
Cell line:
Breast
EMT-6
Colon
SW480
Conc. (mM)
20
21
22
11b
11c
11f
100
30
10
100
30
10
100
30
108
108
109
105
108
110
104
105
106
0
1
0
0
2
1
1
1
0
108
107
105
116
122
115
115
109
106
0
1
3
1
3
8
1
1
4
10
Tri-1,4-disubstituted triazoles
N
N
N
R
N
N
N
N
O
N
N
R
R
O
O
O
12
24
25
26
27
12b
12c
12f
12g
100
30
10
100
30
10
100
30
10
100
30
10
100
100
107
46
63
100
8
40
109
8
90
110
4
2
2
0
6
3
0
1
1
0
1
1
119
113
107
123
123
114
13
70
116
13
3
4
6
6
8
4
0
3
2
0
4
0
98
111
(% IL-1b production ¼ 34 2 and 52 1 respectively; 100 mM). triazole derivatives showed moderate to good activities (Table 7).
The position of the triazole at C-2 (compounds 10) or C-3 The percentage viability data indicated that most 1,5-regioisomers
(compounds 11) in maslinic acid 1 is sometimes decisive in this type 8 exhibited potent anti-proliferative activity. Compound 8d
activity, we cite the case of 10f (% IL-1b production ¼ 100 4; (p-Br) was displayed the most activity in this series against EMT-
100 mM) and 11f (% IL-1b production ¼ 52 1; 100 mM) where 6 (Breast) (Viability (%/Control) ¼ 13%) and SW480 (colon)
the triazole bears the same aromatic system (m-MePh).
(Viability (%/Control) ¼ 34%; 100 mM) cancer cell lines. For the
On the other hand, the tested compounds from the series of tri- 1,4-regioisomers 9, compounds 9a, 9c and 9d exhibited higher
1,4-disubstituted triazoles 12 were found to be the most potent anti-proliferative activity against the two used cancer cell lines at
among the whole synthesized compounds (% IL-1b produc- the concentration of 100 mM compared to the other analogs 9b, 9f
tion ¼ 23–47; 30–100 mM). This finding showed the importance and 9 g. Indeed, compound 9c (p-Cl) was found to be the most
of the number and may be also the position of the triazole active against both EMT-6 (Breast) (Viability (%/Control) ¼ 6%;
moieties to improve the anti-inflammatory activity of maslinic 30 mM) and SW480 (colon) (Viability (%/Control) ¼ 10%;
acid 1. Compounds 12f (m-Me) and 12 g with a naphthyl group on 30 mM). In most cases, 1,4-regioisomers type 9 possess better
the triazole ring showed relatively-important activities (% IL-1b anti-proliferative activity compared to that of 1,5-regioisomers
production ¼ 23 3 and 34 3 respectively; 30 mM) compared to type 8. This finding showed the signification of the region-
the remaining analogs and maslinic acid 1 (% IL-1b produc- chemistry of the triazole formed (1,4- or 1,5-) to this activity
tion ¼ 109 3; 30 mM).
which may be explained by the approach in space of the aryl
group attached to the triazole in relation to the triterpene moiety
(Table 7).
In vitro anti-proliferative activity
The anti-proliferative activity of the synthesized bis-triazoles
10 and 11 were investigated and they did not exhibit any marked
activity. In the series of tri-1,4-disubstituted triazoles 12, only
compounds 12f (m-Me) and 12 g (naphthyl) showed potent
activity against EMT-6 (Breast) (Viability (%/Control) ¼ 8%;
100 mM) and SW480 (colon) (Viability (%/Control) ¼ 13%;
100 mM) cancer cell lines. The above data show the contribution
of the free hydroxyl groups at C-2 and C-3 in maslinic acid 1 to
this activity and also show the importance of nature and the
number of triazoles fixed in these positions.
The anti-proliferative activity of maslinic acid 1 and twenty-four
of its triazole derivatives (8b–g; 9a–d,f,g; 10a,c,f,g; 11a–c,f;
12b,c,f,g) was studied using cultured murine EMT-6 (Breast) and
human SW480 (colon) cancer cell lines. Doxorubicin, etoposide,
5-fluorouracil and methotrexate (10 mM) were used as anti-cancer
references in this study. The obtained data revealed that maslinic
acid 1 was found to be the most anti-proliferative against EMT-6
(Breast) and SW480 (colon) cancer cell lines (Viability
(%/Control) ¼ 5 and 9%, respectively; 100 mM) and most of its

DOI: 10.1080/14756366.2016.1193733
Synthesis of 1,4-triazoles from maslinic acid 17
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Conclusion
In conclusion, we have achieved the low-cost ultrasound irradi-
ation-assisted isolation of maslinic acid 1 (17 g (8.5 mg/g DW)),
under green chemistry condition, from pomace olive (Olea
europaea L.) cultivar: Chemlali. On the other hand, we used it
as starting material to develop an effective, facile and practical
procedure for the regio-specific synthesis of 1,5-triazolyl deriva-
tives by Ru(II)-catalyzed azide-alkyne cycloaddition (RuAAC),
and mono, bis and tri-1,4-triazolyl derivatives by Cu(I)-catalyzed
azide-alkyne cycloaddition (CuAAC), using click-chemistry and
microwave irradiation conditions, avoiding toxic reagents and
solvents. This method afforded twenty-four maslinic acid triazole
derivatives in quantitative yields. Most of the compounds were
evaluated for their anti-inflammatory and anti-proliferative
activities. Our findings showed the contribution of the nature of
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Acknowledgements
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The authors are grateful to Mrs Amna Benzarti and Miss Nadia Msaddek,
NMR service at the Faculty of Monastir, University of Monastir for the
1D and 2D NMR analysis.
Declaration of interest
The authors declare no conflicts of interests. The authors alone are
responsible for the content and writing of this article. This study was
financially supported (LR11ES39) by the Ministry of Higher Education
and Scientific Research of Tunisia.
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