Synthesis, and prediction of molecular properties and antimicrobial activity of some acylhydrazones derived from N-(arylsulfonyl)methionine

Turk J Chem

Turkish Journal of Chemistry

(2016) 40: 510 – 534

¨

http://journals.tubitak.gov.tr/chem/

˙

c

⃝ TUBITAK

doi:10.3906/kim-1509-21

Research Article

Synthesis, and prediction of molecular properties and antimicrobial activity of

some acylhydrazones derived from N -(arylsulfonyl)methionine

1

Esra TATAR , Sevil S¸ENKARDES¸ , Hasan Erdin¸c SELLITEPE

1

1,5

˙

,

1

S¸u¨kriye Gu¨niz KUC¸ UKGUZEL , S¸engu¨l Alpay KARAOGLU , Arif BOZDEVECI ,

2

¨

˘

˙

Erik DE CLERCQ³, Christophe PANNECOUQUE³, Taibi BEN HADDA^4,∗, Ilkay KUC¸ UKGUZEL

1,∗

˙

¨

1

˙

Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Marmara University, Istanbul, Turkey

²Department of Biology, Faculty of Arts and Sciences, Recep Tayyip Erdo˘gan University, Rize, Turkey

³Rega Institute for Medical Research, KU Leuven, Leuven, Belgium

⁴Materials Chemistry Laboratory, Department of Chemistry, Faculty of Sciences, Mohammed Premier University,

Oujda, Morocco

⁵Faculty of Pharmacy, Department of Pharmaceutical Chemistry, Karadeniz Technical University, Trabzon, Turkey

Received: 10.09.2015

•

Accepted/Published Online: 01.12.2015

•

Final Version: 17.05.2016

Abstract:A series of 38 new acylhydrazones [3–40], derived from (2S)-4-(methylsulfanyl)-2-[[(4-methylphenyl)sulfonyl]

amino]butanoic acid hydrazide [2], were synthesized and evaluated for their anti-HIV and antimicrobial activity with

the further aim to develop acylhydrazones carrying an amino acid side chain. All tested compounds possess stronger

activity against gram (+) bacteria. Compound 23 was found active against methicillin-resistant Staphylococcus aureus

(MRSA) with a MIC value of 3.9 µg/mL. The MIC value of compound 30 against Enterococcus faecalis, Listeria

monocytogenes, and Bacillus cereus was 8 µg/mL. A computational study for prediction of ADME and drug-like

properties (solubility, drug-likeness, and drug score) as well as potential toxicity proﬁles of compounds 2–40 was

performed using the Molinspiration online property calculation toolkit and Osiris Property Explorer. As most of our

compounds meet Lipinski’s rule of ﬁve, they promise good solubility and permeability. According to Osiris calculations,

the majority of our compounds are supposed to be nonmutagenic and nonirritating.

Key words: Acylhydrazones, antimicrobial activity, L-methionine, microwave-assisted synthesis, MRSA

1. Introduction

The theme for World Health Day 2011 was selected as “Antimicrobial resistance: No action today no cure

tomorrow” with the view to focus the exponential threat of untreatable and fatal infections due to multidrug

resistance among gram (–) and gram (+) bacteria. Eight new drugs (daptomycin, telithromycin, tigecycline,

doripenem, retapamulin, telavancin, ceftaroline, and ﬁdaxomicin) have been FDA-approved to date. Retapa-

mulin, tigecycline, and telithromycin were the ﬁrst approved members of the new antibiotic classes pleuromutilin,

glycylcycline, and ketolide, respectively. Most of the compounds that entered the market up to 2009 were mod-

iﬁed derivatives of already existing antimicrobials. From then, no new antibiotic class has been suggested.¹

Owing to the literature concerning a notable number of acylhydrazone derivatives with wide spectra of activity

against gram-positive and gram-negative bacteria, and Mycobacteria, acylhydrazones may be considered a new

antibiotic class.²⁻¹²In particular, the work on species-speciﬁc targeted drugs with improved activity against

^∗Correspondence: ikucukguzel@marmara.edu.tr; taibi.ben.hadda@gmail.com

510

TATAR et al./Turk J Chem

resistant pathogens looks promising (Figure 1). Nordfelth et al. reported type III secretion (TTS) inhibitory

activity of some acylated hydrazones of salicyclic aldehydes in respect of data revealing TTS as common viru-

lence system of some gram (–) bacteria: Yersinia spp., Salmonella spp., Shigella spp., Pseudomonas aeruginosa,

enteropathogenic Escherichia coli, enterohemorrhagic E. coli, and Chlamydia spp.¹³Following the discovery of

the lead compound YKAs3003 as an inhibitor of E. coli β -ketoacyl-acyl carrier protein synthase III (ecKAS III)

potential β -ketoacyl-acyl carrier protein synthase III inhibitory activity of vanillic acylhydrazone derivatives

was shown against E. coli.¹⁴⁻¹⁶After Zoraghi et al. had reported methicillin-resistant Staphylococcus aureus

pyruvate kinase (MRSA PK) inhibitory activity of IS-130, more potent and selective analogues of IS-130 were

synthesized and evaluated as anti-PK compounds possessing antistaphylococcal activity, including both MRSA

and multidrug-resistant Staphylococcus aureus (MDRSA) strains.¹⁷β -Ketoacyl-acyl carrier protein synthase III

(KAS III) is another target for inhibiting the growth of S. aureus, and saKAS III inhibitory activity of acyl

hydrazones with 2,3,4-trihydroxybenzylidene and 1,3-dihydroxybenzylidene moieties was recently noted.¹⁵

F

Br

O

N

O

N

H

N

H

CH₃

OH

IS-130

AM-165

Lit. [17]

Br

Cl

O

OH

N

H

Br

O

N

H₃C

N

H

Cl

N

OH

O₂N

OH

HO

OH

YKAs3003

Lit. [14]

Lit. [16]

Lit. [13]

OH

N

Cl

OH

F₃C

OH

Cl

O

N

H

N

H

OH

Cl

Lit. [15]

Figure 1. Structure of similar bioactive compounds IS-130, YKAs3003, and derivatives.

Thiopeptide antibiotics, a class of sulfur-rich, highly modiﬁed cyclic peptides derived from serine, threo-

nine, or cysteine side chains, inspired us to focus on synthesis of new hybrid compounds employing L-methionine

and sulfonamide fragments together with acylhydrazone moiety.¹⁸Bearing the literature data in mind, a series

of acylhydrazones derived from N -(p-toluenesulfonyl) methionine were synthesized and evaluated for their an-

timicrobial activity in accordance with our attempt to develop dual acting compounds for the treatment of both

bacterial and viral diseases and also bacterial co-infections of HIV (+) patients.¹⁹Promising anti-HIV activity

of acylhydrazone scaﬀold, notably carrying an amino acid side chain, encouraged us to evaluate our compounds

for their anti-HIV activity.²⁰⁻²⁹

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TATAR et al./Turk J Chem

2. Results and discussion

2.1. Chemistry

Compound 1 was prepared by tosylation of methyl (2S)-2-amino-4-(methylsulfanyl)butanoate hydrochloride

according to the literature method.²²Compound 2 was obtained by heating compound 1 with hydrazine

hydrate.³⁰Through the condensation reaction of compound 2 and selected aldehyde, ketone, and isatine

derivatives, 38 new acylhydrazone derivatives were synthesized. Compounds 3, 5–26, 28, 30–34, 39, and 40

were synthesized by microwave-assisted method. Since the synthesis of compounds 4, 27, 29, and 35–38 was

not achieved by microwave-assisted method, they were synthesized by reﬂuxing compound 2 with appropriate

aldehyde or ketone derivative in ethanol (Figure 2).

Figure 2. Synthetic route to compounds 1–40. Reagents and conditions : (a) CH₃-C₆H₄-SO₂Cl/TEA, DCM, (b)

NH₂NH₂.H₂O, (c) R₁CHO or R₁R₂CO, EtOH, microwave irradiation, 270 W, 5–10 min, (d) R₁CHO or R₁R₂CO,

EtOH, reﬂux.

512

TATAR et al./Turk J Chem

The purity of compounds 2–40 was conﬁrmed by the data gathered through HPLC and elemental analysis

and their structures were elucidated by IR and ¹H NMR spectroscopy. ¹³C NMR spectroscopy data were

only evaluated for representative compounds (compounds 10, 23, 30, 38). Compounds 1 and 2 have been

previously reported despite there being no data pertaining to the structural characterization of compound

1.³⁰⁻³²The stretching bands due to N–H and ester C=O groups of compound 1 were observed at 3275 and

1734 cm⁻¹, respectively. Bands at 3346, 3281, 3190, and 1668 cm⁻¹were determined in the IR spectrum of

compound 2 and they were attributed to the N–H and hydrazide C=O groups, respectively. The ¹H NMR

spectrum of compound 2 revealed broad singlet signals at 4.02 and 9.08 ppm, conforming with the –NH₂

and –NH protons of the hydrazide moiety. The IR spectral data of our novel acylhydrazones 3–40 were in

accordance with the literature; C=O and C=N stretching data were observed at 1693–1658 and 1626–1587

cm⁻¹, respectively.^29,33−35

The ¹H NMR spectral data of compounds 3–40 revealed supporting evidence to identify their structures.

The singlet signals belonging to the azomethine proton in compounds 8, 11, 14, and 16 were detected at 7.81,

7.85, 7.50, and 7.78 ppm, respectively. The chemical shift of the azomethine proton in compounds 3–7, 9, 10,

12, 13, 15, and 19–34 was detected in the range of 7.48–8.55 ppm as two singlet peaks, while four singlet signals

were observed in the range of 7.87–8.07 ppm due to the azomethine proton of compound 17. The azomethine

proton of compound 18 was observed in the range of 7.85–8.09 ppm as two contiguous multiplets due to the

presence of chiral centers in the bicyclo[2.2.1]hept-5-en-2-yl moiety. Observing more than one signal for each

azomethine and/or –NH– protons of acylhydrazone moiety has already been reported as a result of the existence

of E /Z geometrical isomers and cis/trans conformers.²⁹It has also been noted that hydrazones derived from

aldehyde and substituted hydrazide are prone to exist as E isomers in dimethyl sulfoxide-d₆solution on account

of less steric hindrance compared to Z isomers.^{22,29,36−38}Furthermore, –NH– proton’s signal in the range of

9–12 ppm was attributed to E -acylhydrazones.³⁹The NH proton of acylhydrazone moiety of compounds 4–7,

9–14, 16, 17, 20–23, 25–27, and 29–34 was detected in the range of 9.09–11.73 ppm as two singlet signals.

According to the chemical shifts that we were able to experimentally observe with respect to azomethine and

hydrazide–NH protons of our compounds we may propose that most of our compounds exist in the E -form.

In order to interpret cis/trans equilibria of NH– protons of the acylhydrazone moiety the two sets of signals in

the range of 9.09–11.73 ppm were examined thoroughly and the upﬁeld signal of the mentioned proton between

9.09 and 11.58 ppm was assigned to the cis-conformer, while the downﬁeld signal between 9.22 and 11.73 ppm

was assigned to the trans-conformer.

In the ¹H NMR spectra of compounds 35–38, which were derived from selected ketones, characteristic

signals for CH₃moiety were detected in the range of 2.09–2.28 ppm. The –CH₃proton of compound 37 was

detected at 2.11 and 2.20 ppm as two singlet signals.

The ¹³C NMR spectra of compounds 10, 23, 30, and 38 were also recorded for further support. Detecting

azomethine carbon, acylhydrazone C=O, and some of the aromatic C-atoms and C-atoms of methionine moiety

as two, three, or four peaks instead of one, thus provided conﬁrmatory evidence for the presence of isomers.²⁹

Low-resolution ESI or APCI mass spectra of our compounds were recorded in either positive or negative

ionization mode. The LC-MS/MS (ESI or APCI) analysis of the synthesized compounds gave correct molecular

ion peaks corresponding to (M+H)⁺in positive ionization and (M–H)⁻in negative ionization mode in each

case.

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TATAR et al./Turk J Chem

2.2. Antimicrobial activity evaluation

The synthesized compounds were evaluated for their antimicrobial activity by using agar well diﬀusion and

broth microdilution methods. The results obtained by both methods are given in Table 1. The compounds

(3–6, 11, 12, 14, 15, 17–21, 24–27, 29, 31, 33–37, 39) with MIC values greater than 250 µg/mL against

most of the studied microorganisms were not included in Table 1. The zone of inhibition in millimeters was

measured for compounds 2–40 and the results were recorded. Diameters of 10–20 mm, 8–16 mm, and 12–25

mm were regarded as sensitive for compounds 10, 30, and 23, respectively. The preliminary results by agar

well diﬀusion were veriﬁed by the data gathered through microdilution and the linear relationship between these

two methods was noted.

Compounds 10 and 23 were found to be active against gram (–) bacteria, and E. coli and Y. pseudo-

tuberculosis, of which E. coli is a nonencapsulated bacterium while Y. pseudotuberculosis is an encapsulated

one. Some of our compounds demonstrated moderate growth inhibition of P. aeruginosa, and compound 10,

comprising a 4-cyanophenyl moiety, was reported as the most active against pseudomonas with an MIC value

of 128.7 µg/mL.

All tested compounds were conﬁrmed as possessing stronger activity against gram (+) in comparison

with gram (–) bacteria; especially compounds 2, 13, 16, 37, 39, and 40 exhibited modest growth inhibition

of streptococcus (E. faecalis) and nonsporeforming bacillus (L. monocytogenes). Compounds 30 and 23 were

regarded as the most active compounds against both of these microorganisms, with MIC values of 8 and 15.9

µg/mL. It might be predicted that an increase in molecular hydrophobicity (compounds 39 and 40 possessing

indanone and isatine moieties, respectively) and the presence of a pyridine ring (compounds 16 and 37) increased

gram (+) activity.

With the exception of compounds 23 and 30, the tested compounds were not eﬀective in preventing

the growth of gram (+) coccus, S. aureus, and the clinically isolated coagulase-positive, methicillin-resistant

strain.Compound 23 was found to have promising activity against the gram (+) bacteria MRSA and Bacillus

cereus with an MIC value of 3.9 µg/mL. The MIC value for compound 30 against Enterococcus faecalis, Listeria

monocytogenes, and B. cereus was 8 µg/mL. The reported antibacterial activity of compounds 23 and 30 can

be attributed to furan and thiophene rings both bearing nitro groups. Compounds 23 and 30, together with

compound 38 carrying an adamantyl moiety, were revealed as eﬀective derivatives against B. cereus, which is

a spore-forming bacillus.

Eight compounds among all tested compounds were found to possess light activity against M. smegmatis,

i.e. compounds 23, 30, 31, and 38 (MIC values between 63.8 and 252.5 µg/mL).

The synthesized compounds were also evaluated for their activity against the opportunistic fungal

pathogen Candida albicans and the saprophyte Saccharomyces cerevisiae and their activity proﬁle was qualiﬁed

as insigniﬁcant, except for compounds 7–9 with modest anti-Candida activity (MIC values of compound 7–9

were measured as 65.6, 62.5, and 62.5 µg/mL, respectively). The dose-dependent anti-Candida activity of

compounds 7–9 may be due to the 2,6-dihalogeno and 3,5-bis(triﬂuoro)methyl substitutions, and particularly

the presence of the ﬂuorine atom.

It is interesting to mention that compounds 23 and 30 were found active against the gram (+) bacteria

M. smegmatis, C. albicans, and S. cerevisiae at low dose levels and also compound 23 was noted as the most

active compound against gram (–) microorganisms. Compound 38 was also assessed as a promising derivative

with speciﬁc activity against gram (+) bacteria and M. smegmatis.

514

TATAR et al./Turk J Chem

Table 1. Antimicrobial activity of compounds 2–40 by using microdilution method (MIC, µg/mL) and agar well

diﬀusion method (diameter zones in mm).^a

Minimal inhibition concentration (µg/mL) and diameter of inhibition zones (mm)^b

Comp.

Ec

Yp

Pa

Sa

MRSA

Ef

Li

Bc

Ms

Ca

Sc

131.3

(12)

131.3

(10)

262.3

(9)

>525

(6)

>525

(6)

2

-

262.5

(10)

>525

(6)

>525

(6)

65.6

(12)

>525

(6)

7

-

125

(10)

>500

(6)

>500

(6)

62.5

(15)

125

(10)

8

-

>500

(6)

250

(8)

62.5

(12)

125

(10)

9

-

>515

(6)

128.7

(10)

128.7

(12)

128.7

(10)

>515

(6)

>515

(6)

64.4

(14)

32.2

(20)

10

13

16

22

23

28

30

32

38

40

Amp.

131.3

(10)

262.5

(8)

262.5

(8)

131.3

(10)

131.3

(10)

>525

(6)

-

125

(10)

>500

(6)

125

(11)

>500

(6)

250

(8)

-

128.7

(10)

257.5

(8)

257.5

(8)

257.5

(8)

>515

(6)

>515

(6)

-

15.9

(22)

63.8

(12)

127.5

(12)

7.9

(25)

3.9

(23)

15.9

(20)

3.9

(18)

63.8

(16)

63.8

(14)

63.8

(15)

250

(8)

250

(8)

500

(6)

250

(7)

250

(8)

125

(10)

-

8.0

(10)

16.1

(15)

16.1

(15)

8.0

(12)

8.0

(14)

128.7

(16)

257.5

(8)

64.4

(12)

>500

(6)

250

(8)

250

(7)

125

(10)

-

132.5

(6)

530

(8)

132.5

(12

265

(10)

132.5

(7)

66.3

(12)

132.5

(6)

-

252.5

(6)

126.3

(8)

-

2

(10)

>8

(10)

32

(18)

128

(18)

2

(35)

NT

2

(10)

<1

(15)

4

(35)

Str.

Flu

<8

(25)

<8

(25)

^a"e compounds 3–6, 11, 12, 14, 15, 17–21, 24–27, 29, 31, 33–37, 39, which had no MIC value equal or less than 250 µg/mL against any of

the studied microorganisms, were not included.

^b"e results gathered by agar well di#usion method are given in brackets.

Ec: Escherichia coli ATCC 25922, Yp: Yersinia pseudotuberculosis ATCC 911, Pa: Pseudomonas aeruginosa ATCC 43288, Sa: Staphylococcus

aureus ATCC 25923, MRS: Methicillin-resistant Staphylococcus aureus (MRSA), Ef: Enterococcus faecalis ATCC 29212, Li: Listeria

monocytogenes ATCC 43251, Bc: Bacillus cereus 702 Roma, Ms: Mycobacterium smegmatis ATCC 607, Ca: Candida albicans ATCC 60193,

Saccharomyces cerevisiae RSKK 251, Amp.: Ampicillin, Str.: Streptomycin; Flu.: Fluconazole, (—): no activity, NT: Not tested.

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TATAR et al./Turk J Chem

2.3. Antiviral evaluation

The synthesized compounds were also subjected to a preliminary screening for their anti-HIV activity. None of

them showed any signiﬁcant activity against HIV-1(III_B) or HIV-2(ROD) in MT-4 cells at subtoxic concentra-

tions.

2.4. Prediction of drug-likeness, ADME properties, and toxicity proﬁles of compounds 2–40

ADME properties of the molecules were examined by determination of topological polar surface area (TPSA),

and simple molecular descriptors used by Lipinski in formulating his rule of ﬁve.⁴⁰Calculations were performed

using the Molinspiration online property calculation toolkit.⁴¹TPSA is calculated as a sum of O- and N -

centered polar fragment contributions and is closely related to the hydrogen bonding potential of a compound.

TPSA has been shown to be a very good descriptor for characterizing drug absorption, including intestinal

absorption, bioavailability, Caco-2 permeability, and blood–brain barrier penetration. It is known that molecules

with TPSA values of around 160 or more are expected to exhibit poor intestinal absorption.⁴²⁻⁴⁹TPSA

prediction results of compounds 2–40 within this limit are tabulated in Table 2. It should also be noted that

all of our compounds except 9, 21, 25, and 26 have zero violations of the rule of ﬁve (see Table 2). Two or

more violations of the rule of ﬁve suggest the probability of problems in bioavailability of the drug.⁴²⁻⁴⁹

Table 2. Molinspiration calculations of selected compounds from 2–40 series.

a

Molecular Properties

Compound

TPSA ONH VIOL VOL

2

7

8

9

101

88

111

117

101

147

88

154

108

88

4

2

3

2

3

2

3

17

0

2

0

–

272

374

365

418

372

389

351

337

361

346

361

356

436

390

470

10

13

16

22

23

28

30

32

38

40

120

Streptomycin 335

^aTPSA: Topological polar surface area; ONH: OH-N or O-HN Interaction; VIOL: Violation of Lipinski rules; VOL:

Volume.

Lipophilicity is also an important property for the prediction of per oral bioavailability of drug molecu-

les.⁴²⁻⁴⁹Therefore, clogP values for compounds 2–40 were also calculated by Osiris methodology and compared

with the value obtained for the standard drug streptomycin (Streptom).⁵⁰For the majority of the compounds,

with some exceptions (compounds 20 and 27), the calculated clogP values were 1.0–4.8, and it should be noted

that the clogP value of a molecule should not be greater than 5.0, which is the upper limit for the drugs to be

able to penetrate through biomembranes according to Lipinski’s rule. Therefore, compounds 2–40 are shown

to possess clogP values in the acceptable range (see Table 3).

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TATAR et al./Turk J Chem

Table 3. Osiris calculations of selected compounds from 240 series.

Toxicity Risks^a

TUM IRRIT

Bioavailability and Drug-Score ^b

Compd.

MUT

RE

MW

317

CLP

0.06

S

DL

DS

2

7

-2.66

-13.71

0.16

457

441

541

430

451

3.99

3.48

4.98

3.11

2.86

-5.45

-5.03

-5.96

-5.18

-4.12

-6.11

-7.77

0.25

0.28

0.17

0.29

0.27

8

9

-27.09

-13.39

-4.41

10

13

16

22

23

28

29

30

32

406

395

440

411

425

456

489

2.28

2.47

1.90

3.15

3.49

2.41

3.87

-3.61

-4.08

-5.07

-4.41

-4.76

-5.02

-5.25

-4.46

-4.78

-9.60

-3.56

-3.88

-8.89

-9.35

0.39

0.22

0.11

0.34

0.31

0.29

0.24

38

477

480

581

3.96

2.51

-5.52

-5.39

0.98

-5.58

-3.88

2.00

0.23

0.27

0.48

40

Streptom^c

-8.09

: not toxic;

: slightly toxic;

: highly toxic. ^aMUT: mutagenic; TUM: tumorigenic; IRRIT: irritant; RE: reproductive e"ective.

^bMW : molecular weight, CLP: cLogP, S: Solubility, DL: druglikness, DS: Drug-Score. ^cStreptom: Streptomycin.

It has already been noted that the aqueous solubility of a compound signiﬁcantly aﬀects its absorption

and distribution and low solubility goes along with insuﬃcient absorption. The estimated solubility (S) value is

a unit stripped logarithm (base 10) of a compound’s solubility in mol/L and more than 80% of current pipeline

drugs have the (estimated) log S value greater than –4. In the case of compounds 2–40, values of S are <–3

(except 2) (see Table 3).

Other than these mentioned parameters, electronic distribution, hydrogen bonding characteristics, molecule

size and ﬂexibility, and presence of various pharmacophores also inﬂuence the behavior of a molecule in a

living organism by means of bioavailability, transport properties, aﬃnity to proteins, reactivity, toxicity, and

metabolic stability.⁴²⁻⁴⁹Toxicity risks (mutagenicity, tumorigenicity, irritation, reproduction) and drug-likeness

and drug-score of compounds 2–40 were calculated by the methodology developed by Osiris.⁵⁰The remarkably

well behaved mutagenicity of diverse synthetic molecules is classiﬁed in the database of the company Celerion

Switzerland, which can be used to quantify the role played by various organic groups in promoting or interfering

with the way a drug can associate with DNA. The toxicity risk predictor locates fragments within a molecule,

which indicates a potential toxicity risk. Toxicity risk alerts are the indications that the drawn structure may be

harmful due to the speciﬁed risk category. From the data evaluated in Table 3, it is obvious that the majority

of structures (31 out of 40) are supposed to be nonmutagenic and nonirritating with no reproductive eﬀects

when run through the mutagenicity assessment system in comparison with the standard drug.

517

TATAR et al./Turk J Chem

Table 3 also shows the drug-likeness of compounds 2–40. The majority of the reported compounds 2–40

have low drug scores as compared to the standard drug.

3. Conclusion

Thirty-eight new acylhydrazone derivatives were synthesized and evaluated for their anti-HIV and antimicrobial

activity. By serendipity, our compounds predominantly demonstrated antibacterial activity but none of them

(compounds 2–40) were found to be active against HIV-1 (III_B) or HIV-2 (ROD) strains at subtoxic concen-

trations. According to the results gathered from antimicrobial activity evaluation assays, N -[(2S)-1-[-2-(5-

nitrofuran-2-yl)methylidene]hydrazinyl]-4-(methylsulfanyl)-1-oxobutan-2-yl]-4-methylbenzene-sulfonamide (23)

was active against MRSA with an MIC value of 3.9 µg/mL. Therefore, it could be said that a new acylhydra-

zone derivative that is highly eﬀective in preventing MRSA growth at a low concentration has been discovered

and this compound will be subjected to further development in our future projects. Among all tested acylhy-

drazones, compounds 23 and 30 were the most active derivatives against most of the gram (+) and gram (–)

bacterial strains tested.

4. Experimental

All solvents and reagents were obtained from commercial sources and used without puriﬁcation. All melting

points (^◦C, uncorrected) were determined using a Kleinfeld SMP-II basic model melting point apparatus.

Elemental analyses were conducted using a Leco CHNS-932 instrument and are consistent with the assigned

structures. ESI or APCI positive and negative ionization (low resolution) mass spectra of the synthesized

compounds were obtained using an AB SCIEX API 2000 LC–MS/MS instrument. Infrared spectra were

recorded on a Shimadzu FTIR 8400S and data are expressed in wavenumbers (υ, cm⁻¹). NMR spectra

were recorded on a Bruker AVANCE-DPX 400 at 400 MHz for ¹H NMR and ¹³C NMR and the chemical shifts

were expressed in δ (ppm) downﬁeld from tetramethylsilane (TMS) using DMSO-d₆as solvent. The liquid

chromatographic system consists of an Agilent Technologies 1100 series instrument equipped with a quaternary

solvent delivery system and a model Agilent series G1315 A photodiode array detector. A Rheodyne syringe

loading sample injector with a 50-µL sample loop was used for the injection of the analytes. Chromatographic

data were collected and processed using Agilent Chemstation Plus software. The separation was performed

at ambient temperature by using a reversed phase HiChrom Kromasil 100-5C18 (4.6 mm × 250 mm, 5 µm

particle size) column. All experiments were performed in gradient mode. The mobile phase was prepared by

mixing acetonitrile and bidistilled water (gradient program: 0–3 min 50:50 v/v; 3–6 min 75:25 v/v; 6–9 min

100:0 v/v; 9–12 min 100:0 v/v; 12–15 min 75:25 v/v; 15–18 min 50:50 v/v; 18–20 min 50:50 v/v). Solvent

delivery was employed at a ﬂow rate of 1 mL/min. Detection of the analytes was carried out at 280 nm.

4.1. Chemistry

4.1.1. Methyl (2S)-4-(methylsulfanyl)-2-[[(4-methylphenyl)sulfonyl]amino]butanoate (1)

Methyl (2S)-2-amino-4-(methylsulfanyl)butanoate hydrochloride (Aldrich, 1.99 g, 0.01 mol), was suspended in

dichloromethane (20 mL) in the presence of triethylamine (2.02 g, 0.02 mol) and p-toluenesulfonyl chloride

(1.90 g, 0.01 mol) was added to the reaction medium with stirring at room temperature for 20 h. The crude

product was gained by evaporation of the solvent in vacuo following recrystallization from methanol. Yield

70%. mp 56 ^◦C (MeOH). IR, υ (cm⁻¹): 3275, 2978, 2947, 2916, 1734, 1473, 1433, 1327, 1155. ¹H NMR,

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δ (ppm): 1.71–1.82 (m, 2H, –CH–CH₂–CH₂–SCH₃), 1.93 (s, 3H, –CH–CH₂–CH₂–SCH₃), 2.27–2.37 and

2.39–2.51 (2m, 2H, –CH–CH₂–CH₂–SCH₃), 2.38 (s, 3H, Ar–CH₃), 3.38 (s, 3H, –COOCH₃), 3.91–3.95 (m,

1H, –CH–CH₂–CH₂–SCH₃), 7.37 (d, J =7.8 Hz, 2H, ArH), 7.63 (d, J = 7.8 Hz, 2H, ArH), 8.28 (d, J =9.0

Hz, 1H, –SO₂NH). Anal. calcd. for C₁₃H₁₉NO₄S₂(317.4242): C, 49.19; H, 6.03; N, 4.41%. Found C, 48.60;

H, 6.13; N, 4.51%.

4.1.2. (2S)-4-(Methylsulfanyl)-2-[[(4-methylphenyl)sulfonyl]amino]butanoic acid hydrazide (2)

Compound 1 (3.17 g, 0.01 mol) and hydrazine hydrate were heated under reﬂux for 8 h and 30 mL of methanol

was added to the reaction medium; subsequently the mixture was further heated under reﬂux for 6 h. The

crude product was ﬁltered, washed with NaCl solution (5%), and recrystallized from methanol. Yield 65%.

mp 135 ^◦C (MeOH), lit. 114–116 ^◦C.³⁰HPLC t_R(min.): 5.93. IR, υ (cm⁻¹): 3346, 3281, 3190, 3078,

1668, 1519, 1491, 1311, 1160. ¹H NMR, δ (ppm): 1.56–1.72 (m, 2H, –CH–CH₂–CH₂–SCH₃), 1.90 (s, 3H,

–CH–CH₂–CH₂–SCH₃), 2.11–2.32 (m, 2H, –CH–CH₂–CH₂–SCH₃), 2.37 (s, 3H, Ar–CH₃), 3.72 (t, J = 6.6

Hz, 1H, –CH–CH₂–CH₂–SCH₃), 4.02 (brs, 2H, –CONHNH₂), 7.34 (d, J = 8.1 Hz, 2H, ArH), 7.64 (d, J =

8.1 Hz, 2H, ArH), 7.95 (brs, 1H, –SO₂NH), 9.08 (brs, 1H, –CONHNH₂). Anal. calcd. for C₁₁H₁₉N₃O₃S₂

(317.4275): C, 45.41; H, 6.03; N, 13.24%. Found C, 45.62; H, 5.98; N, 13.23%.

4.1.3. General procedure for microwave-assisted synthesis of the hydrazones (compounds 3, 5–26,

28, 30–34, 39, 40) derived from (2S)-4-(methylsulfanyl)-2-[[(4-methylphenyl)sulfonyl]amino]

butanoic acid hydrazide (2)

Equimolar amounts of compound 2 and appropriate aldeyde, ketone, or isatine derivative were suspended in

5 mL of ethanol and exposed to microwave irradiation through the aid of an unmodiﬁed home microwave

unit (Kenwood, 270 W, 5–10 min). Thin layer chromatography (silica gel F254 (Merck), mobile phase;

chloroform:methanol:glacial acetic acid 93:5:2 v/v/v, 25 ^◦C) was used to monitor the progress of the reaction.

The crude products were recrystallized from appropriate solvents.

4.1.4. General procedure for conventional synthesis of the hydrazones (compounds 4, 27, 29,

35–38) derived from (2S)-4-(methylsulfanyl)-2-[[(4-methylphenyl)-sulfonyl]amino]butanoic

acid hydrazide (2)

Since the synthesis of compounds 4, 27, 29, and 35–38 was not achieved by microwave-assisted method, the

conventional synthesis method consisting of reﬂuxing equimolar amounts of hydrazide and selected aldehyde

or ketone derivative in ethanol in the presence of a few drops of glacial acetic acid was performed. Thin layer

chromatography (silica gel F254 (Merck), mobile phase; chloroform:methanol:glacial acetic acid 93:5:2 v/v/v,

25 ^◦C) was used to monitor the progress of the reaction and the reaction time for isolating suﬃciently pure

product was 4 h. The crude products were ﬁltered and recrystallized from the appropriate solvents.

4.1.5. N -[(2S)-1-[2-(2-Chlorobenzylidene)hydrazinyl]-4-(methylsulfanyl)-1-oxobutan-2-yl]-4-met-

hylbenzenesulfonamide (3)

Yield 72%. mp 143–144 ^◦C (MeOH). HPLC t_R(min.): 7.80. IR, υ (cm⁻¹): 3232, 3155, 3078, 1666, 1593,

1340, 1160. ¹H NMR, δ (ppm): 1.72–1.95 (m, 5H, –CH–CH₂–CH₂–SCH₃), 2.26 and 2.34 (2s, 3H, Ar–CH₃),

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2.36–2.52 (m, 2H, –CH–CH₂–CH₂–SCH₃), 3.82–3.96 and 4.93–4.94 (2m, 1H, –CH–CH₂–CH₂–SCH₃), 7.28–

7.70 (m, 7H, Ar–H and SO₂NH), 7.86–8.09 (m, 2H, Ar–H), 8.30 and 8.52 (2s, 1H, –N=CH–Ar), 11.54 (s, 1H,

–CONHN=). Anal. calcd. for C₁₉H₂₂ClN₃O₃S₂(439.9792): C, 51.87; H, 5.04; N, 9.55%. Found C, 51.66; H,

5.04; N, 9.59%. LC-MS (APCI): Calculated Mmi: 439.0791, (M+H)⁺: 440.0863, (M–H)⁺: 438.0707. Found

(M+H)⁺: 439.5, (M–H)⁺: 437.9.

4.1.6. N -[(2S)-1-[2-(4-Chlorobenzylidene)hydrazinyl]-4-(methylsulfanyl)-1-oxobutan-2-yl]-4-met-

hylbenzenesulfonamide (4)

Yield 60%. mp 160–162 ^◦C (MeOH). HPLC t_R(min.): 8.65. IR, υ (cm⁻¹): 3240, 3063, 1674, 1624, 1614, 1595,

1371, 1157. ¹H NMR, δ (ppm): 1.69–1.95 (m, 5H, –CH–CH₂–CH₂–SCH₃), 2.19 and 2.25 (2s, 3H, Ar–CH₃),

2.50–2.55 (m, 2H, –CH–CH₂–CH₂–SCH₃), 3.91–3.94 and 4.81–4.88 (2m, 1H, –CH–CH₂–CH₂–SCH₃), 6.00

and 6.87 (2d, J = 9.6 Hz,J = 8.7 Hz, 1H, –SO₂NH), 7.08–7.34 and 7.48–7.68 (2m, 8H, Ar–H), 7.69 and 7.92

(2s, 1H, –N=CH–Ar), 10.66 and 10.82 (2s, 1H, –CONHN=). Anal. calcd. for C₁₉H₂₂ClN₃O₃S₂(439.9792):

C, 51.87; H, 5.04; N, 9.55%. Found C, 51.64; H, 4.93; N, 9.46%. LC-MS (APCI): Calculated Mmi: 439.0791,

(M+H)⁺: 440.0863, (M–H)⁺: 438.0707. Found (M+H)⁺: 439.5, (M–H)⁺: 437.9.

4.1.7. N -[(2S)-1-[2-(2,4-Dichlorobenzylidene)hydrazinyl]-4-(methylsulfanyl)-1-oxobutan-2-yl]-4-

methylbenzenesulfonamide (5)

Yield 63%. mp 205–206 ^◦C (MeOH: DMF 7:3 v/v). HPLC t_R(min.): 9.07. IR, υ (cm⁻¹): 3259, 3095,

3061, 1680, 1597, 1348, 1159. ¹H NMR, δ (ppm): 1.63–1.92 (m, 5H, –CH–CH₂–CH₂–SCH₃), 2.17 (s, 3H,

Ar–CH₃), 2.45–2.53 (m, 2H, –CH–CH₂–CH₂–SCH₃), 3.87–3.95 and 4.78–4.86 (2m, 1H, –CH–CH₂–CH₂–

SCH₃), 6.06 and 6.82 (2d, J =9.6 Hz,J =9.0 Hz, 1H, –SO₂NH), 7.07–7.28 (m, 4H, Ar–H), 7.57–7.64 (m, 2H,

Ar–H), 7.85 and 7.89 (2d, J = 8.7 Hz,J = 8.4 Hz, 1H, Ar–H), 8.09 and 8.27 (2s, 1H, –N=CH–Ar), 10.96 and

11.01 (2s, 1H, –CONHN=). Anal. calcd. for C₁₉H₂₁Cl₂N₃O₃S₂(474.4243): C, 48.10; H, 4.46; N, 8.86%.

Found C, 47.99; H, 4.38; N, 8.83%. LC-MS (APCI): Calculated Mmi: 473.0401, (M+H)⁺: 474.0474, (M–H)⁺:

472.0317. Found (M+H)⁺: 473.7, (M–H)⁺: 471.8.

4.1.8. N -[(2S)-1-[2-(2,6-Dichlorobenzylidene)hydrazinyl]-4-(methylsulfanyl)-1-oxobutan-2-yl]-4-

methylbenzenesulfonamide (6)

Yield 62%. mp 221 ^◦C (MeOH: DMF 7:3 v/v). HPLC t_R(min.): 8.21. IR, υ (cm⁻¹): 3234, 3074, 1668,

1597, 1556, 1327, 1151. ¹H NMR, δ (ppm): 1.69–1.80 (m, 2H, –CH–CH₂–CH₂–SCH₃), 1.91 and 1.94 (2s,

3H, –CH–CH₂–CH₂–SCH₃), 2.28 and 2.32 (2s, 3H, Ar–CH₃), 2.45–2.63 (m, 2H, –CH–CH₂–CH₂–SCH₃),

3.91–3.94 and 4.63–4.71 (2m, 1H, –CH–CH₂–CH₂–SCH₃), 5.94 (d, J =9.6 Hz, 1H, –SO₂NH), 7.14–7.33 (m,

5H, Ar–H), 7.63 and 7.68 (2d, J =8.4 Hz,J =8.1 Hz, 2H, Ar–H), 8.04 and 8.19 (2s, 1H, –N=CH–Ar), 10.88

and 10.94 (2s, 1H, –CONHN=). Anal. calcd. for C₁₉H₂₁Cl₂N₃O₃S₂(474.4243): C, 48.10; H, 4.46; N, 8.86%.

Found C, 47.95; H, 4.38; N, 8.83%. LC-MS (APCI): Calculated Mmi: 473.0401, (M+H)⁺: 474.0474, (M–H)⁺:

472.0317. Found (M+H)⁺: 473.9, (M–H)⁺: 471.8.

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4.1.9. N -[(2S)-1-[2-(2-Chloro-6-ﬂuorobenzylidene)hydrazinyl]-4-(methylsulfanyl)-1-oxo-butan-2-

yl]-4-methylbenzenesulfonamide (7)

Yield 36%. mp 185–189 ^◦C (Acetonitrile: DMF 9:1 v/v). HPLC t_R(min.): 7.69. IR, υ (cm⁻¹): 3234, 3078,

1668, 1604, 1327, 1157. ¹H NMR, δ (ppm): 1.71–1.83 (m, 2H, –CH–CH₂–CH₂–SCH₃), 1.96 (s, 3H, –CH–

CH₂–CH₂–SCH₃), 2.32 and 2.36 (2s, 3H, Ar–CH₃), 2.40–2.65 (m, 2H, –CH–CH₂–CH₂–SCH₃), 3.91–3.94

and 4.62–4.70 (2m, 1H, –CH–CH₂–CH₂–SCH₃), 5.90 (d, J =9.6 Hz, 1H, –SO₂NH), 7.06–7.33 (m, 5H, Ar–H),

7.63–7.70 (m, 2H, Ar–H), 8.03 and 8.25 (2s, 1H, –N=CH–Ar), 10.79 and 10.83 (2s, 1H, –CONHN=). Anal.

calcd. for C₁₉H₂₁ClFN₃O₃S₂(457.9697): C, 49.83; H, 4.62; N, 9.18%. Found C, 49.59; H, 4.47; N, 9.04%.

LC-MS (ESI): Calculated Mmi: 457.0696, (M+H)⁺: 458.0769, (M–H)⁺: 456.0613. Found (M+H)⁺: 457.9,

(M–H)⁺: 455.9.

4.1.10. N -[(2S)-1-[2-(2,6-Diﬂuorobenzylidene)hydrazinyl]-4-(methylsulfanyl)-1-oxo-butan-2-yl]-4-

methylbenzenesulfonamide (8)

Yield 41%. mp 174 ^◦C (MeOH). HPLC t_R(min.): 7.02. IR, υ (cm⁻¹): 3232, 3082, 1668, 1626, 1327,

1155. ¹H NMR, δ (ppm): 1.64–1.94 (m, 2H, –CH–CH₂–CH₂–SCH₃), 2.07 (s, 3H, –CH–CH₂–CH₂–SCH₃),

2.37 and 2.41 (2s, 3H, Ar–CH₃), 2.53–2.76 (m, 2H, –CH–CH₂–CH₂–SCH₃), 3.91–3.94 and 4.72–4.80 (2m,

1H, –CH–CH₂–CH₂–SCH₃), 5.70 (d, J = 9.9 Hz, 1H, –SO₂NH), 6.96–7.06 (m, 2H, Ar–H), 7.22–7.46 (m,

3H, Ar–H), 7.72–7.78 (m, 2H, Ar–H), 7.81 (s, 1H, N=CH–Ar), 9.18 (s, 1H, –CONHN=). Anal. calcd. for

C₁₉H₂₁F₂N₃O₃S₂(441.5151): C, 51.69; H, 4.79; N, 9.52%. Found C, 51.49; H, 4.79; N, 9.46%. LC-MS

(APCI): Calculated Mmi: 441.0992, (M+H)⁺: 442.1065, (M–H)⁺: 440.0908. Found (M+H)⁺: 441.5, (M–

H)⁺: 439.9.

4.1.11. N -[(2S)-1-[2-(3,5-Bistriﬂuoromethylbenzylidene)hydrazinyl]-4-(methylsulfanyl)-1-oxobu-

tan-2-yl]-4-methylbenzenesulfonamide (9)

Yield 58%. mp 197–198 ^◦C (MeOH). HPLC t_R(min.): 9.38. IR, υ (cm⁻¹): 3246, 3097, 1681, 1624, 1325,

1161, 1085. ¹H NMR, δ (ppm): 1.73–1.96 (m, 5H, –CH–CH₂–CH₂–SCH₃), 2.26 and 2.33 (2s, 3H, Ar–CH₃),

2.39–2.57 (m, 2H, –CH–CH₂–CH₂–SCH₃), 3.87–3.95 and 4.94–4.99 (2m, 1H, –CH–CH₂–CH₂–SCH₃), 5.95

(d, J =9.6 Hz, 1H, –SO₂NH), 7.16–7.28 (m, 3H, Ar–H), 7.68–7.90 (m, 4H, Ar–H), 8.08 and 8.17 (2s, 1H,

–N=CH–Ar), 11.01 and 11.21 (2s, 1H, –CONHN=). Anal. calcd. for C₂₁H₂₁F₆N₃O₃S₂(541.5301): C,

46.58; H, 3.91; N, 7.76%. Found C, 46.29; H, 3.78; N, 7.65%. LC-MS (APCI): Calculated Mmi: 541.0928,

(M+H)⁺: 542.1001, (M–H)⁺: 540.0844. Found (M+H)⁺: 541.7, (M–H)⁺: 539.9.

4.1.12. N -[(2S)-1-[2-(4-Cyanobenzylidene)hydrazinyl]-4-(methylsulfanyl)-1-oxobutan-2-yl]-4-met-

hylbenzenesulfonamide (10)

Yield 55%. mp 197 ^◦C (EtOH). HPLC t_R(min.): 5.93. IR, υ (cm⁻¹): 3242, 3105, 3086, 2240, 1681, 1599,

1338, 1161. ¹H NMR, δ (ppm): 1.73–1.99 (m, 5H, –CH–CH₂–CH₂–SCH₃), 2.24 and 2.30 (2s, 3H, Ar–CH₃),

2.41–2.48 and 2.52–2,58 (2m, 2H, –CH–CH₂–CH₂–SCH₃), 3.96–3.99 and 4.87–4.94 (2m, 1H, –CH–CH₂–

CH₂–SCH₃), 5.95 and 6.85 (2d, J =9.6 Hz, J = 8.7 Hz, 1H, –SO₂NH), 7.13–7.29 (m, 2H, Ar–H), 7.58–7.75

(m, 6H, Ar–H), 7.79 and 8.06 (2s, 1H, –N=CH–Ar), 10.85 and 11.08 (2s, 1H, –CONHN=). ¹³C NMR, δ

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(ppm): 14.40 and 14.52 (–CH–CH₂–CH₂–SCH₃), 20.83 and 20.91 (Ar–CH₃), 29.14 and 29.47 (–CH–CH₂–

CH₂–SCH₃), 31.07 and 31.85 (–CH–CH₂–CH₂–SCH₃), 51.06 and 54.43 (–CH–CH₂–CH₂–SCH₃), 111.77

and 111.93 (Ar–C), 118.58 and 118.64 (Ar–CN), 126.41 and 126.51 (Ar–C), 127.34 and 127.62 (Ar–C), 129.27

and 129.36 (Ar–C), 132.65 and 132.70 (Ar–C), 138.06, 138.26, 138.38 and 138.50 (Ar–C), 141.83 (Ar–C), 142.44

and 142.55 (–N=CH–Ar), 145.64 (Ar–C), 167.15 and 172.42 (–CONHN=). Anal. calcd. for C₂₀H₂₂N₄O₃S₂

(430.5436): C, 55.79; H, 5.15; N, 13.01%. Found C, 55.38; H, 5.06; N, 12.90%. LC-MS (ESI): Calculated Mmi:

430.1133, (M+H)⁺: 431.1206, (M–H)⁺: 429.1049. Found (M+H)⁺: 431.0, (M–H)⁺: 429.3.

4.1.13. N -[(2S)-1-[2-(4-Nitrobenzylidene)hydrazinyl]-4-(methylsulfanyl)-1-oxobutan-2-yl]-4-met-

hylbenzene-sulfonamide (11)

Yield 82%. mp 219–220 ^◦C (MeOH: DMF 7:3 v/v). HPLC t_R(min.): 6.75. IR, υ (cm⁻¹): 3248, 3066, 1674,

1597, 1581, 1512, 1338, 1165. ¹H NMR, δ (ppm): 1.74–1.99 (m, 5H, –CH–CH₂–CH₂–SCH₃), 2.24 and 2.31

(2s, 3H, Ar–CH₃), 2.47–2.58 (m, 2H, –CH–CH₂–CH₂–SCH₃), 3.95–4.02 and 4.88–4.96 (2m, 1H, –CH–CH₂–

CH₂–SCH₃), 6.01 and 6.89 (2d, J =9.6 Hz, J =8.7 Hz, 1H, –SO₂NH), 7.14–7.28 (m, 2H, Ar–H), 7.64–7.82

(m, 4H, Ar–H), 7.85 (s, 1H, –N=CH–Ar), 8.12–8.20 (m, 2H, Ar–H), 10.96 and 11.18 (2s, 1H, –CONHN=).

Anal. calcd. for C₁₉H₂₂N₄O₅S₂(450.5317): C, 50.65; H, 4.92; N, 12.44%. Found C, 50.77; H, 4.84; N, 12.48%.

LC-MS (APCI): Calculated Mmi: 450.1031, (M+H)⁺: 451.1104, (M–H)⁺: 449.0947. Found (M+H)⁺: 450.7,

(M–H)⁺: 448.9.

4.1.14. N -[(2S)-1-[2-[4-(Prop-2-en-1-yloxy)benzylidene]hydrazinyl]-4-(methylsulfanyl)-1-oxobu-

tan-2-yl]-4-methylbenzenesulfonamide (12)

Yield 62%. mp 150 ^◦C (MeOH). HPLC t_R(min.): 7.78. IR, υ (cm⁻¹): 3232, 3076, 1668, 1602, 1573, 1335,

1161. ¹H NMR, δ (ppm): 1.67–2.13 (m, 5H, –CH–CH₂–CH₂–SCH₃), 2.33 and 2.36 (2s, 3H, Ar–CH₃),

2.63–2.71 (m, 2H, –CH–CH₂–CH₂–SCH₃), 4.56–4.64 (m, 2H, Ar–O–CH₂CH=CH₂), 4.95–5.03 (m, 1H, –

CH–CH₂–CH₂–SCH₃), 5.33–5.38 and 5.44–5.51 (2m, 2H, Ar–O–CH₂CH=CH₂), 5.68 (d, J =9.9 Hz, 1H,

–SO₂NH), 6.03–6.16 (m, 1H, Ar–O–CH₂CH=CH₂), 6.98–7.02 (m, 2H, Ar–H), 7.18–7.33 (m, 2H, Ar–H),

7.61–7.73 (m, 4H, Ar–H), 7.76 and 7.98 (2s, 1H, –N=CH–Ar), 9.49 and 9.61 (2s, 1H, –CONHN=). Anal.

calcd. for C₂₂H₂₇N₃O₄S₂(461.5974): C, 57.24; H, 5.90; N, 9.10%. Found C, 56.80; H, 5.82; N, 9.04%.

LC–MS (APCI): Calculated Mmi: 461.1443, (M+H)⁺: 462.1515, (M–H)⁺: 460.1359. Found (M+H)⁺: 461.6,

(M–H)⁺: 460.0.

4.1.15. N -[(2S)-1-[2-(3-Methoxy-4-hydroxybenzylidene)hydrazinyl]-4-(methylsulfanyl)-1-oxobu-

tan-2-yl]-4-methylbenzenesulfonamide (13)

Yield 42%. mp 186–187 ^◦C (1–BuOH: MeOH 2:1 v/v). HPLC t_R(min.): 3.49. IR, υ (cm⁻¹): 3446, 3302,

3292, 3263, 3174, 3066, 1664, 1600, 1587, 1321, 1153. ¹H NMR, δ (ppm): 1.72–2.02 (m, 5H, –CH–CH₂–CH₂–

SCH₃), 2.24 and 2.29 (2s, 3H, Ar–CH₃), 2.45–2.63 (m, 2H, –CH–CH₂–CH₂–SCH₃), 3.84 and 3.88 (2s, 3H,

Ar–OCH₃), 3.94–3.97 and 4.87–4.94 (2m, 1H, –CH–CH₂–CH₂–SCH₃), 5.89 (d, J =9.6 Hz, 1H, –SO₂NH),

6.86–6.98 (m, 2H, Ar–H), 7.12–7.33 (m, 3H, Ar–H), 7.55 (s, 1H, Ar–OH), 7.61–7.67 (m, 2H, Ar–H), 7.71

and 7.83 (2s, 1H, –N=CH–Ar), 10.32 and 10.37 (2s, 1H, –CONHN=). Anal. calcd. for C₂₀H₂₅N₃O₅S₂

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(451.5596): C, 53.20; H, 5.58; N, 9.31%. Found C, 53.10; H, 5.51; N, 9.22%. LC-MS (APCI): Calculated Mmi:

451.1235, (M+H)⁺: 452.1308, (M–H)⁺: 450.1151. Found (M+H)⁺: 451.4, (M–H)⁺: 449.9.

4.1.16. N -[(2S)-1-[2-(4-(1-Piperidinyl)benzylidene)hydrazinyl]-4-(methylsulfanyl)-1-oxobutan-2-

yl]-4-methylbenzenesulfonamide (14)

Yield 77%. mp 186 ^◦C (MeOH). HPLC t_R(min.): 8.54. IR, υ (cm⁻¹): 3240, 3176, 3055, 1668, 1608, 1595,

1325, 1157. ¹H NMR, δ (ppm): 1.65–2.15 (m, 11H, –CH–CH₂–CH₂–SCH₃, piperidine–CH₂), 2.32 and 2.37

(2s, 3H, Ar–CH₃), 2.65–2.73 (m, 2H, –CH–CH₂–CH₂–SCH₃), 3.32–3.41(m, 4H, piperidine–CH₂), 3.94–3.97

and 4.92–4.99 (2m, 1H, –CH–CH₂–CH₂–SCH₃), 5.69 and 6.07 (2d, J =9.9 Hz, J = 8.1 Hz, 1H, –SO₂NH),

6.51–6.60 (m, 2H, Ar–H), 7.16–7.32 (m, 3H, Ar–H), 7.50 (s, 1H, –N=CH–Ar), 7.54–7.84 (m, 3H, Ar–H), 9.09

and 9.22 (2s, 1H, –CONHN=). Anal. calcd. for C₂₄H₃₂N₄O₃S₂(488.6658): C, 58.99; H, 6.60; N, 11.47%.

Found C, 58.11; H, 6.25; N, 11.72%. LC-MS (ESI): Calculated Mmi: 488.1915, (M+H)⁺: 489.1988, (M–H)⁺:

487.1832. Found (M+H)⁺: 488.9.0, (M–H)⁺: 486.6.

4.1.17. N -[(2S)-1-[2-(4-(4-Morpholinyl)benzylidene)hydrazinyl]-4-(methylsulfanyl)-1-oxo-butan-

2-yl]-4-methylbenzenesulfonamide (15)

Yield 73%. mp 187–189 ^◦C (MeOH: DMF 1:1 v/v). HPLC t_R(min.): 5.49. IR, υ (cm⁻¹): 3273, 3252, 3082,

3049, 1670, 1599, 1330, 1157. ¹H NMR, δ (ppm): 1.71–2.04 (m, 5H, –CH–CH₂–CH₂–SCH₃), 2.25 and 2.29

(2s, 3H, Ar–CH₃), 2.40–2.62 (m, 2H, –CH–CH₂–CH₂–SCH₃), 3.16–3.21 (m, 4H, morpholine–CH₂), 3.77–3.83

(m, 4H, morpholine–CH₂), 3.93–3.96 and 4.83–4.90 (2m, 1H, –CH–CH₂–CH₂–SCH₃), 5.86 (d, J =9.3 Hz,

1H, –SO₂NH), 6.74–6.88 (m, 2H, Ar–H), 7.12–7.28 (m, 2H, Ar–H), 7.49–7.55 (m, 2H, Ar–H), 7.62–7.67 (m,

2H, Ar–H), 7.71 and 7.83 (2s, 1H, –N=CH–Ar), 10.25 (s, 1H, –CONHN=). Anal. calcd. for C₂₃H₃₀N₄O₄S₂

(490.6387): C, 56.30; H, 6.16; N, 11.42%. Found C, 56.09; H, 6.09; N, 11.31%. LC-MS (APCI): Calculated

Mmi: 490.1708, (M+H)⁺: 491.1781, (M–H)⁺: 489.1624. Found (M+H)⁺: 490.5, (M–H)⁺: 489.0.

4.1.18. N -[(2S)-1-[2-(Pyridin-3-ylmethylidene)hydrazinyl]-4-(methylsulfanyl)-1-oxo-butan-2-yl]-

4-methylbenzenesulfonamide (16)

Yield 49%. mp 205–206 ^◦C (MeOH). HPLC t_R(min.): 2.69. IR, υ (cm⁻¹): 3190, 3055, 1678, 1608, 1597,

1327, 1159. ¹H NMR, δ (ppm): 1.75–2.01 (m, 5H, –CH–CH₂–CH₂–SCH₃), 2.29 (s, 3H, Ar–CH₃), 2.51–2.60

(m, 2H, –CH–CH₂–CH₂–SCH₃), 3.94–4.01 and 4.84–4.92 (2m, 1H, –CH–CH₂–CH₂–SCH₃), 6.00 and 6.89

(2d, J =9.3 Hz, J =8.7 Hz, 1H, –SO₂NH), 7.12–7.31 (m, 3H, Ar–H), 7.64–7.69 (m, 2H, Ar–H), 7.78 (s, 1H,

–N=CH–Ar), 7.97–8.07 (m, 1H, Ar–H), 8.52–8.71 (m, 2H, Ar–H), 10.83 and 10.99 (2s, 1H, –CONHN=). Anal.

calcd. for C₁₈H₂₂N₄O₃S₂(406.5222): C, 53.18; H, 5.45; N, 13.78%. Found C, 52.93; H, 5.43; N, 13.69%.

LC-MS (APCI): Calculated Mmi: 406.1133, (M+H)⁺: 407.1206, (M–H)⁺: 405.1049. Found (M+H)⁺: 406.6,

(M–H)⁺: 405.1.

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4.1.19. N -[(2S)-1-[-2-(Cyclohexylmethylidene)hydrazinyl]-4-(methylsulfanyl)-1-oxo-butan-2-yl]-4-

methylbenzenesulfonamide (17)

Yield 78%. mp 119–120 ^◦C (MeOH). HPLC t_R(min.): 8.12. IR, υ (cm⁻¹): 3230, 3056, 1668, 1624, 1330, 1157.

¹H NMR, δ (ppm): 1.18–1.94 (m, 15H, –CH–CH₂–CH₂–SCH₃, cyclohexyl–CH₂), 2.36 (s, 3H, Ar–CH₃),

2.15–2.34 and 2.38–2.52 (2m, 3H, –CH–CH₂–CH₂–SCH₃, cyclohexyl–CH), 3.74–3.76 and 4.66–4.74 (2m, 1H,

–CH–CH₂–CH₂–SCH₃), 7.14 (d, J =4.8 Hz, 1H, –SO₂NH), 7.31–7.34 (m, 2H, Ar–H), 7.60–7.67 (m, 2H, Ar–

H), 7.87, 7.90, 8.05 and 8.07 (4s, 1H, –N=CH–Ar), 10.87 and 10.91 (2s, 1H, –CONHN=). Anal. calcd. for

C₁₉H₂₉N₃O₃S₂(411.5818): C, 55.45; H, 7.10; N, 10.21%. Found C, 55.65; H, 7.02; N, 9.89%. LC-MS (ESI):

Calculated Mmi: 411.1650, (M+H)⁺: 412.1723, (M–H)⁺: 410.1566. Found (M+H)⁺: 411.7, (M–H)⁺: 410.0.

4.1.20. N -[(2S)-1-[2-[Bicyclo[2.2.1]hept-5-en-2-ylmethylidene]hydrazinyl]-4-(methyl-sulfanyl)-1-

oxobutan-2-yl]-4-methylbenzenesulfonamide (18)

Yield 23%. mp 138 ^◦C (MeOH). HPLC t_R(min.): 10.84. IR, υ (cm⁻¹): 3232, 3063, 1668, 1624, 1330,

1157. ¹H NMR, δ (ppm): 1.06–1.36 (m, 4H, bicyclo[2.2.1]hept–5–ene–CH₂), 1.61–1.98 (m, 5H, –CH–CH₂–

CH₂–SCH₃), 2.14–2.35 and 2.37–2.52 (2m, 2H, –CH–CH₂–CH₂–SCH₃), 2.36 (s, 3H, Ar–CH₃), 2.77–3.01

(m, 3H, bicyclo[2.2.1]hept–5–ene–CH), 3.71–3.75 and 4.65–4.72 (2m, 1H, –CH–CH₂–CH₂–SCH₃), 5.92–6.24

(m, 2H, bicyclo[2.2.1]hept–5–ene–CH=CH), 6.91–7.02 (m, 1H, –SO₂NH), 7.30–7.36 (m, 2H, Ar–H), 7.58–7.67

(m, 2H, Ar–H), 7.85–8.09 (2m, 1H, –N=CH–Ar), 10.80, 10.88, 10.92, 10.96 and 10.97 (5s, 1H, –CONHN=).

Anal. calcd. for C₂₀H₂₇N₃O₃S₂(421.5766): C, 56.98; H, 6.46; N, 9.97%. Found C, 57.70; H, 6.49; N, 9.68%.

LC-MS (ESI): Calculated Mmi: 421.1493, (M+H)⁺: 422.1566, (M–H)⁺: 420.1410. Found (M+H)⁺: 421.9,

(M–H)⁺: 420.0.

4.1.21. N -[(2S)-1-[2-[(1,3-Benzodioxol-4-yl)methylidene]hydrazinyl]-4-(methylsulfanyl)-1-oxobu-

tan-2-yl]-4-methylbenzenesulfonamide (19)

Yield 47%. mp 182-184 ^◦C (Acetonitrile). HPLC t_R(min.): 6.78. IR, υ (cm⁻¹): 3252, 3182, 3084, 3049, 1670,

1624, 1338, 1161. ¹H NMR, δ (ppm): 1.76–2.02 (m, 5H, –CH–CH₂–CH₂–SCH₃), 2.23 and 2.28 (2s, 3H, Ar–

CH₃), 2.51–2.61 (m, 2H, –CH–CH₂–CH₂–SCH₃), 3.93–3.95 and 4.61–4.69 (2m, 1H, –CH–CH₂–CH₂–SCH₃),

5.95–6.02 (m, 2H, –O–CH₂–O–), 6.26 (d, J=9.9 Hz, 1H, –SO₂NH), 6.73–6.79 (m, 2H, Ar–H), 7.06–7.28 (m,

3H, Ar–H), 7.61–7.68 (m, 2H, Ar–H), 7.76 and 8.05 (2s, 1H, –N=CH–Ar), 10.65 (s, 1H, –CONHN=). Anal.

calcd. for C₂₀H₂₃N₃O₅S₂(449.5437): C, 53.44; H, 5.16; N, 9.35%. Found C, 53.22; H, 5.10; N, 9.30%.

LC-MS (APCI): Calculated Mmi: 449.1079, (M+H)⁺: 450.1151, (M–H)⁺: 448.0995. Found (M+H)⁺: 450.8,

(M–H)⁺: 447.9.

4.1.22. N -[(2S)-1-[2-[(2,2-Diﬂuoro-1,3-benzodioxol-5-yl)methylidene]hydrazinyl]-4-(methylsul-

fanyl)-1-oxobutan-2-yl]-4-methylbenzenesulfonamide (20)

Yield 42%. mp 189-191 ^◦C (MeOH: DMF 7:3 v/v). HPLC t_R(min.): 8.64. IR, υ (cm⁻¹): 3327, 3275,

3244, 3084, 3061, 1693, 1624, 1331, 1190, 1087. ¹H NMR, δ (ppm): 1.72–1.96 (m, 5H, –CH–CH₂–CH₂–

SCH₃), 2.25 and 2.31 (2s, 3H, Ar–CH₃), 2.51–2.59 (m, 2H, –CH–CH₂–CH₂–SCH₃), 3.94–3.97 and 4.84–4.91

(2m, 1H, –CH–CH₂–CH₂–SCH₃), 5.92 (d, J =9.6 Hz, 1H, –SO₂NH), 6.84–7.28 (m, 4H, Ar–H), 7.47–7.72

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(m, 3H, Ar–H), 7.72 and 7.98 (2s, 1H, –N=CH–Ar), 10.63 and 10.81 (2s, 1H, –CONHN=). Anal. calcd.

for C₂₀H₂₁F₂N₃O₅S₂(485.5246): C, 49.48; H, 4.36; N, 8.43%. Found C, 49.20; H, 4.31; N, 8.43%. LC-

MS (APCI): Calculated Mmi: 485.0890, (M+H)⁺: 486.0963, (M–H)⁺: 484.0806. Found (M+H)⁺: 485.6,

(M–H)⁺: 483.8 .

4.1.23. N -[(2S)-1-[2-[(6-Nitro-1,3-benzodioxol-5-yl)methylidene]hydrazinyl]-4-(methyl-sulfanyl)-1-

oxobutan-2-yl]-4-methylbenzenesulfonamide (21)

Yield 32%. mp 189 ^◦C (MeOH). HPLC t_R(min.): 6.72. IR, υ (cm⁻¹): 3232, 3180, 3064, 1676, 1624, 1519,

1330, 1163. ¹H NMR, δ (ppm): 1.69–1.95 (m, 5H, –CH–CH₂–CH₂–SCH₃), 2.29 and 2.35 (2s, 3H, Ar–CH₃),

2.37–2.52 (m, 2H, –CH–CH₂–CH₂–SCH₃), 3.85–3.95 and 4.91–4.93 (2m, 1H, –CH–CH₂–CH₂–SCH₃), 6.30

(s, 2H, –O–CH₂–O–), 7.29 (m, 3H, Ar–H and –SO₂NH), 7.53–7.69 (m, 3H, Ar–H,), 8.07 (d, J = 9.0 Hz,

1H, Ar–H), 8.32 and 8.55 (2s, 1H, –N=CH–Ar), 11.58 and 11.73 (2s, 1H, –CONHN=). Anal. calcd. for

C₂₀H₂₂N₄O₇S₂(494.5412): C, 48.57; H, 4.48; N, 11.33%. Found C, 48.49; H, 4.45; N, 11.27%. LC-MS (ESI):

Calculated Mmi: 494.0929, (M+H)⁺: 495.1002, (M–H)⁺: 493.0846. Found (M+H)⁺: 494.9, (M–H)⁺: 493.0 .

4.1.24. N -[(2S)-1-[2-[(Furan-2-yl)methylidene]hydrazinyl]-4-(methylsulfanyl)-1-oxo-butan-2-yl]-4-

methylbenzenesulfonamide (22)

Yield 44%. mp 130–132 ^◦C (MeOH). HPLC t_R(min.): 4.57. IR, υ (cm⁻¹): 3480, 3220, 1665, 1599, 1330,

1163. ¹H NMR, δ (ppm): 1.66–1.95 (m, 5H, –CH–CH₂–CH₂–SCH₃), 2.28 and 2.35 (2s, 3H, Ar–CH₃), 2.38–

2.52 (m, 2H, –CH–CH₂–CH₂–SCH₃), 3.83–3.85 and 4.75–4.82 (2m, 1H, –CH–CH₂–CH₂–SCH₃), 6.62–6.64

(brs, 1H, –SO₂NH), 6.88 (t, J =3.6 Hz, 1H, Ar–H), 7.29–7.34 (m, 2H, Ar–H), 7.62–7.68 (m, 2H, Ar–H), 7.83

(m, 1H, Ar–H), 7.98 (d, J =9.0 Hz, 1H, Ar–H), 8.17 and 8.20 (2s, 1H, –N=CH–Ar), 11.31 and 11.43 (2s,

1H, –CONHN=). Anal. calcd. for C₁₇H₂₁N₃O₄S₂.1/2 CH₃OH (411.5172): C, 51.08; H, 5.63; N, 10.21%.

Found C, 50.60; H, 5.20; N, 10.32%. LC-MS (APCI): Calculated Mmi: 395.0973, (M+H)⁺: 396.1046, (M–H)⁺:

394.0889. Found (M+H)⁺: 395.5, (M–H)⁺: 393.9.

4.1.25. N -[(2S)-1-[2-[(5-Nitrofuran-2-yl)methylidene]hydrazinyl]-4-(methylsulfanyl)-1-oxobutan-2-

yl]-4-methylbenzenesulfonamide (23)

Yield 51%. mp 199–200 ^◦C (1-BuOH:MeOH 2:1 v/v). HPLC t_R(min.): 5.53. IR, υ (cm⁻¹): 3275, 3134, 3107,

1668, 1624, 1525, 1348, 1315, 1157. ¹H NMR, δ (ppm): 1.16–1.39 (m, 2H, –CH–CH₂–CH₂–SCH₃), 1.49 (s,

3H, –CH–CH₂–CH₂–SCH₃), 1.85 and 1.90 (2s, 3H, Ar–CH₃), 2.04–2.07 (m, 2H, –CH–CH₂–CH₂–SCH₃),

3.40–3.45 and 4.32–4.40 (2m, 1H, –CH–CH₂–CH₂–SCH₃), 6.75 (d, J =3.0 Hz, 1H, Ar–H), 6.87 (d, J =6.0

Hz, 2H, Ar–H), 7.00, 7.36 and 7.42 (2d, J =6.0 Hz, J =3.0 Hz, and s, 1H, –SO₂NH), 7.19 (d, J =9.1 Hz, 2H,

Ar–H), 7.32 (d, J =3.0 Hz, 1H, Ar–H), 7.63, 7.67 and 8.27 (3s, 1H, –N=CH–Ar), 11.45 (s, 1H, –CONHN=).

¹³C NMR, δ (ppm): 14.33 and 14.49 (–CH–CH₂–CH₂–SCH₃), 20.86 (Ar–CH₃), 29.15 and 29.39 (–CH–CH₂–

CH₂–SCH₃), 31.07 and 31.82 (–CH–CH₂–CH₂–SCH₃), 51.37 and 54.51 (–CH–CH₂–CH₂–SCH₃), 114.07,

114.55 and 114.75 (furan–Ar–C), 115.60 and 119.83 (furan–Ar–C), 126.47 and 126.56 (phenyl–Ar–C), 129.33,

129.44 and 129.48 (phenyl–Ar–C), 131.92 and 135.55 (–N=CH–Ar), 138.08 and 138.33 (phenyl–Ar–C), 142.50

and 142.69 (phenyl–Ar–C), 150.12 (furan–Ar–C), 151.47, 151.76 and 151.94 (furan–Ar–C), 167.47 and 172.48

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(–CONHN=). Anal. calcd. for C₁₇H₂₀N₄O₆S₂(440.4939): C, 46.35; H, 4.58; N, 12.72%. Found C, 46.05;

H, 4.43; N, 13.02%. LC-MS (ESI): Calculated Mmi: 440.0824, (M+H)⁺: 441.0897, (M–H)⁺: 439.0740. Found

(M+H)⁺: 441.0, (M–H)⁺: 439.1.

4.1.26. N-[(2S)-1-[2-[(5-Bromofuran-2-yl)methylidene]hydrazinyl]-4-(methylsulfanyl)-1-oxobutan-

2-yl]-4-methylbenzenesulfonamide (24)

Yield 72%. mp 141–145 ^◦C (EtOH). HPLC t_R(min.): 6.74. IR, υ (cm⁻¹): 3219, 3066, 3030, 1660, 1597,

1325, 1157. ¹H NMR, δ (ppm): 1.66–1.88 (m, 2H, –CH–CH₂–CH₂–SCH₃), 2.01 and 2.11 (2s, 3H, –CH–

CH₂–CH₂–SCH₃), 2.38 and 2.40 (2s, 3H, Ar–CH₃), 2.43–2.72 (m, 2H, –CH–CH₂–CH₂–SCH₃), 4.06–4.09

and 4.87–4.94 (2m, 1H, –CH–CH₂–CH₂–SCH₃), 5.62 and 6.11 (2d, J =9.9 Hz, J =8.1 Hz, 1H, –SO₂NH),

6.42, 6.47 and 6.51 (3d, J =3.6 Hz, J =3.6 Hz and J =3.6 Hz, 1H, ArH), 6.76 and 6.88 (2d, J =3.6 Hz,

J =3.6 Hz 1H, ArH), 7.23–7.34 (m, 2H, ArH), 7.73–7.79 (m, 2H, ArH), 7.48 and 8.05 (2s, 1H, –N=CH–Ar),

9.44, 9.46, 9.83 and 9.85 (4s, 1H, –CONHN). Anal. calcd. for C₁₇H₂₀BrN₃O₄S₂(474.3924): C, 43.04; H,

4.25; N, 8.86%. Found C, 43.15; H, 4.29; N, 8.83%. LC-MS (APCI): Calculated Mmi: 473.0078, (M+H)⁺:

474.0151, (M–H)⁺: 471.9994. Found (M+H)⁺: 473.6, (M–H)⁺: 471.8.

4.1.27. N-[(2S)-1-[2-[(5-(4-Nitrophenyl)furan-2-yl)methylidene]hydrazinyl]-4-(methyl-sulfanyl)-1-

oxobutan-2-yl]-4-methylbenzenesulfonamide (25)

Yield 75%. mp 189 ^◦C (Acetonitrile: DMF 9:1 v/v). HPLC t_R(min.): 7.82. IR, υ (cm⁻¹): 3298, 3254,

3113, 3037, 1664, 1597, 1521, 1330, 1155. ¹H NMR, δ (ppm): 1.72–2.04 (m, 5H, –CH–CH₂–CH₂–SCH₃),

2.27 and 2.32 (2s, 3H, Ar–CH₃), 2.47–2.65 (m, 2H, –CH–CH₂–CH₂–SCH₃), 3.95–4.02 and 4.83–4.91 (2m,

1H, –CH–CH₂–CH₂–SCH₃), 5.95 (d, J =9.6 Hz, 1H, –SO₂NH), 6.79–6.93 (m, 2H, ArH), 7.15–7.23 (m, 2H,

ArH), 7.68 (d, J =8.7 Hz, 2H, ArH), 7.81 (d, J =8.7 Hz, 2H, ArH), 7.48 and 8.01 (2s, 1H, –N=CH–Ar), 8.20

(t, J =9.0 Hz, 2H, ArH), 10.83 and 10.96 (2s, 1H, –CONHN=). Anal. calcd. for C₂₃H₂₄N₄O₆S₂(516.5898):

C, 53.47; H, 4.68; N, 10.85%. Found C, 52.97; H, 4.80; N, 10.65%. LC-MS (APCI): Calculated Mmi: 516.1137,

(M+H)⁺: 517.1210, (M–H)⁺: 515.1053. Found (M+H)⁺: 516.7, (M–H)⁺: 514.9.

4.1.28. N-[(2S)-1-[2-[(5-(4-Chlorophenyl)furan-2-yl)methylidene]hydrazinyl]-4-(methyl-sulfanyl)-1-

oxobutan-2-yl]-4-methylbenzenesulfonamide (26)

Yield 42%. mp 163-165 ^◦C (Acetone: DMF 8:2 v/v). HPLC t_R(min.): 9.04. IR, υ (cm⁻¹): 3213, 3066,

3034, 1658, 1597, 1325, 1157. ¹H NMR, δ (ppm): 1.83–2.15 (m, 5H, –CH–CH₂–CH₂–SCH₃), 2.31 and

2.35 (2s, 3H, Ar–CH₃), 2.42–2.71 (m, 2H, –CH–CH₂–CH₂–SCH₃), 3.99–4.07 and 4.85–4.93 (2m, 1H, –CH–

CH₂–CH₂–SCH₃), 5.85 and 6.63 (2d, J =9.6 Hz, J =8.7 Hz, 1H, –SO₂NH), 6.87 and 6.72 (2d, J =3.6

Hz, J =3.6 Hz, 1H, ArH), 6.78 and 6.84 (2d, J =3.6 Hz, J =3.6 Hz, 1H, ArH), 7.18–7.39 (m, 4H, ArH),

7.62–7.74 (m, 4H, ArH), 7.61 and 7.99 (2s, 1H, –N=CH–Ar), 10.51 and 10.58 (2s, 1H, –CONHN=). Anal.

calcd. for C₂₃H₂₄ClN₃O₄S₂(506.0373): C, 54.59; H, 4.78; N, 8.30%. Found C, 54.40; H, 4.69; N, 8.14%.

LC-MS (APCI): Calculated Mmi: 505.0896, (M+H)⁺: 506.0969, (M–H)⁺: 504.0813. Found (M+H)⁺: 505.6,

(M–H)⁺: 503.9.

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4.1.29. N-[(2S)-1-[2-[(5-(2,4-dichlorophenyl)furan-2-yl)methylidene]hydrazinyl]-4-(methylsulfanyl)-

1-oxobutan-2-yl]-4-methylbenzenesulfonamide (27)

Yield 62%. mp 178 ^◦C (MeOH). HPLC t_R(min.): 10.28. IR, υ (cm⁻¹): 3243, 3063, 3036, 1668, 1597, 1321,

1155. ¹H NMR, δ (ppm): 1.76–2.12 (m, 5H, –CH–CH₂–CH₂–SCH₃), 2.32 and 2.35 (2s, 3H, Ar–CH₃),

2.44–2.69 (m, 2H, –CH–CH₂–CH₂–SCH₃), 4.02–4.06 and 4.85–4.93 (2m, 1H, –CH–CH₂–CH₂–SCH₃), 5.82

and 6.60 (2d, J =9.9 Hz, J =8.7 Hz, 1H, –SO₂NH), 7.18–7.29 (m, 3H, ArH), 7.31 and 7.34 (2d, J =2.1 Hz,

J =2.4 Hz, 1H, ArH), 7.42 and 7.46 (2d, J =2.1 Hz, J =1.8 Hz, 1H, ArH), 7.71–7.91 (m, 4H, ArH), 7.68

and 8.03 (2s, 1H, –N=CH–Ar), 10.57 and 10.59 (2s, 1H, –CONHN=). Anal. calcd. for C₂₃H₂₃Cl₂N₃O₄S₂

(540.4842): C, 51.11; H, 4.29; N, 7.77%. Found C, 50.78; H, 4.15; N, 7.62%. LC-MS (ESI): Calculated Mmi:

539.0507, (M+H)⁺: 540.0579, (M–H)⁺: 538.0423. Found (M+H)⁺: 540.0, (M–H)⁺: 538.1.

4.1.30. N-[(2S)-1-[-2-[(Thiophen-2-yl)methylidene]hydrazinyl]-4-(methylsulfanyl)-1-oxobutan-2-yl]-

4-methylbenzenesulfonamide (28)

Yield 41%. mp 132 ^◦C (MeOH). HPLC t_R(min.): 2.09. IR, υ (cm⁻¹): 3228, 3041, 1662, 1599, 1332, 1163. ¹H

NMR, δ (ppm): 1.72–1.85 (m, 2H, –CH–CH₂–CH₂–SCH₃), 1.94 (s, 3H, –CH–CH₂–CH₂–SCH₃), 2.29 and

2.35 (2s, 3H, Ar–CH₃), 2.38–2.52 (m, 2H, –CH–CH₂–CH₂–SCH₃), 3.82–3.84 and 4.73–4.81 (2m, 1H, –CH–

CH₂–CH₂–SCH₃), 7.11–7.15 (m, 1H, –SO₂NH), 7.31–7.35 (m, 2H, ArH), 7.41–7.46 (m, 1H ArH), 7.62–7.69

(m, 3H, ArH), 7.98–8.04 (m, 1H, ArH), 8.09 and 8.34 (2s, 1H, –N=CH–Ar), 11.34 (s, 1H, –CONHN=). Anal.

calcd. for C₁₇H₂₁N₃O₃S₃(411.5619): C, 49.61; H, 5.14; N, 10.21%. Found C, 49.66; H, 5.08; N, 10.09%.

LC-MS (APCI): Calculated Mmi: 411.0745, (M+H)⁺: 412.0817, (M–H)⁺: 410.0661. Found (M+H)⁺: 411.5,

(M–H)⁺: 409.8.

4.1.31. N-[(2S)-1-[2-[(3-Methylthiophen-2-yl)methylidene]hydrazinyl]-4-(methyl-sulfanyl)-1-oxo-

butan-2-yl]-4-methylbenzenesulfonamide (29)

Yield 59%. mp 152 ^◦C (MeOH). HPLC t_R(min.): 6.93. IR, υ (cm⁻¹): 3255, 3055, 3030, 1668, 1597, 1329,

1159. ¹H NMR, δ (ppm): 1.67–2.08 (m, 5H, –CH–CH₂–CH₂–SCH₃), 2.34, 2.36 and 2.38 (3s, 6H, Ar–CH₃,

thiophene–CH₃), 2.44–2.71 (m, 2H, –CH–CH₂–CH₂–SCH₃), 4.04–4.07 and 4.80–4.87 (2m, 1H, –CH–CH₂–

CH₂–SCH₃), 5.65 and 6.25 (2d, J =9.9 Hz, J =8.1 Hz, 1H, –SO₂NH), 6.84 and 6.90 (2d, J =5.1 Hz, J =4.8

Hz, 1H, ArH), 7.19 (d, J =7.8 Hz, 2H, ArH), 7.28–7.37 (m, 1H, ArH), 7.73 (d, J =8.4 Hz, 2H, ArH), 7.85 and

8.43 (2s, 1H, –N=CH–Ar), 9.51 and 9.67 (2s, 1H, –CONHN=). Anal. calcd. for C₁₈H₂₃N₃O₃S₃(425.5885):

C, 50.80; H, 5.45; N, 9.87%. Found C, 50.64; H, 5.34; N, 9.75%. LC-MS (APCI): Calculated Mmi: 425.0901,

(M+H)⁺: 426.0974, (M–H)⁺: 424.0871. Found (M+H)⁺: 425.5, (M–H)⁺: 423.9.

4.1.32. N-[(2S)-1-[2-[(5-Nitrothiophen-2-yl)methylidene]hydrazinyl]-4-(methylsulfanyl)-1-oxobu-

tan-2-yl]-4-methylbenzenesulfonamide (30)

Yield 61%. mp 209 ^◦C (1-BuOH: MeOH 2:1 v/v). HPLC t_R(min.): 6.51. IR, υ (cm⁻¹): 3225, 1674, 1599,

1531, 1332, 1159. ¹H NMR, δ (ppm) 1.64–1.88 (m, 5H, –CH–CH₂–CH₂–SCH₃), 2.19 and 2.22 (2s, 3H,

Ar–CH₃), 2.25–2.48 (m, 2H, –CH–CH₂–CH₂–SCH₃), 3.85–3.87 and 4.63–4.70 (2m, 1H, –CH–CH₂–CH₂–

SCH₃), 6.24 (d, J =9.3 Hz, 1H, –SO₂NH), 7.01–7.06 (m, 1H, ArH), 7.09 (d, J =8.1 Hz, 2H, ArH), 7.57 (d,

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J =8.1 Hz, 2H, ArH), 7.71–7.73 (m, 1H, ArH), 7.85 and 8.31 (2s, 1H, –N=CH–Ar), 11.08 and 11.37 (2s, 1H,

–CONHN=). Anal. calcd. for C₁₇H₂₀N₄O₅S₃(456.5595): C, 44.72; H, 4.42; N, 12.27%. Found C, 44.01; H,

4.02; N, 13.02%. ¹³C NMR, δ (ppm): 14.38 and 14.64 (–CH–CH₂–CH₂–SCH₃), 20.86 and 20.93 (Ar–CH₃),

29.10 and 29.45 (–CH–CH₂–CH₂–SCH₃), 31.19 and 31.67 (–CH–CH₂–CH₂–SCH₃), 50.79 and 54.40 (–CH–

CH₂–CH₂–SCH₃), 126.51 (phenyl–Ar–C), 129.01, 129.25, 129.33 and 129.38 (thiophene–Ar–C), 129.76, 130.30,

130.38 and 130.48 (phenyl–Ar–C), 133.43, 134.39 and 134.55 (thiophene–Ar–C), 137.02, 137.98 and 138.01 (–

N=CH–Ar), 141.12, 142.55 and 142.63 (phenyl–Ar–C), 144.10 and 146.27 (thiophene–Ar–C), 150.67 and 150.87

(phenyl–Ar–C), 152.27, 152.90, 156.44 and 157.27 (thiophene–Ar–C), 167.29 and 172.40 (–CONHN=). LC-MS

(ESI): Calculated Mmi: 456.0595, (M+H)⁺: 457.0668, (M–H)⁺: 455.0512. Found (M+H)⁺: 456.9, (M–H)⁺:

455.1.

4.1.33. N-[(2S)-1-[2-[(4-Phenylthiophen-2-yl)methylidene]hydrazinyl]-4-(methyl-sulfanyl)-1-oxo-

butan-2-yl]-4-methylbenzenesulfonamide (31)

Yield 77%. mp 185–187 ^◦C (MeOH : DMF 7:3 v/v). HPLC t_R(min.): 8.63. IR, υ (cm⁻¹): 3363, 3238,

3064, 1672, 1597, 1332, 1147. ¹H NMR, δ (ppm): 1.69–2.02 (m, 5H, –CH–CH₂–CH₂–SCH₃), 2.25 and 2.31

(2s, 3H, Ar–CH₃), 2.51–2.65 (m, 2H, –CH–CH₂–CH₂–SCH₃), 3.92–3.98 and 4.72–4.79 (2m, 1H, –CH–CH₂–

CH₂–SCH₃), 5.92 and 6.79 (2d, J =9.6 Hz, J =9.0 Hz, 1H, –SO₂NH), 7.21–7.37 (m, 5H, ArH), 7.45 (d,

J =3.3 Hz, 2H, ArH), 7.49 (d, J =7.2 Hz, 2H, ArH), 7.65 (d, J =8.1 Hz, 2H, ArH), 7.93 and 8.26 (2s, 1H,

–N=CH–Ar), 10.64 and 10.78 (2s, 1H, –CONHN=). Anal. calcd. for C₂₃H₂₅N₃O₃S₃(487.6579): C, 56.65;

H, 5.17; N, 8.62%. Found C, 56.28; H, 5.23; N, 8.56%. LC-MS (APCI): Calculated Mmi: 487.1058, (M+H)⁺:

488.1130, (M–H)⁺: 486.0974. Found (M+H)⁺: 487.7, (M–H)⁺: 486.0.

4.1.34. N-[(2S)-1-[2-[(4-Bromothiophen-2-yl)methylidene]hydrazinyl]-4-(methyl-sulfanyl)-1-oxo-

butan-2-yl]-4-methylbenzenesulfonamide (32)

Yield 50%. mp 155 ^◦C (EtOH). HPLC t_R(min.): 7.72. IR, υ (cm⁻¹): 3335, 3282, 3244, 3169, 3076, 3055,

1676, 1597, 1329, 1161. ¹H NMR, δ (ppm): 1.65–2.06 (m, 5H, –CH–CH₂–CH₂–SCH₃), 2.38 and 2.40 (2s,

3H, Ar–CH₃), 2.53–2.69 (m, 2H, –CH–CH₂–CH₂–SCH₃), 4.06–4.08 and 4.83–4.91 (2m, 1H, –CH–CH₂–CH₂–

SCH₃), 5.63 and 6.14 (2d, J =9.9 Hz, J =8.1 Hz, 1H, –SO₂NH), 7.21–7.34 (m, 4H, ArH), 7.74(d, J =8.1

Hz, 2H, ArH), 7.79 and 8.35 (2s, 1H, –N=CH–Ar), 9.57, 9.59, 9.84 and 9.86 (4s, 1H, –CONHN=). Anal.

calcd. for C₁₇H₂₀BrN₃O₃S₃(490.4580): C, 41.63; H, 4.11; N, 8.57%. Found C, 41.36; H, 4.04; N, 8.41%.

LC-MS (APCI): Calculated Mmi: 488.9850, (M+H)⁺: 489.9922, (M–H)⁺: 487.9766. Found (M+H)⁺: 489.6,

(M–H)⁺: 487.8.

4.1.35. N-[(2S)-1-[2-[(5-Ethylthiophen-2-yl)methylidene]hydrazinyl]-4-(methylsulfanyl)-1-oxobu-

tan-2-yl]-4-methylbenzenesulfonamide (33)

Yield 48%. mp 140–142 ^◦C (MeOH). HPLC t_R(min.): 7.82. IR, υ (cm⁻¹): 3213, 3068, 3030, 1658, 1597,

1325, 1157. ¹H NMR, δ (ppm): 1.38 (t, J =7.5 Hz, 3H, thiophene–CH₂CH₃), 1.64–2.10 (m, 5H, –CH–

CH₂–CH₂–SCH₃), 2.35 and 2.38 (2s, 3H, Ar–CH₃), 2.57–2.73 (m, 2H, –CH–CH₂–CH₂–SCH₃), 2.84–2.89

(q, J =7.5 Hz, 2H, thiophene–CH₂CH₃), 4.79–4.86 (m, 1H, –CH–CH₂–CH₂–SCH₃), 5.63 (d, J =9.6 Hz,

1H, –SO₂NH), 6.75–6.82 (m, 1H, ArH), 7.14–7.34 (m, 3H, ArH), 7.73 (d, J =8.4 Hz, 2H, ArH), 7.78 and

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8.25 (2s, 1H, –N=CH–Ar), 9.36 and 9.46 (2s, 1H, –CONHN=). Anal. calcd. for C₁₉H₂₅N₃O₃S₃(439.6151):

C, 51.91; H, 5.73; N, 9.56%. Found C, 51.95; H, 5.64; N, 9.41%. LC-MS (APCI): Calculated Mmi: 439.1058,

(M+H)⁺: 440.1130, (M–H)⁺: 438.0974. Found (M+H)⁺: 439.5, (M–H)⁺: 438.1.

4.1.36. N-[(2S)-1-[2-[(5-Chlorothiophen-2-yl)methylidene]hydrazinyl]-4-(methyl-sulfanyl)-1-oxo-

butan-2-yl]-4-methylbenzenesulfonamide (34)

Yield 43%. mp 199–200 ^◦C (1-BuOH: MeOH 2:1 v/v). HPLC t_R(min.): 7.74. IR, υ (cm⁻¹): 3207, 3095,

3061, 1660, 1597, 1315, 1157. ¹H NMR, δ (ppm): 1.71–2.00 (m, 5H, –CH–CH₂–CH₂–SCH₃), 2.28 and 2.32

(2s, 3H, Ar–CH₃), 2.41–2.59 (m, 2H, –CH–CH₂–CH₂–SCH₃), 3.91–3.95 and 4.66–4.73 (2m, 1H, –CH–CH₂–

CH₂–SCH₃), 5.85 (d, J =9.3 Hz, 1H, –SO₂NH), 6.74–6.82 (m, 1H, ArH), 6.93 and 6.96 (2d, J =3.9 Hz,

J =3.9 Hz, 1H, ArH), 7.16–7.29 (m, 2H, ArH), 7.65–7.69 (m, 2H, ArH), 7.77 and 8.18 (2s, 1H, –N=CH–Ar),

10.56 and 10.79 (2s, 1H, –CONHN=). Anal. calcd. for C₁₇H₂₀ClN₃O₃S₃(446.0070): C, 45.78; H, 4.52; N,

9.42%. Found C, 45.66; H, 4.51; N, 9.26%. LC-MS (APCI): Calculated Mmi: 445.0355, (M+H)⁺: 446.0428,

(M–H)⁺: 444.0271. Found (M+H)⁺: 445.8, (M–H)⁺: 443.9.

4.1.37. N-[(2S)-1-{2-[1-(Thiophen-3-yl)ethylidene]hydrazinyl} -4-(methylsulfanyl)-1-oxobutan-2-

yl]-4-methylbenzenesulfonamide (35)

Yield 63%. mp 180–182 ^◦C (EtOH). HPLC t_R(min.): 6.98. IR, υ (cm⁻¹): 3242, 3184, 3120, 3072, 1668,

1595, 1315, 1151. ¹H NMR, δ (ppm): 1.73–2.15 (m, 5H, –CH–CH₂–CH₂–SCH₃), 2.28 (s, 3H, –N=C–CH₃),

2.45 (s, 3H, Ar–CH₃), 2.50–2.58 (m, 2H, –CH–CH₂–CH₂–SCH₃), 3.98–4.03 and 4.86–4.93 (2m, 1H, –CH–

CH₂–CH₂–SCH₃), 5.95 (d, J =9.3 Hz, 1H, –SO₂NH), 7.09 (d, J =8.1 Hz, 2H, ArH), 7.19–7.24 (m, 1H,

ArH), 7.25–7.28 (m, 1H, ArH), 7.46–7.70 (m, 3H, ArH), 9.28 and 9.73 (2s, 1H, –CONHN=). Anal. calcd. for

C₁₈H₂₃N₃O₃S₃(425.5885): C, 50.80; H, 5.45; N, 9.87%. Found C, 50.50; H, 5.45; N, 9.79%. LC-MS (APCI):

Calculated Mmi: 425.0901, (M+H)⁺: 426.0974, (M–H)⁺: 424.0817. Found (M+H)⁺: 425.5, (M–H)⁺: 423.9.

4.1.38. N-[(2S)-1-[2-[(5-Chlorothiophen-2-yl)ethylidene]hydrazinyl]-4-(methylsulfanyl)-1-oxobu-

tan-2-yl]-4-methylbenzenesulfonamide (36)

Yield 71%. mp 190 ^◦C (EtOH). HPLC t_R(min.): 8.31. IR, υ (cm⁻¹): 3282, 3219, 3161, 3047, 1660, 1597,

1327, 1153. ¹H NMR, δ (ppm): 1.63–2.07 (m, 5H, –CH–CH₂–CH₂–SCH₃), 2.12 (s, 3H, –N=C–CH₃), 2.39 (s,

3H, Ar–CH₃), 2.53–2.71 (m, 2H, –CH–CH₂–CH₂–SCH₃), 4.78–4.85 (m, 1H, –CH–CH₂–CH₂–SCH₃), 5.61

(d, J =9.9 Hz, 1H, –SO₂NH), 6.85 (d, J =4.2 Hz, 1H, ArH), 6.89 (d, J =4.2 Hz, 1H, ArH), 7.08–7.36 (m,

2H, ArH), 7.73–7.81 (m, 2H, ArH), 8.95 and 8.97 (2s, 1H, –CONHN=). Anal. calcd. for C₁₈H₂₂ClN₃O₃S₃

(460.0336): C, 46.99; H, 4.82; N, 9.13%. Found C, 47.17; H, 4.74; N, 9.14%. LC-MS (APCI): Calculated Mmi:

459.0511, (M+H)⁺: 460.0584, (M–H)⁺: 458.0439. Found (M+H)⁺: 459.7, (M–H)⁺: 457.9.

4.1.39. N-[(2S)-1-{2-[1-(Pyridin-4-yl)ethylidene]hydrazinyl} -4-(methylsulfanyl)-1-oxobutan-2-yl]-

4-methylbenzenesulfonamide (37)

Yield 86%. mp 191 ^◦C (EtOH). HPLC t_R(min.): 3.18. IR, υ (cm⁻¹): 3219, 1674, 1591, 1329, 1163. ¹H

NMR, δ (ppm): 1.72–2.11 (m, 5H, –CH–CH₂–CH₂–SCH₃), 2.11 and 2.20 (2s, 3H, –N=C–CH₃), 2.47 (s,

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3H, Ar–CH₃), 2.52–2.57 (m, 2H, –CH–CH₂–CH₂–SCH₃), 4.05–4.07 and 4.93–5.01 (m, 1H, –CH–CH₂–CH₂–

SCH₃), 6.06 (d, J =9.6 Hz, 1H, –SO₂NH), 7.12–7.42 (m, 2H, ArH), 7.56–7.72 (m, 4H, ArH), 8.54 and 8.60

(2d, J : 6.0 Hz, J : 6.0 Hz, 2H, ArH), 9.82 and 10.05 (2s, 1H, –CONHN=). Anal. calcd. for C₁₉H₂₄N₄O₃S₂

(420.5488): C, 54.26; H, 5.75; N, 13.32%. Found C, 54.26; H, 5.64; N, 13.25%. LC–MS (ESI): Calculated Mmi:

420.1289, (M+H)⁺: 421.1362, (M–H)⁺: 419.1206. Found (M+H)⁺: 421.1, (M–H)⁺: 419.1.

4.1.40. N-[(2S)-1-{2-[1-(Adamantan-1-yl)ethylidene]hydrazinyl} -4-(methylsulfanyl)-1-oxobutan-

2-yl]-4-methylbenzenesulfonamide (38)

Yield 58%. mp 170 ^◦C (EtOH). HPLC t_R(min.): 10.63. IR, υ (cm⁻¹): 3267, 3182, 3066, 1668, 1600, 1330,

1165. ¹H NMR, δ (ppm): 1.64–2.06 (m, 20H, –CH–CH₂–CH₂–SCH₃and adamantan protons), 2.09 (s, 3H,

–N=C–CH₃), 2.39 and 2.45 (2s, 3H, Ar–CH₃), 2.52–2.68 (m, 2H, –CH–CH₂–CH₂–SCH₃), 4.69–4.77 (m, 1H,

–CH–CH₂–CH₂–SCH₃), 5.68 (d, J =9.9 Hz, 1H, –SO₂NH), 7.12–7.28 (m, 2H, ArH), 7.71–7.78 (m, 2H, ArH),

8.19 (s, 1H, –CONHN=). ¹³C NMR, δ (ppm): 10.94 and 11.30 (–N=C–CH₃), 14.42 and 14.68 (–CH–CH₂–

CH₂–SCH₃), 20.92 (Ar–CH₃), 27.58 and 27.64 (adamantan–C), 29.19 and 29.57 (–CH–CH₂–CH₂–SCH₃),

31.74 and 32.31 (–CH–CH₂–CH₂–SCH₃), 36.22 (adamantan–C), 38.96 and 39.00 (adamantan–C), 39.86 and

40.06 (adamantan–C), 51.90 and 54.35 (–CH–CH₂–CH₂–SCH₃), 126.54 (Ar–C), 129.16 and 129.32 (Ar–C),

138.01 and 138.15 (Ar–C), 142.42 and 142.44 (Ar–C), 159.19 and 164.07 (–N=C–CH₃), 166.38 and 172.48

(–CONHN=). Anal. calcd. for C₂₄H₃₅N₃O₃S₂(477.6830): C, 60.34; H, 7.39; N, 8.80%. Found C, 60.13;

H, 7.35; N, 8.72%. LC-MS (ESI): Calculated Mmi: 477.2119, (M+H)⁺: 478.2192, (M–H)⁺: 476.2036. Found

(M+H)⁺: 478.2, (M–H)⁺: 476.3.

4.1.41. N-[(2S)-1-[(2-(2,3-Dihydro-1H-inden-1-ylidene)hydrazinyl]-4-(methylsulfanyl)-1-oxobutan-

2-yl]-4-methylbenzenesulfonamide (39)

Yield 40%. mp 179–184 ^◦C (Acetonitrile). HPLC t_R(min.): 7.46. IR, υ (cm⁻¹): 3267, 3184, 3084, 3066,

1668, 1620, 1325, 1157. ¹H NMR, δ (ppm): 1.63–2.19 (m, 5H, –CH–CH₂–CH₂–SCH₃), 2.36 and 2.42 (2s, 3H,

Ar–CH₃), 2.43–2.85 (m, 4H, –CH–CH₂–CH₂–SCH₃, indene–CH₂), 3.18 (t, J : 6.3 Hz, 2H, indene–CH₂–),

4.98–5.06 (m, 1H, –CH–CH₂–CH₂–SCH₃), 5.68 and 6.10 (2d, J =9.9 Hz, J =7.8 Hz, 1H, –SO₂NH), 7.27–

7.47 (m, 5H, ArH), 7.74–7.95 (m, 3H, ArH), 8.56 (s, 1H, –CONHN=). Anal. calcd. for C₂₁H₂₅N₃O₃S₂

(431.5715): C, 58.44; H, 5.84; N, 9.74%. Found C, 57.95; H, 5.83; N, 9.53%. LC-MS (APCI): Calculated Mmi:

431.1337, (M+H)⁺: 432.1410, (M–H)⁺: 430.1253. Found (M+H)⁺: 431.5, (M–H)⁺: 430.1.

4.1.42. N-[(2S)-1-[(2-(5-Chloro-2-oxo-1,2-dihydro-3H-indol-3-ylidene)hydrazinyl]-4-(methylsul-

fanyl)-1-oxobutan-2-yl]-4-methylbenzenesulfonamide (40)

Yield 38%. mp 227–228 ^◦C (MeOH). HPLC t_R(min.): 7.52. IR, υ (cm⁻¹): 3198, 3180, 3082, 1699, 1674, 1622,

1595, 1334, 1165. ¹H NMR, δ (ppm): 1.76–2.01 (m, 5H, –CH–CH₂–CH₂–SCH₃), 2.29 (s, 3H, Ar–CH₃),

2.52–2.68 (m, 2H, –CH–CH₂–CH₂–SCH₃), 4.98–5.05 (m, 1H, –CH–CH₂–CH₂–SCH₃), 6.25 (d, J =9.9 Hz,

1H, –SO₂NH), 6.80 (d, J =8.4 Hz, 1H, ArH), 7.13–7.28 (m, 3H, ArH), 7.49–7.72 (m, 3H, ArH), 10.53 and

10.64 (2s, 1H, –CONHN=), 12.28 and 13.53 (2s, 1H, indole–NH–). Anal. calcd. for C₂₀H₂₁ClN₄O₄S_2.H₂O

(499.0034): C, 48.14; H, 4.65; N, 11.23%. Found C, 48.33; H, 4.51; N, 11.20%. LC-MS (ESI): Calculated Mmi:

480.0692, (M+H)⁺: 481.0765, (M–H)⁺: 479.0608. Found (M+H)⁺: 480.8, (M–H)⁺: 479.2.

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4.2. Antimicrobial assays

All test microorganisms were obtained from the Reﬁk Saydam Hygiene Institute (Ankara, Turkey) and were

as follows: Escherichia coli (E. coli) ATCC 25922, Yersinia pseudotuberculosis (Y. pseudotuberculosis) ATCC

911, Pseudomonas aeruginosa (P. aeruginosa) ATCC 43288, Staphylococcus aureus (S. aureus) ATCC 25923,

methicillin-resistant Staphylococcus aureus (MRSA), Enterococcus faecalis (E. faecalis) ATCC 29212, Listeria

monocytogenes ATCC 43251, Bacillus cereus (B. cereus) 702 Roma, Mycobacterium smegmatis (M. smegmatis)

ATCC 607, Candida albicans (C. albicans) ATCC 60193, and Saccharomyces cerevisiae (S. cerevisiae) RSKK

251. All the newly synthesized compounds were dissolved in dimethylsulphoxide (DMSO) to prepare stock

solution at 10 mg/mL.

4.2.1. Agar well diﬀusion method

A simple susceptibility screening test using agar-well diﬀusion as adapted earlier was used.^51,52Each bacterium

was suspended in Mueller Hinton (MH) (Difco, Detroit, MI, USA) broth. The yeast-like fungi were suspended

in yeast extract broth. Then the microorganisms were diluted approximately 10⁶colony forming unit (cfu) per

mL. For yeast-like fungi, Sabouraud dextrose agar (SDA) (Difco) was used. Brain heart infusion agar (BHI)

(Difco) was used for M. smegmatis. They were ”ﬂood-inoculated” onto the surface of MH, BHI, and SD agars

and then dried. Five-millimeter diameter wells were cut from the agar using a sterile cork-borer, and 50 µL

of the stock extract substances were delivered into the wells. The plates were incubated for 18 h at 36 ^◦C.

M. smegmatis was grown for 3 days on BHI agar plates at 36 ^◦C.⁵³Antimicrobial activity was evaluated by

measuring the zone of inhibition against the test organism. Ampicillin (10 µg/mL), streptomycin (10 µg/mL),

and ﬂuconazole (5 µg/mL) were the standard drugs. DMSO with dilution of 1:10 was used as the solvent

control to ensure DMSO had no eﬀect on bacterial growth.

4.2.2. Broth microdilution method

All test microorganisms were obtained from the Reﬁk Saydam Hygiene Institute (Ankara, Turkey) and were

as follows: Escherichia coli (E. coli) ATCC 25922, Yersinia pseudotuberculosis (Y. pseudotuberculosis) ATCC

911, Pseudomonas aeruginosa (P. aeruginosa) ATCC 43288, Staphylococcus aureus (S. aureus) ATCC 25923,

methicillin-resistant Staphylococcus aureus (MRSA), Enterococcus faecalis (E. faecalis) ATCC 29212, Listeria

monocytogenes ATCC 43251, Bacillus cereus (B. cereus) 702 Roma, Mycobacterium smegmatis (M. smegmatis)

ATCC 607, Candida albicans (C. albicans) ATCC 60193, and Saccharomyces cerevisiae (S. cerevisiae) RSKK

251. All the newly synthesized compounds were weighed and dissolved in dimethylsulphoxide (DMSO) to

prepare extract stock solution of 10 mg/mL.

The antimicrobial eﬀects of the substances were tested quantitatively in broth media by using double

dilution and the minimal inhibition concentration (MIC) values (µg/mL) were determined.⁵⁴The antibacterial

and antifungal assays were performed in MH broth (Difco) at pH 7.3 and buﬀered yeast nitrogen base (Difco) at

pH 7.0, respectively. BHI (Difco) was used for M. smegmatis.⁵³The MIC was deﬁned as the lowest concentration

that showed no growth. Ampicillin (10 µg/mL), streptomycin (10 µg/mL), and ﬂuconazole (5 µg/mL) were

used as standard antibacterial and antifungal drugs, respectively. DMSO with dilution of 1:10 was used as the

solvent control to ensure DMSO had no eﬀect on bacterial growth.

531

TATAR et al./Turk J Chem

4.3. In vitro antiviral assays

4.3.1. Inhibition of HIV-induced cytopathicity in MT-4 cells

Evaluation of the antiviral activity of the compounds against HIV-1 strain III_Band HIV-2 strain ROD in

MT-4 cells was performed using the MTT assay as previously described.^55,56Stock solutions (10 × ﬁnal

concentration) of test compounds were added in 25-mL volumes to two series of triplicate wells so as to allow

simultaneous evaluation of their eﬀects on mock- and HIV-infected cells at the beginning of each experiment.

Serial ﬁve-fold dilutions of test compounds were made directly in ﬂat-bottomed 96-well microtiter trays using

a Biomek 3000 robot (Beckman Instruments, Fullerton, CA, USA). Untreated control HIV and mock-infected

cell samples were included for each sample. HIV-1(III_B) or HIV-2 (ROD) stock (50 mL) at 100–300 CCID₅₀

(cell culture infectious dose) or culture medium was added to either the infected or mock-infected wells of the

microtiter tray.^57,58Mock-infected cells were used to evaluate the eﬀect of test compound on uninfected cells

in order to assess the cytotoxicity of the test compounds. Exponentially growing MT-4 cells were centrifuged

for 5 min at 220 ×g and the supernatant was discarded.⁵⁹The MT-4 cells were resuspended at 6 × 10⁵

cells/mL, and 50-mL volumes were transferred to the microtiter tray wells. Five days after infection, the

viability of mock- and HIV-infected cells was examined spectrophotometrically by the MTT assay. The MTT

assay is based on the reduction of yellow colored 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide

(MTT) (Acros Organics, Geel, Belgium) by mitochondrial dehydrogenase of metabolically active cells to a

blue-purple formazan that can be measured spectrophotometrically. The absorbances were read in an eight-

channel computer-controlled photometer (Saﬁre2, Tecan, Mechelen, Belgium), at two wavelengths (540 and 690

nm). All data were calculated using the median OD (optical density) value of three wells. The 50% cytotoxic

concentration (CC₅₀) was deﬁned as the concentration of the test compound that reduced the absorbance

(OD₅₄₀) of the mock-infected control sample by 50%. The concentration achieving 50% protection from the

cytopathic eﬀect of the virus in infected cells was deﬁned as the 50% eﬀective concentration (EC₅₀).

Acknowledgment

This work was supported by the Research Fund of Marmara University, project number: SAG-A-060510-0109.

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Article Doi

Synthesis, and prediction of molecular properties and antimicrobial activity of some acylhydrazones derived from N-(arylsulfonyl)methionine

DOI: 10.3906/kim-1509-21

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