Parallel one-pot synthesis and structure-activity relationship study of symmetric formimidoester disulfides as a novel class of potent non-nucleoside HIV-1 reverse transcriptase inhibitors

Article abstract of DOI:10.1016/j.bmc.2008.05.010

The molecular duplication of non-nucleoside reverse transcriptase inhibitor (NNRTI) O-(2-phthalimidoethyl)-N-arylthiocarbamates (C-TCs) led to the identification of symmetric formimidoester disulfides (DSs) as a novel class of potent NNRTIs. The lead compound 1 [dimer of the isothiocarbamic form of TC O-(2-phthalimidoethyl)-N-phenylthiocarbamate] turned out to prevent the wild-type HIV-1 multiplication in MT-4 cell culture with an EC₅₀ value of 0.35 μM. In order to perform a structure-activity relationship (SAR) study, we prepared 40 analogues of 1 by an unprecedented one-pot method of solution-phase parallel synthesis. The SAR strategy was focused on the variation of the N-aryl portion (mono-, di- and trisubstitution of the phenyl ring and its replacement with a 1-naphthyl, cyclopropyl or benzyl group) and of the 2-phthalimidoethyl moiety (introduction of a methyl on the phthalimide substructure, replacement of the phthalimide moiety with a phenyl ring and elongation of the ethyl linker). Most DSs proved to inhibit the wild-type HIV-1 replication in cell-based assays and 15 of them were active at nanomolar concentrations. The most potent congeners (11, 15, 16, 17, 18, 19, 20 and 32, EC₅₀: 10-70 nM) shared the N-para-substituted phenyl moiety. Compound 17 tested in enzyme assay against recombinant wild-type reverse transcriptase displayed an IC₅₀ value of 0.74 μM. Compounds 19 and 33 were active at micromolar concentrations against the clinically relevant Y181C and/or K103R resistant mutants.

Full text of DOI:10.1016/j.bmc.2008.05.010

Bioorganic & Medicinal Chemistry 16 (2008) 6353–6363
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry
journal homepage: www.elsevier.com/locate/bmc
Parallel one-pot synthesis and structure–activity relationship study
of symmetric formimidoester disulfides as a novel class of potent
non-nucleoside HIV-1 reverse transcriptase inhibitors
a
a
a
a
b,
*
Sara Cesarini a, , Andrea Spallarossa , Angelo Ranise , Silvia Schenone , Olga Bruno , Paolo La Colla
,
*
Laura Casula b, Gabriella Collu b, Giuseppina Sanna b, Roberta Loddo b
a Dipartimento di Scienze Farmaceutiche, Università di Genova, Viale Benedetto XV 3, I-16132 Genova, Italy
b Dipartimento di Scienze e Tecnologie Biomediche, Università di Cagliari, Cittadella Universitaria, S.S. 554, Km 4,500, I-09042 Monserrato (Cagliari), Italy
a r t i c l e i n f o
a b s t r a c t
Article history:
The molecular duplication of non-nucleoside reverse transcriptase inhibitor (NNRTI) O-(2-phthalimido-
ethyl)–N-arylthiocarbamates (C-TCs) led to the identification of symmetric formimidoester disulfides
(DSs) as a novel class of potent NNRTIs. The lead compound 1 [dimer of the isothiocarbamic form of
TC O-(2-phthalimidoethyl)–N-phenylthiocarbamate] turned out to prevent the wild-type HIV-1 multipli-
cation in MT-4 cell culture with an EC50 value of 0.35 lM. In order to perform a structure–activity rela-
tionship (SAR) study, we prepared 40 analogues of 1 by an unprecedented one-pot method of solution-
phase parallel synthesis. The SAR strategy was focused on the variation of the N-aryl portion (mono-, di-
and trisubstitution of the phenyl ring and its replacement with a 1-naphthyl, cyclopropyl or benzyl
group) and of the 2-phthalimidoethyl moiety (introduction of a methyl on the phthalimide substructure,
replacement of the phthalimide moiety with a phenyl ring and elongation of the ethyl linker). Most DSs
proved to inhibit the wild-type HIV-1 replication in cell-based assays and 15 of them were active at nano-
molar concentrations. The most potent congeners (11, 15, 16, 17, 18, 19, 20 and 32, EC50: 10–70 nM)
shared the N-para-substituted phenyl moiety. Compound 17 tested in enzyme assay against recombinant
wild-type reverse transcriptase displayed an IC50 value of 0.74 lM. Compounds 19 and 33 were active at
micromolar concentrations against the clinically relevant Y181C and/or K103R resistant mutants.
Ó 2008 Elsevier Ltd. All rights reserved.
Received 31 January 2008
Revised 29 April 2008
Accepted 5 May 2008
Available online 7 May 2008
Keywords:
Symmetric formimidoester disulfides
HIV-1
Non-nucleoside reverse transcriptase
inhibitors
Parallel one-pot synthesis
1. Introduction
capable of inhibiting clinically relevant NNRTI-resistant
mutants.13,14
Reverse transcriptase (RT) is a key enzyme in the HIV replica-
tion cycle and is one of the main targets in the development of
drugs for treating HIV infection and AIDS.1–5 Non-nucleoside RT
inhibitors (NNRTIs) bind to an allosteric hydrophobic pocket lo-
cated at about 10 Å far from the polymerase active site and lock
the enzyme into an inactive form by affecting the geometry of
the polymerase active site aspartyl residues.6 In the past 15 years
more than 50 structurally diverse NNRTIs have been described.6–12
Three NNRTIs, nevirapine (ViramuneÒ), delavirdine (RescriptorÒ)
and efavirenz (SustivaÒ) have been approved by FDA for the treat-
ment of HIV infection. Other NNRTIs, like thiocarboxanilide UC-
781, capravirine, dapivirine, rilpivirine and etravirine, are currently
under clinical investigation.3 The fact that cross-resistance extends
to the whole NNRTI class calls for development of new agents
In our previous studies, we reported the discovery of the potent
NNRTI classes of O-(2-phthalimidoethyl)–N-arylthiocarbamates
(C-TCs)15 and structurally related compounds, such as ring-opened
analogues (O-TCs),15 N-acylated derivatives (ATCs)16 and non-
phthalimidic congeners (TCs)17,18 (Figure 1a shows the leads C-
TC 12, O-TC 51, ATC 25c, TC 1 and TC 29.) C-TCs and TCs are isos-
terically related to the NNRTI family of N-phenethyl-N0-thia-
zolylthiourea (PETT) derivatives,19,20 of which Trovirdine is one
of the most representative analogues (Fig. 1b).
During chemical studies on the N-sulfonylation of C-TCs, the
symmetric formimidoester disulfide21 (DS) 1 (Fig. 2) was isolated.
Compound 1 resulted from the molecular duplication of the isot-
hiocarbamic form of O-(2-phthalimidoethyl)–N-phenylthiocarba-
mate (C-TC 12, Fig. 1a). Since examples of anti-HIV symmetric
disulfides (e.g., disulfide benzamides,22,23 Fig. 3) and of symmetric
HIV-RT inhibitors (e.g., Suramine and naphthalenedisulfonic acid
derivatives,24 Fig. 3) have been reported in the literature, we
wanted to test 1 against wild-type HIV-1 in cell-based assay. The
compound showed an EC50 value of 0.35 lM, being 3.4-fold more
* Corresponding authors. Tel.: +39 010 353 8370; fax: +39 010 353 8358 (S.C.);
tel.: +39 070 675 4148; fax: +39 070 675 4210 (P.L.C.).
E-mail addresses: sara.cesarini@unige.it (S. Cesarini), placolla@unica.it
(P. La Colla).
0968-0896/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmc.2008.05.010

6354
S. Cesarini et al. / Bioorg. Med. Chem. 16 (2008) 6353–6363
(a) TCs and structurally related compounds
O
COOH
S
S
H
N
N
O
N
H
O
N
H
O
O
C-TC 12
O
O-TC 51
S
S
N
X
O
N
O
N
H
O
O
X = N: TC 1
X = CH: TC 29
ATC 25c
(b) PETT derivatives
S
S
N
N
N
H
NH
Br
N
H
NH
N
S
Trovirdine
PETT
Figure 1. Chemical structure of C-TC 12,15 O-TC 51,15 ATC 25c,16 TC 1,17 TC 29,17 PETT and Trovirdine.
(40) or by replacing the phthalimide moiety with a phenyl ring
(41) (Table 4).
b
2. Chemistry
O
N
S
In the modern drug discovery process,25 and particularly in lead
identification and optimization, parallel synthesis plays an impor-
tant role as it allows to produce a (large) number of compounds in
short times by using simple and rapid purification methods. Re-
cently, solution-phase chemistry has largely supplanted solid-
phase chemistry as the method of choice for parallel synthesis of
small organic molecules.26
O
O
a
N
S
N
N
O
O
a
O
DS 1–41 were prepared in parallel by an unprecedented solu-
tion-phase method (Scheme 1), by using ordered arrays of spatially
separated reaction vessels (Carousel-6TM reaction station). The
parallelization of the procedure was accomplished by varying
and optimizing the reaction conditions that had led to the synthe-
sis of DS 1 (data concerning the procedure set-up not shown). The
convergent one-pot procedure combined two building blocks:
alcohols and isothiocyanates (Fig. 4). Starting alcohols A1–4 (Fig.
4a) were first transformed into their corresponding salts (S1–4) in
the presence of sodium hydride in dry polar aprotic solvents
(DMF or THF) and then condensed in situ with the suitable isothi-
ocyanate (I1–38, Fig. 4b) to give the corresponding thiocarbamate
sodium salts (B1–41). The sequential addition of N,N,N0,N0-tetra-
methylethylenediamine (TMEDA) and tosyl chloride resulted in
the dimerization of the isothiocarbamic form of salts B by the for-
mation of a disulfide bridge. The reaction consisted in the oxidation
of B thiocarbonyl sulfur caused by tosyl chloride, acting as an atyp-
ical oxidizing reagent. The presence of TMEDA greatly increased
the yields. The work-up simply required addition of water, fol-
lowed by filtrations or extractions, and the final products were
purified by crystallization. The yields ranged from 8% to 94%.
The reaction sequence for DS preparation represents a new syn-
thetic methodology to afford symmetric formimidoester disulfides
b
Figure 2. Chemical structure of the lead compound DS 1 segmented in chemo-
functional portions a and b.
potent than its monomer C-TC 12.15 This encouraged us to further
study the dimerization reaction in order to set-up a parallel syn-
thesis method for rapid analoguing of 1, aimed at the structure–
activity relationship (SAR) profiling.
Our SAR strategy was focused on structural modifications of the
lead 1 (Fig. 2) by keeping constant the O-(2-phthalimidoethyl) sub-
structure (portion a) and varying the N-phenyl moiety (portion b)
(1–38, Tables 1–3). In particular, we investigated the monosubsti-
tution with functional groups with various electronic (inductive
and/or mesomeric), steric and lipophilic properties at positions
ortho, meta and para (1–20); the di- and trisubstitution with equal
(21–29, 34) or different (30–33, 35) groups, and the replacement of
the phenyl ring with a 1-naphthyl (36), cyclopropyl (37) or benzyl
group (38). We also synthesized three disulfides in which the N-
phenyl ring was para-bromo-substituted or unsubstituted, and
portion a was modified by lengthening the ethyl linker (39), by
introducing a methyl at position 4 of the phthalimide substructure

S. Cesarini et al. / Bioorg. Med. Chem. 16 (2008) 6353–6363
6355
O
O
S
S
NH
HN
HN
S
O
HN
S
O
S
S
H2N
O
O
NH2
O
O
O
O
PD024886
NHR
NHR
PD022551: R = H
PD156202: R = COCH3
O
O
H
N
O
H
N
NaO3S
NH SO3Na
HN
N
H
N
H
O
O
SO3Na
NaO3S
SO3Na
SO3Na
suramine
O
O
H3C
CH3
14
O
O
14
HO3S
naphthalenedisulphonic acid derivative
SO3H
Figure 3. Chemical structure of the anti-HIV symmetric disulfide benzamides PD02251,22 PD15620222 and PD024886,22 and of the symmetric HIV-RT inhibitors Suramine
and a naphthalenedisulfonic acid derivative.24
from thiocarbamates: in the literature this conversion is reported
to be accomplished by using common oxidizing reagents,27–32
which instead proved to be ineffective for DS synthesis. In fact,
when tosyl chloride was replaced by iodine, permanganate, sulfu-
ric anhydride–pyridine complex, pyridinium chlorochromate, ox-
one or N-chlorosuccinimide, the progenitor thiocarbamate or
unidentified products were recovered.
The formation of the disulfide bridge has been indirectly con-
firmed by 13C NMR and 1H NMR spectra (lack of the C@S carbon
and NH proton signals, respectively) and by IR spectra (absence
of the N–H stretching band and presence of the C@N stretching
band at 1625–1662 cmꢀ1).
In principle four different DS geometric isomers are possible, but,
because of the symmetry of the molecule, their number diminishes
to three (Z,Z; E,Z; and E,E, Fig. 5). Computational analysis (see Section
5.3) performed on a simplified derivative of 1 (Fig. 5), selected as a
model compound, predicted the Z,Z-isomer to be, respectively,
1.62 and1.00 kcal/mollowerin energythanthe E,Z-and E,E-isomers,
and therefore potentially favoured. In the future, X-ray crystallogra-
phy will be employed to define the stereochemistry of DSs.
dexes (SI). Trovirdine was employed as the reference molecule (Ta-
bles 1–4). To determine whether the title compounds targeted
HIV-1 RT, the most potent disulfide was tested also in enzyme as-
say against the HIV-1 virionic RT (vRT) (Table 5). The most active
DSs were screened in cell-based assays against the clinically rele-
vant K103R, Y181C and K103N/Y181C resistant mutants,33,34 using
Efavirenz as reference molecule (Table 6).
The results of Table 1 suggest that, as observed also for C-TCs,15
the substitution at the para position of the N-phenyl ring has signif-
icant impact on anti-HIV-1 activity: in fact, all the para-substituted
analogues (11–20), with the exception of the 4-acetyl 14, showed
nanomolar EC50 values (10–100 nM), with a 3.5- to 35-fold increase
in potency compared to the lead 1. The 4-fluoro (15), 4-chloro (16)
and 4-bromo (17) derivatives were more or as active as Trovirdine.
In particular DS 17, with an EC50 of 10 nM, was the most potent DS
of the series. The ortho and meta positional isomers resulted to be
less potent than the corresponding para congeners (15 vs 6 and 3;
16 vs 7 and 4; 11 vs 2; 12 vs 5; 17 vs 8; 19 vs 9; 20 vs 10). The intro-
duction of a chloro (7) or a nitro (9) group at position meta led to sub-
micromolar inhibitors, even if less potent than the lead 1, while the
other meta derivatives (5, 6, 8, 10) prevented the viral replication at
micromolar concentrations. The ortho substitution was detrimental
and only the introduction of a fluorine atom (3), less bulky than a
chlorine (4) or a methyl (2), was tolerated. The electronic properties
of theN-phenylringsubstituentdid notseemto affecttheactivity;in
fact, the most potent of the para-substituted analogues bore either
electron-withdrawing groups, such as fluoro (15), chloro (16), bro-
mo (17), iodo (18), nitro (19), or electron-donating groups, such as
methyl (11) and methoxy (20), and, among the meta derivatives,
3. Biological results and discussion
The antiretroviral activity of DS 1–41 was evaluated in MT-4
cell-based assays by assessing the reduction of the HIV-1 induced
cytopathogenicity. The results are expressed as EC50 values. In par-
allel with antiretroviral activity, the DS-induced cytotoxicity was
evaluated in mock-infected MT-4 cells. The results are expressed
as CC50 values, which have been used to calculate the selectivity in-

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S. Cesarini et al. / Bioorg. Med. Chem. 16 (2008) 6353–6363
Table 1
Table 3
Effects of the N-phenyl monosubstitution on cytotoxicity and anti-HIV-1 activity of
Effects of the cycle variation in portion b on cytotoxicity and anti-HIV-1 activity of DS
DS 1–20a
36–38a
O
S
O
S
N
O
N
N
O
N
O
R'
O
2
X
2
SId
b
c
Compound
R0
CC50
EC50
8.0
SId
b
c
Compound
X
CC50
EC50
36
37
38
1-Naphthyl
Cyclopropyl
Benzyl
>100
>100
>100
60
13
1
2
3
4
H
2-CH3
2-F
80
11
43
9
0.35
>11
1.2
>9
2.3
229
<1
36
<1
9.6
>100
7.0
0.02
—
14
3000
Trovirdine
2-Cl
a,b,c,d
See legend to Table 1.
5
6
7
8
3-CF3
3-F
3-Cl
22
38
36
89
5.0
7.6
0.4
90
3-Br
6.0
15
9
10
11
12
13
14
15
16
17
18
19
20
3-NO2
3-OCH3
4-CH3
4-CF3
4-CN
4-COCH3
4-F
4-Cl
4-Br
4-I
4-NO2
4-OCH3
>100
80
21
>100
>100
>100
29
88
42
48
>100
90
0.7
1.3
0.04
0.1
0.1
143
6.1
Table 4
Effects of the modifications of portion a on cytotoxicity and anti-HIV-1 activity of DS
525
>1000
>1000
>4.2
1450
5500
4200
1600
>1429
1500
3000
39–41a
24
0.02
0.02
0.01
0.03
0.07
0.06
0.02
S
N
X
n
O
G
Trovirdine
60
a
Data mean values for three separate experiments. Variation among triplicate
samples was less than 10%.
2
b
Compound concentration (lM) required to reduce the viability of mock-infec-
SId
b
c
Compound
G
n
X
CC50
EC50
ted cells by 50%, as determined by the MTT method.
c
39
40
41
Phthalimido
2
1
1
Br
Br
H
>100
>100
70
>100
1.3
—
>77
6.4
Compound concentration (lM) required to achieve 50% protection of MT-4 cell
4-Methylphthalimido
Phenyl
from HIV-1 induced cytopathogenicity, as determined by the MTT method.
d
11
0.02
Selectivity index: CC50/EC50 ratio.
Trovirdine
60
3,000
a,b,c,d
See legend to Table 1.
Table 2
Effects of the N-phenyl di- and trisubstitution on cytotoxicity and anti-HIV-1 activity
of DS 21–35a
the activity trend was chloro (7) > nitro (9) > methoxy (10) > fluoro
(6) > bromo (8). At the para position, a hydrophobic substituent,
such as a methyl (11) or halogen atom (15–18), was preferred to a
relatively hydrophilic functionality, such as a nitro- (19), cyano-
(13) or acetyl- (14) group (in particular the acetyl group caused a
dramatic potency decrease).
O
S
N
O
N
The N-phenyl di- and trisubstitution led generally to active
compounds (Table 2). In particular DS 22 (2,4-difluoro), 30 (3-
chloro-4-methyl) and 32 (4-chloro-3-nitro) showed EC50 values
in the nanomolar concentration range. DS 30 and 32 were, respec-
tively, 1.8- and 5-fold more potent than the lead 1. The difluoro-
derivatives resulted to be more active than the corresponding di-
chloro-congeners (22 vs 26 and 23 vs 27), with the exception of
the 3,5-analogues, which in both cases exhibited no antiviral activ-
ity (24, 29). In this connection, the replacement of the chlorine
atoms with methyl groups (endowed with similar steric and lipo-
philic properties, but opposite electronic features) was beneficial
(21). The introduction of a substituent at position para confirmed
to be effective: the 2,4,6-trifluoro-DS (34) and the 2,4- and 3,4-
dihalosubstituted derivatives (22, 26, 33 and 28, 30–32, respec-
tively) were endowed with higher activity than the corresponding
analogues not bearing an halogen atom at the para position. Be-
sides, the most potent disubstituted derivatives had a substituent
at position 4 (22, 30 and 32). The steric hindrance of the ortho-sub-
stituent seemed to affect the activity, as the 2-fluoro- (22, 23) and
2,6-difluoro- (34) derivatives were more active than the analogues
O
X,Y,(Z)
2
b
c
Compound
X,Y,(Z)
CC50
EC50
SId
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
3,5-(CH3)2
2,4-F2
2,5-F2
>100
27
3.0
0.5
1.3
>37
18
4.0
>100
7.0
>42
0.2
28
0.07
1.8
1.2
>33
541
40
52
37
37
3,5-F2
<1
2,3-Cl2
2,4-Cl2
2,5-Cl2
3,4-Cl2
3,5-Cl2
2.1
>25
—
>14
<1
>500
3.6
257
44
>100
>100
>100
42
>100
>100
18
3-Cl-4-CH3
4-Cl-3-CF3
4-Cl-3-NO2
4-Br-2-CH3
2,4,6-F3
80
39
33
—
3000
2,6-(CH3)2-4-Br
>100
60
>100
0.02
Trovirdine
a,b,c,d
See legend to Table 1.

S. Cesarini et al. / Bioorg. Med. Chem. 16 (2008) 6353–6363
6357
R'
N
O
O
N
N
R
R
R'
R
S
S
S
S
O
Na+
(a)
(b)
(c)
O
R
OH
R
O
Na+
R
N
R'
1-41
R'
A1-4
S1-4
B1-41
Scheme 1. Reagents and conditions: (a) NaH (1 equiv), dry DMF (THF for 3, 23, 37, 38, 41), rt, 30 min; (b) R0NCS (I1–38, 1 equiv), rt, 2 h; (c) TMEDA (2.1 equiv), TsCl (1.6 equiv),
rt, 5 h. For the structure list of alcohols A1–4 and isothiocyanates I1–38, see Figure 4.
(a) Alcohols A1-4
O
n
OH
N
W
OH
O
A1: W = H; n= 1
A4
A2: W = CH3; n= 1
A3: W = H; n= 2
(b) Isothiocyanates R'NCS (I1-38
)
R'
I1 phenyl
I2 2-tolyl
I3 2-fluorophenyl
I4 2-chlorophenyl
I5 3-trifluoromethylphenyl
I6 3-fluorophenyl
I7 3-chlorophenyl
I8 3-bromophenyl
I9 3-nitrophenyl
R'
I20 4-methoxyphenyl
I21 3,5-dimethylphenyl
I22 2,4-difluorophenyl
I23 2,5-difluorophenyl
I24 3,5-difluorophenyl
I25 2,3-dichlorophenyl
I26 2,4-dichlorophenyl
I27 2,5-dichlorophenyl
I28 3,4-dichlorophenyl
I29 3,5-dichlorophenyl
I30 3-chloro-4-methylphenyl
I31 4-chloro-3-trifluoromethylphenyl
I32 4-chloro-3-nitrophenyl
I33 4-bromo-2-methylphenyl
I34 2,4,6-trifluorophenyl
I35 2,6-dimethyl-4-fluorophenyl
I36 1-naphthyl
I10 3-methoxyphenyl
I11 4-tolyl
I12 4-trifluoromethylphenyl
I13 4-cyanophenyl
I14 4-acetylphenyl
I15 4-fluorophenyl
I16 4-chlorophenyl
I17 4-bromophenyl
I18 4-iodophenyl
I37 cyclopropyl
I19 4-nitrophenyl
I38 benzyl
Figure 4. Building blocks used.
bearing more encumbering groups at those positions (25–27, 33,
35). At the meta position of the 3,4-derivatives, a chlorine atom
or a nitro group were favoured in comparison with a trifluoro-
methyl (compare 28, 30 and 32 with 31).
Data of Table 3 show that the replacement of the N-phenyl ring
with a more sterically demanding 1-naphthyl (36) and the inser-
tion of a methylene between the phenyl and the thiocarbamic
function (38) caused, respectively, a 23- and 20-fold drop in activ-
N
N
N
O
S
S
O
S
S
O
S
S
O
O
O
Table 5
Activity of 17 in enzyme assay against HIV-1 virionic RT (vRT)a
N
N
N
b
Compound
IC50 (lM)
17
0.74
1.06
0.02
Trovirdine
Efavirenz
Z,Z
E,Z
E,E
a
See legend to Table 1.
Compound concentration (lM) required to inhibit the HIV-1 virion-associated
Figure 5. The three possible geometric isomers of the simplified derivative of 1 (2-
phthalimidoethyl substituents replaced by methyl groups) used in the computa-
tional analysis.
b
RT (vRT) activity by 50%.

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S. Cesarini et al. / Bioorg. Med. Chem. 16 (2008) 6353–6363
Table 6
pot procedure has been parallelized thus enabling a rapid analogu-
ing. Many DSs were micro- and nanomolar inhibitors and proved
to target RT. The N-phenyl para-substitution was found particu-
larly beneficial and the most potent DS so far synthesized (17:
para-bromo) displayed an EC50 value of 10 nM. Two disulfides re-
sulted moderately effective against Y181C and/or K103R mutant
strains. Overall, these results encourage us to further study DSs,
with the aim at determining their stereochemistry, mode of bind-
ing to RT and structural features to improve the resistance profile.
Anti-HIV-1 activity of 19 and 33 against Y181C and K103R resistant mutantsa
c
Compound
EC50 (lM)
Y181C
K103R
19
33
Efavirenz
57
35
0.01
62
n.a.b
0.04
a,cSee legend to Table 1.
b
Not active.
ity (36 and 38 vs 1), whereas the replacement of the phenyl with a
cyclopropyl (37) produced activity loss.
5. Experimental protocols
5.1. Chemistry
Regarding the modifications on portion a (Table 4), the intro-
duction of a methyl at position 4 of the phthalimide substructure
was not beneficial (40 vs 17), differently from TCs where this var-
iation caused potency enhancement.15 The elongation of the ethyl
linker to propyl led to an inactive compound (compare 39 with 17).
Also the omission of the benzofused five-membered ring (41) had a
negative impact on the inhibitory activity, which nevertheless re-
mained in the micromolar concentration range.
To determine whether the title compounds targeted HIV-1 RT,
the DS 17 was tested in enzyme assay against the HIV-1 virion-asso-
ciated RT (vRT) (Table 5). The disulfide resulted to be 1.4-fold more
potent than Trovirdine and 37-fold less potent than Efavirenz. The
considerable difference of potency in enzyme- and cell-based assays
(observed also for Trovirdine, C-TCs15 and ATCs16 could be ascribed
to two factors. The first one is that vRT is a p51–p66 dimer engaged
in complex interactions with the viral genome and core proteins that
may not become totally disrupted during virion lysis, thus affecting
the bindingof the NNRTI to thenon-nucleoside inhibitor bindingsite
(NNIBS). A second explanation is the possibility that DSs are slow
binding kinetics inhibitors.35
Interestingly, DS 1, 3, 5, 7, 10, 15–17 resulted to be more po-
tent than the corresponding C-TCs endowed with the same sub-
stitution pattern, while DS 2, 9, 11–14, 18–20, 36 and 41 turned
out to be less active.15,17 The X-ray analysis of C-TC/RT com-
plexes36 has demonstrated that the hydrogen bond between
the C-TC NH group and the Lys101 main chain carbonyl is one
of the interactions which contribute the most to stabilize the
complexes. Since DSs are unable to establish this hydrogen bond
(owing to the dimerization of the C-TC isothiocarbamic form),
the differences in activity between the dimers (DSs) and the
monomers (C-TCs) might correlate with a different mode of
binding to RT of the two classes of inhibitors. In order to eluci-
date the binding mode of the title compounds, crystallographic
studies on RT/DS complexes will be performed.
5.1.1. General
All chemicals were purchased by Chiminord and Aldrich
Chemical, Milan (Italy). Solvents were of reagent grade. THF
was distilled in the presence of sodium. DMF was dried on
molecular sieves (5 Å 1/1600 inch pellets). Unless otherwise sta-
ted, all commercial reagents were used without further purifica-
tion. Organic solutions were dried over anhydrous sodium
sulfate. Thin layer chromatography (TLC) system for routine
monitoring the course of reactions and confirming the purity
of analytical samples employed aluminium-backed silica gel
plates (Merck DC-Alufolien Kieselgel 60 F254): CHCl3 or diethyl
ether was used as developing solvents and detection of spots
was made by UV light and/or by iodine vapours.
The parallel solution-phase chemistry was performed by using a
Carousel-6TM reaction station (Radleys Discovery Technologies, Ital-
ian distributor: StepBio, Bologna). The evaporation of solutions in
parallel fashion was performed with an EvaposelTM apparatus (Rad-
leys Discovery Technologies, Italian distributor: StepBio, Bologna)
operating at reduced pressure of about 15–20 Torr. Yields were not
optimized.
Melting points were determined on a Fisher–Johns apparatus and
are uncorrected. IR spectra were recorded on a Perkin Elmer 398
spectrometer as KBr discs. 1H NMR and 13C NMR spectra were re-
corded in CDCl3, DMSO-d6 or CF3COOD on a Varian Gemini 200
instrument. Chemical shifts were reported in d (ppm) units relative
to the internal standard tetramethylsilane, and the splitting patterns
were described as follows: s (singlet), d (doublet), dd (doublet of
doublets), t (triplet), m (multiplet) and br s (broad singlet). The first
order values reported for coupling constants J were given in Hz. Ele-
mental analyses were performed by an EA1110 Elemental Analyser
(Fison-Instruments, Milan) and were within 0.4% of the theoretical
values. The synthesis of Trovirdine and alcohol A2 was accomplished
according to published procedures.15,19
In cell-based assays, the Y181C, K103R and K103N + Y181C mu-
tated strains proved to be unsusceptible to the DSs, with the excep-
tion of 19 and 33 (Table 6), which turned out to be weakly active
against Y181C and/or K103R resistant mutants.
All compounds, except the N-ortho-substituted-phenyl deriva-
tives 2 and 4 and the N-3,5-dihalosubstituted-phenyl derivatives
24 and 29, showed values of CC50 higher than EC50 (CC50 in several
cases superior to 100 lM). DS 1, 11–13, 15–20, 22, 30 and 32 (Ta-
bles 1 and 2) displayed good selectivity indexes.
5.1.2. Parallel synthesis of disulfides 1–41
Sodium hydride dispersion (60%) in mineral oil (0.40 g,
10 mmol) was added at rt in a single portion into each numbered
round-bottomed flask of a Carousel-6TM reaction station, containing
a stirred solution of the suitable alcohol A1–4 (10 mmol) in 25 mL of
dry DMF (THF for 3, 23, 37, 38 and 41). After stirring for 30 min, the
proper isothiocyanate I1–38 (10 mmol) was added to each reaction
mixture, which was then stirred for 2 h at rt (for 38, the addition of
25 mL of dry DMF was required to allow the stirring of the thick
suspension formed). Then, TMEDA (2.44 g, 21 mmol) and tosyl
chloride (3.05 g, 16 mmol) were added sequentially, each one in
one portion. The resulting mixture was vigorously stirred at rt
for 5 h, and then in most cases diluted with 150 mL of water. For
3, 23, 37, 38 and 41, each reaction mixture was first transferred
into an EvaposelTM-tube and, after evaporation of THF in vacuo in
parallel fashion using an EvaposelTM apparatus, 40 mL of water
were added into each tube; the contents of the tubes were then
4. Conclusions
A novel class of potent NNRTIs was discovered and a SAR study
has been performed. The scaffold novelty came out from the
molecular duplication of the isothiocarbamic form of NNRTI C-
TCs. To the best of our knowledge, this is the first example of sym-
metric disulfides as NNRTIs, and the procedure by which they have
been obtained represents a new synthetic method to prepare sym-
metric formimidoester disulfides from thiocarbamates. The one-

S. Cesarini et al. / Bioorg. Med. Chem. 16 (2008) 6353–6363
6359
transferred into a set of beakers and 110 mL of water were added
into each beaker.
J = 5.2 Hz, 4H, 2CH2N), 4.36 (t, J = 5.2 Hz, 4H, 2CH2O), 6.88–6.99
(m, 4H, arom. H), 7.14–7.29 (m, 4H, arom. H), 7.56–7.79 (m,
8H, phthal. arom. H). Anal. Calcd for C36H24F6N4O6S2: C, 54.96;
H, 3.07; N, 7.12; S, 8.15. Found: C, 55.22; H, 3.25; N, 7.01; S, 8.19.
Two different types of work-up were carried out depending
on whether a filterable precipitate was obtained (i) or not (ii).
Work-up (i) (9, 10, 14, 22, 24, 26, 29 and 36–38): the precipitates
obtained were filtered off in parallel by an in-house device and
dissolved in CH2Cl2 (120 mL). The solutions were washed with
water (2ꢁ 30 mL), dried over anhydrous Na2SO4 and filtered in
parallel through pads of Florisil (diameter 5 ꢁ 2 cm) by an in-
house device. Evaporation in parallel under reduced pressure
using an EvaposelTM apparatus gave residues, which were purified
by crystallization from the suitable solvents or solvent mixtures.
Work-up (ii) (1–8, 11–13, 15–21, 23, 25, 27, 28, 30–35, and 39–
41): the contents of the round-bottomed flasks/beakers were
transferred into a set of separating funnels. After parallel extrac-
tion with diethyl ether (CH2Cl2 for 1, 12, 13, 15, 19, 20, 30 and
32) (3ꢁ 50 mL), the combined extracts of each reaction were
washed with water (5ꢁ 30 mL), dried over anhydrous Na2SO4
and filtered in parallel through pads of Florisil (diameter
5 ꢁ 2 cm) by an in-house device. Evaporation in parallel under
reduced pressure using an EvaposelTM apparatus gave residues,
which were purified by crystallization from the suitable solvents
or solvent mixtures.
5.1.2.6. 2-[2-({({[2-(1,3-Dioxo-1,3-dihydro-2H-isoindol-2-yl)-
ethoxy][(3-fluorophenyl)imino]methyl}dithio)[(3-fluorophenyl)-
imino]methyl}oxy)ethyl]-1,3-dioxoisoindoline 6. Mp 159–161 °C;
yield: 18% from diethyl ether. IR (KBr) cmꢀ1: 1781, 1718, 1647.
1H NMR (CDCl3) d: 3.86–3.98 (m, 4H, 2CH2N), 4.26–4.41 (m, 4H,
2CH2O), 6.44–6.75 (m, 6H, arom. H), 6.99–7.13 (m, 2H, arom. H),
7.58–7.83 (m, 8H, phthal. arom. H). Anal. Calcd for
C
34H24F2N4O6S2: C, 59.47; H, 3.52; N, 8.16; S, 9.34. Found: C,
59.22; H, 3.79; N, 8.16; S, 9.27.
5.1.2.7. 2-[2-({({[2-(1,3-Dioxo-1,3-dihydro-2H-isoindol-2-yl)-
ethoxy][(3-chlorophenyl)imino]methyl}dithio)[(3-chlorophenyl)-
imino]methyl}oxy)ethyl]-1,3-dioxoisoindoline
7. Mp
140–
141 °C; yield: 15% from DCM/ethanol. IR (KBr) cmꢀ1: 1782,
1718, 1642. 1H NMR (CDCl3) d: 4.03 (t, J = 5.2 Hz, 4H, 2CH2N),
4.45 (t, J = 5.2 Hz, 4H, 2CH2O), 6.70–6.88 (m, 4H, arom. H), 6.96–
7.22 (m, 4H, arom. H), 7.67–7.96 (m, 8H, phthal. arom. H). Anal.
Calcd for C34H24Cl2N4 O6S2: C, 56.75; H, 3.36; N, 7.79; S, 8.91.
Found: C, 56.66; H, 3.39; N, 7.71; S, 8.88.
5.1.2.1. 2-(2-{[({[2-(1,3-Dioxo-1,3-dihydro-2H-isoindol-2-yl)-
ethoxy](phenylimino)methyl}dithio)(phenylimino)methyl]oxy}-
ethyl)-1,3-dioxoisoindoline 1. Mp 152–154 °C; yield: 44% from
CH2Cl2/ethanol. IR (KBr) cmꢀ1: 1782, 1719, 1643. 1H NMR (CDCl3)
d: 3.95 (t, J = 5.4 Hz, 4H, 2CH2N), 4.33 (t, J = 5.4 Hz, 4H, 2CH2O),
6.71–7.16 (m, 10H, arom. H), 7.57–7.83 (m, 8H, phthal. arom. H).
Anal. Calcd for C34H26N4O6S2: C, 62.76; H, 4.03; N, 8.61; S, 9.85.
Found: C, 62.72; H, 4.13; N, 8.68; S, 9.52.
5.1.2.8. 2-[2-({({[2-(1,3-Dioxo-1,3-dihydro-2H-isoindol-2-yl)ethoxy]-
[(3-bromophenyl)imino]methyl}dithio)[(3-bromophenyl)imino]-
methyl}oxy)ethyl]-1,3-dioxoisoindoline
8. Mp
128–130 °C;
yield: 84% from DCM/diethyl ether. IR (KBr) cmꢀ1: 1782, 1718,
1652. 1H NMR (CDCl3) d: 4.03 (t, J = 5.0 Hz, 4H, 2CH2N), 4.45 (t,
J = 5.0 Hz, 4H, 2CH2O), 6.75–6.84 (m, 2H, arom. H), 6.94–7.24 (m,
6H, arom. H), 7.67–7.94 (m, 8H, phthal. arom. H). Anal. Calcd for
C34H24Br2N4O6S2: C, 50.51; H, 2.99; N, 6.93; S, 7.93. Found: C,
5.1.2.2. 2-[2-({({[2-(1,3-Dioxo-1,3-dihydro-2H-isoindol-2-yl)-
ethoxy][(2-methylphenyl)imino]methyl}dithio)[(2-methylphenyl)-
imino]methyl}oxy)ethyl]-1,3-dioxoisoindoline 2. Mp 150–
152 °C; yield: 57% from CH2Cl2/ethanol. IR (KBr) cmꢀ1: 2950,
1778, 1717, 1642. 1H NMR (CDCl3) d: 2.03 (s, 6H, 2CH3), 3.91–
4.26 (m, 4H, 2CH2N), 4.35–4.68 (m, 4H, 2CH2O), 6.76–7.18 (m,
8H, arom. H), 7.58–7.95 (m, 8H, phthal. arom. H). Anal. Calcd
for C36H30N4O6S2: C, 63.70; H, 4.45; N, 8.25; S, 9.45. Found: C,
63.79; H, 4.62; N, 8.01; S, 9.21.
50.43; H, 3.31; N, 6.63; S, 7.58.
5.1.2.9. 2-[2-({({[2-(1,3-Dioxo-1,3-dihydro-2H-isoindol-2-yl)-
ethoxy][(3-nitrophenyl)imino]methyl}dithio)[(3-nitrophenyl)-
imino]methyl}oxy)ethyl]-1,3-dioxoisoindoline
9. Mp
187–
189 °C; yield: 44% from DCM/methanol. IR (KBr) cmꢀ1
:
1771, 1708, 1629, 1526, 1334. 1H NMR (DMSO-d6) d: 3.85–
3.96 (m, 4H, 2CH2N), 4.68–4.79 (m, 4H, 2CH2O), 7.37–7.99
(m, 16H, arom. H). Anal. Calcd for C34H24N6O10S2: C, 55.13;
H, 3.27; N, 11.35; S, 8.66. Found: C, 55.19; H, 3.48; N,
11.22; S, 8.46.
5.1.2.3. 2-[2-({({[2-(1,3-Dioxo-1,3-dihydro-2H-isoindol-2-yl)-
ethoxy][(2-fluorophenyl)imino]methyl}dithio)[(2-fluorophenyl)-
imino]methyl}oxy)ethyl]-1,3-dioxoisoindoline
3. Mp
113–
5.1.2.10. 2-[2-({({[2-(1,3-Dioxo-1,3-dihydro-2H-isoindol-2-yl)-
ethoxy][(3-methoxyphenyl)imino]methyl}dithio)[(3-methoxy-
phenyl)imino]methyl}oxy)ethyl]-1,3-dioxoisoindoline 10. Mp
117–119 °C; yield: 17% from DCM/diethyl ether. IR (KBr)
115 °C; yield: 9% from acetone/ethanol. IR (KBr) cmꢀ1: 1775, 1717,
1635. 1H NMR (CDCl3) d: 3.88–4.08 (m, 4H, 2CH2N), 4.32–4.53 (m,
4H, 2CH2O), 6.73–7.07 (m, 8H, arom. H), 7.57–7.88 (m, 8H, phthal.
arom. H). Anal. Calcd for C34H24F2N4O6S2: C, 59.47; H, 3.52; N,
8.16; S, 9.34. Found: C, 59.67; H, 3.79; N, 7.94; S, 9.25.
cmꢀ1
:
1777, 1721, 1639. 1H NMR (CDCl3) d: 3.67 (s, 6H,
2CH3), 3.86–3.95 (m, 4H, 2CH2N), 4.25–4.33 (m, 4H, 2CH2O),
6.28–6.55 (m, 6H, arom. H), 6.94–7.01 (m, 2H, arom. H), 7.55–
7.77 (m, 8H, phthal. arom. H). Anal. Calcd for C36H30N4O8S2: C,
60.83; H, 4.25; N, 7.88; S, 9.02. Found: C, 60.81; H, 4.32; N,
7.87; S, 9.09.
5.1.2.4. 2-[2-({({[2-(1,3-Dioxo-1,3-dihydro-2H-isoindol-2-yl)-
ethoxy][(2-chlorophenyl)imino]methyl}dithio)[(2-chlorophen-
yl)imino]methyl}oxy)ethyl]-1,3-dioxoisoindoline 4. Mp 153–
155 °C; yield: 45% from DCM/ethanol. IR (KBr) cmꢀ1: 1776, 1718,
1634. 1H NMR (CDCl3) d: 4.11 (t, J = 5.2 Hz, 4H, 2CH2N), 4.52 (t,
J = 5.2 Hz, 4H, 2CH2O), 6.93–7.24 (m, 8H, arom. H), 7.68–7.92 (m,
8H, phthal. arom. H). Anal. Calcd for C34H24Cl2N4O6S2: C, 56.75; H,
3.36; N, 7.79; S, 8.91. Found: C, 56.52; H, 3.32; N, 7.67; S, 8.89.
5.1.2.11. 2-[2-({({[2-(1,3-Dioxo-1,3-dihydro-2H-isoindol-2-yl)-
ethoxy][(4-methylphenyl)imino]methyl}dithio)[(4-methylphenyl)-
imino]methyl}oxy)ethyl]-1,3-dioxoisoindoline 11. Mp 139–
141 °C; yield: 47% from DCM/methanol. IR (KBr) cmꢀ1: 2927,
1780, 1709, 1632. 1H NMR (CDCl3) d: 2.22 (s, 6H, 2CH3), 3.94
(t, J = 5.4 Hz, 4H, 2CH2N), 4.32 (t, J = 5.4 Hz, 4H, 2CH2O), 6.58–
6.70 (m, 4H, arom. H), 6.88–6.99 (m, 4H, arom. H), 7.59–7.83
(m, 8H, phthal. arom. H). Anal. Calcd for C36H30N4O6S2: C,
63.70; H, 4.45; N, 8.25; S, 9.45. Found: C, 63.61; H, 4.42; N,
8.17; S, 9.54.
5.1.2.5. 2-[2-({({[2-(1,3-Dioxo-1,3-dihydro-2H-isoindol-2-yl)-
ethoxy][(3-trifluoromethylphenyl)imino]methyl}dithio)[(3-
trifluoromethylphenyl)imino]methyl}oxy)ethyl]-1,3-dioxoiso-
indoline 5. Mp 125–126 °C; yield: 68% from diethyl ether/etha-
nol. IR (KBr) cmꢀ1: 1781, 1717, 1662. 1H NMR (CDCl3) d: 3.93 (t,

6360
S. Cesarini et al. / Bioorg. Med. Chem. 16 (2008) 6353–6363
5.1.2.12. 2-[2-({({[2-(1,3-Dioxo-1,3-dihydro-2H-isoindol-2-yl)-
ethoxy][(4-trifluoromethylphenyl)imino]methyl}dithio)[(4-tri-
fluoromethylphenyl)imino]methyl}oxy)ethyl]-1,3-dioxoisoin-
doline 12. Mp 189–191 °C; yield: 32% from DCM/ethanol. IR
(KBr) cmꢀ1: 1781, 1722, 1641. 1H NMR (CDCl3) d: 3.98–4.09 (m,
4H, 2CH2N), 4.38–4.49 (m, 4H, 2CH2O), 6.89–6.99 (m, 4H, arom.
H), 7.42–7.51 (m, 4H, arom. H), 7.76–7.88 (m, 8H, phthal. arom.
H). Anal. Calcd for C36H24F6N4O6S2: C, 54.96; H, 3.07; N, 7.12; S,
8.15. Found: C, 54.84; H, 3.16; N, 7.05; S, 8.21.
1780, 1710, 1632. 1H NMR (CDCl3) d: 3.95–4.13 (m, 4H, 2CH2N),
4.28–4.49 (m, 4H, 2CH2O), 6.65–6.90 (m, 4H, arom. H), 7.25–
7.45 (m, 4H, arom. H), 7.67–7.91 (m, 8H, phthal. arom. H). Anal.
Calcd for C34H24Br2N4O6S2: C, 50.51; H, 2.99; N, 6.93; S, 7.93.
Found: C, 50.55; H, 3.13; N, 6.89; S, 7.86.
5.1.2.18. 2-[2-({({[2-(1,3-Dioxo-1,3-dihydro-2H-isoindol-2-yl)-
ethoxy][(4-iodophenyl)imino]methyl}dithio)[(4-iodophenyl)-
imino]methyl}oxy)ethyl]-1,3-dioxoisoindoline 18. Mp 133–
135 °C; yield: 27% from DCM/petroleum ether. IR (KBr) cmꢀ1
:
5.1.2.13. 2-[2-({({[2-(1,3-Dioxo-1,3-dihydro-2H-isoindol-2-yl)-
ethoxy][(4-cyanophenyl)imino]methyl}dithio)[(4-cyanophenyl)-
imino]methyl}oxy)ethyl]-1,3-dioxoisoindoline 13. Mp 222–
1782, 1719, 1634. 1H NMR (CDCl3) d: 3.95–4.14 (m, 4H, 2CH2N),
4.29–4.50 (m, 4H, 2CH2O), 6.55–6.74 (m, 4H, arom. H), 7.44–7.63
(m, 4H, arom. H), 7.72–7.95 (m, 8H, phthal. arom. H). Anal. Calcd
for C34H24I2N4O6S2: C, 45.25; H, 2.68; N, 6.21; S, 7.11. Found: C,
45.55; H, 2.73; N, 5.95; S, 6.86.
224 °C; yield: 20% from DCM/petroleum ether. IR (KBr) cmꢀ1
:
2224, 1776, 1709, 1634. 1H NMR (CDCl3) d:3.93 (t, J = 5.2 Hz,
4H, 2CH2N), 4.33 (t, J = 5.2 Hz, 4H, 2CH2O), 6.78–6.90 (m, 4H,
arom. H), 7.33–7.43 (m, 4H, arom. H), 7.64–7.78 (m, 8H, phthal.
arom. H). 13C NMR (CDCl3) d: 36.43 (2CH2N), 67.29 (2CH2O),
107.77 (2CN), 119.20 (2C), 122.43 (4CH), 123.57 (4 phthal. CH),
131.97 (4 phthal. C), 133.37 (4CH), 134.45 (4 phthal. CH),
149.85 (2C), 153.90 (2C@N), 167.94 (4C@O). Anal. Calcd for
5.1.2.19. 2-[2-({({[2-(1,3-Dioxo-1,3-dihydro-2H-isoindol-2-yl)-
ethoxy][(4-nitrophenyl)imino] methyl}dithio)[(4-nitrophenyl)-
imino]methyl}oxy)ethyl]-1,3-dioxoisoindoline 19. Mp 239–241 °C;
yield: 44% from DCM/methanol. IR (KBr) cmꢀ1: 1777, 1720, 1634,
1504, 1346. 1H NMR (CF3COOD) d: 4.25–4.46 (m, 4H, 2CH2N), 5.00–
5.19 (m, 4H, 2CH2O), 7.46–7.72 (m, 4H, arom. H), 7.86–8.05 (m, 8H,
phthal. arom. H), 8.18–8.35 (m, 4H, arom. H). Anal. Calcd for
C
36H24N6O6S2: C, 61.71; H, 3.45; N, 11.99; S, 9.15. Found: C,
62.00; H, 3.45; N, 12.08; S, 9.09.
C34H24N6O10S2: C, 55.13; H, 3.27; N, 11.35; S, 8.66. Found: C, 54.81; H,
5.1.2.14. 2-[2-({({[2-(1,3-Dioxo-1,3-dihydro-2H-isoindol-2-yl)-
ethoxy][(4-acetylphenyl)imino]methyl}dithio)[(4-acetylphenyl)-
imino]methyl}oxy)ethyl]-1,3-dioxoisoindoline 14. Mp 214–
216 °C; yield: 54% from DMF/ethanol. IR (KBr) cmꢀ1: 1778, 1710,
1681, 1636. 1H NMR (CDCl3) d: 2,58 (s, 6H, 2CH3), 3.97–4.10
(m, 4H, 2CH2N), 4.37–4.50 (m, 4H, 2CH2O), 6.83–6.96 (m, 4H,
arom. H), 7.67–7.93 (m, 12H, arom. H). 13C NMR (CDCl3) d:
26.60 (2CH3), 36.51 (2CH2N), 66.97 (2CH2O), 121.59 (4CH),
123.55 (4 phthal. CH), 129.82 (4CH), 132.01 (4 phthal. C),
133.37 (2C), 134.33 (4 phthal. CH), 150.23 (2C), 153.58
(2C@N), 167.95 (4 phthal. C@O), 197.17 (2C@O). Anal. Calcd
for C38H30N4O8S2: C, 62.11; H, 4.12; N, 7.62; S, 8.73. Found: C,
62.05; H, 4.43; N, 7.55; S, 8.64.
3.47; N, 11.35; S, 8.72.
5.1.2.20. 2-[2-({({[2-(1,3-Dioxo-1,3-dihydro-2H-isoindol-2-yl)-
ethoxy][(4-methoxyphenyl)imino]methyl}dithio)[(4-methoxyphenyl)-
imino]methyl}oxy)ethyl]-1,3-dioxoisoindoline 20. Mp 159–161 °C;
yield: 8% from DCM/MeOH. IR (KBr) cmꢀ1: 1778, 1710, 1632. 1H
NMR (CDCl3) d: 3.79 (s, 6H, 2CH3), 3.99–4.19 (m, 4H, 2CH2N),
4.30–4.51 (m, 4H, 2CH2O), 6.70–6.93 (m, 8 H, arom. H), 7.75–
7.93 (m, 8H, phthal. arom. H). Anal. Calcd for C36H30N4O8S2: C,
60.83; H, 4.25; N, 7.88; S, 9.02. Found: C, 60.71; H, 4.48; N,
7.65; S, 8.63.
5.1.2.21. 2-[2-({({[2-(1,3-Dioxo-1,3-dihydro-2H-isoindol-2-yl)-
ethoxy][(3,5-dimethylphenyl)imino]methyl}dithio)[(3,5-dimeth-
ylphenyl)imino]methyl}oxy)ethyl]-1,3-dioxoisoindoline 21. Mp
144–146 °C; yield: 39% from DCM/ethanol. IR (KBr) cmꢀ1: 1779,
1722, 1643. 1H NMR (CDCl3) d: 2.14 (s, 12H, 4CH3), 3.90–4.01
(m, 4H, 2CH2N), 4.31–4.43 (m, 4H, 2CH2O), 6.30–6.36 (m, 4H,
arom. H-2 and H-6), 6.57–6.64 (m, 2H, arom. H-4), 7.58–7.83
(m, 8H, phthal. arom. H). Anal. Calcd for C38H34N4O6S2: C,
64.57; H, 4.85; N, 7.93; S, 9.07. Found: C, 64.69; H, 5.07; N,
7.75; S, 8.97.
5.1.2.15. 2-[2-({({[2-(1,3-Dioxo-1,3-dihydro-2H-isoindol-2-yl)-
ethoxy][(4-fluorophenyl)imino]methyl}dithio)[(4-fluorophenyl)-
imino]methyl}oxy)ethyl]-1,3-dioxoisoindoline 15. Mp 153–
155 °C; yield: 26% from DCM/ethanol. IR (KBr) cmꢀ1: 1778,
1711, 1630. 1H NMR (CDCl3) d: 3.85–3.96 (m, 4H, 2CH2N),
4.24–4.36 (m, 4H, 2CH2O), 6.57–6.93 (m, 8H, arom. H), 7.56–
7.78 (m, 8H, phthal. arom. H). Anal. Calcd for C34H24F2N4O6S2:
C, 59.47; H, 3.52; N, 8.16; S, 9.34. Found: C, 59.76; H, 3.60; N,
8.15; S, 9.30.
5.1.2.22. 2-[2-({({[2-(1,3-Dioxo-1,3-dihydro-2H-isoindol-2-yl)-
ethoxy][(2,4-difluorophenyl)imino]methyl}dithio)[(2,4-difluoro-
phenyl)imino]methyl}oxy)ethyl]-1,3-dioxoisoindoline 22. Mp
155–157 °C; yield: 39% from diethyl ether/methanol. IR (KBr)
cmꢀ1: 1775, 1722, 1639. 1H NMR (CDCl3) d: 3.88–4.01 (m, 4H,
2CH2N), 4.33–4.43 (m, 4H, 2CH2O), 6.51–6.92 (m, 6H, arom. H),
7.58–7.83 (m, 8H, phthal. arom. H). Anal. Calcd for C34H22F4N4O6S2:
C, 56.51; H, 3.07; N, 7.75; S, 8.87. Found: C, 56.60; H, 3.08; N, 7.71;
S, 8.90.
5.1.2.16. 2-[2-({({[2-(1,3-Dioxo-1,3-dihydro-2H-isoindol-2-yl)-
ethoxy][(4-chlorophenyl)imino]methyl}dithio)[(4-chlorophenyl)-
imino]methyl}oxy)ethyl]-1,3-dioxoisoindoline
16. Mp
185–
187 °C; yield: 31% from diethyl ether. IR (KBr) cmꢀ1: 1779,
1708, 1632. 1H NMR (CDCl3) d: 3.84–3.97 (m, 4H, 2CH2N),
4.20–4.35 (m, 4H, 2CH2O), 6.61–6.73 (m, 4H, arom. H), 6.97–
7.12 (m, 4H, arom. H), 7.56–7.80 (m, 8H, phthal. arom. H). 13C
NMR (CDCl3) d: 36.48 (2CH2N), 66.72 (2CH2O), 122.96 (4CH),
123.53 (4 phthal. CH), 129.23 (4CH), 129.66 (2C), 132.02 (4
phthal. C), 134.30 (4 phthal. CH), 144.32 (2C), 153.90 (2C@N),
5.1.2.23. 2-[2-({({[2-(1,3-Dioxo-1,3-dihydro-2H-isoindol-2-yl)-
ethoxy][(2,5-difluorophenyl)imino]methyl}dithio)[(2,5-difluo-
rophenyl)imino]methyl}oxy)ethyl]-1,3-dioxoisoindoline 23. Mp
123–125 °C; yield: 26% from diethyl ether. IR (KBr) cmꢀ1: 1780,
1721, 1644. 1H NMR (CDCl3) d: 3.97 (t, J = 5.0 Hz, 4H, 2CH2N),
4.42 (t, J = 5.0 Hz, 4H, 2CH2O), 6.53–6.88 (m, 6H, arom. H), 7.60–
7.83 (m, 8H, phthal. arom. H). Anal. Calcd for C34H22F4N4O6S2: C,
56.51; H, 3.07; N, 7.75; S, 8.87. Found: C, 56.45; H, 3.38; N, 7.64;
S, 8.69.
167.96 (4C@O). Anal. Calcd for
C34H24Cl2N4O6S2: C, 56.75;
H, 3.36; N, 7.79; S, 8.91. Found: C, 56.71; H, 3.35; N, 7.81; S,
8.51.
5.1.2.17. 2-[2-({({[2-(1,3-Dioxo-1,3-dihydro-2H-isoindol-2-yl)-
ethoxy][(4-bromophenyl)imino]methyl}dithio)[(4-bromophenyl)-
imino]methyl}oxy)ethyl]-1,3-dioxoisoindoline
17. Mp
146–
148 °C; yield: 35% from acetone/diethyl ether. IR (KBr) cmꢀ1
:

S. Cesarini et al. / Bioorg. Med. Chem. 16 (2008) 6353–6363
6361
5.1.2.24. 2-[2-({({[2-(1,3-Dioxo-1,3-dihydro-2H-isoindol-2-yl)-
ethoxy][(3,5-difluorophenyl) imino]methyl}dithio)[(3,5-difluo-
rophenyl)imino]methyl}oxy)ethyl]-1,3-dioxoisoindoline 24. Mp
145–147 °C; yield: 36% from diethyl ether. IR (KBr) cmꢀ1: 1781,
1717, 1647. 1H NMR (CDCl3) d: 3.87–3.97 (m, 4H, 2CH2N), 4.28–
4.39 (m, 4H, 2CH2O), 4.15–4.49 (m, 6H, arom. H), 7.58–7.82 (m,
8H, phthal. arom. H). Anal. Calcd for C34H22F4N4O6S2: C, 56.51; H,
3.07; N, 7.75; S, 8.87. Found: C, 56.76; H, 3.42; N, 7.36; S, 8.88.
4.58 (m, 4H, 2CH2O), 6.68–7.22 (m, 6H, arom. H), 7.73–7.96
(m, 8H, phthal. arom. H). Anal. Calcd for C36H28Cl2N4O6S2: C,
57.83; H, 3.77; N, 7.49; S, 8.58. Found: C, 58.02; H, 4.02; N,
7.32; S, 8.57.
5.1.2.31. 2-[2-({({[2-(1,3-Dioxo-1,3-dihydro-2H-isoindol-2-yl)-
ethoxy][(4-chloro-3-trifluoromethylphenyl)imino]methyl}dithio)-
[(4-chloro-3-trifluoromethylphenyl)imino]methyl}oxy)ethyl]-1,3-
dioxoisoindoline 31. Mp 163–164 °C; yield: 54% from diethyl
ether/ethanol. IR (KBr) cmꢀ1: 1777, 1711, 1640. 1H NMR (CDCl3)
d: 3.91 (t, J = 5.0 Hz, 4H, 2CH2N), 4.33 (t, J = 5.0 Hz, 4H, 2CH2O),
6.87 (dd, J = 8.4 Hz, J = 2.4 Hz, 2H, arom. H-6), 7.09 (d, J = 2.4 Hz,
2H, arom. H-2), 7.21 (d, J = 8.4 Hz, 2H, arom. H-5), 7.55–7.77
(m, 8H, phthal. arom. H). Anal. Calcd for C36H22F6Cl2N4O6S2: C,
50.54; H, 2.59; N, 6.55; S, 7.49. Found: C, 50.43; H, 2.69; N,
6.54; S, 7.30.
5.1.2.25. 2-[2-({({[2-(1,3-Dioxo-1,3-dihydro-2H-isoindol-2-yl)-
ethoxy][(2,3-dichlorophenyl)imino]methyl}dithio)[(2,3-dichloro-
phenyl)imino]methyl}oxy)ethyl]-1,3-dioxoisoindoline 25. Mp
134–135 °C; yield: 59% from diethyl ether/ethanol. IR (KBr)
cmꢀ1: 1776, 1721, 1639. 1H NMR (CDCl3) d: 3.88–4.05 (m, 4H,
2CH2N), 4.33–4.51 (m, 4H, 2CH2O), 6.71–7.08 (m, 6H, arom. H),
7.53–7.88 (m, 8H, phthal. arom. H). Anal. Calcd for C34H22Cl4N4
O6S2: C, 51.79; H, 2.81; N, 7.11; S, 8.13. Found: C, 51.79; H,
3.18; N, 6.94; S, 8.27.
5.1.2.32. 2-[2-({({[2-(1,3-Dioxo-1,3-dihydro-2H-isoindol-2-yl)-
ethoxy][(4-chloro-3-nitrophenyl)imino]methyl}dithio)[(4-chloro-
3-nitrophenyl)imino]methyl}oxy)ethyl]-1,3-dioxoisoindoline
32. Mp 169–170 °C; yield: 57% from DCM. IR (KBr) cmꢀ1: 1771,
1724, 1634. 1H NMR (CDCl3) d: 3.87–3.98 (m, 4H, 2CH2N),
4.33–4.43 (m, 4H, 2CH2O), 6.97 (dd, J = 8.6 Hz, J = 2.4 Hz, 2H,
arom. H-6), 7.24–7.37 (m, 4H, arom. H-2 and H-5), 7.62–7.79
(m, 8H, phthal. arom. H). Anal. Calcd for C34H22Cl2N6O10S2: C,
50.54; H, 2.74; N, 10.38; S, 7.92. Found: C, 50.41; H, 2.90; N,
10.20; S, 8.20.
5.1.2.26. 2-[2-({({[2-(1,3-Dioxo-1,3-dihydro-2H-isoindol-2-yl)-
ethoxy][(2,4-dichlorophenyl)imino]methyl}dithio)[(2,4-dichloro-
phenyl)imino]methyl}oxy)ethyl]-1,3-dioxoisoindoline
26. Mp
130–132 °C; yield: 55% from diethyl ether. IR (KBr) cmꢀ1: 1775,
1718, 1643. 1H NMR (CDCl3) d: 3.92–4.08 (m, 4H, 2CH2N),
4.36–4.47 (m, 4H, 2CH2O), 6.78–7.11 (m, 6H, arom. H), 7.60–
7.82 (m, 8H, phthal. arom. H). Anal. Calcd for C34H22Cl4N4O6S2:
C, 51.79; H, 2.81; N, 7.11; S, 8.13. Found: C, 51.66; H, 3.14; N,
7.00; S, 8.10.
5.1.2.33. 2-[2-({({[2-(1,3-Dioxo-1,3-dihydro-2H-isoindol-2-yl)-
ethoxy][(4-bromo-2-methylphenyl)imino]methyl}dithio)[(4-
bromo-2-methylphenyl)imino]methyl}oxy)ethyl]-1,3-dioxo-
isoindoline 33. Mp 125–127 °C; yield: 57% from diethyl ether. IR
(KBr) cmꢀ1: 1771, 1708, 1634. 1H NMR (CDCl3) d: 1.91 (s, 6H,
2CH3), 3.91–4.02 (m, 4H, 2CH2N), 4.33–4.43 (m, 4H, 2CH2O), 6.50–
6.58 (m, 2H, arom. H), 6.95–7.04 (m, 4H, arom. H), 7.61–7.78 (m,
8H, phthal. arom. H). Anal. Calcd for C36H28Br2N4O6S2: C, 51.69; H,
3.37; N, 6.70; S, 7.67. Found: C, 51.94; H, 3.40; N, 6.31; S, 7.60.
5.1.2.27. 2-[2-({({[2-(1,3-Dioxo-1,3-dihydro-2H-isoindol-2-yl)-
ethoxy][(2,5-dichlorophenyl)imino]methyl}dithio)[(2,5-dichloro-
phenyl)imino]methyl}oxy)ethyl]-1,3-dioxoisoindoline
27. Mp
173–175 °C; yield: 49% from DCM/ethanol. IR (KBr) cmꢀ1: 1776,
1715, 1639. 1H NMR (CDCl3) d: 4.01–4.25 (m, 4H, 2CH2N), 4.47–
4.67 (m, 4H, 2CH2O), 6.91–7.28 (m, 6H, arom. H), 7.70–7.91
(m, 8H, phthal. arom. H). Anal. Calcd for C34H22Cl4N4O6S2: C,
51.79; H, 2.81; N, 7.11; S, 8.13. Found: C, 51.85; H, 3.15; N,
6.80; S, 8.11.
5.1.2.34. 2-[2-({({[2-(1,3-Dioxo-1,3-dihydro-2H-isoindol-2-yl)-
ethoxy][(2,4,6-trifluorophenyl)imino]methyl}dithio)[(2,4,6-triflu-
orophenyl)imino]methyl}oxy)ethyl]-1,3-dioxoisoindoline 34. Mp
167–169 °C; yield: 30% from diethyl ether. IR (KBr) cmꢀ1: 1772,
1714, 1639. 1H NMR (CDCl3) d: 3.97–4.08 (m, 4H, 2CH2N),
4.53–4.63 (m, 4H, 2CH2O), 6.65–6.77 (m, 4H, arom. H), 7.63–
7.84 (m, 8H, phthal. arom. H). Anal. Calcd for C34H20F6N4O6S2:
C, 53.83; H, 2.66; N, 7.38; S, 8.45. Found: C, 53.63; H, 3.01; N,
7.07; S, 8.80.
5.1.2.28. 2-[2-({({[2-(1,3-Dioxo-1,3-dihydro-2H-isoindol-2-yl)-
ethoxy][(3,4-dichlorophenyl)imino]methyl}dithio)[(3,4-dichlo-
rophenyl)imino]methyl}oxy)ethyl]-1,3-dioxoisoindoline 28. Mp
195–197 °C; yield: 57% from DCM/ethanol. IR (KBr) cmꢀ1: 1781,
1721, 1634. 1H NMR (CDCl3) d: 3.96–4.08 (m, 4H, 2CH2N), 4.38–
4.50 (m, 4H, 2CH2O), 6.73 (dd, J = 8.6 Hz, J = 2.4 Hz, 2H, arom. H-
6), 6.97 (d, J = 2.4 Hz, 2H, arom. H-2), 7.26 (d, J = 8.4 Hz, 2H, arom.
H-5), 7.70–7.93 (m, 8H, phthal. arom. H). Anal. Calcd for
C
34H22Cl4N4O6S2: C, 51.79; H, 2.81; N, 7.11; S, 8.13. Found: C,
51.57; H, 2.99; N, 7.15; S, 8.12.
5.1.2.35. 2-[2-({({[2-(1,3-Dioxo-1,3-dihydro-2H-isoindol-2-yl)-
ethoxy][(4-bromo-2,6-dimethylphenyl)imino]methyl}dithio)-
[(4-bromo-2,6-dimethylphenyl)imino]methyl}oxy)ethyl]-1,3-
dioxoisoindoline 35. Mp 185–187 °C; yield: 49% from ethyl ace-
tate. IR (KBr) cmꢀ1: 1777, 1713, 1638. 1H NMR (CDCl3) d: 1.86 (s,
12H, 4CH3), 3.97–4.08 (m, 4H, 2CH2N), 4.55–4.65 (m, 4H, 2CH2O),
6.82 (br s, 4H, arom. H-3 and H-5), 7.69–7.84 (m, 8H, phthal. arom.
H). Anal. Calcd for C38H32Br2N4O6S2: C, 52.79; H, 3.73; N, 6.48; S,
7.42. Found: C, 52.49; H, 3.76; N, 6.55; S, 7.24.
5.1.2.29. 2-[2-({({[2-(1,3-Dioxo-1,3-dihydro-2H-isoindol-2-yl)-
ethoxy][(3,5-dichlorophenyl)imino]methyl}dithio)[(3,5-dichloro-
phenyl)imino]methyl}oxy)ethyl]-1,3-dioxoisoindoline
29. Mp
184–186 °C; yield: 72% from diethyl ether. IR (KBr) cmꢀ1: 1783,
1719, 1650. 1H NMR (CDCl3) d: 3.90–3.98 (m, 4H, 2CH2N), 4.35–
4.44 (m, 4H, 2CH2O), 6.64–6.70 (m, 4H, arom. H-2 and H-6),
6.94–6.98 (m, 2H, arom. H-4), 7.61–7.83 (m, 8H, phthal. arom.
H). Anal. Calcd for C34H22Cl4N4O6S2: C, 51.79; H, 2.81; N, 7.11;
S, 8.13. Found: C, 51.51; H, 3.18; N, 7.05; S, 8.09.
5.1.2.36. 2-[2-({({[2-(1,3-Dioxo-1,3-dihydro-2H-isoindol-2-yl)-
ethoxy][(1-naphthyl)imino]methyl}dithio)[(1-naphthyl)imino]-
methyl}oxy)ethyl]-1,3-dioxoisoindoline 36. Mp 179–180 °C;
yield: 49% from DCM/methanol. IR (KBr) cmꢀ1: 1776, 1719,
1625. 1H NMR (CDCl3) d: 3.95–4.13 (m, 4H, 2CH2N), 4.46–4.63
(m, 4H, 2CH2O), 6.76–6.85 (m, 2H, arom. H), 7.09–7.90 (m, 20H,
arom. H). Anal. Calcd for C42H30N4O6S2: C, 67.19; H, 4.03; N,
7.46; S, 8.54. Found: C, 66.95; H, 4.12; N, 7.31; S, 8.94.
5.1.2.30. 2-[2-({({[2-(1,3-Dioxo-1,3-dihydro-2H-isoindol-2-yl)-
ethoxy][(3-chloro-4-methylphenyl)imino]methyl}dithio)[(4-
methyl-3-chlorophenyl)imino]methyl}oxy)ethyl]-1,3-dioxo-
isoindoline 30. Mp 123–125 °C; yield: 15% from petroleum
ether/methanol. IR (KBr) cmꢀ1
:
1777, 1710, 1635. 1H NMR
(CDCl3) d: 2.32 (s, 6H, 2CH3), 3.99–4.18 (m, 4H, 2CH2N), 4.35–

6362
S. Cesarini et al. / Bioorg. Med. Chem. 16 (2008) 6353–6363
5.1.2.37. 2-(2-{[({[2-(1,3-Dioxo-1,3-dihydro-2H-isoindol-2-yl)-
ethoxy](cyclopropylimino)methyl}dithio)(cyclopropylimino)-
methyl]oxy}ethyl)-1,3-dioxoisoindoline 37. Mp 164–165 °C;
yield: 34% from diethyl ether/methanol. IR (KBr) cmꢀ1: 1780,
1714, 1629. 1H NMR (CDCl3) d: 0.28–0.58 (m, 8H, 4 cycloprop.
CH2), 2.50–2.63 (m, 2H, 2 cycloprop. CH), 3.81 (t, J = 5.4 Hz, 4H,
2CH2N), 4.10 (t, J = 5.4 Hz, 4H, 2CH2O), 7.55–7.81 (m, 8H, phthal.
arom. H). 13C NMR (CDCl3) d: 7.82 (4 cycloprop. CH2), 30.74 (2
cycloprop. CH), 36.74 (2CH2N), 65.16 (2CH2O), 123.42 (4CH),
132.21 (4C), 134.00 (4CH), 153.09 (2C@N), 167.99 (4C@O). Anal.
Calcd for C28H26N4O6S2: C, 58.12; H, 4.53; N, 9.68; S, 11.08.
Found: C, 58.19; H, 4.63; N, 9.31; S, 10.96.
reference molecule (Z,Z isomer) was generated and energy mini-
mized using the MM2 force field included in MacroModel.37
A
Drive analysis (Macromodel) was performed on the torsion angles
defined by atoms S–C@N–C(Ar). The following parameters were
set: starting angle: 0; angle increment: 30°; total rotation: 360°.
The E,E and Z,E isomers obtained by the Drive analysis were super-
imposed to the original Z,Z isomer to assess that the conformation
of the S–S bond was retained. For energy comparison, the three iso-
mers were energy minimized using the Hamiltonian AM1 as
implemented in MOPAC package version 6.0. All the calculations
were performed in vacuo on Silicon Graphic O2 workstation. Pre-
dicted isomer energies: Z,Z (77.29 kcal/mol); E,E (78.29 kcal/mol);
E,Z (79.91 kcal/mol).
5.1.2.38. 2-(2-{[({[2-(1,3-Dioxo-1,3-dihydro-2H-isoindol-2-yl)-
ethoxy](benzylimino)methyl}dithio) (benzylimino)methyl]oxy}-
ethyl)-1,3-dioxoisoindoline 38. Mp 113–115 °C; yield: 41%
from diethyl ether. IR (KBr) cmꢀ1: 1782, 1714, 1633. 1H NMR
(CDCl3) d: 3.89–4.03 (m, 4H, 2CH2N), 4.31–4.48 (m, 4H, 2CH2O),
4.60–4.71 (m, 4H, 2CH2Bn), 6.95–7.28 (m, 10H, arom. H), 7.57–
7.81 (m, 8H, phthal. arom. H). Anal. Calcd for C36H30N4O6S2: C,
63.70; H, 4.45; N, 8.25; S, 9.45. Found: C, 63.35; H, 4.53; N,
8.17; S, 9.21.
Acknowledgements
This work was supported by MURST (Cofinanziamento Nazio-
nale), CNR (Rome) and Ministero Italiano della Salute – Istituto
Superiore di Sanità (grant n° 40D.46). Fondazione Carige is grate-
fully acknowledged for financially supporting S.C. The authors
thank Mr. O. Gagliardo for the microanalyses, Mr. F. Tuberoni, Dr.
C. Rossi, Dr. M. Anzaldi and Dr. R. Raggio for the IR and NMR
spectra.
5.1.2.39. 2-[3-({({[3-(1,3-Dioxo-1,3-dihydro-2H-isoindol-2-yl)-
propoxy][(4-bromophenyl)imino]methyl}dithio)[(4-bromophenyl)-
imino]methyl}oxy)propyl]-1,3-dioxoisoindoline 39. Mp 193–195 °C;
yield: 57% from diethyl ether/ethanol. IR (KBr) cmꢀ1: 1780, 1727,
1637. 1H NMR (CDCl3) d: 2.13–2.33 (m, 4H, 2CH2), 3.81–3.99 (m,
4H, 2CH2N), 4.38–4.57 (m, 4H, 2CH2O), 6.73–6.92 (m, 4H, arom.
H), 7.36–7.55 (m, 4H, arom. H), 7.68–7.92 (m, 8H, phthal. arom.
H). Anal. Calcd for C36H28Br2N4O6S2: C, 51.69; H, 3.37; N, 6.70;
S, 7.66. Found: C, 51.63; H, 3.65; N, 6.62; S, 7.33.
References and notes
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5.1.2.40. 2-[2-({({[2-(1,3-Dioxo-1,3-dihydro-5-methyl-2H-isoin-
dol-2-yl)ethoxy][(4-bromophenyl)imino]methyl}dithio)[(4-bromo-
phenyl)imino]methyl}oxy)ethyl]-1,3-dioxo-5-methyl-isoindoline
40. Mp 193–195 °C; yield: 94% from DCM/ethanol. IR (KBr) cmꢀ1
:
1781, 1724, 1638. 1H NMR (CDCl3) d: 2.54 (s, 6H, 2CH3), 3.97–4.05
(m, 4H, 2CH2N), 4.37–4.45 (m, 4H, 2CH2O), 6.68–6.78 (m, 4H, arom.
H), 7.25–7.36 (m, 4H, arom. H), 7.51–7.77 (m, 6H, phthal. arom. H).
Anal. Calcd for C36H28Br2N4O6S2: C, 51.69; H, 3.37; N, 6.70; S, 7.66.
Found: C, 51.73; H, 3.52; N, 6.68; S, 7.65.
16. Ranise, A.; Spallarossa, A.; Schenone, S.; Bruno, O.; Bondavalli, F.; Vargiu, L.;
Marceddu, T.; Mura, M.; La Colla, P.; Pani, A. J. Med. Chem. 2003, 46, 768.
17. Cesarini, S.; Spallarossa, A.; Ranise, A.; Fossa, P.; La Colla, P.; Sanna, G.; Collu, G.;
Loddo, R. Bioorg. Med. Chem. 2008, 16, 4160.
18. Cesarini, S.; Spallarossa, A.; Ranise, A.; Bruno, O.; La Colla, P.; Secci, B.; Collu, G.;
Loddo, R. Bioorg. Med. Chem. 2008, 16, 4173.
5.1.2.41. {[(2-Phenylethoxy){[(2-phenylethoxy)(phenylimino)-
methyl]dithio}methylene]amino}benzene 41. Mp 60–62 °C;
yield: 23% from acetone/methanol. IR (KBr) cmꢀ1: 1629. 1H NMR
(CDCl3) d: 2.98 (t, J = 6.6 Hz,, 4H, 2CH2Ph), 4.44 (m, 4H, 2CH2O),
6.75–6.86 (m, 4H, arom. H), 7.02–7.12 (m, 4H, arom. H), 7.17–
7.34 (m, 12H, arom. H). 13C NMR (CDCl3) d: 35.28 (2CH2), 70.70
(2CH2O), 121.89 (4CH), 124.57 (2CH), 126.81 (2CH), 128.78
(4CH), 129.31 (4CH), 129.43 (4CH), 138.28 (2C), 146.27 (2C),
153.98 (2C@N). Anal. Calcd for C30H28N2O2S2: C, 70.28; H, 5.50;
N, 5.46; S, 12.51. Found: C, 70.34; H, 5.69; N, 5.42; S, 12.48.
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The biological evaluation of DS 1–41 was performed according
to previously reported procedures.15,16
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[(Methoxy{[methoxy(phenylimino)methyl]dithio}methy-
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two 2-phthalimidoethyl substituents replaced by two methyl
groups) has been selected as template molecule for the study of
formimidoester disulfides stereochemistry. The structure of the
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