Pentafluorosulfanyl-containing triclocarban analogs with potent antimicrobial activity

Article abstract of DOI:10.3390/molecules23112853

Concerns have been raised about the long-term accumulating effects of triclocarban, a polychlorinated diarylurea widely used as an antibacterial soap additive, in the environment and in human beings. Indeed, the Food and Drug Administration has recently banned it from personal care products. Herein, we report the synthesis, antibacterial activity and cytotoxicity of novel N,N'-diarylureas as triclocarban analogs, designed by reducing one or more chlorine atoms of the former and/or replacing them by the novel pentafluorosulfanyl group, a new bioisostere of the trifluoromethyl group, with growing importance in drug discovery. Interestingly, some of these pentafluorosulfanyl-bearing ureas exhibited high potency, broad spectrum of antimicrobial activity against Gram-positive bacterial pathogens, and high selectivity index, while displaying a lower spontaneous mutation frequency than triclocarban. Some lines of evidence suggest a bactericidal mode of action for this family of compounds.

Full text of DOI:10.3390/molecules23112853

molecules
Article
Pentafluorosulfanyl-containing Triclocarban Analogs
with Potent Antimicrobial Activity
Eugènia Pujol 1,† , Núria Blanco-Cabra 2,†, Esther Julián 3 , Rosana Leiva 1, Eduard Torrents 2,
*
and Santiago Vázquez 1,
*
1
Laboratori de Química Farmacèutica (Unitat Associada al CSIC), Facultat de Farmàcia i Ciències de
l Alimentació, and Institute of Biomedicine (IBUB), Universitat de Barcelona, Av. Joan XXIII, 27-31,
0
08028 Barcelona, Spain; epujol@ub.edu (E.P.); rosana.leiva58@gmail.com (R.L.)
Bacterial Infections and Antimicrobial Therapies, Institute for Bioengineering of Catalonia (IBEC),
The Barcelona Institute of Science and Technology, Baldiri Reixac 15-21, 08028 Barcelona, Spain;
nblanco@ibecbarcelona.eu
Departament de Genètica i de Microbiologia, Facultat de Biociències, Universitat Autònoma de Barcelona,
08193 Bellaterra, Spain; esther.julian@uab.cat
2
3
*
Correspondence: etorrents@ibecbarcelona.eu (E.T.); svazquez@ub.edu (S.V.); Tel.: +34-934-034-756 (E.T.);
+34-934-024-533 (S.V.)
†
These authors contributed equally to this paper.
ꢀꢁꢂꢀꢃꢄꢅꢆꢇ
Academic Editor: Marta Barniol-Xicota
Received: 16 October 2018; Accepted: 26 October 2018; Published: 2 November 2018
ꢀꢁꢂꢃꢄꢅꢆ
Abstract: Concerns have been raised about the long-term accumulating effects of triclocarban,
a polychlorinated diarylurea widely used as an antibacterial soap additive, in the environment
and in human beings. Indeed, the Food and Drug Administration has recently banned it from
personal care products. Herein, we report the synthesis, antibacterial activity and cytotoxicity of
novel N,N0-diarylureas as triclocarban analogs, designed by reducing one or more chlorine atoms
of the former and/or replacing them by the novel pentafluorosulfanyl group, a new bioisostere of
the trifluoromethyl group, with growing importance in drug discovery. Interestingly, some of these
pentafluorosulfanyl-bearing ureas exhibited high potency, broad spectrum of antimicrobial activity
against Gram-positive bacterial pathogens, and high selectivity index, while displaying a lower
spontaneous mutation frequency than triclocarban. Some lines of evidence suggest a bactericidal
mode of action for this family of compounds.
Keywords: antibacterial; Gram-positive; N,N0-diarylureas; pentafluorosulfanyl; Staphylococcus
aureus; triclocarban
1. Introduction
The presence of N,N0-diarylureas in medicinal chemistry is of great importance due to their
broad spectrum of biological activities. They have been widely studied in the field of insecticides [
and infectious diseases such as malaria [ ], schistosomiasis and tuberculosis [ ], immunology [
and oncology [
antimicrobial agent in personal care products such as bar soaps, deodorants, detergents, and other
disinfectants [ ]. In recent years, public concerns have been raised regarding its potential toxicological
effects in mammals and its environmental accumulation [ 11]. Studies show that, when applied
in the skin, this antibacterial is absorbed through it and can even be detected in human plasma,
urine, and milk [10 13]. Furthermore, TCC has been recognized as an endocrine disruptor at high
concentrations [ 10], resulting in hormonal effects, and more recently, the mechanisms through
which it can alter cardiac function have been elucidated [14]. Moreover, it has been reported that
1]
2
3
,
4
5,
6
]
7
], among others. Triclocarban (TCC) is a N,N0-diarylurea commonly used as an
8
9–
–
9
,
Molecules 2018, 23, 2853; doi:10.3390/molecules23112853
www.mdpi.com/journal/molecules

Molecules 2018, 23, 2853
2 of 17
TCC is a potent inhibitor of soluble epoxide hydrolase, which may lead to alterations in human
physiology [15]. Due to its three chlorine atoms, the biodegradation of TCC is so slow that it can persist
in the environment for years [11
,14]. Indeed, studies have demonstrated that it accumulates in aquatic
habitats [ 13 16 19]. On the basis of the above, the safety of this antimicrobial agent in long-term
9, , –
daily use has not yet been demonstrated. Since 2017, the Food and Drug Administration (FDA) has
banned the use of TCC and triclosan, a related antimicrobial agent, in consumer products. Therefore,
the development of alternative agents to TCC and triclosan for the use in consumer products is an
appealing topic to researchers [20].
The trifluoromethyl group is commonly used in medicinal chemistry as a bioisosteric replacement
of chlorine atoms. Therefore, it is not surprising that a few N,N0-diarylureas containing a
trifluoromethyl unit also displayed promising antibacterial activities [1]; this is the case for cloflucarban
(TFC, 3-trifluoromethyl-4,40-dichlorocarbanilide), a trifluoromethyl-substituted diarylurea that shares
not only the same spectrum of activity with TCC, but also a similar pattern of absorption, distribution,
excretion and toxicity [21–23].
Very recently, a new bioisoster of the trifluoromethyl unit has been introduced in medicinal
chemistry: the pentafluorosulfanyl group (SF5), a relatively new polyfluorinated substituent that has
been applied in agro and material chemistry [24,25]. When compared to its isostere trifluoromethyl
group, the SF5-group is considered a “super-trifluoro-methyl group”, since it bears advantageous
properties, including tetragonal bipyramidal shape, high electronegativity (3.65 vs. 3.36 for the
trifluoromethyl group), high lipophilicity, large steric volume (slightly less than that of tert-butyl but
greater than trifluoromethyl), and confirmed hydrolytic and chemical stability [24,26–31]. Due to its
unique properties, the presence of SF5 in medicinal chemistry has been increasing in the last decade,
to the extent that it is nowadays considered to be an extremely attractive substituent in medicinal
applications [24–27]. Indeed, a new antimalarial SF5-containing drug, DSM-265, has recently entered
clinical trials [32].
Despite the increasing research around the pentafluorosulfanyl group, little is known about
the environmental impact of SF5-containing molecules [33]. Among the performed studies, it has
been shown that the degradation of SF5-substituted aryl compounds results in environmentally-mild
products [34].
Bearing in mind that the presence of SF5 in this field is increasing in the last few years [24],
and that it has a more environmentally-benign profile compared to the chlorine atom, the aim of
the present work was to introduce this novel group on the N,N0-diarylurea scaffold in order to
obtain new antimicrobial agents (Figure 1). Herein, we report the design, synthesis, and biological
evaluation of novel SF5-analogs of TCC, which could be a good starting point for a new generation of
antibacterial ingredients.
Figure 1. Chemical structures of triclocarban, cloflucarban, and general structure of the new
0
N,N -diarylureas presented in this work.

Molecules 2018, 23, 2853
3 of 17
2. Results and Discussion
2.1. Chemistry
All the N,N0-diarylureas were prepared following a quite simple and straightforward procedure,
which consisted of the coupling of phenyl isocyanates with the corresponding anilines under three
slightly different reaction conditions. In turn, aryl isocyanates were commercially available or formed
in situ from their corresponding anilines by reaction with triphosgene in the presence of triethylamine
as a base, in an organic solvent such as toluene. Compounds were synthesized in low to moderate
yields, since it was observed that dimerization products from the starting aromatic amines were often
predominant (Scheme 1 and Figure 2). The structure of these diarylureas was confirmed by IR, 1H, 13C,
and 19F NMR, elemental analysis, and/or HRMS (see material and methods section and supplementary
materials for further details).
Scheme 1. Synthesis◦of novel diarylureas. (a) CH2Cl2, rt, overnight; (b) pyridine, rt, 1 h; (c) n-BuLi,
anhydrous THF,
materials for details.
−
78 C to rt, overnight. See Figure 2, material and methods section and supplementary
H
H
H
N
H
N
H
N
H
N
N
N
X
SF5
Cl
Cl
Cl
O
O
O
Cl
Cl
Cl
Cl
F5S
TCC, X = Cl
Cloflucarban, X = CF3
1
2
Cl
H
N
H
H
N
H
N
H
N
H
N
N
SF5
SF5
SF5
SF5
O
O
O
Cl
Cl
Cl
F5S
Cl
3
4
5
Cl
H
N
H
N
H
N
H
N
H
N
H
N
SF5
SF5
O
O
O
F5S
F5S
Cl
SF5
SF5
6
7
8
H
N
H
N
H
N
H
N
H
N
H
N
F5S
O
O
O
O
F5S
F5S
SF5
9
10
11
H
N
H
N
H
N
H
H
N
H
F3C
Cl
CF3
Cl
N
CF3
Cl
F5S
Cl
N
SF5
Cl
O
O
Cl
12
13
14
Figure 2. Pentafluorosulfanyl ureas
1–14. Compounds
1
to
6
and
8
are new. Compounds
9,
11, 13 and
14 have been recently disclosed by us in a patent application [35]. Compounds
7
[36], 10
[37] and 12 [1]
were previously known.

Molecules 2018, 23, 2853
4 of 17
2.2. Antibacterial Activity, Selectivity Index and Structure-Activity Relationships
The antibacterial activity of the final compounds against several Gram-positive and
Gram-negative bacterial pathogens was evaluated by determination of the minimum inhibitory
concentration values (MIC50) (Table 1). To check if these molecules had a safer profile than TCC, and to
demonstrate their possible use as topic antibacterial compounds, we next evaluated their toxicity (CC50,
cytotoxic concentration 50%) on eukaryotic cells using a macrophages viability measure. In agreement
with previous reports, TCC and cloflucarban displayed antibacterial activity in Gram-positive bacteria
(Table 1), whereas no activity was detected against Gram-negative pathogens (data not shown) [38].
Similarly, the new analogs synthesized in this work did not show antibacterial activity against the
Gram-negative pathogens P. aeruginosa and E. coli (data not shown). It is worthy of note that while the
activity of TCC and cloflucarban in Gram-positive bacteria was restricted to the Staphylococcus genera
included in this work (S. aureus, S. epidermidis, and a S. aureus methicillin resistant clinical isolate), most
of the newly-designed pentafluorosulfanyl derivatives had a broader antimicrobial activity spectrum
than TCC and cloflucarban, being active against Streptococcus mutants and Enterococcus faecalis bacterial
strains. Remarkably, although clinical isolates are usually more resistant to antibiotics, the clinical
isolate S. aureus methicillin resistant (MRSA) showed almost the same antimicrobial sensitivity as the
other laboratory strain, indicating no mechanisms of resistance to these compounds in this clinical
isolate (Table 1).
Table 1. MIC50, cytotoxicity and selectivity index (SI) of compounds 1–14.a
MIC50 (µg/mL) b,c
CC50 (µg/mL) d
Compound
S. aureus S. aureus MRSA
S. epidermis
S. mutants
E. faecalis
TCC
TFC
1
2
3
4
5
6
7
8
9
10
11
12
13
14
0.5 (29)
0.5 (27.4)
1 (4.8)
0.5 (29)
0.5 (27.4)
1 (4.8)
1 (4.8)
0.5 (110)
0.5 (56)
0.5 (10.2)
0.5 (8.4)
0.5 (26.2)
0.5 (26)
0.5 (25)
0.05 (412)
0.5 (67)
0.5 (29)
0.5 (27.4)
1 (4.8)
1 (4.8)
1 (55)
0.5 (56)
0.5 (10.2)
0.5 (8.4)
0.5 (26.2)
0.5 (26)
0.5 (25)
0.5 (41.2)
0.5 (67)
0.5 (67.6)
0.5 (49.2)
0.5 (20)
NA e
NA
5
5
NA
NA
>20
1 (4.8)
1 (4.8)
NA
14.5
13.7
4.8
4.8
55
28
5.6
4.2
13.1
13
12.5
20.6
33.5
33.8
24.6
10
1 (4.8)
0.5 (110)
0.5 (56)
0.5 (10.2)
0.5 (8.4)
0.5 (26.2)
0.5 (26)
0.5 (25)
0.05 (412)
0.5 (67)
0.5 (67.6)
0.5 (49.2)
0.5 (20)
NA
5
0.5 (10.2)
0.5 (8.4)
>20
0.5 (10.2)
0.5 (8.4)
5
0.5 (26)
0.5 (25)
0.5 (41.2)
>10
2 (16.9)
0.5 (49.2)
0.5 (20)
NA
0.5 (25)
0.5 (41.2)
0.5 (67)
2 (16.9)
0.5 (49.2)
0.5 (20)
0.3 (112.7)
0.5 (49.2)
0.5 (20)
a For each tested compound, MIC50 values are represented in the first row, whereas SI values are indicated in brackets.
b
MIC50 values were determined against the following Gram-positive bacterial strains: Staphylococcus aureus (ATCC
12600); Staphylococcus aureus methyciline resistant; Staphylococcus epidermis (ATCC 1798); Streptococcus mutants (ATCC
c
25175); Enterococcus faecalis (ATCC 19433). All the compounds were inactive against two Gram-negative bacterial
d
strains: Escherichia coli (ATCC 700926) and Pseudomonas aeruginosa (ATCC 15692). CC50 values were determined
e
against murine macrophages cells (J-774A.1). NA, no antibacterial activity detected (MIC50 > 100 µg/mL).
Taking into account the very similar activities and cytotoxicities of TCC and cloflucarban, we first
synthesized pentafluorosulfanyl analog
against the Staphylococcus genera, and was additionally active against S. mutants and E. faecalis bacterial
strains. However, was more cytotoxic than TCC and cloflucarban, resulting in lower selectivity
indexes. A similar trend was observed with compound . Notwithstanding, the cytotoxicity does
not seem to be directly related with the introduction of the SF5 group, since two isomers of , ureas
and , were less cytotoxic, although they were not active against S. mutants and E. faecalis. Further
replacement of the Cl of the left-hand ring in and for SF5, as in and , respectively, restored the
activity against S. mutants and E. faecalis but, again, in line with an increase in cytotoxicity.
1, that maintained the potency of the parent compounds
1
2
1
3
4
3
4
5
6

Molecules 2018, 23, 2853
5 of 17
While these initial results showed that the replacement of a chlorine atom for the
pentafluorosulfanyl group was indeed a promising approach, the higher cytotoxicity of several of
these novel derivatives remained as a worrying issue. Hence, we next evaluated the removal of
a chlorine atom of the aforementioned compounds. Ureas
removal of a chlorine atom in and , respectively, were endowed with very similar antimicrobial
activities and cytotoxicities than TCC. Finally, replacement of the remaining chlorine atom in by a
second pentafluorosulfanyl group led to , a compound with similar cytotoxicity than TCC but with
broader spectrum of action. Similarly, moving from to 10 gave rise to a very promising compound,
7 and 8, conceptually generated by the
1
2
7
9
8
active against the five Gram-positive bacterial strains studied and with selectivity indexes of up to 412.
Isomer 11, although being also an interesting compound, was less potent than 10.
Finally, starting from cloflucarban, we briefly evaluated the introduction of a fourth electron
withdrawing group. The three evaluated compounds, 12–14, were active against the five Gram-positive
bacterial strains with cytotoxicities similar or slightly better than those of TCC and cloflucarban.
Overall, it seems that the introduction of a fourth electron withdrawing group is not worthwhile.
2.3. Diarylureas Show a Bacteriolytic Mode of Action
To better understand how the different compounds affect the viability of S. aureus, bacterial cells
were stained using the Live/Dead viability test and visualized under the fluorescent microscope.
This experiment allows us to observe the membrane integrity, since Syto9 green only labels bacterial
DNA if the cells are viable and propidium iodide can only enter bacteria cells with a damaged
membrane, staining the whole cell red.
Treatment of bacterial cells during 4 h with TCC and novel compounds
the proportion of non-viable cells and diminished the total cells, particularly with compounds
and 12, suggesting a bacteriolytic mode of action for this chemical family of compounds (Figure 3A).
3, 5, 6 and 9–13, increased
3, 5,
6
Figure 3.
(A) Live/Dead analysis of S. aureus. Green fluorescence indicates live cells, and red
fluorescence suggests dead cells. (B) Membrane damage analysis by FM 4-46 staining. Scale bar
correspond to 5 µm.
Additionally, we microscopically visualized the changes in bacterial cell integrity by label plasma
membrane of living cells using the vital stain FM 4-64 (Figure 3B). Staining the untreated cells resulted

Molecules 2018, 23, 2853
6 of 17
in uniform membrane accumulations. On the other hand, cells treated with TCC and compounds 10
and 12 resulted in stained membrane blebs, possibly originating from severe membrane deformations,
which is an indication that the primary antibacterial mode of action of these compounds may involve
membrane damage.
2.4. Antimicrobial Activity of the New Diarylureas on Removal of Biofilms in Catheters and on Disinfection on
Contaminated Surfaces
Given that TCC is widely used as an antimicrobial agent in personal care products (soaps,
deodorants, detergents, and others), we tested the capacity of TCC derivatives in disinfecting a
contaminated surface area. As shown in Figure 4A, compounds 9, 10, 12 and 13 have substantial
capacity to remove a contaminated glass area at the same level as TCC, indicating the same capacity of
these new compounds to be used as a disinfectant.
Figure 4.
and ( ) on biofilms growing on catheters. * indicates statistically significant difference to the control
(untreated) experiment (p-value < 0.05 in pairwise t-test calculated with GraphPad 6.0). CPX was
(A) Antibacterial effect of compounds on disinfection of contaminated surfaces by S. aureus
B
used as a control in all antimicrobial experiments, with a MIC50 of 0.5
pathogens tested. cfu, colony-forming unit.
µg/mL against all the bacteria
Furthermore, S. aureus is one of the leading causes of catheter-related bacteremia due to the
colonization of surgical devices in hospitals by a biofilm form of growth. For that reason, it is highly
important to develop protocols and new methodologies to treat and remove pre-existing biofilms in
medical devices, especially in catheters. Hence, we studied whether the selected compounds were
active in terms of removing biofilms formed in a catheter mode of infection by this bacteria, and we
compared the results with TCC and the antibiotic ciprofloxacin (CPX), which is endowed with potent
anti-biofilm activity. It is worth noting that compounds 10 and 12 showed the same percentage of
biofilm removing capacity in catheters than TCC, whereas the reduction produced by these compounds
is similar to the reduction of biofilm due to the treatment with ciprofloxacin (Figure 4B).
2.5. New Compounds Show Less Spontaneous Mutation Rates Compared to TCC
Increasing resistance to antimicrobials is an enormous problem for our society. For this reason,
during the development of new antimicrobials, it is common to assess the frequency of spontaneous,
resistant mutants within a bacterial population to warrant that this is not a serious issue that
compromises further development [39]. We therefore studied the spontaneous mutation rates of
S. aureus induced by TCC and selected diarylureas as described in the materials and methods section.
As indicated in Table 2, TCC had a mutation rate of 4
×
10−9, similar to that of 12 (5
×
10−10).
Interestingly, compounds 10 and 13, at the same concentration as TCC, showed no induced
3, 9,
mutation rates, which indicated the difficulty that such compounds have in inducing any spontaneous
resistance in S. aureus.

Molecules 2018, 23, 2853
7 of 17
Table 2. Spontaneous mutation rates in S. aureus to different diarylureas.
Compound (10 µg/ mL)
Frequency of Mutation
−9
TCC
3
9
10
11
12
13
4 × 10
0
0
0
−1
−10
5 × 10
5 × 10
0
3. Materials and Methods
3.1. Chemical Synthesis
3.1.1. General Methods
Commercially-available reagents and solvents were used without further purification unless stated
otherwise. 2-chloro-3-(pentafluoro-
6-sulfanyl)aniline, 2-chloro-5-(pentafluoro- 6-sulfanyl)aniline and
4-chloro-3-(pentafluoro-
6-sulfanyl)aniline were synthesized according to a reported procedure [40].
λ
λ
λ
Preparative normal phase chromatography was performed on a CombiFlash Rf 150 (Teledyne Isco,
Lincoln, NE, USA) with pre-packed RediSep Rf silica gel cartridges. Thin-layer chromatography
was performed with aluminum-backed sheets with silica gel 60 F254 (Merck, Darmstadt, Germany,
ref 1.05554), and spots were visualized with UV light and 1% aqueous solution of KMnO4. Melting
1
points were determined in open capillary tubes with a MFB 595010M Gallenkamp. 400 MHz H,
100.6 MHz 13C and 376.5 MHz 19F NMR spectra were recorded on a Varian Mercury 400 or on
1
a Bruker 400 Avance III spectrometers. Then, 500 MHz H NMR spectra were recorded on a
Varian Inova 500 spectrometer. The chemical shifts are reported in ppm (δ scale) relative to internal
tetramethylsilane, and coupling constants are reported in Hertz (Hz). Assignments given for the
NMR spectra of the compounds have been carried out on the basis of DEPT, COSY 1H/1H (standard
procedures), and COSY 1H/13C (gHSQC and gHMBC sequences) experiments. IR spectra were run on
Perkin-Elmer Spectrum RX I (Waltham, MA, USA) or Nicolet Avatar 320 FT-IR spectrophotometers.
Absorption values are expressed as wave-numbers (cm−1); only significant absorption bands are
given. High-resolution mass spectrometry (HRMS) analyses were performed with an LC/MSD TOF
Agilent Technologies spectrometer. The elemental analyses were carried out in a Flash 1112 series
Thermofinnigan elemental microanalyzator (A5) to determine C, H, N and S. HPLC/MS were
determined with a HPLC Thermo Ultimate 3000SD (Thermo Scientific Dionex, Waltham, MA, USA)
coupled to a photodiode array detector DAD-3000 (Thermo Scientific Dionex, Waltham, MA, USA)
and mass spectrometer LTQ XL ESI-ion trap (Thermo Scientific, Waltham, MA, USA) with Xcalibur
v2.2 acquisition software (Thermo Scientific, Waltham, MA, USA) (HPLC-PDA-MS). 5
µL of sample
0.5 mg/mL in methanol were injecte◦d, using a ZORBAX Extend-C18 3.5
µ
m 2.1
×
50 mm column
(Agilent, Santa Clara, CA, USA) at 30 C. The mobile phase was a mixture of A = formic acid 0.05% in
water and B = formic acid 0.05% in acetonitrile with the method described as follows: flow 0.6 mL/min,
5% B-95% A 3 min, 100% B 4 min, 95% B-5% A 8 min. Purity is given as % of absorbance at 254 nm;
UV-Vis spectra were collected every 0.2 s between 650 and 275 nm; data from mass spectra were
analyzed by electrospray ionization in positive mode every 0.3 s between 50 and 1000 Da. The analytical
samples of all of the new compounds, which were subjected to pharmacological evaluation, possessed
a purity of ≥95%, as evidenced by either their elemental analyses or their HPLC-MS.
3.1.2. General Procedures for the Synthesis of Aryl Isocyanates
A solution of aniline (1 Eq) in toluene (5 or 10 mL) was treated with triphosgene (0◦.5 Eq).
Triethylamine (1 Eq) was immediately added, and the reaction mixture was stirred at 70 C for
2 h. Afterwards pentane (1 mL) was added, and a white precipitate was formed. The mixture was

Molecules 2018, 23, 2853
8 of 17
filtered and pentane was evaporated under vacuum at room temperature to give the corresponding
isocyanate in toluene solution that was used in the next step without further purification.
3.1.3. General Procedure A for the Synthesis of Ureas 2–6
To a solution of the previously-obtained aryl isocyanate was added the substituted aniline in
dichloromethane (5 mL). The suspension was stirred at room temperature overnight. Crude ureas
were purified by column chromatography or were crystallized in the appropriate solvent.
3.1.4. General Procedure B for the Synthesis of Ureas 1, 7 and 8
The commercially-available 4-chlorophenylisocyanate (1 Eq) was added with stirring to a solution
of the required pentafluorosulfanylaniline (1 Eq) in pyridine (1.5 or 2 mL). The mixture was allowed to
stand at room temperature for 1 h. Afterwards it was poured into water and the precipitate formed
was removed by filtration. The final compounds were purified by crystallization from methanol or by
column chromatography (hexane/ethyl acetate mixtures).
3.1.5. General Procedure C for the Synthesis of Ureas 9–14
The aniline was dissolved in anhydrous THF (5 or 12 mL) under argon and cooled to
−
78 ◦C on
a dry ice in acetone bath. Afterwards 2.5 M n-butyllithium in hexanes (1.1, 1.2 or 1.3 Eq) was added
dropwise. The reaction mixture was then removed from the dry ice in acetone bath and tempered
to 0 ◦C with an ice bath. The appropriate isocyanate, prepared in the previous step or commercially
available, was then stirred under argon and continuously added to the reaction mixture. The mixture
was stirred at room temperature overnight. Methanol (4 or 5 mL) was added to quench any unreacted
n-butyllithium. Purification by column chromatography provided the desired diarylureas.
1-(4-Chloro-3-(pentafluoro-
(151 mg, 0.98 mmol) and 4-chloro-3-(pentafluoro-
λ
6-sulfanyl)phenyl)-3-(4-chlorophenyl) urea
6-sulfanyl)aniline (250 mg, 0.98 mmol) in pyridine
1. From 4-chlorophenylisocyanate
λ
(1.5 mL) and following general procedure B, a white solid (280 mg) was obtained. Column
◦
chromatography (hexane/ ethyl acetate) furnished urea
IR (KBr)
1
(66 mg, 17%) as a white solid, mp 222–223 C.
ν
: 412, 503, 569, 599, 654, 678, 752, 789, 811, 824, 854, 864, 891, 926, 1012, 1039, 1093, 1127,
1241, 1284, 1300, 1385, 1401, 1479, 1493, 1546, 1576, 1595, 1650, 3084, 3129, 3182, 3298 cm−1. H NMR
(400 MHz, DMSO-d6) δ: 7.34 [m, 2 H, 30(50)-H], 7.49 [m, 2 H, 20(60)-H], 7.60 (dd, J = 8.8 Hz, J0 = 2.0 Hz,
1 H, 6-H), 7.64 (d, J = 8.8 Hz, 1 H, 5-H), 8.38 (d, J = 2.0 Hz, 1 H, 2-H), 9.04 (broad s, 1 H) and 9.30 (broad
1
s, 1 H) (2 NH). 13C NMR (100.6 MHz, CD3OD) : 120.7 (m, CH, C2), 121.9 [CH, C20(60)], 122.9 (C, C4),
δ
124.1 (CH, C6), 129.0 (C, C40), 129.8 [CH, C30(50)], 133.9 (CH, C5), 139.0 (C, C1 or C10), 140.1 (C, C10 or
C1), 154.5 (C, CO). The signal for C3 was not observed. 19F NMR (376.5 MHz, DMSO-d6)
J = 152.3 Hz, 4 F, SF4F), 85.9 (quint, J = 152.3 Hz, 1 F, SF4F). Anal. calcd for C13H9Cl2F5N2OS
C 39.13, H 2.48, N 6.76, S 7.74. Found: C 38.92, H 2.65, N 6.67, S 7.47.
δ
: 66.8 (d,
0.1C5H12:
·
1-(3,4-Dichlorophenyl)-3-(4-pentafluoro-
(222 mg, 1.18 mmol) in dichloromethane (3 mL) and 4-(pentafluoro-
1.18 mmol) in toluene (3 mL) and following general procedure A, urea
obtained as a white solid. The analytical sample was obtained by crystallization from dichloromethane
λ
6-sulfanyl)phenyl) urea
2
. From 3,4-dichlorophenylisocyanate
6-sulfanyl)aniline (259 mg,
(130 mg, 30% yield) was
λ
2
(119 mg), mp (dichloromethane) 226–227 ◦C. IR (KBr)
ν
: 614, 667, 694, 825, 849, 859, 1030, 1104, 1133,
1194, 1234, 1265, 1302, 1325, 1378, 1390, 1412, 1477, 1504, 1545, 1595, 1665, 3116, 3205, 3356 cm−1. H
1
NMR (400 MHz, DMSO-d6)
5-H), 7.65 [m, 2 H, 20(60)-H], 7.81 [m, 2 H, 30(50)-H], 7.87 (d, J = 4.0 Hz, 1 H, 2-H), 9.13 (broad s, 1 H)
and 9.33 (broad s, 1 H) (2 NH). 13C NMR (100.6 MHz, DMSO-d6) : 117.8 [CH, C20(60)], 118.7 (CH,
C6), 119.6 (CH, C2), 123.6 (C, C4), 126.8 [m, CH, C30(50)], 130.6 (CH, C5), 131.1 (C, C3), 139.5 (C, C1),
δ
: 7.36 (dd, J = 12.0 Hz, J0 = 4.0 Hz, 1 H, 6-H), 7.53 (d, J = 12.0 Hz, 1 H,
δ
0
0
142.8 (C, C1 ), 146.2 (m, C, C4 ), 152.0 (C, CO). 19F NMR (376.5 MHz, DMSO-d6)
4 F, S 4F), 89.2 (quint, J = 150.8 Hz, 1 F, SF4 ). Anal. calcd for C13H9Cl2F5N2OS: C 38.35, H 2.23, N 6.88,
S 7.87. Found: C 38.63, H 2.30, N 6.61, S 7.54.
δ: 65.1 (d, J = 150.8 Hz,
F
F

Molecules 2018, 23, 2853
9 of 17
1-(2-Chloro-5-(pentafluoro-
λ
6-sulfanyl)phenyl)-3-(4-chlorophenyl) urea
3
. By following general procedure
for the synthesis of aryl isocyanates, 2-chloro-5-(pentafluoro-
in toluene (5 mL) was reacted with triphosgene (175 mg, 0.59 mmol) in the presence of triethylamine
(0.16 mL, 1.18 mmol) to afford 2-chloro-5-(pentafluoro-
6-sulfanyl)phenylisocyanate in toluene
λ
6-sulfanyl)aniline (300 mg, 1.18 mmol)
λ
solution. From this previously-obtained isocyanate and 4-chloroaniline (151 mg, 1.18 mmol) in
dichloromethane (5 mL) and following general procedure A, a white gum (443 mg) was obtained.
Column chromatography (◦hexane/ ethyl acetate) furnished urea
3 (226 mg, 47% overall yield) as
a white solid, mp 195–196 C. IR (KBr)
ν
: 503, 578, 602, 621, 664, 731, 807, 831, 844, 863, 951, 1015,
1065, 1090, 1234, 1285, 1420, 1461, 1492, 1547, 1591, 1645, 1702, 2848, 2925, 3285, 3325 cm−1. H NMR
(400 MHz, DMSO-d6) δ: 7.35 [m, 2 H, 30(50)-H], 7.51 [m, 2 H, 20(60)-H], 7.54 (dd, J = 8.8 Hz, J0 = 2.8 Hz,
1 H, 4-H), 7.72 (d, J = 8.8 Hz, 1 H, 3-H), 8.84 (d, J = 2.8 Hz, 1 H, 6-H), 8.66 (broad s, 1H) and 9.69 (broad
1
s, 1 H) (2 NH). 13C NMR (100.6 MHz, DMSO-d6) : 117.5 (m, CH, C6), 120.0 [CH, C20(60)], 120.0 (m,
δ
CH, C4), 125.2 (C, C2), 126.1 (C, C40), 128.8 [CH, C30(50)], 129.9 (CH, C3), 136.6 (C, C1), 137.9 (C,
C10), 151.4 (quint, 2JCF = 17.2 Hz, C, C5), 151.9 (C, CO). 19F NMR (376.5 MHz, DMSO-d6)
: 63.8 (d,
J = 151.5 Hz, 4 F, SF4F), 86.7 (quint, J = 151.5 Hz, 1 F, SF4
). HRMS-ESI+ m/z [M + H]+ calcd for
[C13H9Cl2F5N2OS + H+]: 406.9806, found: 406.9803. HPLC (254 nm): tR = 4.45 min (100%).
δ
F
1-(2-Chloro-3-(pentafluoro- . By following general procedure
6-sulfanyl)phenyl)-3-(4-chlorophenyl) urea
for the synthesis of aryl isocyanates, 2-chloro-3-(pentafluoro-
6-sulfanyl)aniline (300 mg, 1.18 mmol)
in toluene (5 mL) was reacted with triphosgene (175 mg, 0.59 mmol) in the presence of triethylamine
(0.16 mL, 1.18 mmol) to afford 2-chloro-3-(pentafluoro-
6-sulfanyl)phenylisocyanate in toluene
λ
4
λ
λ
solution. From this previously-obtained isocyanate and 4-chloroaniline (151 mg, 1.18 mmol) in
dichloromethane (5 mL) and following general procedure A, a white solid (194 mg) was obtained.
Column chromatography (hexane/ ethyl acetate) gave urea
4 (40 mg, 8% overall yield) as a white
solid, mp 218–219 ◦C. IR (KBr)
ν
: 605, 652, 711, 729, 779, 799, 810, 840, 849, 875, 931, 1014, 1054, 1089,
1155, 1224, 1250, 1284, 1302, 1398, 1417, 1463, 1493, 1546, 1594, 1663, 1713, 3217, 3305, 3340 cm−1. H
1
NMR (400 MHz, DMSO-d6)
δ
: 7.36 [m, 2 H, 30(50)-H], 7.50 [m, 2 H, 20(60)-H], 7.56 (t, J = 8.4 Hz, 1 H,
0
0
5-H), 7.78 (dd, J = 8.4 Hz, J = 1.2 Hz, 1 H, 4-H), 8.35 (dd, J = 8.4 Hz, J = 1.2 Hz, 1 H, 6-H), 8.65 (broad s,
1 H) and 9.63 (broad s, 1 H) (2 NH). 13C NMR (100.6 MHz, CD3OD)
CH, C4), 126.5 (CH, C6), 128.0 (CH, C5), 129.0 (C, C2), 129.9 [CH, C30(50)], 139.1 (C, C1), 139.5 (C, C10),
152.7 (m, C, C3), 154.3 (C, CO). 19F NMR (376.5 MHz, DMSO-d6)
: 67.7 (d, J = 152.3 Hz, 4 F, SF4F),
86.2 (quint, J = 152.3 Hz, 1 F, SF4 ). Anal. calcd for C13H9Cl2F5N2OS: C 38.35, H 2.23, N 6.88, S 7.87.
Found: C 38.71, H 2.36, N 6.63, S 7.60.
δ
: 121.5 [CH, C20(60)], 125.1 (m,
δ
F
1-(2-Chloro-5-(pentafluoro-
6-sulfanyl)phenyl)-3-(4-(pentafluoro-
general procedure for the synthesis of aryl isocyanates, 2-chloro-5-(pentafluoro-
(500 mg, 1.96 mmol) in toluene (10 mL) was reacted with triphosgene (290 mg, 0.98 mmol)
in the presence of triethylamine (0.27 mL, 1.96 mmol) to afford 2-chloro-5-(pentafluoro-λ6
sulfanyl)phenylisocyanate in toluene solution. From this previously-obtained isocyanate and
4-(pentafluoro-
6-sulfanyl)aniline (272 mg, 1.07 mmol) in dichloromethane (5 mL) and following
general procedure A, a yellowish gum (443 mg) was obtained. Column chromatography (hexane/
ethyl acetate) gave urea : 582,
(55 mg, 10% overall yield) as a white solid, mp 224–225 ◦C. IR (KBr)
λ
λ
6-sulfanyl)phenyl) urea
5. By following
λ
6-sulfanyl)aniline
-
λ
5
ν
598, 647, 665, 723, 805, 828, 848, 860, 949, 1043, 1063, 1105, 1196, 1239, 1272, 1288, 1327, 1419, 1466,
1
1506, 1522, 1560, 1597, 1618, 1670, 1685, 3094, 3141, 3209, 3383 cm−1. H NMR (400 MHz, DMSO-d6)
δ
: 7.59 (dd, J = 8.8 Hz, J0 = 2.8 Hz, 1 H, 4-H), 7.67 [m, 2 H, 20(60)-H], 7.75 (d, J = 8.8 Hz, 1 H, 3-H),
7.84 [m, 2 H, 30(50)-H], 8.82 (d, J = 2.8 Hz, 1 H, 6-H), 8.78 (broad s, 1 H) and 10.06 (broad s, 1 H)
(2 NH). 13C NMR (100.6 MHz, CD3OD) : 119.0 [CH, C20(60)], 119.6 (quint, 3JCF = 5.2 Hz, CH, C6),
δ
121.8 (quint, 3JCF = 4.4 Hz, CH, C4), 126.9 (C, C2), 128.1 [quint, 3JCF = 4.7 Hz, CH, C30(50)], 130.6 (CH,
C3), 137.6 (C, C1), 143.6 (C, C10), 149.1 (m, C, C40 or C5), 153.65 (m, C, C5 or C40), 153.70 (C, CO).
19F NMR (376.5 MHz, CD3OD)
δ: 63.8 (d, J = 150.6 Hz, 4 F, SF4F), 65.1 (d, J = 150.6 Hz, 4 F, SF4F),

Molecules 2018, 23, 2853
10 of 17
86.6 (quint, J = 150.6 Hz, 1 F, SF4
F
), 89.0 (quint, J = 150.6 Hz, 1 F, SF4
F
). HRMS-ESI− m/z [M
−
H]−
calcd for [C13H8ClF10N2OS2-H]−: 496.9612, found: 496.9624. HPLC (254 nm): tR = 4.22 min (100%).
1-(2-Chloro-3-(pentafluoro-
general procedure for the synthesis of aryl isocyanates, 4-(pentafluoro-
2.06 mmol) in toluene (10 mL) was reacted with triphosgene (306 mg, 1.03 mmol) in the presence of
triethylamine (0.29 mL, 2.06 mmol) to afford 4-(pentafluoro-
6-sulfanyl)phenylisocyanate in toluene
solution. From this previously-obtained isocyanate and 2-chloro-3-(pentafluoro-
6-sulfanyl)aniline
(285 mg, 1.12 mmol) in dichloromethane (5 mL) and following general procedure A, a white solid
(920 mg) was obtained. Column chromatography (hexane/ethyl acetate) gave urea (89.6 mg, 16%
λ
6-sulfanyl)phenyl)-3-(4-(pentafluoro-
λ
6-sulfanyl)phenyl) urea
6-sulfanyl)aniline (453 mg,
6. By following
λ
λ
λ
6
overall yield) as a white solid, mp 245–246 ◦C. IR (KBr)
ν
: 541, 580, 598, 655, 708, 728, 779, 826, 854,
1054, 1102, 1158, 1195, 1225, 1262, 1301, 1412, 1464, 1506, 1546, 1596, 1668, 3134, 3209, 3341 cm−1. H
1
NMR (400 MHz, DMSO-d6) δ: 7.58 (t, J = 8.4 H0z, 1 H, 5-H), 7.66 [m, 2 H, 20(60)-H], 7.78–7.87 [complex
0
0
signal, 3 H, 4-H, 3 (5 )-H], 8.34 (dd, J = 8.4 Hz, J = 1.2 Hz, 1 H, 6-H), 8.80 (broad s, 1 H) and 9.99 (broad
s, 1 H) (2 NH). 13C NMR (100.6 MHz, CD3OD) : 119.0 [CH, C20(60)], 125.3 (quint, 3JCF = 5.2 Hz, CH,
δ
C4), 126.7 (CH, C6), 128.0–128.1 [complex signal, 1 C and 3 CH, C2, C5 and C30(50)], 139.2 (C, C1),
143.7 (C, C10), 149.1 (m, C, C40 or C3), 153.0 (m, C, C3 or C40), 153.9 (C, CO). 19F NMR (376.5 MHz,
DMSO-d6)
1 F, SF4 ), 89.1 (quint, J = 150.6 Hz, 1 F, SF4
S 12.86. Found: C 31.30, H 1.82, N 5.31, S 12.61.
δ: 65.1 (d, J = 150.6 Hz, 4 F, SF4F), 67.7 (d, J = 152.7 Hz, 4 F, SF4F), 86.1 (quint, J = 152.7 Hz,
F
F). Anal. calcd for C13H9ClF10N2OS: C 31.30, H 1.82, N 5.62,
1-(4-Chlorophenyl)-3-(3-(pentafluoro-
6-sulfanyl)phenyl) urea
1.95 mmol) and 3-(pentafluoro-
6-sulfanyl)aniline (427 mg, 1.95 mmol) in pyridine (2 mL) and following
general procedure B, urea (448 mg, 62% yield) was obtained as a pale white solid by crystallization
from methanol, mp (methanol) 204–205 ◦C (reported 203.5-205 ◦C [36]). IR (KBr)
: 644, 686, 698, 752,
λ
7. From 4-chlorophenylisocyanate (300 mg,
λ
7
ν
781, 794, 804, 842, 872, 926, 940, 1013, 1063, 1091, 1115, 1177, 1237, 1288, 1306, 1401, 1422, 1443, 1485,
1
1558, 1597, 1660, 3069, 3097, 3195, 3318 0cm−1. H NMR (400 MHz, DMSO-d6)
δ
0: 7.33 [m, 2 H, 3(5)-H],
0
0
7.45–7.59 [complex signal, 5 H, 2(6)-H, 4 -H, 5 -H, 6 -H], 8.23 (t, J = 4.0 Hz, 1 H, 2 -H), 8.95 (broad s, 1 H)
and 9.16 (broad s, 1 H) (2 NH). 13C NMR (100.6 MHz, DMSO-d6)
δ
: 114.9 (m, CH, C20),0118.8 (m, CH,
0
0
C4 ), 120.1 [CH, C2(6)], 121.8 (m, CH, C6 ), 125.7 (C, C4), 128.5 [CH, C3(5)], 129.6 (CH, C5 ), 138.2 (C, C1
or C1 ), 140.3 (C, C1 or C1), 152.3 (C, CO), 153.2 (dquint, 2JCF = 16.1 Hz, C, C3 ). 19F NMR (376.5 MHz
DMSO-d6) : 63.6 (d, J = 151.0 Hz, 4 F, SF4F), 87.7 (quint, J = 151.0 Hz, 1 F, SF4 ). Anal. calcd for
C13H10ClF5N2OS: C 41.89, H 2.70, N 7.52, S 8.60. Found: C 42.00, H 2.74, N 7.39, S 8.47.
,
0
0
0
δ
F
1-(4-Chlorophenyl)-3-(4-(pentafluoro- . From 4-chlorophenylisocyanate (300 mg,
6-sulfanyl)phenyl) urea
1.95 mmol) and 4-(pentafluoro-
6-sulfanyl)aniline (427 mg, 1.95 mmol) in pyridine (2 mL) and following
general procedure B, urea
λ
8
λ
8
(580 mg, 80% yield) was obtained as a pale white solid by crystallization
◦
from methanol, mp (methanol) 231–232 C. IR (KBr)
ν
: 666, 699, 754, 782, 802, 829, 868, 1016, 1090, 1102,
1193, 1216, 1239, 1269, 1300, 1411, 1492, 1504, 1547, 1594, 1610, 1664, 1711, 3086, 3140, 3202, 3324 cm−1
.
1H NMR (400 MHz, DMSO-d6)
δ: 7.34 [m, 2 H, 3(5)-H], 7.50 [m, 2 H, 2(6)-H], 7.64 [d, J = 8.0 Hz, 2 H,
2 (6 )-H], 7.80 [m, 2 H, 3 (5 )-H], 8.96 (broad s, 1 H) and 9.22 (broad s, 1 H) (2 NH). 13C NMR (100.6 MHz,
0
0
0
0
3
DMSO-d6)
δ
: 117.6 [CH, C20(60)], 120.1 [CH, C2(6)], 125.9 (C, C4), 126.8 [quint, JCF = 4.02 Hz, CH,
C30(50)], 128.7 [CH, C3(5)], 138.2 (C, C1), 143.0 (C, C10), 146.1 (dquint, 2JCF = 16.1 Hz, C, C40), 152.1 (C,
CO). 19F NMR (376.5 MHz, DMSO-d6)
: 65.2 (d, J = 150.8 Hz, 4 F, SF4F), 89.3 (quint, J = 150.8 Hz,
1 F, SF4 ). Anal. calcd for C13H10ClF5N2OS: C 41.89, H 2.70, N 7.52, S 8.60. Found: C 42.03, H 2.89,
δ
F
N 7.41, S 8.55.
1-(3-(Pentafluoro-
λ
6-sulfanyl)phenyl)-3-(4-(pentafluoro-
λ
6-sulfanyl)phenyl) urea
6-sulfanyl)aniline (350 mg, 1.60 mmol)
9. By following general
procedure for the synthesis of aryl isocyanates, 3-(pentafluoro-
in toluene (5 mL) was reacted with triphosgene (237 mg, 0.80 mmol) in the presence of triethylamine
(0.22 mL, 1.60 mmol) to afford 3-(pentafluoro-
6-sulfanyl)phenylisocyanate in toluene solution.
From this previously-obtained isocyanate, 4-(pentafluoro-
6-sulfanyl)aniline (246 mg, 1.12 mmol) in
λ
λ
λ

Molecules 2018, 23, 2853
11 of 17
anhydrous THF (5 mL) and 2.5 M n-butyllithium in hexanes (0.6 mL, 1.46 mmol) and following general
procedure C, a brown gum (742 mg) was obtained after quenching any unreacted n-butyllithium
with methanol (5 mL). Column chromatography (hexane/ ethyl acetate) gave urea
9
(102 mg, 52%
: 1103, 1196, 1229, 1304, 1410, 1487,
: 7.48–7.57 (complex
overall yield) as a pale white solid, mp 216–217 ◦C [35]. IR (KBr)
ν
1
1549, 1597, 1665, 3088, 3134, 3204, 3321 cm−1. H NMR (400 MHz, DMSO-d6)
δ
signal, 2 H, 4-H, 5-H), 7.58 (dt, J = 8.0 Hz, J0 = 2.0 Hz, 1 H, 6-H), 7.67 [m, 2 H, 20(60)-H], 7.81 [m, 2 H,
30(50)-H], 8.24 (m, 1 H, 2-H), 9.27 (broad s, 1 H) and 9.34 (broad s, 1 H) (2 NH). 13C NMR (100.6 MHz,
DMSO-d6)
C30(50)], 129.7 (CH, C5), 140.1 (C, C1), 142.8 (C, C10), 146.3 (dquint, 2JCF = 16.1 Hz, C, C40), 152.2 (C,
CO), 153.2 (dquint, 2JCF = 16.1 Hz, C, C3). 19F NMR (376.5 MHz, DMSO-d6)
: 63.6 (d, J = 150.4 Hz, 4 F,
), 89.2 (quint, J = 151.0, 1 F,
δ
: 115.3 (m, CH, C2), 117.9 [CH, C20(60)], 119.2 (m, CH, C4), 122.1 (CH, C6), 126.8 [m, CH,
δ
S
F4F), 65.1 (d, J = 151.0 Hz, 4 F, SF4F), 87.6 (quint, J = 150.4 Hz, 1 F, SF4F
SF4F). HRMS-ESI− m/z [M − H]− calcd for [C13H10F10N2OS2-H]−: 463.0002, found: 463.0017. HPLC
(254 nm): tR = 4.04 min (100%).
1,3-bis(4-(Pentafluoro-
of aryl isocyanates, 4-(pentafluoro-
reacted with triphosgene (175 mg, 0.59 mmol) in the presence of triethylamine (0.16 mL, 1.18 mmol) to
afford 4-(pentafluoro-
6-sulfanyl)phenylisocyanate in toluene solution. From this previously-obtained
isocyanate, 4-(pentafluoro-
6-sulfanyl)aniline (235 mg, 1.07 mmol) in anhydrous THF (5 mL) and 2.5 M
λ
6-sulfanyl)phenyl) urea 10. By following general procedure for the synthesis
6-sulfanyl)aniline (259 mg, 1.18 mmol) in toluene (5 mL) was
λ
λ
λ
n-butyllithium in hexanes (0.53 mL, 1.28 mmol) and following general procedure C, an orange gum
(618 mg) was obtained after quenching any unreacted n-butyllithium with methanol (4 mL). Column
chromatography (hexane/ethyl acetate) gave urea 10 (120 mg, 24% overall yield) as a white solid, mp
235 ◦C (dec) (reported 285.9–287.6 ◦C, followed by immediate decomposition [37]). IR (ATR)
ν: 668,
685, 752, 780, 798, 818, 1013, 1100, 1192, 1212, 1245, 1307, 1317, 1358, 1401, 1411, 1504, 1544, 1593, 1659,
1
1713, 1974, 2010, 2035, 2066, 2846, 2017, 2958, 3205, 3297, 3323 cm−1. H NMR (400 MHz, DMSO-d6)
δ:
7.66 [d, J = 8.8 Hz, 4 H, 2(6)-H], 7.82 [m, 4 H, 3(5)-H], 9.37 (broad s, 2 H, NH). 13C NMR (100.6 MHz,
DMSO-d6)
: 117.8 [CH, C2(6)], 126.8 [m, CH, C3(5)], 142.7 (C, C1), 146.4 (quint, 2JCF = 16.1 Hz, C,
C4), 152.0 (C, CO). 19F NMR (376.5 MHz, DMSO-d6)
: 65.1 (d, J = 150.4 Hz, 4 F, SF4F), 89.1 (quint,
J = 150.4 Hz, 1 F, SF4 ). Anal. calcd for C13H10F10N2OS2 0.65C5H12: C 38.18, H 3.51, N 5.48, S 12.54.
Found: C 38.56, H 3.19, N 5.48, S 12.17.
δ
δ
F
·
1,3-bis(3-(Pentafluoro-
6-sulfanyl)phenyl) urea 11. By following general procedure for the synthesis
of aryl isocyanates, 3-(pentafluoro-
6-sulfanyl)aniline (350 mg, 1.60 mmol) in toluene (5 mL) was
reacted with triphosgene (237 mg, 0.80 mmol) in the presence of triethylamine (0.22 mL, 1.60 mmol) to
afford 3-(pentafluoro-
6-sulfanyl)phenylisocyanate in toluene solution. From this previously-obtained
isocyanate, 3-(pentafluoro-
6-sulfanyl)aniline (351 mg, 1.60 mmol) in anhydrous THF (5 mL) and 2.5 M
λ
λ
λ
λ
n-butyllithium in hexanes (0.86 mL, 2.08 mmol) and following general procedure C, a beige solid
(710 mg) was obtained after quenching any unreacted n-butyllithium with methanol (4 mL). Column
chromatography (hexane/ ethyl acetate) gave urea 11 (183 mg, 49% overall yield) as a pale white
solid. The analytical sample was obtained by crystallization from ethyl acetate, mp (ethyl acetate)
267–268 ◦C [35]. IR (KBr)
(400 MHz, DMSO-d6)
2-H), 9.27 (broad s, 2 H, NH). 13C NMR (100.6 MHz, DMSO-d6)
C4), 122.2 (CH, C6), 129.7 (CH, C5), 140.2 (C, C1), 152.5 (C, CO), 153.2 (quint, 2JCF = 16.1 Hz, C, C3).
ν
: 1117, 1242, 1314, 1418, 1485, 1599, 1663, 3102, 3202, 3310 cm−1. H NMR
1
δ: 7.48–7.57 (complex signal, 4 H, 4-H, 5-H), 7.61 (m, 2 H, 6-H), 8.21 (m, 2 H,
δ: 115.3 (m, CH, C2), 119.2 (m, CH,
19F NMR (376.5 MHz, DMSO-d6)
δ: 63.6 (d, J = 151.0 Hz, 4 F, SF4F), 87.6 (quint, J = 151.0 Hz, 1 F,
SF4F). HRMS-ESI− m/z [M − H]− calcd for [C13H10F10N2OS2-H]−: 463.0002, found: 463.0022. HPLC
(254 nm): tR = 4.01 min (100%).
1,3-bis(4-Chloro-3-(trifluoromethyl)phenyl) urea 12
.
From the commercially available 4-chloro-3-
(trifluoromethyl)phenylisocyanate (261 mg, 1.18 mmol) in anhydrous THF (12 mL),
4-chloro-3-(trifluoromethyl)aniline (209 mg, 1.07 mmol) in anhydrous THF (12 mL) and 2.5 M
n-butyllithium in hexanes (0.49 mL, 1.18 mmol) and following general procedure C, an orange gum

Molecules 2018, 23, 2853
12 of 17
(468 mg) was obtained after quenching any unreacted n-butyllithium with methanol (4 mL). Column
chromatography (hexane/ethyl acetate) gave urea 12 (156 mg, 35% overall yield) as a beige solid,
mp 231–232 ◦C (reported 231–232 ◦C [
1]). IR (ATR) ν: 654, 664, 677, 742, 749, 773, 804, 829, 886, 897,
940, 964, 1031, 1057, 1111, 1129, 1168, 1214, 1227, 1263, 1294, 1318, 1405, 1421, 1478, 1529, 1545, 1594,
1
1659, 1695, 1713, 1842, 1943, 2144, 2211, 2351, 1852, 2919, 3312, 3328, 3607, 3643, 3669, 3695 cm−1. H
NMR (400 MHz, DMSO-d6) δ
: 7.61 (d, J = 8.4 Hz, 2 H, 5-H), 7.67 (dd, J = 8.4 Hz, J0 = 2.0 Hz, 2 H, 6-H),
8.08 (d, J = 2.0 Hz, 2 H, 2-H), 9.33 (broad s, 2 H, NH). 13C NMR (100.6 MHz, DMSO-d6)
δ: 117.2 (q,
3JCF = 5.9 Hz, CH, C2), 122.79 (q, 1JCF = 273.0 Hz, C, CF3), 122.80 (q, 3JCF = 1.9 Hz, C, C4), 123.5 (CH,
C6), 126.7 (q, 2JCF = 30.6 Hz, C, C3), 132.0 (CH, C5), 138.9 (C, C1), 152.3 (C, CO). 19F NMR (376.5 MHz,
−
− −
H] calcd for [C15H8Cl2F6N2O-H] : 414.9845,
DMSO-d6)
δ
:
−
61.5 (S, 3 F, CF3). HRMS-ESI m/z [M
−
found: 414.9839. HPLC (254 nm): tR = 3.52 min (100%).
1-(4-Chloro-3-(trifluoromethyl)phenyl)-3-(2-chloro-5-(pentafluoro-
general procedure for the synthesis of aryl isocyanates, 2-chloro-5-(pentafluoro-
(350 mg, 1.38 mmol) in toluene (5 mL) was reacted with triphosgene (204 mg, 0.69 mmol) in the presence
of triethylamine (0.19 mL, 1.38 mmol) to afford 2-chloro-5-(pentafluoro-
6-sulfanyl)phenylisocyanate
λ
6-sulfanyl)phenyl) urea 13. By following
6-sulfanyl)aniline
λ
λ
in toluene solution. From this previously-obtained isocyanate, 4-chloro-3-(trifluoromethyl)aniline
(296 mg, 1.51 mmol) in anhydrous THF (12 mL) and 2.5 M n-butyllithium in hexanes (0.73 mL,
1.78 mmol) and following general procedure C, a brown oil (767 mg) was obtained after quenching any
unreacted n-butyllithium with methanol (5 mL). Column chromatography (hexane/ethyl acetate) gave
urea 13 (138 mg, 22% overall yield) as a white solid, mp 156–157 ◦C [35]. IR (ATR)
ν: 632, 666, 684,
701, 727, 742, 760, 801, 812, 840, 855, 863, 906, 950, 963, 1034, 1065, 1111, 1126, 1175, 1216, 1229, 1260,
1283, 1301, 1329, 1372, 1408, 1459, 1485, 1513, 1546, 1582, 1592, 1608, 1654, 1695, 1715, 1769, 1905, 1925,
1
2025, 2179, 2323, 2369, 2851, 2917, 2953, 3276, 3328, 3671, 3733, 3795, 3815 cm−1. H NMR (400 MHz,
DMSO-d6)
7.73 (d, J = 8.8 Hz, 1 H, 30-H), 8.05 (d, J = 1.2 Hz, 1 H, 2-H), 8.79 (d, J = 2.4 Hz, 1 H, 60-H), 8.73 (broad
δ
: 7.58 (dd, J = 8.8 Hz, J0 = 2.4 Hz, 1 H, 40-H), 7.62–7.71 (complex signal, 2 H, 5-H, 6-H),
s, 1 H) and 10.04 (broad s, 1 H) (2 NH). 13C NMR (100.6 MHz, DMSO-d6) : 116.9 (q, 3JCF = 5.7 Hz,
δ
CH, C2), 117.8 (m, CH, C600), 120.5 (m, CH, C40), 122.7 (q, 1JCF = 273.0 Hz, C, CF3), 123.1 (m, C, C4),
0
123.3 (CH, C6), 125.7 (C, C2 ), 126.8 (q, 2JCF = 30.8 Hz, C, C3), 130.0 (CH, C3 ), 132.2 (CH, C5), 136.3 (C,
C10), 138.5 (C, C1), 151.4 (m, C, C50), 152.0 (C, CO). 19F NMR (376.5 MHz, DMSO-d6)
CF3), 63.9 (d, J = 151.4 Hz, 4 F, SF4F), 86.5 (quint, J = 151.4 Hz, 1 F, SF4
). HRMS-ESI− m/z [M
calcd for [C14H8Cl2F8N2OS-H]−: 472.9534, found: 472.9534. HPLC (254 nm): tR = 3.63 min (100%).
δ
: –61.5 (S, 3 F,
F
−
H]−
1,3-bis(4-Chloro-3-(pentafluoro-
6-sulfanyl)phenyl) urea 14. By following general procedure for the
synthesis of aryl isocyanates, 4-chloro-3-(pentafluoro-
6-sulfanyl)aniline (350 mg, 1.37 mmol) in
toluene (5 mL) was reacted with triphosgene (204 mg, 0.69 mmol) in the presence of triethylamine
(0.20 mL, 1.37 mmol) to afford 4-chloro-3-(pentafluoro-
6-sulfanyl)phenylisocyanate in toluene
solution. From this previously-obtained isocyanate, 4-chloro-3-(pentafluoro-
6-sulfanyl)aniline
λ
λ
λ
λ
(278 mg, 1.09 mmol) in anhydrous THF (5 mL) and 2.5 M n-butyllithium in hexanes (0.60 mL,
1.42 mmol) and following general procedure C, an orange gum (675 mg) was obtained after quenching
any unreacted n-butyllithium with methanol (4 mL). Column chromatography (hexane/ethyl acetate)
gave urea 14 (136 mg, 23% overall yield) as a white solid, mp 237–238 ◦C [35]. IR (ATR)
ν
: 1042, 1130,
1227, 1290, 1396, 1477, 1545, 1587, 1645, 1699, 3030, 3138, 3306 cm−1. H NMR (400 MHz, DMSO-d6)
δ:
1
7.64 (d, J = 8.8 Hz, 2 H, 5-H), 7.68 (dd, J = 8.8 Hz, J0 = 2.0 Hz, 2 H, 6-H), 8.34 (d, J = 2.0 Hz, 2 H, 2-H),
9.47 (broad s, 2 H, NH). 13C NMR (100.6 MHz, DMSO-d6)
: 119.0 (m, CH, C2), 120.4 (C, C4), 123.7 (CH,
C6), 133.0 (CH, C5), 138.9 (C, C1), 150.0 (m, C, C3), 152.4 (C, CO). 19F NMR (376.5 MHz, DMSO-d6)
66.9 (d, J = 152.5 Hz, 4 F, S 4F), 85.8 (quint, J = 152.5 Hz, 1 F, SF4
). HRMS-ESI− m/z [M H]− calcd
for [C13H8Cl2F10N2OS2-H]−: 530.9223, found: 530.9236. HPLC (254 nm): tR = 4.35 min (98%).
δ
δ:
F
F
−

Molecules 2018, 23, 2853
13 of 17
3.2. Bacterial Strains and Growth Conditions
Wild-type Staphylococcus aureus CECT 86 (ATCC 12600), Staphylococcus epidermidis CECT 231
(ATCC 1798), Streptococcus mutans CECT 479 (ATCC 25175), Enterococcus faecalis CECT 481 (ATCC
19433), Escherichia coli K12 MG1655 CECT 433 (ATCC 700926) and Pseudomonas aeruginosa PAO1 CECT
4122 (ATCC 15692) were obtained from the Spanish Type Culture Collection (CECT). Staphylococcus
aureus MRSA was kindly obtained from Dr Joan Gavaldà laboratory. All strains were routinely
cultivated in TSB (tryptic soy broth) or LB (Luria-Bertani) medium (Scharlab) at 37 ◦C.
3.3. Antibacterial Susceptibility Testing
Bacterial strains were tested in the presence of different compounds; each strain was grown in TSB
medium to OD550
≈
0.1 and plated in a microtiter plate (Corning 3596 Polystyrene Flat Bottom 96 Well,
Corning, NY, USA) with different compound concentrations according to the Clinical Laboratory
Standards Institute (CLSI) guidelines, as previously described [41]. The plate was incubated at 37 ◦C
and 150 rpm and growth curves were monitored for 8 h taking the absorbance (OD550 nm) every 15 min
in an SPARK Multimode microplate reader (Tecan, Männedorf, Switzerland). The minimal inhibitory
concentration 50% (MIC50) was defined as the compound concentration that reduces bacterial growth,
determined as the OD550, by 50%.
3.4. Antibacterial Effect of Compounds on Cleaning a Surface
Sterile cover glasses (2.4 cm
×
5 cm) (Duran) were placed into a petri dish with a solution of
peptone water (Sigma-Aldrich, St. Louis, MO, USA) inoculated with S. aureus at an OD550
≈
0.1 and
◦
incubated at 20 C without shaking. After 16 h, the cover glasses were washed with phosphate buffered
saline (PBS), and the different compounds were added at a concentration of 3
incubation, the covers were placed directly on agar plates to quantify viable cells (cfu/mL). The viable
×
MIC. After 1 h of
counts at control experiment were 550 ± 114 cfu.
3.5. Antibacterial Effect of Compounds on Biofilms Growing on Catheters
Sterile pieces of catheter (1 cm width and 2 mm diameter) were incubated in 10 ml tubes with
1 mL TSB with 0.2% glucose inoculated with S. aureus at OD550
at 37 C, all tubes were washed three times with PBS to remove non-adhered bacteria (planktonic) and,
≈
0.1. After three days without shaking
◦
after, the different compounds were added at a 1
×
MIC concentration. After overnight incubation,
tubes were washed three times with PBS and 1 mL PBS + 0.05% TWEEN solution was added to each
tube. All tubes were placed in an ultrasonic bath (VWR) for 5 min and then vortexed for 30 s to
remove adhered bacteria (growing in biofilm). The control group contained media only. Biofilm viable
cells (cfu) were determined by plating serial dilutions on agar plates. The viable counts at control
experiment were 3.8 × 106 ± 1.2 × 106 cfu/mL.
3.6. Fluorescent Microscopy Viability Test Analysis
S. aureus was grown in TSB medium at 37 ◦C and 150 rpm to reach an OD550 of 0.2,
where different compounds were added at 1
×
MIC. After 4 h in shaking conditions, cells
(1 mL) were centrifuged and stained using the LIVE/DEAD BacLight Bacterial Viability kit
(Thermo Fisher Scientific). After 30 min at room temperature under dark conditions, cells
were washed with PBS to remove nonspecific stain. Fluorescent bacteria were visualized by
a Nikon inverted fluorescent microscope ECLISPSE Ti-S/L100 (Nikon) coupled with a DS-Qi2
Nikon camera (Nikon). To access membrane integrity, cells were also stained with 10
µg/mL
of N-(3-triethylammoniumpropyl)-4-(6-(4-(diethylamino)phenyl)hexatrienyl)pyridinium dibromide
(FM® 4-64, Thermo Fisher Scientific). The dye was added after a 10 min treatment with the compounds
at 1 × MIC on S. aureus grown in TSB medium at 37 ◦C and 150 rpm until an OD550 ≈ 1.

Molecules 2018, 23, 2853
14 of 17
3.7. Spontaneous Mutation Frequency to Resistance
A culture of S. aureus (1010 cfu/mL) was plated in TSA agar plates containing different compounds
at 10 g/mL. The inoculum viable cells were determined by cfu counting. The spontaneous
µ
compound-resistant mutation frequency was calculated by dividing the number of resistant colonies
by the total viable cells.
3.8. Mammalian Cytotoxicity Determination
J-774A.1 murine macrophages cells (DSMZ ACC 170) were seeded in a microtiter plate
(
2 × 104 cells per well) (Corning 3596 Polystyrene Flat Bottom 96 Well, Corning), infected with
the different compounds at different concentrations, and diluted in complete medium (Gibco)
without antibiotics. After 24 h at 37 ◦C, the supernatants were removed and a 10% of MTT
solution (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide, Sigma-Aldrich) was added
to determine cell viability. The formazan produced after 3 h was dissolved with acidic isopropanol,
and absorbance was measured at 550 nm with a SPARK Multimode microplate reader (Tecan). CC50
was calculated with GraphPad Prism 6.00 (GraphPad Software) as the concentration of compound that
reduces the cell viability by 50%.
4. Patents
A PCT patent application has been filed. See PCT WO2018/010856A1 (priority data 13 July 2016).
5. Conclusions
Thirteen new diarylureas featuring the scarcely-explored pentafluorosulfanyl group have been
synthesized as analogs of TCC, a widely-used antimicrobial agent that has recently been banned by
the FDA. Overall, the novel derivatives showed similar potency and comparable or broader spectrum
of activity than TCC. Compound 10, with higher potency, a broader spectrum of activity, and higher
selectivity index emerged as the most promising compound. A bactericidal mode of action for this
family of ureas was suggested by preliminary experiments. It is worthy of note that some of these new
molecules removed preexisting S. aureus biofilms, which is important in food industry as well as in
hospital settings, and displayed a lower spontaneous mutation frequency in S. aureus than TCC.
Supplementary Materials: The following are available online. copies of the 1H, 13C and 19F NMR spectra of the
new compounds.
Author Contributions: E.P., N.B.-C., E.J. and R.L. performed the experiments; all the authors analyzed the data;
E.P. wrote the first draft of the article; E.P., E.T. and S.V. reviewed and edited the manuscript; E.T. and S.V. designed
and supervised the experiments and secured funding.
Funding: This research was funded by the Ministerio de Economía Industria y Competitividad (Agencia Estatal de
Investigación, AEI) and Fondo Europeo de Desarrollo Regional (MINECO-FEDER) (Projects SAF2017-82771 and
BIO2015-63557-R) and Generalitat de Catalunya (2017 SGR 106, 2017 SGR1079 and CERCA programme). E.P.
thanks the Institute of Biomedicine of the Universitat de Barcelona (IBUB) for a PhD grant.
Acknowledgments: The authors wish to thank Josep Astola, Zoe Downer and Johanna Binding for
technical assistance.
Conflicts of Interest: E.P., R.L. and S.V. are inventors of the Universitat de Barcelona patent application on the
compounds reported here. The other authors declare no conflict of interest. The founding sponsors had no role
in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript,
and in the decision to publish the results.
References
1.
Schetty, G.; Stammbach, W.; Zinkernagel, R. Insecticidal Derivatives of Diphenyl Urea. U.S. Patent 2745874,
15 May 1956.

Molecules 2018, 23, 2853
15 of 17
2.
3.
4.
Zhang, Y.; Anderson, M.; Weisman, J.L.; Lu, M.; Choy, C.J.; Boyd, V.A.; Price, J.; Siga, M.; Clark, J.;
Connelly, M.; et al. Evaluation of diarylureas for activity against Plasmodium falciparum. ACS Med. Chem. Lett.
2010, 1, 460–465. [CrossRef] [PubMed]
Cowan, N.; Dätwyler, P.; Ernst, B.; Wang, C.; Vennerstro, J.L.; Spangenberg, T.; Keiser, J. Activities of
N,N0-diarylurea MMV665852 analogs against Schistosoma mansoni. Antimicrob. Agents Chemother. 2015
59, 1935–1941. [CrossRef] [PubMed]
,
Brown, J.R.; North, E.J.; Hurdle, J.G.; Morisseau, C.; Scarborough, J.S.; Sun, D.; Korduláková, J.;
Scherman, M.S.; Jones, V.; Grzegorzewicz, A.; et al. The structure-activity relationship of urea derivatives as
anti-tuberculosis agents. Bioorg. Med. Chem. 2011, 19, 5585–5595. [CrossRef] [PubMed]
5.
6.
Sviripa, V.; Zhang, W.; Conroy, M.D.; Schmidt, E.S.; Liu, A.X.; Truong, J.; Chunming, L.; Watt, D.S. Fluorinated
N,N -diarylureas as AMPK activators. Bioorg. Med. Chem. Lett. 2013, 23, 1600–1603. [CrossRef] [PubMed]
0
Jin, Q.; Nie, H.; McCleland, B.W.; Widdowson, K.L.; Palovich, M.R.; Elliott, J.D.; Goodman, R.M.; Burman, M.;
0
Sarau, H.M.; Ward, K.W.; et al. Discovery of potent and orally bioavailable N,N -diarylurea antagonists for
the CXCR2 chemokine receptor. Bioorg. Med. Chem. Lett. 2004, 14, 4375–4378. [CrossRef] [PubMed]
7.
Denoyelle, S.; Chen, T.; Chen, L.; Wang, Y.; Klosi, E.; Halperin, J.A.; Aktas, B.H.; Chorev, M. In vitro inhibition
of translation initiation by N,N0-diarylureas–potential anti-cancer agents. Bioorg. Med. Chem. Lett. 2012
,
22, 402–409. [CrossRef] [PubMed]
Roman, D.P.; Barnett, E.H.; Balske, R.J. Cutaneous antiseptic activity of 3,4,4 -trichlorocarbanilide. Proc. Sci.
Sect. Toilet. Goods Assoc. 1957, 28, 1213–1214.
0
8.
9.
Ahn, C.K.; Zhao, B.; Chen, J.; Cherednichenko, G.; Sanmarti, E.; Denison, M.S.; Lasley, B.; Pessah, I.N.;
Kültz, D.; Chang, D.P.Y.; et al. In vitro biologic activities of the antimicrobials triclocarban, its analogs, and
triclosan in bioassay screens: Receptor-based bioassay screens. Environ. Health Perspect. 2008, 16, 1203–1210.
[CrossRef] [PubMed]
10. Schebb, N.H.; Inceoglu, B.; Ahn, K.C.; Morisseau, C.; Gee, S.J.; Hammock, B.D. Investigation of
human exposure to triclocarban after showering and preliminary evaluation of its biological effects.
Environ. Sci. Technol. 2011, 45, 3109–3115. [CrossRef] [PubMed]
11. Venkatesan, A.K.; Pycke, B.F.G.; Barber, L.B.; Lee, K.E.; Halden, R.U. Occurrence of triclosan, triclocarban,
and its lesser chlorinated congeners in Minnesota freshwater sediments collected near wastewater treatment
plants. J. Hazard. Mater. 2012, 229–230, 29–35. [CrossRef] [PubMed]
12. Scharpf, L.G., Jr.; Hill, I.D.; Maibach, H.I. Percutaneous penetration and disposition of triclocarban in man:
Body showering. Arch. Environ. Health 1975, 30, 7–14. [CrossRef] [PubMed]
13. Schebb, N.H.; Buchholz, B.A.; Hammock, B.D.; Rice, R.H.J. Metabolism of the antibacterial triclocarban by
human epidermal keratinocytes to yield protein adducts. Biochem. Mol. Toxicol. 2012, 26, 230–234. [CrossRef]
[PubMed]
14. Xie, W.; Zhang, W.; Ren, J.; Li, W.; Zhou, L.; Cui, Y.; Chen, H.; Yu, W.; Zhuang, X.; Zhang, Z.; et al.
Metabonomics indicates inhibition of fatty acid synthesis,
β-oxidation, and tricarboxylic acid cycle in
triclocarban-induced cardiac metabolic alterations in male mice. J. Agric. Food. Chem. 2018, 66, 1533–1542.
[CrossRef] [PubMed]
15. Liu, J.; Qiu, H.; Morisseau, C.; Hwang, S.H.; Tsai, H.; Ulu, A.; Chiamvimonvat, N.; Hammock, B.D. Inhibition
of soluble epoxide hydrolase contributes to the anti-inflammatory effect of antimicrobial triclocarban in a
murine model. Toxicol. Appl. Pharmacol. 2011, 255, 200–206. [CrossRef] [PubMed]
16. Chalew, T.E.; Halden, R.U. Environmental exposure of aquatic and terrestrial biota to triclosan and
triclocarban. J. Am. Water Works Assoc. 2009, 45, 4–13. [CrossRef] [PubMed]
17. Halden, R.U.; Paull, D.H. Analysis of triclocarban in aquatic samples by liquid chromatography electrospray
ionization mass spectrometry. Environ. Sci. Technol. 2004, 38, 4849–4855. [CrossRef] [PubMed]
18. Ying, G.; Yu, X.; Kookana, R.S. Biological degradation of triclocarban and triclosan in a soil under aerobic and
anaerobic conditions and comparison with environmental fate modelling. Environ. Pollut. 2007, 150, 300–305.
[CrossRef] [PubMed]
0
19. Gledhill, W.E. Biodegradation of 3,4,4 -trichlorocarbanilide, TCC®, in sewage and activated sludge. Water Res.
1975, 9, 649–654. [CrossRef]
20. FDA Issues Final Rule on Safety and Effectiveness of Antibacterial Soaps. Available online: https://www.
fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm517478.htm (accessed on 14 October 2018).

Molecules 2018, 23, 2853
16 of 17
21. Hiles, R.A. Metabolism and toxicity of halogenated carbanilides: Absorption, distribution and excretion of
0
0
radioactivity from 3,4,4 -trichloro[14C]carbanilide (TCC) and 3-trifluoromethyl-4,4 -dichloro[14C]carbanilide
(TFC) in rats. Food Cosmet. Toxicol. 1977, 15, 205–211. [CrossRef]
22. Jeffcoat, A.R.; Handy, R.W.; Francis, M.T.; Willis, S.; Wall, M.E.; Birch, C.G.; Hiles, R.A. The metabolism
and toxicity of halogenated carbanilides.
Biliary metabolites of 3,4,40-trichloro-carbanilide and
0
3-trifluoromethyl-4,4 -dichlorocarbanilide in the rat. Drug Metab. Dispos. 1977, 5, 157–166. [PubMed]
23. Markgraf, J.H.; Quinn, H. Antibacterial composition. U.S. Patent 3485919, 23 December 1969.
24. Savoie, P.R.; Welch, J.T. Preparation and utility of organic pentafluorosulfanyl-containing compounds.
Chem. Rev. 2015, 115, 1130–1190. [CrossRef] [PubMed]
25. Altomonte, S.; Zanda, M. Synthetic chemistry and biological activity of pentafluorosulphanyl (SF5) organic
molecules. J. Fuorine Chem. 2012, 143, 57–93. [CrossRef]
26. Bassetto, M.; Ferla, S.; Pertusati, F. Polyfluorinated groups in medicinal chemistry. Future Med. Chem. 2015
7, 527–546. [CrossRef] [PubMed]
,
27. Welch, J.T. Applications of pentafluorosulfanyl substitution in life sciences research. In Fluorine in
Pharmaceutical and Medicinal Chemistry: From Biophysical Aspects to Clinical Applications; Gouverneur, V.,
Müller, K., Eds.; World Scientific: London, UK, 2012; pp. 175–207.
28. Saethre, L.J.; Berrah, N.; Bozek, J.D.; Boerve, K.J.; Carroll, T.X.; Kukk, E.; Gard, G.L.; Winter, R.; Thomas, T.D.
Chemical insights from high-resolution X-ray photoelectron spectroscopy and ab initio theory: Propyne,
trifluoropropyne, and ethynylsulfur pentafluoride. J. Am. Chem. Soc. 2001, 123, 10729–10737. [CrossRef]
[PubMed]
29. Kanishchev, O.S.; Dolbier, W.R., Jr. Generation of ortho-SF5-benzyne and its diels alder reactions with
−
furans: Synthesis of 1-SF5-naphthalene, its derivatives, and 1,6(1,7)-bis-SF5-naphthalenes. J. Org. Chem. 2016
,
81, 11305–11311. [CrossRef] [PubMed]
30. Sheppard, W.A. Arylsulfur pentafluorides. J. Am. Chem. Soc. 1962, 84, 3072–3076. [CrossRef]
31. Westphal, M.V.; Wolfstädter, B.T.; Plancher, J.; Gatfield, J.; Carreira, E.M. Evaluation of tert-butyl isosteres:
Case studies of physicochemical and pharmacokinetic properties, efficacies, and activities. ChemMedChem.
2015, 10, 461–469. [CrossRef] [PubMed]
32. Phillips, M.A.; Lotharius, J.; Marsh, K.; White, J.; Dayan, A.; White, K.L.; Njoroge, J.W.; El Mazouni, F.; Lao, Y.;
Kokkonda, S.; et al. A long-duration dihydroorotate dehydrogenase inhibitor (DSM265) for prevention and
treatment of malaria. Sci. Transl. Med. 2015, 7, 296ra111. [CrossRef] [PubMed]
33. Murphy, C.D. Microbial degradation of fluorinated drugs: Biochemical pathways, impacts on the
environment and potential applications. Appl. Microbiol. Biotechnol. 2016, 100, 2617–2627. [CrossRef]
[PubMed]
34. Jackson, D.A.; Mabury, S.A. Environmental properties of pentafluorosulfanyl compounds: Physical
properties and photodegradation. Environ. Toxicol. Chem. 2009, 28, 1866–1879. [CrossRef] [PubMed]
35. Zarei, M.; Vázquez-Carrera, M.; Vázquez, S.; Leiva, R.; Pujol, E. HRI Activators Useful for the Treatment of
Cardiometabolic Diseases. Patent PCT WO2018/010856A1, 18 January 2018.
36. Raasch, M.S. Ureido-Substituted Arylsulfur Pentafluorides. U.S. Patent 3073861, 15 January 1963.
37. Karagiannidis, L.E.; Haynes, C.J.E.; Holder, K.J.; Kirby, I.L.; Moore, S.J.; Wells, N.J.; Gale, P.A. Highly effective
yet simple transmembrane anion transporters based upon ortho-phenylenediamine bis-ureas. Chem. Commun.
2014, 50, 12050–12053. [CrossRef] [PubMed]
38. Walsh, S.E.; Maillard, J.Y.; Russell, A.D.; Catrenich, C.E.; Charbonneau, D.L.; Bartolo, R.G. Activity and
mechanisms of action of selected biocidal agents on Gram-positive and -negative bacteria. J. Appl. Microbiol.
2003, 94, 240–247. [CrossRef] [PubMed]
39. Hughes, D.; Karlén, A. Discovery and preclinical development of new antibiotics. Upsala J. Med. Sci. 2014
119, 162–169. [CrossRef] [PubMed]
,
40. Kleemann, H.; Weck, R. Ortho-Substituted Pentafluorosulfanylbenzenes, Process for Their Preparation and
Their Use as Valuable Synthetic Intermediates. U.S. Patent 7932416 B2, 26 April 2011.

Molecules 2018, 23, 2853
17 of 17
41. Barniol-Xicota, M.; Escandell, A.; Valverde, E.; Julián, E.; Torrents, E.; Vázquez, S. Antibacterial activity of
novel benzopolycyclic amines. Bioorg. Med. Chem. 2015, 23, 290–296. [CrossRef] [PubMed]
Sample Availability: Samples of the compounds are available from the authors.
©
2018 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access
article distributed under the terms and conditions of the Creative Commons Attribution
(CC BY) license (http://creativecommons.org/licenses/by/4.0/).