Synthesis, spectroscopic characterization, and in vitro antibacterial evaluation of novel functionalized sulfamidocarbonyloxyphosphonates

Article abstract of DOI:10.3390/molecules23071682

Several new sulfamidocarbonyloxyphosphonates were prepared in two steps, namely carbamoylation and sulfamoylation, by using chlorosulfonyl isocyanate (CSI), α-hydroxyphosphonates, and various amino derivatives and related (primary or secondary amines, β-amino esters, and oxazolidin-2-ones). All structures were confirmed by ¹H, ¹³C, and ³¹P NMR spectroscopy, IR spectroscopy, and mass spectroscopy, as well as elemental analysis. Eight compounds were evaluated for their in vitro antibacterial activity against four reference bacteria including Gram-positive Staphylococcus aureus (ATCC 25923), and Gram-negative Escherichia coli (ATCC 25922), Klebsiella pneumonia (ATCC 700603), Pseudomonas aeruginosa (ATCC 27853), in addition to three clinical strains of each studied bacterial species. Compounds 1a–7a and 1b showed significant antibacterial activity compared to sulfamethoxazole/trimethoprim, the reference drug used in this study.

Full text of DOI:10.3390/molecules23071682

molecules
Article
Synthesis, Spectroscopic Characterization, and In
Vitro Antibacterial Evaluation of Novel
Functionalized Sulfamidocarbonyloxyphosphonates
Abdeslem Bouzina 1, Khaoula Bechlem 1, Hajira Berredjem 2, Billel Belhani 1, Imène Becheker 2,
Jacques Lebreton 3, Marc Le Borgne 4 ID , Zouhair Bouaziz 4, Christelle Marminon 4,
*
ID
and Malika Berredjem 1,
*
1
Laboratory of Applied Organic Chemistry, Synthesis of Biomolecules and Molecular Modelling Group,
Badji-Mokhtar—Annaba University, Box 12, 23000 Annaba, Algeria; bouzinaabdeslem@yahoo.fr (A.B.);
bechlemkhaoula92@yahoo.com (K.B.); billelbelhani@yahoo.com (B.B.)
2
3
4
Laboratory of Applied Biochemistry and Microbiology, Department of Biochemistry, Badji-Mokhtar-Annaba
University, Box 12, 23000 Annaba, Algeria; hajira.berredjem@univ-annaba.dz (H.B.);
i_mene7@msn.com (I.B.)
CNRS, Université de Nantes, Chimie et Interdisciplinarité: Synthèse, Analyse, Modélisation (CEISAM),
UMR CNRS 6230, 2 rue de la Houssinière, BP92208, CEDEX 3, 44322 Nantes, France;
jacques.lebreton@univ-nantes.fr
Université de Lyon, Université Lyon 1, Faculté de Pharmacie—ISPB, EA 4446 Bioactive Molecules and
Medicinal Chemistry, SFR Santé Lyon-Est CNRS UMS3453—INSERM US7, CEDEX 8, 69373 Lyon, France;
marc.le-borgne@univ-lyon1.fr (M.L.B.); zouhair.bouaziz@univ-lyon1.fr (Z.B.)
Correspondence: christelle.marminon-davoust@univ-lyon1.fr (C.M.); malika.berredjem@univ-annaba.org
(M.B.); Tel.: +33-478772867 (C.M.); +213-38876567 (M.B.)
*
ꢀꢁꢂꢀꢃꢄꢅꢆꢇ
ꢀꢁꢂꢃꢄꢅꢆ
Received: 18 June 2018; Accepted: 5 July 2018; Published: 10 July 2018
Abstract: Several new sulfamidocarbonyloxyphosphonates were prepared in two steps,
namely carbamoylation and sulfamoylation, by using chlorosulfonyl isocyanate (CSI),
α
-hydroxyphosphonates, and various amino derivatives and related (primary or secondary amines,
-amino esters, and oxazolidin-2-ones). All structures were confirmed by 1H, 13C, and 31P NMR
β
spectroscopy, IR spectroscopy, and mass spectroscopy, as well as elemental analysis. Eight compounds
were evaluated for their in vitro antibacterial activity against four reference bacteria including
Gram-positive Staphylococcus aureus (ATCC 25923), and Gram-negative Escherichia coli (ATCC 25922),
Klebsiella pneumonia (ATCC 700603), Pseudomonas aeruginosa (ATCC 27853), in addition to three clinical
strains of each studied bacterial species. Compounds 1a–7a and 1b showed significant antibacterial
activity compared to sulfamethoxazole/trimethoprim, the reference drug used in this study.
Keywords: sulfamides; phosphonates; carbamoylation; sulfamoylation; antibacterial activity
1. Introduction
The synthesis and reactivity of sulfamides (sulfonyl analogues of ureas) have attracted much
interest in the last decades [
biological activities such as anti-mycobacterial, anticonvulsant, anti-hypoglycemic, anticancer, and
enzyme inhibition (e.g., carbonic anhydrase I, HIV-1 protease, elastase, carboxypeptidase A) [ ].
1]. A large number of sulfamide derivatives have been reported to show
2–9
These important compounds have been synthesized by various routes, most of them using the reaction
of a sulfonyl chloride with ammonia or primary and secondary amines [10]. Another approach utilizes
the amide exchange of a sulfamide by heating with an amine [11]. In parallel, many synthetic efforts
have also focused on sulfonamide derivatives that have shown great potency to inhibit important
Molecules 2018, 23, 1682; doi:10.3390/molecules23071682
www.mdpi.com/journal/molecules

Molecules 2018, 23, 1682
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biological targets such as cox-2, carbonic anhydrase (e.g., isoenzymes I, II, VII, IX), and NaV1.7, or to
block, for example, the Chlamydia fatty acid synthesis [12–16].
In addition, the extensive interest in the synthesis of bifunctional sulfonamide or
sulfamide-phosphonate derivatives is due to their broad biological activities. In Figure 1, the structures
of six bifunctional compounds are depicted. Biasone et al. [17] demonstrated that analogues of
α
-biphenylsulfonylamino 2-methylpropyl phosphonate
metalloproteinases (MMPs). New sildenafil analogue
50-sulfonamide moiety of the phenyl ring has shown promising in vitro PDE5 inhibitory activity [18].
Sulfonamide derivative containing a single difluoromethylene phosphonate group has been
discovered to be a potent inhibitor of protein tyrosine phosphatase PTP1B [19]. A series of phosphonate
derivatives of mycophenolic acid were described as anticancer, antiviral, and anti-inflammatory
agents [20]. Compound shows the highest insecticidal activity against plant pests [21]. It should
be pointed out that to the best of our knowledge, it is the only example of compounds containing a
sulfamidocarbonyloxyphosphonate moiety described in the literature. Finally, Winum et al. [22
1
exhibit potency against several matrix
2
containing a phosphonate group in the
3
4
5
]
reported the synthesis of sulfamide analogues of fotemustine
evaluation on two human melanoma cell lines.
6 along with preliminary in vitro
Figure 1. Structure of diverse sulfonamide and sulfamide derivatives containing a phosphonate-type group.
Since the 1930’s, sulfamide and sulfonamide derivatives have had a special place in the
anti-infectious strategies and their therapeutic application continues to be investigated, as illustrated
by this recent work on the use of sulfonamide agents against Staphylococcus aureus (SA) of the CNS [23].
They demonstrated that sulfadiazine and sulfamethoxazole (SMX) (Figure 2) exhibited strong activity
against bacteria. Fosfomycin (Figure 2) is another well-known antibacterial agent with a structure
containing a phosphonate motif and may be prescribed alone or in combination (e.g., with vancomycin).
Unfortunately, year after year, increased bacterial resistance to sulfonamides/sulfamides [24] to the
combination sulfamethoxazole-trimethoprim (SMX-TMP) [25] and to fosfomycin [26] has limited
their use. Moreover, the appearance of multidrug resistant Gram-positive bacteria, in particular
methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococci (VRE), has
become a major health problem [27]. So, new research on drug discovery needs to be intensively
developed for designing new antibacterial agents.
Figure 2. Structures of drugs approved for human use.

Molecules 2018, 23, 1682
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In continuation of our interest in the preparation of sulfonamide and sulfamide derivatives [28
we decided to include both motifs, sulfamido and phosphonate, on each targeted compound and
then to obtain new hybrids also containing an -phenyl on the phosphonate methylene. For this
–31],
α
preliminary study, we opted to select a set of various substituents -NR2R3 and -PO(OR1)2 in order to
shape the first SAR trends in this series (Figure 3). To link these motifs, we chose a carbonyloxy-type
spacer present in compounds
5
and
6 (Figure 1). The first-step reaction using chlorosulfonyl
isocyanate and the corresponding
α
-hydroxyphosphonate-type intermediate allowed us to synthesize
all N-chlorosulfonyl carbamate intermediates. In the second step, the key structural sequence,
sulfamidocarbonyloxyphosphonate, was achieved directly from various amines. The antibacterial
activity of eight phosphonate derivatives (1a–7a and 1b) was studied against representative reference
strains Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922, Klebsiella pneumoniae ATCC
700603, and Pseudomonas aeruginosa ATCC 27853, as well as diverse clinical strains. Inhibition zones
were performed by the disc diffusion method and the MIC values were determined by the dilution
broth method [32]. The combination SMX-TMP, currently employed to treat bacterial infections, was
used as the reference standard.
Figure 3. General formula of studied compounds.
2. Results and Discussion
2.1. Chemistry
The synthetic route for the preparation of a novel series of sulfamidocarbonyloxyphosphonates
1a–8a is outlined in Scheme 1. The synthesis was carried out in two steps. First, carbamoylation
under anhydrous conditions of commercial chlorosulfonyl isocyanate with the corresponding
α-hydroxyphosphonate (R1 = methyl or ethyl), easily prepared in a single step [33,34], quantitatively
afforded the corresponding N-chlorosulfonyl carbamate intermediate. Reaction with various primary
◦
or secondary amines in the presence of triethylamine at 0 C then gave the target compounds 1a
–
8a in
excellent yields (92–99%) within 60–90 min (Table 1).
Scheme 1. Synthesis of sulfamidocarbonyloxyphosphonates 1a–8a from primary or secondary amines.

Molecules 2018, 23, 1682
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To increase the scope of this reaction, we synthesized other sulfamidocarbonyloxyphosphonates
using diverse (S)-amino acid esters (Scheme 2). The isolated yields of the products 1b 3b, obtained as
–
a mixture of diastereoisomers (Table 2), were in the range of 84–94% yield after 90 min of reaction.
Scheme 2. Synthesis of sulfamidocarbonyloxyphosphonates 1b–3b from amino acid esters.
These satisfactory and encouraging results have prompted us to develop a third subseries
(Scheme 3, Table 3), by using oxazolidin-2-one as a building block in order to synthesize new potential
bioactive molecules. The new compound 1c was obtained with a very good yield (92%).
Scheme 3. Synthesis of sulfamidocarbonyloxyphosphonate 1c from oxazolidin-2-one.
Spectrometric methods confirmed the structures of all the sulfamidocarbonyloxyphosphonates
synthesized. Their physicochemical and analytical data are depicted in Tables 1–3. The FT-IR spectrum
showed the characteristic signals of the three functions, namely the carbamate NH stretching−a1t
3300–3250 cm−1 and its C=O stretching at 1750–1730 cm−1, the phosphonate group at 1255–1234 cm
and the sulfamide group with its two signals at 1185–1118 cm−1 and 1384–1356 cm−1. The molecular
peak [M + H]+ obtained by ESI-MS was always present and corresponded to each synthesized
compound. NMR spectra were recorded using CDCl3 as the solvent and are available in the
supplementary material part. The 1H spectrum always exhibited a dramatically deshielded doublet
,
at 6 ppm corresponding to the COOCH
(Ph)POOR proton with its expected coupling constant 2JH-P
frequently around 12–14 Hz. The two methoxy groups of the phosphonate appeared as two separate
doublets (3JH-P~10 Hz) at 3.5 and 3.7 ppm, while the NH of the carbamate appeared as a broad singlet
at
δ
8–11 ppm. The 13C spectrum was also characteristic due to the expected doublets related to
the presence of the phosphorus (JC-P couplings): (i) the methoxy of the phosphonates at 54 ppm
(2JC-P~7–8 Hz), and (ii) the aromatic ring (3JC-P~6 Hz and 4JC-P~1–3 Hz) [35
shifts are particular, as the carbonyl of the carbamate at 150 ppm (doublet with a JC-P = 12 Hz
,
36]. The 13C chemical
3

Molecules 2018, 23, 1682
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coupling constant) and the greatly deshielded COO
C
H(Ph)POOR carbon at 70 ppm (doublet with
a 1JC-P = 170 Hz coupling constant).
To determine the initial interest of these novel functionalized sulfamidocarbonyloxyphosphonates
as antibacterial agents, we only selected eight derivatives (including seven from the first sub-series)
for testing their potency against sixteen bacterial strains. This first biological study can confirm the
interest to modulate such a scaffold.
Table 1. The physical data and yields for sulfamidocarbonyloxyphosphonates 1a
–
8a synthesized from
primary and secondary amines.
◦
Entry
1a
-NR2R3
Target Molecule
Yield %
m.p.
C
99
131–133
137–139
144–146
136–138
187–189
2a
3a
4a
5a
98
98
96
96
6a
94
153–155
7a
8a
93
97
152–154
151–153

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Table 2. Physical data and yields for sulfamidocarbonyloxyphosphonates 1b–3b synthesized from
amino acid esters.
◦
m.p. C
Entry
R4
Target Molecule
Yield
1b
2b
91
118–120
125–127
94
84
3b
116–118
Table 3. Physical data and yield for the sulfamidocarbonyloxyphosphonate 1c synthesized
from oxazolidin-2-one.
◦
Entry
1c
Target Molecule
Yield %
m.p.
C
92
123–125
2.2. In Vitro Antibacterial Evaluation of Sulfamidocarbonyloxyphosphonates
A total of twelve clinical strains of Gram-positive and Gram-negative bacteria and four control strains
(S. aureus ATCC 25923, E. coli ATCC 25922, P. aeruginosa ATCC 27853, and K. pneumoniae ATCC 700603)
were used to investigate the antibacterial activity. The eight tested sulfamidocarbonyloxyphosphonate
derivatives (compounds 1a–7a and 1b) showed antibacterial activity with a varying degree of inhibitory
effect on the growth of the bacterial strains (Tables 4 and 5).
The disk diffusion is just a qualitative method to determine whether a particular bacterium is
susceptible to the action of a specific antimicrobial agent. The presence or the absence of a clear
region around the disk is an indication of the inhibition or lack of inhibition of the bacterial
growth. Then, the size of the zone of inhibition indicates the degree of sensitivity of bacteria to
an antimicrobial drug. We could use the terms “resistant, intermediate, and sensitive” to discuss
the results obtained. As shown in Table 4, the diameters of the inhibition zone (DIZ) of the tested
compounds against the bacteria strains ranged from 12–26 mm. The values obtained with the positive
control sulfamethoxazole-trimethoprim (SXT) ranged between 17 and 22 mm for both clinical and
control strains. Furthermore, some P. aeruginosa and K. pneumoniae strains (P. aeruginosa 1, K. pneumoniae
1 and 3) were resistant (R) towards SXT. It should be noted that P. aeruginosa is known to be
a multidrug resistant bacteria due to its remarkable ability of acquiring mechanisms of resistance to
some antimicrobial agents.
Tested sulfamidocarbonyloxyphosphonate derivatives were more active toward Gram-negative
bacteria than Gram-positive ones. Compound 4a was inactive on all three clinical strains of S. aureus

Molecules 2018, 23, 1682
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(only DIZ = 12 mm for S. aureus ATCC 25923). Compounds 2a
,
3a
,
6a
,
7a, and 1b exerted intermediate
activity on S. aureus (12
≤
DIZ
≤
16 mm). The best activities on S. aureus (DIZ > 16 mm, result reported
as sensitive) were observed with compounds 1a (S. aureus 3) and 5a (S. aureus 1 and 3) with zone sizes
of 17, 18, and 17 mm, respectively. Nevertheless, SXT seems to give better results, with zone sizes of
between 18 and 22 mm. On E. coli strains, all tested compounds and STX gave results with inhibition
zones between 17 and 25 mm. Among them, compounds 3a and 4a were the most active molecules
against E. coli, with inhibition diameters of 25 mm for E. coli ATCC 25922 and 24 mm for E. coli 2.
For P. aeruginosa strains, the inhibition zones were between 17 and 26 mm. Their susceptibility was
really marked with compounds 1a, 4a, and 5a, with zone sizes between 18 and 26 mm. Compound 1a
showed the best activity against strains P. aeruginosa ATCC 27853 and P. aeruginosa 2, with an inhibition
diameter of 26 mm. SXT exhibited less activity against the four P. aeruginosa strains tested. For example,
in the cases of P. aeruginosa ATCC 27853 and P. aeruginosa 2, the inhibition zones of STX were equal to
17 and 20 mm, respectively. Concerning K. Pneumoniae, all tested sulfamidocarbonyloxyphosphonate
derivatives were globally active, with inhibition zones superior to 15 mm. The best activity was
obtained with compound 4a, with inhibition zones of 24 and 25 mm for clinical strains.
After the evidence of in vitro antibacterial activity against the tested strains in the disk diffusion
test, the Minimum Inhibitory Concentration (MIC) values were determined. As shown in Table 5,
most derivatives exhibited low MIC values against the different strains of bacteria employed when
compared with STX (MIC = 25
E. coli and P. aeruginosa strains, ranging between 0.5 and 32
and 6a exerted the most intense activity, especially on P. aeruginosa, with MIC values ranging between
0.5 and 1 g/mL for 1a and 1 and 4 g/mL for 3a and 6a. As regards compound 4a, it was very
active against E. coli strains, with MIC values between 0.5 and 4 g/mL. For K. pneumoniae, the best
results were obtained with compounds 1a and 4a, with MIC values in the range of 4 to 8 g/mL and 2
to 16 g/mL, respectively. Concerning S. aureus strains, all MIC values were superior to 64 g/mL,
µg/mL). All the tested compounds showed the best MIC values against
µ
g/mL. In particular, compounds 1a 3a,
,
µ
µ
µ
µ
µ
µ
except for compound 1b (15 ≤ MIC ≤ 18 µg/mL).
Overall, our results showed that the sulfamidocarbonyloxyphosphonates possessed a good
concentration dependent antibacterial activity, especially against the tested Gram-negative bacteria at
MIC values ranging between 0.5–32 µg/mL for compound 1a, and 0.5 and 16 µg/mL for compound 4a.
Among the eight compounds tested, only compound 1b exerted antibacterial activity against S. aureus.
Table 4. Diameters of the inhibition zone (DIZ) of sulfamidocarbonyloxyphosphonate derivatives
1a–7a, 1b, and SXT toward Gram-positive and Gram-negative bacteria.
Molecules
Diameters of Inhibition Zone (DIZ) in mm a
Bacterial Strains
1a
2a
3a
4a
5a
6a
7a
1b
SXT
S. aureus ATCC 25923
S. aureus 1
S. aureus 2
15
16
16
17
16
15
15
14
14
14
16
15
12
R b
R
15
18
16
17
12
13
15
14
13
14
12
13
13
12
13
15
22
20
18
18
S. aureus 3
R
E. coli ATCC 25922
E. coli 1
E. coli 2
24
17
22
20
23
22
19
22
25
18
24
23
25
20
24
22
23
20
22
19
21
20
18
18
23
19
23
20
18
18
20
17
20
18
18
20
E. coli 3
P. aeruginosa ATCC 27853
P. aeruginosa 1
P. aeruginosa 2
26
24
26
25
20
20
19
21
18
20
20
21
23
18
20
22
19
18
20
22
19
20
19
21
20
18
18
19
18
20
17
R
17
R
20
18
P. aeruginosa 3
K. pneumoniae ATCC
700603
K. pneumoniae 1
K. pneumoniae 2
K. pneumoniae 3
22
19
13
20
19
20
21
19
22
22
20
20
21
21
18
18
17
18
25
25
24
15
20
19
18
18
19
19
16
22
15
R
21
R
17
R
a
b
All tests were performed in triplicate. R: Resistant.

Molecules 2018, 23, 1682
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Table 5. Minimum inhibitory concentrations (MICs) of the sulfamidocarbonyloxyphosphonate
derivatives 1a–7a and 1b toward Gram-positive and Gram-negative bacteria.
Molecules
MIC (µg/mL) a
Bacterial Strains
1a
2a
3a
4a
5a
6a
7a
1b
S. aureus ATCC 25923
S. aureus 1
S. aureus 2
128
128
64
128
256
128
128
256
256
128
128
512
R b
R
256
64
128
128
128
128
64
256
256
128
128
15
15
18
15
S. aureus 3
64
R
128
E. coli ATCC 25922
E. coli 1
E. coli 2
1
32
4
2
2
16
2
0.5
4
0.5
1
2
8
4
2
16
16
4
8
4
8
18
18
20
17
16
16
32
E. coli 3
8
4
16
32
P. aeruginosa ATCC 27853
P. aeruginosa 1
P. aeruginosa 2
0.5
0.5
1
1
2
2
6
4
2
2
1
2
4
4
2
2
2
4
2
1
2
2
4
4
2
8
4
18
20
17
R
P. aeruginosa 3
0.5
K. pneumoniae ATCC 700603
K. pneumoniae 1
K. pneumoniae 2
4
4
8
8
32
64
16
16
256
32
16
16
2
2
128
128
32
128
64
128
64
32
128
128
64
19
15
R
K. pneumoniae 3
32
4
128
21
a
All tests were performed in triplicate and STX was used as the positive control (MIC = 25 µ
g/mL). b R: Resistant.
3. Materials and Methods
3.1. General Information
All chemicals and solvents were purchased from common commercial sources and were used as
received without any further purification. All reactions were monitored by TLC on silica Merck 60
F254 percolated aluminum plates and were developed by spraying with ninhydrin solution. Column
chromatography was performed with Merck silica gel (230–400 mesh). Proton nuclear magnetic
resonance (1H NMR) spectra were recorded on Bruker or Jeol spectrometers at 400 MHz. Chemical
shifts are reported in
δ units (ppm) with TMS as the reference (δ 0.00). All coupling constants
(J) are reported in Hertz. Multiplicity is indicated by one or more of the following: b (broad), s
(singlet), d (doublet), t (triplet), q (quartet), dd (doublet of doublet), and m (multiplet). The Carbon
nuclear magnetic resonance (13C NMR) spectra were recorded on Bruker (Reinstetten, Germany)
or Jeol (JNM-ECS400 (Tokyo, Japan) spectrometers at 100.62 MHz. Chemical shifts are reported
in
δ units (ppm) and coupling constants (J) are reported in Hertz. Phosphorus nuclear magnetic
resonance (31P NMR) spectra and Fluor (19F NMR) nuclear magnetic resonance spectra were recorded
on a Bruker spectrometer at 161.98 MHz and 316.48 MHz, respectively. Infrared spectra were recorded
on a Perkin Elmer 600 (Waltham, Massachusetts, USA) spectrometer. The Mass spectra were recorded
on a shimadzu QP 1100 Ex mass spectrometer operating at an ionization potential of 70 eV. Elemental
analysis was recorded on a EURO E.A. 3700 apparatus. All melting points were recorded on a Büchi
B-545 (Taufkirchen, Germany) apparatus in open capillary tubes.
Ultrasound assisted reactions were carried out using a FUNGILAB ultrasonic bath (Barcelona,
Spain) with a frequency of 40 kHz and a nominal power of 250 W. The reactions were carried out in
an open glass tube (diameter: 25 mm; thickness: 1 mm; volume: 20 mL) at room temperature.
3.2. Typical Experimental Procedure for the Synthesis of Sulfamidocarbonyloxyphosphonates 1a–8a, 1b–3b,
and 1c
α
-Hydroxyphosphonates were synthesized in 94% overall yield starting from benzaldehyde and
trialkylphosphites under ultrasound irradiation according to the procedure described in reference [34].
A solution of -hydroxyphosphonate (1.1 equiv) in anhydrous CH2Cl2 (5 mL) was added
α
dropwise to a stirring solution of chlorosulfonyl isocyanate (CSI) (1 equiv) in anhydrous CH2Cl2
(5 mL) at 0 ◦C over a period of 20 min. The resulting solution was transferred to a mixture of primary

Molecules 2018, 23, 1682
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or secondary amine (1.1 equiv) or amino acid ester or oxazolidin-2-one in anhydrous CH2Cl2 (10 mL)
in the presence of triethylamine (1.1–1.5 equiv). The reaction mixture was stirred at 0 ◦C for less than
1–2 h, and then neutralized by adding a solution of aqueous HCl 0.1 M to pH 7. The organic layer was
extracted, washed with water, dried over anhydrous sodium sulfate, filtered, and concentrated in vacuo.
The pure products were crystallized in a mixture of diethyl ether/n-hexane (1.5:1) at 6 ◦C overnight.
The pure sulfamidocarbonyloxyphosphonates were finally filtered and dried in excellent yields.
(Dimethoxyphosphoryl)(phenyl)methyl (N-benzylsulfamoyl)carbamate (1a). White powder, 99% yield, m.p.
131–133 ◦C, Rf = 0.43 (CH2Cl2/MeOH, 90:10). IR (KBr, cm−1): 3365, 3298, 1733, 1481, 1364, 1249, 1170.
3
3
1H-NMR (400 MHz, CDCl3)
δ
: 3.57 (d, 3H, JH-P = 10.4 Hz, C
3-OP), 4.11 (dd, 1H, J1 = 13.6 Hz, J2 = 5.4 Hz, C
5.61 (bs, 1H, N
-SO2), 6.00 (d, 1H, 2JH-P = 12.0 Hz, C
-Ar), 7.47–7.53 (m, 2H, -Ar), 8.90 (bs, 1H, N
H
3-OP), 3.77 (d, 3H, JH-P = 10.8 Hz,
-N),
-Ar), 7.36–7.42 (m, 3H,
: 48.15 (CH2),
C
H
H-N), 4.23 (dd, 1H, J1 = 14.0 Hz, J2 = 5.6 Hz, CH
H
H
*-OP), 7.18–7.28 (m, 5H, H
H
H
H
-C=O). 13C-NMR (100.62 MHz, CDCl3)
δ
54.19 (d, JC-P = 7 Hz, POCH3), 54.48 (d, JC-P = 7 Hz, POCH3), 72.52 (d, JC-P = 172 Hz, CH*-OP), 128.03
(2C, d, JC-P = 6 Hz), 128.18 (2C), 128.34 (2C), 128.54, 128.96 (2C, d, JC-P = 4 Hz), 129.58, 132.41, 135.54,
150.49 (d, JC-P = 11 Hz, C=O). 31P-NMR (161.98 MHz, CDCl3)
δ: 19.10. Anal. Calc. for C17H21N2O7PS:
C 47.66, H 4.94, N 6.54, S 7.48. Found: C 47.71, H 4.89, N 6.52, S 7.44%. ESI-MS: (m/z) = 429.1 [M + H]+.
(Dimethoxyphosphoryl)(phenyl)methyl(N-(2-methoxyphenyl)sulfamoyl)carbamate (2a). White powder, 98%
yield, m.p. 137–139 ◦C, Rf = 0.40 (CH2Cl2/MeOH, 90:10). IR(KBr, cm−1): 3342, 3275, 1733, 1489, 1361,
1
1252, 1136. H-NMR (400 MHz, CDCl3)
δ
: 3.50 (d, 3H, 3JH-P= 10.8 Hz, C
H
3-OP), 3.54 (s, 3H, C
*-OP), 6.75 (dd, 1H, J1 = 8.0 Hz,
J2 = 1.2 Hz, Hortho-Ar OMe), 6.84 (td, 1H, J1 = 7.6 Hz, J2 = 1.2 Hz, Hmetha-Ar), 7.07 (td, 1H, J1 = 6.8 Hz,
J2 = 1.2 Hz, -Ar), 7.31–7.39 (m, 5H, -Ar), 7.43 (dd, 1H, J1 = 8.0 Hz, J2 = 1.6 Hz, ortho-Ar NH), 7.55
(bs, 1H, N -SO2), 9.85 (bs, 1H, N : 54.16 (d, JC-P = 7 Hz,
-C=O). 13C-NMR (100.62 MHz, CDCl3)
H3-O),
3.62 (d, 3H, 3JH-P = 10.8 Hz, C 3-OP), 5.94 (d, 1H, 2JH-P = 14.0 Hz, C
H H
H
H
H
H
H
δ
POCH3), 54.26 (d, JC-P = 7 Hz, POCH3), 55.79 (OCH3), 72.20 (d, JC-P = 174 Hz, CH*-OP), 111.09, 120.87,
121.04, 121.37, 125.95, 128.09 (2C, d, JC-P = 6 Hz), 128.86, 129.33 (2C, d, JC-P = 3 Hz), 132.52, 149.73,
150.09 (d, JC-P = 12 Hz, C=O). 31P-NMR (161.98 CDCl3)
δ: 18.81. Anal. Calc. for C17H21N2O8PS:
C 45.95, H 4.76, N 6.30, S 7.22. Found: C 45.90, H 4.81, N 6.28, S 7.26%. ESI-MS: (m/z) = 445.1 [M + H]+.
(Dimethoxyphosphoryl)(phenyl)methyl(morpholinosulfonyl)carbamate (3a). White powder, 98% yield, m.p.
144–146 ◦C, Rf = 0.47 (CH2Cl2/MeOH, 90:10). IR (KBr, cm−1): 3447, 3297, 1732, 1481, 1361, 1247, 1185,
3
769, 687. 1H-NMR (400 MHz, CDCl3)
δ
: 3.29–3.31 (m, 4H, 2 C
2-O), 3.84 (d, 3H,3JH-P = 10.8 Hz, C
-Ar), 7.51–7.55 (m, 2H, -Ar), 9.92 (bs, 1H, N
: 46.70 (2C, CH2-N), 54.23 (d, JC-P = 7 Hz, POCH3), 54.38 (d, JC-P = 7 Hz,
POCH3), 66.32 (2C, CH2-O), 72.09 (d, JC-P = 174 Hz, CH*-OP), 128.16 (2C, d, JC-P = 6 Hz), 128.92 (2C, d,
C-P = 1 Hz), 129.56 (d, JC-P = 3 Hz), 132.46, 150.72 (d, JC-P = 12 Hz, C=O). 31P-NMR (161.98 CDCl3)
H
H
2-N), 3.56 (d, 3H, JH-P = 10.4 Hz,
C
H
3-OP), 3.65–3.67 (m, 4H, 2 C
H
3-OP), 6.02 (d, 1H, 2JH-P = 13.6 Hz,
-C=O). 13C-NMR
C
H
*-OP), 7.37–7.40 (m, 3H,
H
H
H
(100.62 MHz, CDCl3)
δ
J
δ:
18.93. Anal. Calc. for C14H21N2O8PS: C 41.18, H 5.18, N 6.86, S 7.85. Found: C 41.22, H 5.23, N 6.83,
S 7.81%. ESI-MS: (m/z) = 409.1 [M + H]+.
(Dimethoxyphosphoryl)(phenyl)methyl(N-(3-fluorophenyl)sulfamoyl)carbamate (4a). White powder, 96%
yield, m.p. 136–138 ◦C, Rf = 0.41 (CH2Cl2/MeOH, 90:10). IR (KBr, cm−1): 3311, 3297, 1758, 1477, 1355,
1
1251, 1166. H-NMR (400 MHz, CDCl3)
δ
: 3.62 (dd, 3H, J1 = 38.8 Hz, J2 = 10.4 Hz, C
*-O), 6.88–7.04 (m, 3H,
: 54.85, 54.90, 71.86, 73.21, 128.14, 128.30, 129.23, 129.65,
12.91, 131.15, 131.75, 134.19, 134.56, 138.25, 138.45, 150.36. 31P-NMR (161.98 CDCl3) 20.61. 19F-NMR
H
3-O), 3.72 (dd, 3H,
J1 = 10.4 Hz, J2 = 1.2 Hz, CH3-O), 5.95 (d, 1H, J = 13.6, C
6H,
-Ar). 13C-NMR (100.62 MHz, CDCl3)
H
H-Ar), 7.19–7.41 (m,
H
δ
(316.48 MHz, CDCl3)
δ
:
−
111.62. Anal. Calc. for C16H18FN2O7PS: C 44.45, H 4.20, N 6.48, S 7.42.
Found: C 44.40, H 4.23, N 6.52, S 7.41%. ESI-MS: (m/z) = 433.1 [M + H]+.
(Diethoxyphosphoryl)(phenyl)methyl(N-phenylsulfamoyl)carbamate (5a). White powder, 96% yield, m.p.
187–189 ◦C, Rf = 0.42 (CH2Cl2/MeOH, 90:10). IR (KBr, cm−1): 3447, 3297, 1733, 1481, 1384, 1247, 1185.
1H-NMR (400 MHz, CDCl3)
δ: 1.03 (t, 3H, J = 7.0 Hz, CH3), 1.30 (t, 3H, J = 7.0 Hz, CH3), 3.59–3.68 (m,

Molecules 2018, 23, 1682
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1H, C
(s, 1H, N
2H, J = 7.6 Hz,
(CH3), 63.96 (CH2), 64.10 (CH2), 72.46 (d, JC-P = 170 Hz, CH*-OP), 119.77 (2C), 124.46, 128.31 (2C, d,
C-P = 6 Hz), 128.76 (2C), 128.90 (2C), 129.32, 134.25, 136.86, 150.40 (d, JC-P = 16 Hz, C=O). 31P-NMR
H
2-O), 3.82–3.90 (m, 1H, C
-SO2), 6.80 (dd, 2H, J1 = 8.8 Hz, J2 = 1.2 Hz,
-Ar), 7.20–7.26 (m, 5H,
-Ar).13C-NMR (100.62 MHz, CDCl3)
H
2-O), 4.07–4.17 (m, 2H, C
H
2-O), 5.82 (d, 1H, J = 8.8 Hz, C
-Ar), 7.02 (t, 1H, J = 7.6 Hz,
: 16.32 (CH3), 16.59
H
*OP), 6.47
H
H
H-Ar), 7.15 (t,
H
H
δ
J
(161.98 MHz, CDCl3) δ: 19.61. Anal. Calc. for C18H23N2O7PS: C 48.87, H 5.24, N 6.33, S 7.25. Found:
C 48.93, H 5.21, N 6.28, S 7.26%. ESI-MS: (m/z) = 443.1 [M + H]+.
(Dimethoxyphosphoryl)(phenyl)me◦thyl(3,4-dihydroisoquinolin-2(1H)-yl)sulfonylcarbamate (6a).
Color
powder, 94% yield, m.p. 153–155 C, Rf = 0.49 (CH2Cl2/MeOH, 90:10). IR (KBr, cm−1): 3258, 1750, 1360,
1
1454, 1234, 1120. H-NMR (400 MHz, CDCl3)
δ
: 2.87 (t, 2H, J = 6.0 Hz, CAr
-
CH2-CH2), 3.55 (d, 3H, 3JH-P
3-O), 4.52 (s,
-Ar), 7.14–7.16 (m, 2H, -Ar),
-C=O). 13C-NMR (100.62 MHz, CDCl3)
: 28.38 (CH2), 44.47 (NCH2), 47.78 (NCH2), 54.63 (2C, POCH3), 72.04 (d, JC-P = 178 Hz, CH*-OP),
126.4, 126.6, 127.1, 128.6 (2C), 128.8, 129.60 (2C), 129.80, 131.41, 132.4, 133.2, 150.95 (d, JC-P = 16 Hz,
= 10.0 Hz, C
2H, CAr
CH2-N), 6.00 (d, 1H, 2JH-P = 12.0 Hz, C
7.33–7.36 (m, 3H, -Ar), 7.48-7.51 (m, 2H, -Ar), 9.91 (s, 1H, NH
H
3-OP), 3.60 (t, 2H, J = 6.0 Hz, CH2-CH2-N), 3.75 (d, 3H, 3JH-P = 10.0 Hz, C
H
-
H*-O), 7.01–7.08 (m, 2H,
H
H
H
H
δ
C=O). 31P-NMR (161.98 MHz, CDCl3)
δ: 18.76. Anal. Calc. for C19H23N2O7PS: C 50.22, H 5.10, N 6.10,
S 7.06. Found: C 50.19, H 5.15, N 6.16, S 7.10%. ESI-MS: (m/z) = 453.2 [M − H]+.
(Dimethoxyphosphoryl)(phenyl)methyl(4-phenylpiperazin-1-yl)sulfonylcarbamate (7a). White powder, 93%
yield, m.p. 152–154 ◦C, Rf = 0.50 (CH2Cl2/MeOH, 90:10). IR (KBr, cm−1): 3337, 1741, 1449, 1360, 1248,
1
1167. H-NMR (400 MHz, CDCl3)
δ
: 3.10–3.40 (m, 4H, 2 CH2-N-SO2), 3.42–3.62 (m, 4H, 2 CH2-N-CAr),
3-O), 3.75 (d, 3H, J = 10.8 Hz, C
3-O), 6.05 (d, 1H, 2JH-P = 14.0 Hz, CH*-O),
-Ar), 7.25–7.40 (m, 5H, -Ar), 7.45–7.56 (m, 2H,
-Ar). 13C-NMR (100.62 MHz,
: 46.78 (2C, NCH2), 48.90 (2C, NCH2), 54.61 (d, JC-P = 7 Hz, POCH3), 54.62 (d, JC-P = 7 Hz,
POCH3), 70.86 (d, JC-P = 142.4 Hz, CH*-OP), 117.37 (2C), 120.93, 127.87 (2C, d, JC-P = 5 Hz), 128.57,
128.92 (2C), 129.65 (2C), 132.49, 136.81, 151.27 (d, JC-P = 12 Hz, C=O). 31P-NMR (161.98 MHz, CDCl3)
3.67 (d, 3H, J = 10.6 Hz, C
6.80–6.96 (m, 3H,
CDCl3)
H
H
H
H
H
δ
δ:
19.82. Anal. Calc. for C20H26N3O7PS: C 49.68, H 5.42, N 8.69, S 6.63. Found: C 49.73, H 5.46, N 8.65,
S 6.67%. ESI-MS: (m/z) = 482.3 [M − H]+.
(Diethoxyphosphoryl)(phenyl)methyl(N-propylsulfamoyl)carbamate (8a). White powder, 97% yield, m.p.
◦
151–153 C, Rf = 0.43 (CH2Cl2/MeOH, 90:10). IR (KBr, cm−1): 3369, 3061, 1758, 1475, 1355, 1240,
1
1156, 763, 697. H-NMR (400 MHz, CDCl3)
δ
: 0.72 (t, 3H, J = 8.8 Hz, C
2-Pr), 1.37 (t, 3H, J = 9.4 Hz, C 3-OEt), 2.48–2.59 (m, 1H, C
2-N), 3.67–4.05 (m, 2H, CH2-OP), 4.25 (1H, m, NH), 4.74 (dq, 2H, 3JH-P = 11.8 Hz,
2-OP), 6.00 (dd, 1H, 2JH-P = 11.3 Hz, J = 8.8 Hz, CH*-O), 7.35–7.38 (m, 3H,
-Ar),
-Ar). Anal. Calc. for C15H25N2O7PS: C 44.11, H 6.17, N 6.86, S 7.85. Found: C 44.29,
H
3-Pr), 1.09 (t, 3H, J = 9.4 Hz,
C
H
3-OEt), 1.12–1.27 (m, 2H, C
2.78–2.87 (m, 1H, C
3JH-H = 7.5 Hz, C
7.50–7.52 (m, 2H,
H 6.79, N 6.91, S 7.80%. ESI-MS: (m/z) = 409.2 [M + H]+.
H
H
H
2-N),
H
H
H
H
(SR)
and
(SS)-Ethyl-2-((N-(((dimethoxyphosphoryl)(phenyl)methoxy)carbonyl)sulfamoyl)amino)
-4-methylpentanoate (1b). White powder, 91% yield; m.p. 118–120 ◦C, Rf = 0.39 (CH2Cl2/MeOH, 90:10).
IR (KBr, cm−1): 3274, 1747 (l), 1470, 1371, 1251, 1164. H-NMR (400 MHz, CDCl3)
12H, C
(m, 2H, 1C
δ
: 0.81–0.87 (m,
2-CHisop), 1.20
3-O), 3.60–3.75
1
H
3-CHisop), 1.05–1.35 (m, 6H, O-CH2-C
H
3), 1.36–1.60 (m, 4H, 2C
3-O), 3.52 (d, 3H, J = 10.6 Hz, C
H
isop+ 1C
H
H
H
2-CHisop), 3.51 (d, 3H, J = 10.6 Hz, C
H
(m, 1H, CH*-NH), 3.75–3.99 (m, 3H, -O-CH2-CH3 + CH*-NH), 3.78 (d, 6H, J = 10.8 Hz, C
4.00–4.25 (m, 2H, -O-CH2-CH3), 5.79 (bs, 1H, N
-SO2), 5.96 (d, 1H, J = 13.9 Hz, CH*-O), 6.00 (d, 1H,
J = 14.3 Hz, CH*-O), 6.21 (bs, 1H, N
-SO2), 7.32–7.40 (m, 6H, -Ar), 7.50-7.56 (m, 4H, -Ar), 9.86
(bs, 1H, N : 14.04 (2CH3), 22.76 (4C), 24.37 (2C), 41.95(2C),
-C=O). 13C-NMR (100.62 MHz, CDCl3)
H3-O),
H
H
H
H
H
δ
54.19 (2POCH3), 54.44 (2POCH3), 55.55 (2C), 61.63 (2OCH2), 72.13 (2C, d, JC-P = 142.4 Hz, CH*-OP),
128.03 (4C), 128.12 (2C), 128.75 (4C, d, JC-P = 5 Hz), 132.50 (2C), 150.60 (2C, d, JC-P = 2 Hz, C=O), 172.01
(2C=O). 31P-NMR (161.98 MHz, CDCl3)
δ
: 21.61. Anal. Calc. for C18H29N2O9PS: C 45.00, H 6.08,
N 5.83, S 6.67. Found: C 45.07, H 6.04, N 5.81, S 6.72%. ESI-MS: (m/z) = 481.1 [M + H]+.

Molecules 2018, 23, 1682
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(SR)
and
(SS)-Ethyl-2-((N-(((dimethoxyphosphoryl)(phenyl)methoxy)carbonyl)sulfamoyl)amino)
◦
-3-phenylpropanoate (2b). White powder, 94% yield; m.p. 125–127 C, Rf = 0.41 (CH2Cl2/MeOH,
90:10). IR (KBr, cm−1): 3279, 1744 (l), 1455, 1373, 1249, 1162. H-NMR (400 MHz, CDCl3)
δ
: 1.01 (t,
2-Ar), 3.49 (d,
*-NH + -O-C 2-CH3),
-SO2), 4.86 (s, 1H, N -SO2), 5.97
(d, 1H, J = 13.5 Hz, CH*-O), 5.98 (d, 1H, J = 14.3 Hz, CH*-O), 7.00–7.12 (m, 2H,
-Ar), 7.11–7.41 (m,
14H, -Ar), 7.42–7.48 (m, 4H, : 13.98 (2CH3), 38.99 (2CH2),
-Ar). 13C-NMR (100.62 MHz, CDCl3)
1
3H, J = 7.6 Hz, C
6H, J = 9.2 Hz, C
4.09–4.20 (m, 1H, C
H
H
3-CH2-O), 1.02 (t, 3H, J = 7.6 Hz, C
3-O), 3.82 (d, 6H, J = 9.6 Hz, C 3-O), 3.75–4.00 (m, 3H, C
*-NH), 4.25–4.50 (m, 3H, -O-C 2-CH3 +
H3-CH2-O), 2.85–3.15 (m, 4H, CH
H
H
H
H
H
N
H
H
H
H
H
δ
54.27 (2C, d, JC-P = 6.9 Hz, POCH3), 54.45 (2C, d, JC-P = 6.9 Hz, POCH3), 57.74 (2CH), 61.76 (2OCH2),
71.14 (2C, d, JC-P = 155.6 Hz, CH*-OP), 128.06 (4C, d, JC-P = 6 Hz), 128.09 (4C), 128.57 (4C), 128.79 (4C),
129.51 (4C, d, JC-P = 6 Hz), 132.2 (2C), 135.5 (2C), 150.69 (2C=O), 170.66 (2C=O). 31P-NMR (161.98 MHz,
CDCl3)
δ: 23.42. Anal. Calc. for C21H27N2O9PS: C 49.02, H 5.29, N 5.44, S 6.23. Found: C 45.07, H 6.04,
N 5.81, S 6.72%. ESI-MS: (m/z) = 515.21 [M + H]+.
(SR)
and
(SS)-Ethyl-2-((N-(((dimethoxyphosphoryl)(phenyl)methoxy)carbo◦nyl)sulfamoyl)
amino)-3-(1H-indol-3-yl) propanoate (3b). White powder, 84% yield; m.p. 116–118 C; Rf = 0.39
(CH2Cl2/MeOH, 90:10). IR (KBr, cm−1): 3274, 1747, 1471, 1371, 1250, 1164. H-NMR (400 MHz, CDCl3)
1
δ
: 0.99 (t, 3H, J = 7.20 Hz, C
2-CH*), 3.30–3.50 (m, 8H, 2C
(m, 2H, OC
2), 6.20 (d, 2H, J = 7.8 Hz, CH*-O), 6.68–6.98 (m, 6H,
7.37–7.40 (m, 6H, -Ar), 9.60 (bs, 2H, N δ
-C=O). 31P-NMR (161.98 MHz, CDCl3)
H
3-CH2-O), 1.06 (t, 3H, J = 7.2 Hz, C
3-O + 2C *CO), 3.82–4.00 (m, 8H, 2C
-Ar), 7.18–7.26 (m, 8H,
: 20.61. Anal. Calc.
H
3-CH2-O), 3.11 (d, 4H, J = 6.0 Hz,
3-O + OC 2), 4.21–4.26
-Ar),
C
H
H
H
H
H
H
H
H
H
H
for C23H28N3O9PS: C 49.91, H 5.10, N 7.59, S 5.79. Found: C 49.97, H 5.04, N 7.68, S 5.83%. ESI-MS:
(m/z) = 553.21 [M]+.
(Dimethoxyphosphoryl)(phenyl)methyl ((2-oxooxazolidin-3-yl)sulfonyl)carbamate (1c). White powder; 92%
yield; m.p. 123–125 ◦C; Rf = 0.38 (CH2Cl2/MeOH, 90:10). IR (KBr, cm−1): 3255, 1748, 1663, 1357, 1254,
1118, 757, 629; 1H-NMR (400 MHz, CDCl3)
δ
: 3.40–3.43 (m, 2H, C
3-OP), 3.75 (d, 3H, 3JH-P = 8.0 Hz, CH3-OP), 4.60–4.63 (m, 2H, C
*-OP), 7.31–7.35 (m, 3H, -Ar), 7.37-7.39 (m, 2H, H δ: 46.58,
-Ar). 13C-NMR (100.62 MHz, CDCl3)
H
2-N), 3.61 (d, 3H, 3JH-P = 8.0 Hz,
H
2-O), 6.04 (d, 1H, 2JH-P = 12.0 Hz,
C
C
H
H
H
54.92 (d, JC-P = 7 Hz, POCH3), 54.95 (d, JC-P = 7 Hz, POCH3), 70.76, 71.02 (d, JC-P = 171 Hz, CH*-OP),
127.93 (2C, d, JC-P = 3 Hz), 128.75, 128.99 (2C, d, JC-P = 2 Hz), 133.52, 155.06 (C=O), 155.12 (d, JC-P = 12 Hz,
C=O). 31P-NMR (161.98 MHz, CDCl3)
δ: 18.93. Anal. Calc. for C13H17N2O9PS: C 38.24, H 4.20, N 6.86,
S 7.85. Found: C 38.20, H 4.25, N 6.89, S 7.81%. ESI-MS: (m/z) = 431.5 [M + Na]+.
3.3. Determination of In Vitro Antibacterial Activity
The antimicrobial activity of the synthesized compounds was evaluated in vitro against Gram
positive and Gram negative bacteria. Serial dilutions of the tested compounds in acetone were made
in a concentration range from 0.5 to 512 µg/mL. All tests were performed in triplicate.
Firstly, compounds 1a–7a and 1b were screened for antibacterial activity by using the Kirby Bauer
disc diffusion test on Mueller-Hinton agar plates. The medium was poured into Petri plates and
allowed to solidify. These plates were inoculated with a bacterial inoculum prepared in physiologically
sterile water with an OD of about 0.08. Sterilized disks of 6 mm (Schleicher and Schule, Germany)
were each impregnated with 20 µL of different concentrations of the compounds and were deposited
on the plates. The latter were then left at room temperature for 2 h and incubated at 37 ◦C for 24 h.
The diameters of the inhibition zones (mm) were measured in accordance with the recommendations
of the clinical and laboratory standards institute (CLSI 2017) [32]. For each bacterial strain, the best
inhibition zone obtained was reported in Table 4.
Secondly, the MIC values were determined by the dilution broth method following the procedure
recommended by the CLSI [32]. The serial dilutions of compounds, ranging from concentrations
of 0.5 to 512
for 24 h. The MIC value was considered as the lowest concentration showing visual inhibition of
µ
g/mL, T were inoculated with fresh bacterial inoculums and then incubated at 37 ◦C

Molecules 2018, 23, 1682
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growth. Sulfamethoxazole-trimethoprime (Bio-Rad, Marseille, France) was used as the positive control
(CMI = 25 µg/mL). Disks embedded with acetone were used as a negative one.
4. Conclusions
In summary, 12 new and original sulfamidocarbonyloxyphosphonates were synthesized and fully
characterized by 1H, 13C, and 31P NMR spectroscopy, IR spectroscopy, and mass spectroscopy, as well as
elemental analysis. The synthesized compounds 1a–7a and 1b were screened for in vitro evaluation as
a proof of concept for designing new antibacterial agents containing both sulfamido and phosphonate
moieties. Standard strains were chosen according to the screening protocol including Gram-positive
and Gram-negative bacteria, which represent micro-organisms associated with important infections.
All compounds showed promising in vitro antibacterial activity. Additionally, it has been demonstrated
that our derivatives have more antibacterial effects on Gram-negative bacteria than Gram-positive
ones except for compound 1b (R1=CH3, R2=CH(iBu)COOEt, R3=H). This latter is the only one active
on both Gram-negative and Gram-positive bacteria. Compound 1a (R1=CH3, R2=Bn, R3=H) had more
pronounced activity against P. aeruginosa, whereas compound 4a (R1=CH3, R2=3-F-C6H4, R3=H) had
more activity on E. coli. Antibacterial effects will be investigated in further studies to explain the
susceptibility of bacteria to our compounds. Further pharmacomodulation efforts are in progress to
explore the impact of new substituents on the phenyl moiety and thereby will offer new expectations
for sulfamidocarbonyloxyphosphonates as novel antibacterial agents.
Supplementary Materials: Supplementary materials are available on line.
Author Contributions: A.B., K.B., and B.B. synthesized all compounds presented in this article; J.L. and C.M.
contributed to the identification of all synthesized products by NMR and MS; I.B. and H.B. performed the
bioassays of compounds; Z.B., C.M., and M.L.B. wrote and revised the paper; J.L. revised the paper; M.B. started
the project, designed the molecules, and wrote and revised the paper.
Funding: APC was sponsored by MDPI. This research received no external funding.
Acknowledgments: This work was financially supported by The General Directorate for Scientific Research and
Technological Development (DG-RSDT), Algerian Ministry of Scientific Research, Applied Organic Chemistry
Laboratory (FNR 2000).
Conflicts of Interest: The authors declare no conflict of interest.
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Sample Availability: Samples of the synthesized compounds are available from the corresponding authors.
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