Click Synthesis and Antimicrobial Screening of Novel Isatin-1,2,3-Triazoles with Piperidine, Morpholine, or Piperazine Moieties

Full text of DOI:10.1080/00304948.2017.1320515

Organic Preparations and Procedures International
The New Journal for Organic Synthesis
ISSN: 0030-4948 (Print) 1945-5453 (Online) Journal homepage: http://www.tandfonline.com/loi/uopp20
Click Synthesis and Antimicrobial Screening
of Novel Isatin-1,2,3-Triazoles with Piperidine,
Morpholine, or Piperazine Moieties
Mohamed R. Aouad
To cite this article: Mohamed R. Aouad (2017) Click Synthesis and Antimicrobial Screening
of Novel Isatin-1,2,3-Triazoles with Piperidine, Morpholine, or Piperazine Moieties, Organic
Preparations and Procedures International, 49:3, 216-227, DOI: 10.1080/00304948.2017.1320515
To link to this article: http://dx.doi.org/10.1080/00304948.2017.1320515
Published online: 01 Jun 2017.
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Date: 02 June 2017, At: 18:25

Organic Preparations and Procedures International, 49:216–227, 2017
Copyright Ó Taylor & Francis Group, LLC
ISSN: 0030-4948 print / 1945-5453 online
DOI: 10.1080/00304948.2017.1320515
Click Synthesis and Antimicrobial Screening of
Novel Isatin-1,2,3-Triazoles with Piperidine,
Morpholine, or Piperazine Moieties
Mohamed R. Aouad1,2
1Department of Chemistry, Faculty of Science, Taibah University, Al-Madinah
Al-Munawarah 30002, Saudi Arabia
2Department of Chemistry, Faculty of Sciences, University of Sciences and
Technology Mohamed Boudiaf, Laboratoire de Chimie et Electrochimie des
Complexes Metalliques (LCECM) USTO-MB, P.O. Box 1505, El M‘nouar,
Oran 31000, Algeria
Indoles are one of the most prevalent classes of pharmacologically active azoles and have
found applications as antibacterial, antifungal, anti-mycobacterial, antiviral, anti-HIV,
antitumor and anticonvulsant agents.1–6 Among these, some 1H-indole-2,3-dione (isatin)
compounds incorporating a 1,2,3-triazole scaffold were recently found to exhibit signifi-
cant antimalarial and anticancer activities.7–10 The 1,2,3-triazole ring system is a common
structural motif for a number of chemotherapeutic agents that have exhibited remarkable
biological potential in areas that include antitubercular, anti-inflammatory, antifungal,
antibacterial, and anticancer activities.11–16 Recent advances in modern heterocyclic
chemistry have introduced the 1,2,3-triazole moiety as a connecting spacer to link two
pharmacophore sites together and generate original bifunctional drugs.17,18 Conversely,
the piperidine, morpholine and piperazine moieties are key structural units in drug design
due to their insertion into several drug molecules, including thioridazine, linezolid, levo-
floxacin, trifluoroperazine, gatifloxacin, itraconazole, posaconazole and eperezolid.19–22
In view of the fact that the presence of two pharmacophoric sites in one molecule could
generate relevant compounds with increased medicinal potentialities,23–25 the present
study reports the click synthesis and antimicrobial screening of novel isatin-1,2,3-tria-
zoles appended with piperidine, morpholine or piperazine moieties connected via a meth-
ylene and/or an acetyl linkage.
Two classes of isatin-1,2,3-triazole hybrids were synthesized by the Cu(I)-mediated
click chemistry approach via regioselective addition of the N-propargylated isatin 1 with
different cyclic secondary amine azides 2a-h (Scheme 1) or by the addition of azidoacetyl
isatin 5 with various propargylated cyclic secondary amines 6a-h (Scheme 2). For that
purpose, isatin was used as a starting material, which, when treated with propargyl bro-
mide in the presence of NaH and DMF, yielded the precursor N-propargylated isatin.8
Received January 1, 2017; in final form January 26, 2017.
Address correspondence to Mohamed R. Aouad, Department of Chemistry, Faculty of Science,
Taibah University, Al-Madinah Al-Munawarah 30002, Saudi Arabia. E-mail: mr_aouad@yahoo.fr
216

Click Synthesis and Antimicrobial Screening
217
The second precursors, namely, N-azidoacetyl-tethered piperidine, morpholine or
piperazine derivatives 2a-g, were synthesized by an initial base-catalyzed acylation of the
corresponding cyclic secondary amines with bromoacetyl bromide based on previously
reported methods.26, 27 The obtained a-bromoacetamides were treated with sodium azide
to yield the azidoacetamide derivatives 2a-g. These derivatives, when treated with prop-
argylated isatin 1, ligated the terminal CꢀC bond of 1 to the azide building blocks of the
heterocyclic units using Huisgenꢀs copper(I)-catalyzed 1,3-dipolar cycloaddition to yield
targeted hybrids 3a-g with an acetyl linkage between the isatin and the 1,2,3-triazole. The
reaction was conducted in t-BuOH/H2O (1:1) in the presence of sodium ascorbate and
copper sulfate at room temperature for 5–8 h to afford the target compounds with yields
of 82–89% (Scheme 1).
Scheme 1 Click synthesis of isatin-1,2,3-triazole hybrids 3a-g.
Spectroscopic characterization (IR, NMR, MS and EA) of these compounds
confirmed the success of the click reaction. The disappearance of the azido and alkyne
absorbance bands in the IR (2100–2200 cm¡1) for compounds 3a-g confirmed their
involvement in the dipolar cycloaddition reaction. All compounds contained common
1
1
features in their H NMR and 13C NMR spectra. Their H NMR spectra displayed a
characteristic singlet at dH 8.08–8.25 ppm corresponding to the aromatic proton of C-5
on the triazole ring, while the N-CH2 protons appeared at dH 4.83–4.99 ppm as a singlet.

218
Aouad
The resonances of the methylene protons of the acetyl group were observed as two dis-
tinct singlets at dH 5.41–5.67 ppm. In addition, the proton NMR spectrum of 3c revealed
the appearance of a triplet at dH 2.50 ppm and a multiplet at dH 3.45–3.57 ppm that were
attributed to the morpholine NCH2 and OCH2 protons, respectively. Conversely, the eight
piperazine protons in 3f appeared as two triplets at dH 2.75 and 2.84 ppm. In the 13C NMR
spectrum of compound 3c, the methylene carbons of the morpholine ring were observed
at dc 35.0 and 50.6 ppm, while the methylene carbon flanked between the isatin and
1,2,3-triazole moieties appeared at dc 40.4 ppm, and the acetyl methylene carbon was
observed at dH 64.3 ppm.
The azidoacetyl isatin 5 required for the preparation of the second class of 1,2,3-tria-
zole hybrids 7a-g was prepared initially by phase transfer catalysis acylation (Bu4NCBr¡,
K2CO3, THF/H2O) with bromoacetyl bromide at 0ꢁC for 2 h, followed by azidolysis with
sodium azide at room temperature for 12 h (Scheme 2).
Scheme 2 Synthesis of 1-(2-azidoacetyl)indoline-2,3-dione (5).
For compound 5, the presence of the azido group was inferred by the presence of a
characteristic absorption band at 2110 cm¡1 in its IR spectrum. In the 1H NMR spectrum,
the azidomethylene protons resonated as one singlet at dH 4.02 ppm. The aromatic isatin
protons appeared at their usual chemical shifts (dH 7.28–7.78 ppm). The 13C NMR spec-
trum showed one signal in the aliphatic region at dC 50.8 ppm, which was attributed to
the azidomethyl carbon.
The synthesis of the propargylated piperidine, morpholine and piperazine derivatives
6a-g was carried out using previously published protocols involving base-assisted alkyl-
ation of the appropriate cyclic secondary amines with propargyl bromide,28–30 resulting
in the isolation of precursors 6a-g. To build the targeted isatin-1,2,3-triazole hybrids 7a-g
attached to the un/substituted piperidine, morpholine or piperazine rings via an acetyl
spacer, the propargylated building blocks 6a-g were treated with 5 (Scheme 3). For exam-
ple, the coupling of 5 with the propargylated piperidine 6a in a 1:1 t-BuOH/H2O mixture
and a catalytic amount of Na2SO4 and CuSO4 for 6 h afforded the novel isatin-1,2,3-tria-
zole hybrid 1-(2-(4-(piperidin-1-ylmethyl)-1H-1,2,3-triazol-1-yl)acetyl)indoline-2,3-
dione (7a) in 86% yield (Scheme 3). The synthesis has also been adopted for the other six
analogues of 6a to afford the respective isatin-based cyclic secondary amines carrying a
1,2,3-triazole ring 7b-g in 80–87% yields.
The structures of the 1,2,3-triazole hybrids 7a-g have been established by IR, 1H NMR,
13C NMR and MS. In their IR spectra, the lack of absorption bands in the 2100–2200 cm¡1
region characteristic of the azido and the CꢀC groups confirmed the formation of the 1,2,3-
triazole ring. All the synthesized click products 7a-g showed one distinct singlet in the aro-
matic region around dH 7.95–8.12 ppm that was attributable to the triazolyl C5-H proton.
The singlets at dH 3.73–4.02 ppm and dH 4.78–5.24 ppm were assigned to the methylene
protons of the triazole –CH2R and the acetyl connecting units, respectively. In addition, all

Click Synthesis and Antimicrobial Screening
219
Scheme 3 Click synthesis of isatin-1,2,3-triazole hybrids 7a-g.
the aliphatic protons of the cyclic secondary amine residues resonated in the upfield region
(see experimental details). The success of the cycloaddition reaction was further supported
by 13C NMR, as the peaks due to the alkyne carbons were replaced with new resonances
due to the carbons of the triazole ring; these new resonances appeared in the region charac-
teristic of sp2 carbons (dc 117.4–120.8 ppm).
The preliminary antimicrobial activity results are expressed as the minimum inhibi-
tion concentration (MIC) using the broth dilution method and are summarized in
Table 1.31, 32 It is obvious from the screening results that the antimicrobial activity of the
designed click products appeared to be governed by the nature of the cyclic secondary
amine (piperidine, morpholine or piperazine) as well as the position of the acetyl linkage
in the skeleton moieties. The majority of the tested compounds displayed promising inhi-
bition activity with MIC values of 4–16 mg/ml. Based on the antimicrobial bioassay
results, compounds 3a-d were found to be more potent towards bacterial strains compared
to the fungal strains. In general, the highest antibacterial inhibitions, with an MIC range
of 8–16 mg/ml, were displayed by compounds containing a piperazine moiety (3e-g). The
antifungal screening data of compounds 3a-d showed weak antifungal inhibition with an
MIC range of 62.5–125 mg/ml against all of the tested fungal strains. The incorporation
of a piperazine moiety was found to confer higher antifungal activity with an MIC of
16 mg/ml, as exhibited by compounds 3e-g. Another interesting observation is based on
the position of the acetyl linkage with regards to the 1,2,3-triazole scaffold. The presence
of the acetyl group between the indole and the 1,2,3-triazole moieties plays a significant
role in enhancing antibacterial and antifungal activities. This conclusion is supported by
the promising antimicrobial inhibition displayed by the seven compounds 7a-g towards

220
Aouad
Table 1
Antimicrobial Screening Results of Compounds 3a-g and 7a-g Expressed as MIC
(mg/mL)
Gram-Positive Organisms
Gram-Negative Organisms
Fungi
Af Ca
Compounds
Sp
Bs
Sa
Pa
Ec
Kp
3a
3b
3c
3d
3e
3f
3g
7a
7b
7c
7d
7e
7f
7g
16
16
16
16
16
8
31.25
31.25
16
16
8
31.25
31.25
31.25
31.25
8
16
31.25
16
31.25
16
16
16
16
16
8
16
16
16
16
16
16
8
31.25
31.25
31.25
16
16
8
62.5 62.5
125 62.5
62.5 62.5
125 62.5
16
16
16
16
16
16
16
8
8
16
8
8
8
8
16
16
16
8
8
31.25 16
31.25 16
16
8
8
16
16
16
8
8
16
16
8
16
16
16
16
16
—
16
16
16
8
8
16
8
16
8
8
8
4
4
8
4
4
8
4
8
4
4
4
8
4
4
16
—
Ciprofloxacin
Fluconazole
ꢀ5
ꢀ1
ꢀ5
ꢀ5
ꢀ1
ꢀ1
—
—
—
—
—
—
ꢀ1 ꢀ1
all bacterial and fungal strains with MIC values of 4–8 mg/ml and 16–31.25 mg/ml,
respectively. Among them, those with a piperazine moiety, 7e-g, showed the greatest
antibacterial (MIC 4–8 mg/ml) and antifungal (MIC 8–16 mg/ml) inhibition activity.
In conclusion, novel isatin-1,2,3-triazoles appended with piperidines, morpholines or
piperazines connected via an acetyl or methylene linkage were synthesized and screened
for their antibacterial and antifungal activities against a panel of pathogenic bacterial and
fungal strains. Antimicrobial activity profiles confirmed the dependence of the activity on
the nature of the cyclic secondary amine appended to the 1,2,3-triazole ring. Interestingly,
the isatin-1,2,3-triazole hybrids containing a piperazine unit appeared to be the most
active among the tested compounds with an MIC of 4–8 mg/ml.
Experimental Section
All melting points were recorded on a Mel-temp apparatus (SMP10) and are uncorrected.
The IR spectra were measured in a KBr matrix using a SHIMADZU FTIR-8400S
spectrometer. NMR spectra were measured with an Advance Bruker NMR spectrometer
operating at 400 MHz (for 1H) and 100 MHz (for 13C). Tetramethylsilane (TMS) was used
as the internal standard. The EI mass spectra were measured by a Finnigan MAT 95XL spec-
trometer. Elemental analyses were measured using a GmbH-Vario EL III Element Analyzer.
Typical Procedure for the Synthesis of Isatin-1,2,3-Triazole Hybrids 3a-g
To a stirred solution of equimolar amounts of the propargylated isatin 1 and the appropri-
ate azidoacetamide cyclic secondary amine 2a-g dissolved in a 1:1 mixture of t-BuOH

Click Synthesis and Antimicrobial Screening
221
and water was added CuSO4 (0.3 eq) and Na-ascorbate (0.6 eq) at ambient temperature.
The reaction was stirred for an additional 5–8 h at ambient temperature until the
consumption of the starting material was confirmed by TLC. The reaction mixture was
quenched with water and the crude product was extracted with ethyl acetate (3 £
50 mL). The organic phase was dried over anhydrous sodium sulfate, the excess solvent
was reduced under vacuum to yield the targeted 1,2,3-triazoles 3a-g, and the crude prod-
ucts were crystallized from ethanol.
1-((1-(2-Oxo-2-(Piperidin-1-yl)Ethyl)-1H-1,2,3-Triazol-5-yl)Methyl)Indoline-2,
3-Dione (3a)
Yield 88%, mp 180–181ꢁC; IR: 3048 (Ar-H), 2837–2979 (CH str.), 1725 (CDO),
1615 cm¡1 (CDO). 1H NMR (400 MHz, DMSO-d6) dH 1.29–1.33 (2H, m, CH2CH2CH2),
1.69–1.80 (4H, m, 2 x NCH2CH2), 2.35 (2H, t, J D 4.0 Hz, NCH2), 2.65 (2H, t,
J D 4.0 Hz, NCH2), 4.90 (2H, s, NCH2-CDC), 5.41 (1H, s, NCHCO), 5.44 (1H, s,
NCHCO), 7.18–7.25 (2H, m, ArH), 7.62–7.69 (2H, m, ArH), 8.21 (1H, s, CH-1,2,3-tria-
zole); 13C NMR (100 MHz, DMSO-d6) dC 22.2 (CH2CH2CH2), 24.8 (NCH2CH2), 37.9
(NCH2), 42.0 (NCH2-CDC), 64.8 (NCH2CO), 112.4, 118.6, 123.9, 125.5, 126.8, 137.9,
151.5, 157.8, 165.0, 184.1 (Ar-C, CDO). EI MS (m/z): 353.23 (MC).
Anal. Calcd. For C18H19N5O3: C, 61.18; H, 5.42; N, 19.82. Found: C, 61.29; H, 5.55;
N, 19.69.
1-((1-(2-(4-Methylpiperidin-1-yl)-2-Oxoethyl)-1H-1,2,3-Triazol-5-yl)Methyl)-
Indoline-2,3-di-one (3b)
Yield 86%, mp 198–199ꢁC; IR: 3064 (Ar-H), 2848–2937 (CH str.), 1717 (CDO),
1
1604 cm¡1 (CDO). H NMR (400 MHz, DMSO-d6) dH 1.06 (3H, d, J D 4.0 Hz, CH3),
1.25–1.30 (1H, m, CH2CHCH2), 1.52–1.74 (4H, m, 2 x NCH2CH2), 2.22–2.28 (2H, m,
NCH2), 2.41–2.47 (2H, m, NCH2), 4.83 (2H, s, NCH2-CDC), 5.48 (1H, s, NCHCO), 5.55
(1H, s, NCHCO), 7.10–7.17 (2H, m, ArH), 7.58–7.66 (2H, m, ArH), 8.17 (1H, s, CH-
1,2,3-triazole); 13C NMR (100 MHz, DMSO-d6) dC 14.9 (CH3), 21.8 (CH2CHCH2), 24.1
(NCH2CH2), 38.4 (NCH2), 42.2 (NCH2-CDC), 65.7 (NCH2CO), 112.1, 117.4, 123.5,
125.6, 126.9, 137.4, 151.1, 157.4, 164.5, 184.7 (Ar-C, CDO). EI MS (m/z): 367.22 (MC).
Anal. Calcd. For C19H21N5O3: C, 62.11; H, 5.76; N, 19.06. Found: C, 61.95; H, 5.59;
N, 19.20.
1-((1-(2-Morpholino-2-Oxoethyl)-1H-1,2,3-Triazol-5-yl)Methyl)Indoline-2,3-Dione
(3c)
Yield 89%, mp 211–212ꢁC; IR: 3078 (Ar-H), 2855–2960 (CH str.), 1722 (CDO),
1
1610 cm¡1 (CDO). H NMR (400 MHz, DMSO-d6) dH 2.50 (4H, t, J D 4.0 Hz, 2 x
NCH2), 3.45–3.57 (4H, m, 2 x OCH2), 4.99 (2H, s, NCH2-CDC), 5.46 (1H, s, NCHCO),
5.49 (1H, s, NCHCO), 7.12–7.20 (2H, m, ArH), 7.56–7.66 (2H, m, ArH), 8.15 (1H, s,
CH-1,2,3-triazole); 13C NMR (100 MHz, DMSO-d6) dC 35.0 (NCH2), 40.4 (NCH2-
CDC), 50.6 (OCH2), 64.3 (NCH2CO), 111.2, 117.5, 123.6, 124.4, 125.2, 138.0, 150.1,
157.7, 164.3, 183.0 (Ar-C, CDO). EI MS (m/z): 355.04 (MC).
Anal. Calcd. (%) for C17H17N5O4: C, 57.46; H, 4.82; N, 19.71. Found: C, 57.60; H,
4.76; N, 19.59.

222
Aouad
1-((1-(2-(3-Methylmorpholino)-2-Oxoethyl)-1H-1,2,3-Triazol-5-yl)Methyl)-Indoline-
2,3-Dione (3d)
Yield 87%, mp 234–235ꢁC; IR: 3078 (Ar-H), 2828–2948 (CH str.), 1725 (CDO),
1
1620 cm¡1 (CDO). H NMR (400 MHz, DMSO-d6) dH 1.31 (3H, d, J D 4.0 Hz, CH3),
2.56–2.72 (m, 3H, CHCH3, NCH2), 3.52–3.59 (4H, m, 2 x OCH2), 4.95 (2H, s, NCH2-
CDC), 5.42 (1H, s, NCHCO), 5.45 (1H, s, NCHCO), 7.16–7.21 (2H, m, ArH), 7.51–7.60
(2H, m, ArH), 8.14 (1H, s, CH-1,2,3-triazole); 13C NMR (100 MHz, DMSO-d6) dC 18.5
(CH3), 32.6, 36.2 (NCH2), 41.1 (NCH2-CDC), 50.4, 51.1 (OCH2), 66.1 (NCH2CO),
111.7, 116.9, 123.8, 125.0, 125.8, 139.2, 151.2, 157.8, 166.7, 184.5 (Ar-C, CDO). EI MS
(m/z): 369.21 (MC).
Anal. Calcd. (%) for C18H19N5O4: C, 58.53; H, 5.18; N, 18.96. Found: C, 58.67; H,
5.11; N, 19.13.
1-((1-(2-(4-Methylpiperazin-1-yl)-2-Oxoethyl)-1H-1,2,3-Triazol-5-yl)Methyl)
Indoline-2,3-Dione (3e)
Yield 88%, mp 248–249ꢁC; IR: 3047 (Ar-H), 2844–2982 (CH str.), 1726 (CDO),
1
1624 cm¡1 (CDO). H NMR (400 MHz, DMSO-d6) dH 2.23 (3H, s, NCH3), 2.66 (4H,
t, J D 4.0 Hz, 2 x NCH2), 2.74 (4H, t, J D 4.0 Hz, 2 x NCH2), 4.87 (2H, s, NCH2-
CDC), 5.48 (1H, s, NCHCO), 5.53 (1H, s, NCHCO), 7.11–7.17 (2H, m, ArH), 7.50–
7.58 (2H, m, ArH), 8.08 (1H, s, CH-1,2,3-triazole); 13C NMR (100 MHz, DMSO-d6)
dC 32.3 (NCH3), 36.2 (NCH2), 41.6 (NCH2-CDC), 44.5 (NCH2), 60.8 (NCH2CO),
111.8, 118.0, 124.1, 124.9, 125.7, 139.4, 151.4, 156.9, 165.2, 184.3 (Ar-C, CDO). EI
MS (m/z): 368.04 (MC).
Anal. Calcd. (%) for C18H20N6O3: C, 58.69; H, 5.47; N, 22.81. Found: C, 58.77; H,
5.56; N, 22.74.
1,10-((1,10-(Piperazine-1,4-Diyl)bis(2-Oxoethane-2,1-Diyl))bis(1H-1,2,3-Triazole-5,
1-Diyl))bis-(Methylene))bis(Indoline-2,3-Dione) (3f)
Yield 84%, mp 265–266ꢁC; IR: 3082 (Ar-H), 2827–2951 (CH str.), 1722 (CDO),
1
1618 cm¡1 (CDO). H NMR (400 MHz, DMSO-d6) dH 2.75 (4H, t, J D 4.0 Hz, 2 x
NCH2), 2.84 (4H, t, J D 4.0 Hz, 2 x NCH2), 4.83 (2H, s, NCH2-CDC), 4.90 (2H, s,
NCH2-CDC), 5.36 (2H, s, 2 x NCHCO), 5.45 (2H, s, 2 x NCHCO), 7.16–7.23 (4H, m,
ArH), 7.46–7.52 (4H, m, ArH), 8.16 (2H, s, 2 x CH-1,2,3-triazole); 13C NMR (100 MHz,
DMSO-d6) dC 38.7 (NCH2), 40.8 (NCH2), 42.9 (NCH2-CDC), 60.1 (NCH2CO), 111.3,
118.7, 124.0, 125.1, 125.8, 139.7, 152.8, 156.3, 165.7, 185.8 (Ar-C, CDO). EI MS (m/z):
622.29 (MC).
Anal. Calcd. (%) for C30H26N10O6: C, 57.87; H, 4.21; N, 22.50. Found: C, 57.69; H,
4.13; N, 22.66.
1,10-((1,10-((2-Methylpiperazine-1,4-Diyl)bis(2-Oxoethane-2,1-Diyl))bis(1H-1,2,
3-Triazole-5,1-Diyl))bis(Methylene))bis(Indoline-2,3-Dione) (3g)
Yield 82%, mp 288–289ꢁC; IR: 3064 (Ar-H), 2842–2964 (CH str.), 1718 (CDO),
1
1628 cm¡1 (CDO). H NMR (400 MHz, DMSO-d6) dH 1.34 (3H, d, J D 4.0 Hz, CH3),
2.51–2.60 (2H, m, CHCH3, NCH2), 2.70–2.76 (1H, m, NCH2), 2.82 (2H, t, J D 4.0 Hz,
NCH2), 2.92–2.99 (2H, m, NCH2), 4.91 (2H, s, NCH2-CDC), 5.06 (2H, s, NCH2-CDC),

Click Synthesis and Antimicrobial Screening
223
5.37 (1H, s, NCHCO), 5.44 (2H, s, NCH2CO), 5.67 (1H, s, NCHCO), 7.12–7.27 (4H, m,
ArH), 7.46–7.63 (4H, m, ArH), 8.19 (1H, s, CH-1,2,3-triazole), 8.25 (1H, s, CH-1,2,3-tri-
azole); 13C NMR (100 MHz, DMSO-d6) dC 17.9 (CH3), 31.4, 37.8, 39.0, 41.6 (NCH2),
42.7, 44.2 (NCH2-CDC), 65.3, 67.9 (NCH2CO), 111.5, 112.4, 115.7, 123.4, 124.0, 125.2,
125.7, 138.4, 139.7, 150.1, 151.9, 157.2, 158.8, 165.4, 166.0, 183.1, 184.7 (Ar-C, CDO).
EI MS (m/z): 636.30 (MC).
Anal. Calcd. (%) for C31H28N10O6: C, 58.49; H, 4.43; N, 22.00. Found: C, 58.58; H,
4.52; N, 21.88.
Synthesis and Characterization of 1-(2-Azidoacetyl)Indoline-2,3-Dione (5)
To a stirred solution of isatin (1 eq), K2CO3 (1.2 eq), Bu4NCBr¡ (0.4 eq) in a mixture of
THF:water (5:1) (10 mL), was added bromoacetyl bromide (1.2 eq) at 0ꢁC. The reaction
continued for 2 h at 0ꢁC and was monitored by TLC. Upon completion, the reaction mix-
ture was treated with sodium azide (2.0 equiv.) at room temperature for 12 h. The crude
product was extracted with ethyl acetate (3 £ 20 mL), and the organic extracts were
washed with brine solution and finally water. The excess solvent was removed under
reduced pressure to afford compound 5. Yield 92%, mp 164–165ꢁC; IR: 3020 (Ar-H),
1
2848–2936 (CH str.), 1715 (CDO), 1580 cm¡1 (CDC). H NMR (400 MHz, DMSO-d6)
dH 4.02 (2H, s, CH2), 7.28–7.37 (2H, m, ArH), 7.68–7.78 (2H, m, ArH); 13C NMR
(100 MHz, DMSO-d6) dC 53.4 (CH2), 111.9, 122.0, 123.9, 129.8, 136.1, 151.8, 165.8,
170.2, 184.3 (Ar-C, CDO). EI MS (m/z): 230.13 (MC).
Anal. Calcd. (%) for C10H6N4O3: C, 52.18; H, 2.63; N, 24.34. Found: C, 52.32; H,
2.50; N, 24.48.
Typical Procedure for the Synthesis of Isatin-1,2,3-Triazole Hybrids 7a-g
To a stirred solution of equimolar amounts of 5 and the appropriate propargylated cyclic
secondary amine 6a-g dissolved in a 1:1 mixture of t-BuOH and water was added CuSO4
(0.3 eq) and Na-ascorbate (0.6 eq) at ambient temperature. The reaction was stirred for an
additional 6–10 h at ambient temperature until TLC confirmed the complete reaction of
the starting material. The reaction mixture was quenched with water and the crude prod-
uct was extracted with ethyl acetate (3 £ 50 mL). The organic phase was dried over
anhydrous sodium sulfate, the excess solvent was reduced under vacuum to yield the tar-
geted 1,2,3-triazoles 7a-g, and the crude products were crystallized from ethanol.
1-(2-(4-(Piperidin-1-yl)Methyl-1H-1,2,3-Triazol-1-yl)Acetyl)Indoline-2,3-Dione (7a)
Yield 86%, mp 193–194ꢁC; IR: 3031 (Ar-H), 2868–2940 (CH str.), 1708 (CDO),
1611 cm¡1 (CDO). 1H NMR (400 MHz, DMSO-d6) dH 1.49–1.60 (6H, m, CH2CH2CH2,
2 x NCH2CH2), 2.42 (2H, dd, J D 4.0 Hz, 12.0 Hz, NCH2), 2.63 (2H, dd, J D 4.0 Hz,
12.0 Hz, NCH2), 3.84 (2H, s, NCH2-CDC), 4.95 (1H, s, NCHCO), 5.16 (1H, s, NCHCO),
7.23–7.32 (2H, m, ArH), 7.68–7.77 (2H, m, ArH), 7.96 (1H, s, CH-1,2,3-triazole); 13C
NMR (100 MHz, DMSO-d6) dC 23.6 (CH2CH2CH2), 25.3 (NCH2CH2), 38.6 (NCH2),
46.4 (NCH2-CDC), 65.0 (NCH2CO), 112.8, 117.4, 123.2, 126.7, 128.1, 138.8, 154.7,
162.4, 172.7, 185.6 (Ar-C, CDO). EI MS (m/z): 353.04 (MC).
Anal. Calcd. (%) for C18H19N5O3: C, 61.18; H, 5.42; N, 19.82. Found: C, 61.05; H,
5.54; N, 19.66.

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Aouad
1-(2-(4-((4-Methylpiperidin-1-yl)Methyl)-1H-1,2,3-Triazol-1-yl)Acetyl)Indoline-2,
3-Dione (7b)
Yield 84%, mp 215–216ꢁC; IR: 3084 (Ar-H), 2826–2950 (CH str.), 1720 (CDO),
1
1616 cm¡1 (CDO). H NMR (400 MHz, DMSO-d6) dH 1.11 (3H, d, J D 4.0 Hz, CH3),
1.33–1.36 (1H, m, CH2CHCH2), 1.48–1.52 (2H, m, NCH2CH2), 1.68–1.73 (2H, m,
NCH2CH2), 2.32–2.38 (2H, m, NCH2), 2.56–2.61 (2H, m, NCH2), 3.73 (2H, s, NCH2-
CDC), 4.86 (1H, s, NCHCO), 5.04 (1H, s, NCHCO), 7.26–7.33 (2H, m, ArH), 7.65–7.73
(2H, m, ArH), 7.95 (1H, s, CH-1,2,3-triazole); 13C NMR (100 MHz, DMSO-d6) dC 15.6
(CH3), 22.5 (CH2CHCH2), 24.9 (NCH2CH2), 37.9 (NCH2), 47.1 (NCH2-CDC), 66.5
(NCH2CO), 112.4, 118.3, 123.1, 125.9, 127.8, 137.2, 155.3, 161.2, 171.9, 184.9 (Ar-C,
CDO). EI MS (m/z): 367.11 (MC).
Anal. Calcd. (%) for C19H21N5O3: C, 62.11; H, 5.76; N, 19.06. Found: C, 62.22; H,
5.59; N, 19.16.
1-(2-(4-(Morpholinomethyl)-1H-1,2,3-Triazol-1-yl)Acetyl)Indoline-2,3-Dione (7c)
Yield 87%, mp 228–229ꢁC; IR: 3043 (Ar-H), 2838–2976 (CH str.), 1726 (CDO),
1614 cm¡1 (CDO). 1H NMR (400 MHz, DMSO-d6) dH 2.58 (4H, dd, J D 4.0 Hz, 12 Hz,
2 x NCH2), 3.73 (4H, dd, J D 4.0 Hz, 12 Hz, 2 x OCH2), 3.92 (2H, s, NCH2-CDC), 4.99
(1H, s, NCHCO), 5.18 (1H, s, NCHCO), 7.21–7.28 (2H, m, ArH), 7.59–7.68 (2H, m,
ArH), 8.01 (1H, s, CH-1,2,3-triazole); 13C NMR (100 MHz, DMSO-d6) dC 38.4 (NCH2),
46.6 (NCH2-CDC), 52.8 (OCH2), 66.8 (NCH2CO), 111.7, 118.1, 123.9, 125.8, 126.8,
138.7, 151.4, 162.0, 172.1, 185.3 (Ar-C, CDO). EI MS (m/z): 355.06 (MC).
Anal. Calcd. (%) for C17H17N5O4: C, 57.46; H, 4.82; N, 19.71. Found: C, 57.33; H,
4.94; N, 19.67.
1-(2-(4-((3-Methylmorpholino)Methyl)-1H-1,2,3-Triazol-1-yl)Acetyl)Indoline-2,
3-Dione (7d)
Yield 85%, mp 247–248ꢁC; IR: 3029 (Ar-H), 2844–2980 (CH str.), 1728 (CDO),
1
1603 cm¡1 (CDO). H NMR (400 MHz, DMSO-d6) dH 1.18 (3H, d, J D 4.0 Hz, CH3),
2.49–2.60 (3H, m, CHCH3, NCH2), 3.50 (1H, dd, J D 4.0 Hz, 12 Hz, OCH), 3.68–3.77
(3H, m, 2 x OCH2), 3.96 (2H, s, NCH2-CDC), 5.03 (1H, s, NCHCO), 5.20 (1H, s,
NCHCO), 7.18–7.24 (2H, m, ArH), 7.56–7.64 (2H, m, ArH), 7.99 (1H, s, CH-1,2,3-tria-
zole); 13C NMR (100 MHz, DMSO-d6) dC 19.3 (CH3), 39.2, 43.4 (NCH2), 48.9
(NCH2-CDC), 53.2, 55.0 (OCH2), 67.9 (NCH2CO), 112.2, 117.8, 123.5, 125.6, 126.2,
139.0, 151.9, 162.5, 172.4, 185.3 (Ar-C, CDO). EI MS (m/z): 369.20 (MC).
Anal. Calcd. (%) for C18H19N5O4: C, 58.53; H, 5.18; N, 18.96. Found: C, 58.62; H,
5.30; N, 19.09.
1-(2-(4-((4-Methylpiperazin-1-yl)Methyl)-1H-1,2,3-Triazol-1-yl)Acetyl)Indoline-2,
3-Dione (7e)
Yield 87%, mp 263–264ꢁC; IR: 3019 (Ar-H), 2865–2923 (CH str.), 1718 (CDO),
1
1600 cm¡1 (CDO). H NMR (400 MHz, DMSO-d6) dH 2.31 (3H, s, NCH3), 2.47–2.53
(4H, m, 2 x NCH2), 2.67 (2H, t, J D 4.0 Hz, NCH2), 2.74 (2H, t, J D 4.0 Hz, NCH2),
3.94 (2H, s, NCH2-CDC), 4.96 (1H, s, NCHCO), 5.13 (1H, s, NCHCO), 7.15–7.22 (2H,
m, ArH), 7.52–7.59 (2H, m, ArH), 8.05 (1H, s, CH-1,2,3-triazole); 13C NMR (100 MHz,

Click Synthesis and Antimicrobial Screening
225
DMSO-d6) dC 34.6 (NCH3), 39.0, 46.1 (NCH2), 52.4 (NCH2-CDC), 68.3 (NCH2CO),
112.0, 118.4, 124.5, 125.2, 126.2, 139.8, 151.1, 162.4, 173.9, 185.0 (Ar-C, CDO). EI MS
(m/z): 368.04 (MC).
Anal. Calcd. (%) for C18H20N6O3: C, 58.69; H, 5.47; N, 22.81. Found: C, 58.54; H,
5.38; N, 22.95.
1,10-(2,20-(4,40-(Piperazine-1,4-Diyl)bis(Methylene))bis(1H-1,2,3-Triazole-4,1-Diyl))
bis(Acetyl))bis-(Indoline-2,3-Dione) (7f)
Yield 81%, mp 278–279ꢁC; IR: 3062 (Ar-H), 2856–2970 (CH str.), 1714 (CDO),
1
1613 cm¡1 (CDO). H NMR (400 MHz, DMSO-d6) dH 2.60–2.64 (4H, m, 2 x NCH2),
2.72–2.75 (4H, m, 2 x NCH2), 4.02 (4H, s, 2 x NCH2-CDC), 4.98 (2H, s, 2 x NCHCO),
5.22 (2H, s, 2 x NCHCO), 7.12–7.21 (4H, m, ArH), 7.48–7.61 (4H, m, ArH), 8.00 (2H, s,
2 x CH-1,2,3-triazole); 13C NMR (100 MHz, DMSO-d6) dC 43.6 (NCH2), 44.2 (NCH2),
52.9 (NCH2-CDC), 65.4 (NCH2CO), 111.6, 118.0, 124.4, 125.9, 126.4, 139.2, 152.5,
162.7, 172.1, 185.0 (Ar-C, CDO). EI MS (m/z): 622.29 (MC).
Anal. Calcd. (%) for C30H26N10O6: C, 57.87; H, 4.21; N, 22.50. Found: C, 57.80; H,
4.35; N, 22.38.
1,10-(2,20-(4,40-((2-Methylpiperazine-1,4-Diyl)bis(Methylene))bis(1H-1,2,3-Triazole-
4,1-Diyl))bis(Acetyl))bis(Indoline-2,3-Dione) (7g)
Yield 80%, mp 296–297ꢁC; IR: 3087 (Ar-H), 2871–2935 (CH str.), 1729 (CDO),
1
1602 cm¡1 (CDO). H NMR (400 MHz, DMSO-d6) dH 1.21 (3H, d, J D 4.0 Hz, CH3),
2.46–2.52 (1H, m, CHCH3), 2.65–2.71 (2H, m, NCH2), 2.75–2.81 (1H, m, NCH), 2.84–
2.90 (2H, m, NCH2), 3.05–3.09 (1H, m, NCH), 3.79 (2H, s, NCH2-CDC), 3.95 (2H, s,
NCH2-CDC), 4.78 (1H, s, NCHCO), 4.90 (1H, s, NCHCO), 5.13 (1H, s, NCHCO), 5.24
(1H, s, NCHCO), 7.18–7.26 (4H, m, ArH), 7.43–7.69 (4H, m, ArH), 8.08 (1H, s, CH-
1,2,3-triazole), 8.12 (1H, s, CH-1,2,3-triazole); 13C NMR (100 MHz, DMSO-d6) dC 18.4
(CH3), 42.6, 47.8, 49.9 (NCH2), 54.4, 56.8 (NCH2-CDC), 61.7, 65.2 (NCH2CO), 111.9,
112.1, 118.8, 120.8, 124.5, 126.7, 127.2, 138.7, 139.8, 151.3, 152.6, 162.1, 163.0, 172.6,
172.9, 185.7, 186.1 (Ar-C, CDO). EI MS (m/z): 636.14 (MC).
Anal. Calcd. (%) for C31H28N10O6: C, 58.49; H, 4.43; N, 22.00. Found: C, 58.34; H,
4.48; N, 21.82.
Antibacterial and Antifungal Screening
The designed click products 3a-g and 7a-g were assessed for their antibacterial and anti-
fungal inhibition potency using the broth dilution method31, 32 towards six pathogenic
bacterial strains (gram-positive: Bacillus subtilis, Streptococcus pneumonia and Staphylo-
coccus aureus; gram-negative: Escherichia coli, Pseudomonas aeruginosa and Klebsiella
pneumonia) and two fungal strains (Aspergillus fumigatus and Candida albicans).
Acknowledgment
The author is very grateful to Dr. Linda Aouad, Faculty of Medicine, University of Djilali
Liabes, Sidi Bel Abbes, Algeria, for her valuable assistance in the biological screening.

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Aouad
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