Anti-HIV activity of aromatic and heterocyclic thiazolyl thiourea compounds

Article abstract of DOI:10.1016/S0960-894X(01)00011-7

Several thiazolyl thiourea derivatives were designed and synthesized as non-nucleoside inhibitors (NNRTI) of HIV-1 reverse transcriptase. Six lead compounds were identified that showed subnanomolar IC₅₀ values for the inhibition of HIV replicat

Full text of DOI:10.1016/S0960-894X(01)00011-7

Bioorganic & Medicinal ChemistryLetters 11 (2001) 523±528
Anti-HIV Activity of Aromatic and Heterocyclic Thiazolyl
Thiourea Compounds
T. K. Venkatachalam,a,b Elise A. Sudbeck,a,c Chen Maoa,c and Fatih M. Uckuna,d,*
aDrug Discovery Program, Parker Hughes Institute, St. Paul, MN 55113, USA
bDepartment of Chemistry, Parker Hughes Institute, St. Paul, MN 55113, USA
cDepartment of Structural Biology, Parker Hughes Institute, St. Paul, MN 55113, USA
dDepartment of Virology, Parker Hughes Institute, St. Paul, MN 55113, USA
Received 11 May2000; accepted 7 December 2000
AbstractÐSeveral thiazolyl thiourea derivatives were designed and synthesized as non-nucleoside inhibitors (NNRTI) of HIV-1
reverse transcriptase. Six lead compounds were identi®ed that showed subnanomolar IC50 values for the inhibition of HIV repli-
cation, were minimallytoxic to human peripheral blood mononuclear cells (PBMC) with CC 50 values ranging from 28 to >100 mM,
and showed remarkablyhigh selectivityindices ranging from 28,000 to >100,000. The most promising compound was N-[1-(1-
0
furoylmethyl)]-N -[2-(thiazolyl)]thiourea (compound 6), which showed potencyagainst two NNRTI-resistant HIV-1 isolates (A17
and A17 variant) at nanomolar to low micromolar concentrations, exhibited much greater potencyagainst both wild-t yp e as well as
NNRTI-resistant HIV-1 than nevirapine, delavirdine, HI-443, and HI-244, was minimallytoxic to PBMC, and had a selectivity
index of >100,000. The potency and minimal cytotoxicity of these aromatic/heterocyclic thiourea compounds suggest that they may
be potentiallyuseful as anti-AIDS drugs. # 2001 Published byElsevier Science Ltd.
1À15
as useful anti-
AIDS drugs, we have identi®ed several structurallydis-
tinct thiourea compounds as potent NNRTIs of HIV-1
One of the main molecular targets in contemporary
drug discoverye€orts against human immunode®ciency
virus (HIV-1) is reverse transcriptase (RT), a vital
enzyme that is responsible for the reverse transcription
derivatives of thiourea compounds1
1
6À25
RT.
We have previouslyreported and established
1À3
of the retroviral RNA to proviral DNA.
The three
SARs for
compounds.
that the 5-bromopyridyl group would tightly bind to the
a
series of 5-bromopyridyl thiourea
Our modeling studies have indicated
1
6À24
categories of antiretroviral agents in use are nucleoside
analogues (such as AZT), protease inhibitors (such as
nel®navir), and the recentlyintroduced non-nucleoside
inhibitors (NNRTIs) such as nevirapine, delavirdine,
and efavirenz. Unlike nucleoside analogues, NNRTIs
1
4,26À28
Wing 1 region of the binding pocket.
Similarly,
the thiazolyl group is expected to favorably bind to the
same region in the Wing 1 region of the binding pocket.
Here, we now report the synthesis and anti-HIV activity
of 13 novel aromatic/heterocyclic thiazolyl thiourea
compounds.
4
À10
bind to an allosteric site of HIV-1 RT,
which is
Ê
approximately10 A awayfrom the cata lt yi c site.
NNRTI binding induces the rotamer conformation
changes of some residues (Y181 and Y188) and renders
the `thumb' region more rigid, therebyaltering the sub-
strate binding mode and leading to a noncompetitive
For the synthesis of the thiazolyl thiourea compounds,12
we followed the general procedure shown in Scheme 1.
In brief, thiocarbonyldimidazole and 2-aminothiazole
5
À10
inhibition of the enzyme.
In a systematic search for
Scheme 1.
*Corresponding author. Tel.: +1-612-697-9228; fax: +1-612-697-1042; e-mail: fatih_uckun@ih.org
0960-894X/01/$ - see front matter # 2001 Published byElsevier Science Ltd.
PII: S0960-894X(01)00011-7

524
T. K. Venkatachalam et al. / Bioorg. Med. Chem. Lett. 11 (2001) 523±528
(
A) were added to 100 mL of dryacetonitrile under
puri®ed using silica gel column chromatography. The
physicochemical properties of the compounds were
determined using standard analytical methods and the
X-raycr ys tal structures of four compounds are shown
in Figure 1.
nitrogen atmosphere and stirred at room temperature
for 12±15 h. The precipitate was ®ltered, washed with
cold acetonitrile, and dried thoroughlyunder vacuum to
yield the thiocarbonyl (B) intermediate. In the sub-
sequent step, this compound was taken up in a dry¯ask
under nitrogen, 20 mL of anhydrous dimethylforma-
mide was added to B and the contents were stirred for
2
9
We examined these thiazolyl thiourea compounds for
anti-HIV activitybydetermining their abilityto inhibit
the replication of the HIV-1 strain HTLVIIIB in human
peripheral blood mononuclear cells (PBMC) from heal-
thyindividuals. Of the 13 compounds, four (viz., com-
pounds 9, 10, 11, and 12) were inactive with IC50 values
ranging from 1 to >100 mM (Table 1). Three com-
pounds (2, 4, and 13) showed moderate activityand
inhibited HIV-1 replication at nanomolar concentra-
tions. The remaining six lead compounds (1, 3, and 5±8)
inhibited HIV-1 replication with subnanomolar IC50
values. These compounds were minimallytoxic to
PBMC with CC50 values ranging from 28 mM to
>100 mM and their selectivityindices were remarkably
high ranging from 28,000 to >100,000 (Table 1). The six
3
the appropriate amine dissolved in 10 mL of drydime-
0 min at room temperature. To this solution, we added
thylformamide and heated the reaction mixture to
ꢀ
1
00 C over an oil bath for 15 h. The reaction mixture
was cooled and poured into ice water and the contents
were stirred for an additional hour until a precipitate
appeared. The precipitate (C) was ®ltered, washed with
cold water several times and dried under vacuum. This
precipitate was taken up in ethyl acetate and washed
with water and brine and ®nallythe separated ethly
acetate layer was dried over anhydrous sodium sulfate.
Filtration and evaporation of the solvent gave the
desired thiourea compounds (C) which were further
Ê
ꢀ
Figure 1. X-raycr ys tal structures of compounds 2, 6, 7, and 8. 30% probabilityellipsoids, l=0.71073 A. (A) Compound 2, T=22 C, space group
Ê
Ê
Ê
ꢀ
ꢀ
ꢀ
Ê
3
Pbca, unit cell: a=14.8206(11) A, b=8.2577(6) A, c=22.1026(16) A, a=90 , b=90 , g=90 , volume=2705.0(3) A , Z=8, y range for data col-
lection=1.84±28.28 , total re¯ections collected=15,621, independent re¯ections=3208 (Rint=0.051), data:restraints:parameters=3208:0:162, R1
I>2s(I))=0.060, wR2=0.13, Goodness of Fit on F =1.013. (B) Compound 6, T=25 C, space group P-1, unit cell: a=4.3794(2) A, b=10.0075(5)
ꢀ
2
ꢀ
Ê
(
Ê
Ê
ꢀ
ꢀ
ꢀ
Ê
3
ꢀ
A, c=12.3539(6) A, a=92.2930(10) , b=90.4950(10) , g=97.7950(10) , volume=535.95(4) A , Z=2, y range for data collection=1.65±27.11 ,
total re¯ections collected=5978, independent re¯ections=2344 (Rint=0.020), data:restraints:parameters=2344:0:145, R1 (I>2s(I))=0.030,
2
ꢀ
Ê
wR2=0.084, Goodness of Fit on F =1.069. (C) Compound 7, T=23 C, space group P-1, unit cell: a=5.2849(3) A, b=10.3435(7) A, c=11.8578(7)
Ê
Ê
ꢀ
ꢀ
ꢀ
Ê
3
ꢀ
A, a=77.1380(10) , b=83.6470(10) , g=85.3720(10) , volume=627.00(7) A , Z=2, y range for data collection=1.77±26.04 , total re¯ections col-
lected=3528, independent re¯ections=2413 (Rint=0.013), data:restraints:parameters=2413:0:163, R1 (I>2s(I))=0.032, wR2=0.094, Goodness of
2
ꢀ
Ê
Ê
Ê
ꢀ
ꢀ
Fit on F =1.056. (D) Compound 8, T=26 C, space group P2 /n, unit cell: a=8.3723(7) A, b=5.5107(4) A, c=30.946(3) A, a=90 , b=94.798(2) ,
1
ꢀ
Ê
3
ꢀ
ꢀ
g=90 , volume=1422.8(2) A , Z=4, y range for data collection=1.32 to 27.67 , total re¯ections collected=8193, independent re¯ections=3172
2
(Rint=0.018), data:restraints:parameters=3172:0:193, R1 (I>2s(I))=0.042, wR2=0.12, Goodness of Fit on F =1.090.

T. K. Venkatachalam et al. / Bioorg. Med. Chem. Lett. 11 (2001) 523±528
Table 1. Anti-HIV activityof thiazol yl thiourea compounds a
525
Potencyand selectivity
Activityagainst NNRTI-resistant HIV IC 50 (mM)
Compound
R
IC50 HTLVIIIB (mM)
CC50 (mM)
SI
A17
A17 variant
1
<
0.001
71
71,000
>100
ND
2
3
4
5
6
7
8
9
0.007
4
>100
>100
40
571
>100,000
1429
0.9
4.4
3.9
0.6
2.0
>100
>100
>100
1.3
<0.001
0.07
<0.001
<0.001
<0.001
<0.001
40,000
>100,000
35,000
28,000
N.D
>100
35
0.6
>100
>100
3.7
28
2.2
ND
ND
ND
ND
2.1
>100
N.D
ND
100
18
ND
ND
ND
ND
1.5
10
11
12
13
>100
ND
1
9
100
2
0.009
10
1111
Nevirapine
Delavirdine
N.A.
N.A.
0.034
0.009
ND
ND
ND
ND
>100
50
>100
>100
HI-443
HI-244
0.030
0.007
>100
>100
ND
ND
0.048
3.3
0.070
>100
aNormal human peripheral blood mononuclear cells (PBMNC) from HIV-negative donors were cultured 72 h in RPMI 1640 supplemented with 20% (v/v) heat-inacti-
vated fetal bovine serum (FBS), 3% interleukin-2, 2 mM l-glutamine, 25 mM HEPES, 2 g/L NaHCO
exposure to the HIV-1 strain HTLVIIIB at a multiplicityof infection (MOI) of 0.1 during a 1-h adsorption period at 37 C in a humidi®ed 5% CO
3
, 50 mg/mL gentamicin, and 4 mg/mL phytohemagglutinin prior to
ꢀ
2
atm. Subsequently,
6
cells were cultured in 96-well microtiter plates (100 mL/well; 2Â10 cells/mL) in the presence of various concentrations of analogues and aliquots of culture supernatants
31,21
were removed from the wells on the 7th dayafter infection for p24 antigen assa ys , as previouslydescribed.
The applied p24 enzyme immunoassay (EIA) was the
unmodi®ed kinetic assaycommerciallyavailable from Coulter Corporation/Immunotech, Inc. (Westbrooke, ME), which utilizes a murine mAb to HIV cor e protein
coated onto microwell strips to which the antigen present in the test culture supernatant samples binds. Percent viral inhibition was calculated byc omparing the p24
values from the test substance-treated infected cells with p24 values from untreated infected cells (i.e., virus controls). The e€ects of various treatments on cell viability
31,32
were also examined and the results were expressed as the cytotoxic concentration (CC)50 values.
SI=CC50/IC50
The selectivityindices (SI) were calculated using the formula:
.

526
T. K. Venkatachalam et al. / Bioorg. Med. Chem. Lett. 11 (2001) 523±528
lead compounds (1, 3, and 5±8) were 9±34 times more
potent than the standard NNRTI nevirapine and dela-
virdine and 7±30 times more potent than our previously
reported NNRTIs HI-443 and HI-244 (Table 1). We
also examined the activityof compounds 1±8 and com-
pound 13 against NNRTI-resistant HIV-1 strains A17
with a Y181C mutation in RT and A17 variant with a
Y181C plus K103N mutations in RT. Both A17 and
A17 variant are resistant to nevirapine as well as dela-
virdine (Table 1). Even though compounds 1 and 7
inhibited wild-type HIV-1 at subnanomolar concentra-
tions, theywere ine€ective against A17. Bycomparison,
compounds 2±6, 8, and 13 inhibited A17 at nanomolar
concentrations with IC50 values ranging from 0.6 mM to
pounds 1, 2, and 4 have geometric features similar to the
previously published 5-bromopyridyl thiourea com-
1
8,30
pounds
containing an ethyl linker and similarly
demonstrated potent activityagainst wild- tpy e RT.
Compounds 3, 7, and 12 all have a three-atom linker
group longer than in other compounds, suggesting a
tight contact with the Wing 2 region of the binding
pocket without steric clash. The potencies of com-
pounds 5, 8, and 13 are consistent with our previously
proposed working hypothesis that a larger group that
can favorablyinteract with the Wing 2 region of the
binding site is a desirable feature for inhibition of these
mutants because Y181C and Y188C mutations result in
1
8
a larger binding pocket. A larger group that binds to
the Wing 2 region of the binding site combined with a
smaller thiazolyl group appears to deliver more potency
against the mutant strains. The outstanding activityof
compound 6 is however not anticipated and appears to
reverse the trend that we have proposed before. Com-
pared with compound 1, it has a shorter linker group
and a smaller Wing 2 group yet demonstrates better
inhibition against both mutant strains, suggesting
perhaps a novel binding mode.
4
.4 mM, which are approximately1 log better than the
IC50 values of HI-443 or HI-244 and 1±2 logs better
than the IC50 values of nevirapine or delavirdine against
the same NNRTI-resistant HIV-1 strain (Table 1).
Compounds 2±4 and 7 were ine€ective against A17
variant. Bycomparison, compounds 5, 6, 8, and 13 were
verye€ective against A17 variant with IC 50 values ran-
ging from 0.6 mM to 3.7 mM, which are similar to the
IC50 value of HI-443 and almost 2 logs better than the
IC50 values of nevirapine, delavirdine, or compound HI-
2
(
44 against the same NNRTI-resistant HIV-1 strain
Table 1). The most promising compounds were 5, 6, 8,
A number of thiazolyl thioureas were designed and
synthesized as non-nucleoside inhibitors (NNRTIs) of
human immunode®ciencyvirus (HIV-1) reverse tran-
scriptase (RT). Among the thiazolyl substituted deriva-
tives, both the heterocyclic as well as alicyclic
compounds elicited anti-HIV-1 activities at nanomolar
levels. Compounds 5, 8, and 13 were potent against
wild-type HIV as well as A17 and A17 variant mutant
strains, consistent with our previous prediction that a
larger Wing 2 group is advantageous for inhibition of
these mutant strains. The most promising compound, 6,
which showed potencyagainst two NNRTI-resistant
HIV-1 isolates (A17 and A17 variant) at nanomolar to
low micromolar concentrations, exhibited much greater
potencyagainst both wild-t yp e as well as NNRTI-resis-
tant HIV-1 than nevirapine, delavirdine, HI-443, and
HI-244, was minimallytoxic to PBMC, and had a
selectivityindex of >100,000. Because of their potency
and minimal cytotoxicity, these aromatic/heterocyclic
thiourea compounds maypotentiallybe useful as anti-
AIDS drugs.
and 13. These four compounds were e€ective against
both NNRTI-resistant HIV-1 isolates at nanomolar to
low micromolar concentrations and exhibited much
greater potencyagainst both wild- tpy e as well as
NNRTI-resistant HIV-1 than nevirapine, delavirdine,
HI-443, and HI-244 (Table 1). Among these four com-
pounds, the most promising was the novel compound 6
since it was minimallytoxic to PBMC and had a selec-
tivityindex of >100,000 (Table 1).
The X-raystructures of compounds 2 and 6±8 con-
®
NNRTI binding pocket
rmed that the essential binding components for the
9À25
1
are present in these new
compounds. These components include a butter¯y
shape for the molecule, an intramolecular hydrogen
bond, and one amide hydrogen bond donor. The crystal
structures of 2 and 6±8 show that each molecule con-
tains an intramolecular hydrogen bond between a
thiourea NH and a thiazolyl nitrogen atom (Fig. 1). The
more compact molecular conformation resulting from
this hydrogen bond allows the molecule to more easily
®
is consistent with molecular modeling studies evaluating
t into the non-nucleoside binding site of HIV RT and
References and Notes
how NNRTI compounds can bind to HIV RT.1
7À19
The
crystal structures of the four compounds and the dock-
ing studies also indicate that conformations of these
thiazolyl thiourea compounds could be adjusted (using
a di€erent rotamer conformation) to ®t the binding
pocket, and the individual interactions between the
compound and the binding pocket determine the bind-
ing anity. The 4-hydroxyl group of compound 10 was
predicted to interact unfavorablywith W229 and would
have a low binding anitywith RT as revealed pre-
viously by a similar 5-bromopyridyl thiourea com-
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1
9,22
pound.
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7
. Smerdon, S. J.; Jager, J.; Wang, J.; Kohlstaedt, L. A.;

T. K. Venkatachalam et al. / Bioorg. Med. Chem. Lett. 11 (2001) 523±528
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ꢀ
mers, D. Nat. Struct. Biol. 1995, 2, 293.
9
36%, mp 193±194 C; UV (MeOH) l
207, 212, 215, 232,
max
. Ding, J.; Das, K.; Tantillo, C.; Zhang, W.; Clark, A. D.,
236, 255, 289 nm; IR n 3219, 3151, 3087, 3003, 2935, 1595,
1552, 1531, 1471, 1298, 1263, 1211, 1188, 1134, 1076, 846, 812,
Jr.; Jessen, S.; Lu, X.; Hsiou, Y.; JacoboMolina, A.; Andries,
K.; Pauwels, R.; Moereels, H.; Koymans, L.; Janssen, P. A. J.;
Smith, R. H. J.; KroegerKoepke, R.; Michejda, C. J.; Hughes,
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À1
1
686 cm ; H NMR (DMSO-d
6
) d 11.66 (br s,1H), 9.69 (br s,
1H), 7.34 (d, 2H, J=3.3 Hz), 7.08 (d, 1H, J=3.6 Hz), 6.97±
1
3
6
6.93 (m, 2H), 3.78 (q, 2H), 3.12 (t, 2H); C NMR (DMSO-d )
1
0. Ren, J.; Esnouf, R.; Hopkins, A.; Ross, C.; Jones, Y.;
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1. Ahgren, C.; Backro, K.; Bell, F. W.; Cantrell, A. S.;
d 178.3, 161.9, 141.1, 136.5, 127.1, 125.6, 124.4, 112.1, 45.9,
28.6; MALDI-TOF 270.7 (M+1). N-[2-(1-Cyclohex-
0
1
enylethyl)]-N -[2-(thiazolyl)]thiourea (2): yield 38%, mp 153±
ꢀ
Clemens, M.; Colacino, J. M.; Deeter, J. B.; Engelhardt,
J. A. M. H.; Jaskunas, S. R.; Johansson, N. G.; Jordan, C. L.;
Kasher, J. S.; Kinnick, M. D.; Lind, P.; Lopez, C.; Morin,
J. M. J.; Muesing, M. A.; Noreen, R.; Oberg, B.; Paget, C. J.;
Palkowitz, J. A.; Parrish, C. A.; Pranc, P.; Rippy, M. K.;
Rydergard, C.; Sahlberg, C.; Swanson, S.; Ternansky, R. J.;
Unge, T.; Vasile€, R. T.; Vrang, L.; West, S. J.; Zhang, H.;
Zhou, X. X. Antimicrob. Agents Chemother. 1995, 39, 1329.
154 C; UV (MeOH) lmax 209, 258, 288 nm; IR n 3170, 2993,
2922, 2833, 1565, 1514, 1489, 1379, 1307, 1257, 1238, 1180,
À1
1
11330, 1093, 1084, 1059, 920, 829, 730, 707 cm ; H NMR
(DMSO-d ) d 11.58 (br s, 1H), 9.69 (br s, 1H), 7.34 (d, 1H,
6
J=3.6 Hz), 7.08 (d, 1H, J=3.6 Hz), 5.45 (s, 1H), 3.60 (q, 2H,
3
1
J=5.7 Hz), 2.18 (t, 2H), 1.91 (d, 4H), 1.57±1.46 (m, 4H);
C
NMR (DMSO-d ) d 177.6, 161.7, 136.8, 134.3, 123.2, 112.2,
6
42.9, 36.5, 27.7, 25.0, 22.7, 22.2; MALDI-TOF 270.2 (M+2).
0
1
2. Bell, F. W.; Cantrell, A. S.; Hogberg, M.; Jaskunas, S. R.;
N-[2-(Phenoxyethyl)]-N -[2-(thiazolyl)]thiourea (3): yield 48%,
ꢀ
Johansson, N. G.; Jordan, C. L.; Kinnick, M. D.; Lind, P.;
Morin, J. M.; Noreen, R., Jr.; Oberg, B.; Palkowitz, J. A.;
Parrish, C. A.; Pranc, P.; Sahlberg, C.; Ternansky, R. T.;
Vasile€, R. T.; Vrang, L.; West, S. J.; Zhang, H.; Zhou, X. X.
J. Med. Chem. 1995, 38, 4929.
mp 168±169 C; UV (MeOH) lmax 204, 259, 286 nm; IR n
3610, 3556, 3180, 3039, 2935, 2875, 1566, 1511, 1460, 1284,
À1
1
1248, 1184, 1112, 1082, 1053, 756, 690, 605 cm ; H NMR
(DMSO-d ) d 11.70 (s, 1H), 9.88 (s, 1H), 7.39 (s, 1H), 7.31±
7.26 (t, 2H, J=7.2 Hz), 7.11 (s, 1H), 6.98±6.91 (m, 3H), 4.16 (t,
6
1
3
1
3. Cantrell, A. S.; Engelhardt, P.; Hogberg, M.; Jaskunas,
2H), 3.93 (t, 2H); C NMR (DMSO-d ) d 160.7, 158.2, 129.6,
6
S. R.; Johansson, N. G.; Jordan, C. L.; Kangasmetsa, J.;
Kinnick, M. D.; Lind, P.; Morin, J. M.; Muesing, M. A., Jr.;
Noreen, R.; Oberg, B.; Pranc, P.; Sahlberg, C.; Ternansky,
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Ikemizu, S.; Slater, M.; Milton, J.; Balzarini, J.; Stuart, D. I.;
Stammers, D. K. J. Biol. Chem. 2000, 275, 5633.
120.9, 114.6, 112.3, 65.6, 43.8; MALDI-TOF 280.8 (M+2). N-
0
[2-(4-Methylphenyl)ethyl]-N -[2-(thiazolyl)]thiourea (4): yield
ꢀ
40%, mp 166±167 C; UV (MeOH) l
208, 212, 259,
max
290 nm; IR n 3170, 3047, 2997, 2943, 2920, 2850, 1562, 1514,
1449, 1348, 1323, 1279, 1217, 1196, 1159, 1097, 1053, 1020,
À1
1
952, 868, 804, 760, 700 cm ; H NMR (DMSO-d
6
) d 11.58 (s,
1H), 9.66 (s, 1H), 7.34±7.32 (dd, 1H, J=3.9 Hz), 7.15±7.07 (q,
3
1
5H), 3.76±3.69 (q, 2H), 2.85±2.80 (t, 2H), 2.25 (s, 3H);
C
1
5. Hogberg, M.; Engelhardt, P.; Vrang, L.; Zhang, H.
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6. Mao, C.; Vig, R.; Venkatachalam, T. K.; Sudbeck, E. A.;
Uckun, F. M. Bioorg. Med. Chem. Lett. 1998, 8, 2213.
7. Mao, C.; Sudbeck, E. A.; Venkatachalam, T. K.; Uckun,
F. M. Bioorg. Med. Chem. Lett. 1999, 9, 1593.
8. Mao, C.; Sudbeck, E. A.; Venkatachalam, T. K.; Uckun,
F. M. Antiviral Chem. Chemother. 1999, 10, 233.
9. Mao, C.; Sudbeck, E. A.; Venkatachalam, T. K.; Uckun,
F. M. Biochem. Pharmacol. 2000, 60, 1251.
0. Uckun, F. M.; Mao, C.; Pendergrass, S.; Maher, D.; Zhu,
NMR (DMSO-d ) d 178.6, 162.4, 136.4, 135.9, 129.6, 129.2,
6
112.7, 46.6, 34.5, 31.5, 21.5; MS (MALDI-TOF) 279.3
0
1
(M+1). N-[1-(1-Adamantyl)methyl]-N -[2-(thiazolyl)]thiourea
ꢀ
(5): yield 43%, mp 196±198 C; UV (MeOH) lmax 204, 208,
1
259, 289 nm; IR n 3166, 3041, 2898, 2844, 1569, 1510, 1197,
À1
1
1180, 779, 744, 678 cm
; H NMR (DMSO-d ) d 10.96 (s,
6
1
1H), 10.66 (s, 1H), 7.34 (d, 1H, J=3.9 Hz), 6.84 (d, 1H,
J=3.6 Hz), 6.84 (d, 2H, J=5.1 Hz), 2.18 (s, 3H), 2.02 (s, 2H),
1
3
1
6
1.77±1.63 (m, 10H); C NMR (DMSO-d ) d 177.4, 161.9,
137.6, 110.9, 57.8, 40.5, 36.9, 33.9, 31.0, 28.3; MALDI-TOF
0
2
309 (M+2). N-[1-(1-Furoylmethyl)]-N -[2-(thiazolyl)]thiourea
ꢀ
D.; Tuel-Ahlgren, L.; Venkatachalam, T. K. Bioorg. Med.
Chem. Lett. 1999, 9, 2721.
(6): yield 40%; mp 119±121 C; UV (MeOH) lmax 204, 214,
257, 292 nm; IR n 3170, 3071, 3030, 1565, 1509, 125,
À1
1
2
1. Uckun, F. M.; Pendergrass, S.; Maher, D.; Zhu, D.; Tuel-
1179 cm ; H NMR (CDCl ) d 11.10 (s, 2H), 7.39 (q, 1H),
3
Ahlgren, L.; Mao, C.; Venkatachalam, T. K. Bioorg. Med.
Chem. Lett. 1999, 9, 3411.
7.30 (d, 1H, J=3.6 Hz), 6.82 (d, 1H, J=3.9 Hz), 6.38±6.33 (m,
1
3
3
2H), 4.93 (d, 2H); C NMR (CDCl ) d 177.8, 161.9, 150.1,
2
2. Uckun, F. M.; Mao, C.; Pendergrass, S.; Maher, D.; Zhu,
142.6, 137.9, 111.6, 110.7, 108.5, 42.65; MALDI-TOF 241.9.
0
D.; Tuel-Ahlgren, L.; Venkatachalam, T. K. Antiviral Chem.
Chemother. 2000, 11, 135.
N-[3-(2-Imidazole)propyl]-N -[2-(thiazolyl)]thiourea (7): yield
ꢀ
44%; mp 176±177 C; UV (MeOH) lmax 213, 258, 289 nm; IR
À1
1
23. Vig, R.; Mao, C.; Venkatachalam, T. K.; Tuel-Ahlgren,
L.; Sudbeck, E. A.; Uckun, F. M. Bioorg. Med. Chem. 1998, 6,
n 3190, 3051, 2932, 1565, 1514, 1225 cm ; H NMR (DMSO-
d6) d 11.39 (s, 1H), 9.98 (s, 1H), 7.53 (s, 1H), 7.25 (d, 1H,
J=3.9 Hz), 7.02 (s, 1H), 6.88 (s, 1H), 6.85 (d, 1H, J=3.6 Hz),
1
2
789.
4. Venkatachalam, T. K.; Sudbeck, E. A.; Mao, C.; Uckun,
1
3
3.54 (q, 2H), 3.01 (t, 2H), 2.12±2.03 (m, 2H); C NMR
(DMSO-d ) d 178.9, 162.4, 137.5, 137.3, 129.2, 119.5, 111.9,
102.8, 44.6, 30.5; MALDI-TOF 269.7. N-[2-(2-Indole)ethyl]-
F. M. Bioorg. Med. Chem. Lett. 2000, 10, 2071.
5. Uckun, F. M. et al. U.S. Patent 5,998,411, 1999. Uckun,
6
2
0
ꢀ
F. M. et al. U.S. Patent 09/224,677, 2000. Uckun, F. M., et al.,
U.S. Patent 09/338,685, 2000.
26. Ren, J.; Nichols, C.; Bird, L. E.; Fujiwara, T.; Sugimoto,
H.; Stuart, D. I.; Stammers, D. K. J. Biol. Chem. 2000, 275,
N -[2-(thiazolyl)]thiourea (8): yield 51%; mp 212±213 C; UV
(MeOH) lmax 204, 207, 221, 285 nm; IR n 3386, 3164, 3076,
À1
1
3035, 1560, 1514, 1184, 750 cm ; H NMR (DMSO-d ) d
6
11.56 (s, 1H), 10.86 (s, 1H), 9.73 (s, 1H), 7.62 (d, 1H,
J=7.5 Hz), 7.35 (s, 1H), 7.31 (t, 1H), 7.20 (s, 1H), 7.07 (d, 1H,
J=6.9 Hz), 7.03 (s, 1H), 6.96 (t, 1H), 3.81 (q, 2H), 3.00 (t, 2H);
1
2
4316.
7. Ren, J.; Esnouf, R. M.; Hopkins, A. L.; Warren, J.; Bal-
1
3
zarini, J.; Stuart, D. I.; Stammers, D. K. Biochem. 1998, 37,
4394.
C NMR (DMSO-d ) d 178.4, 162.3, 136.9, 127.7, 123.8,
6
1
121.7, 119.1, 118.9, 112.7, 112.1, 111.8, 102.8, 45.9, 24.9;

528
T. K. Venkatachalam et al. / Bioorg. Med. Chem. Lett. 11 (2001) 523±528
0
0
MALDI-TOF 304.2. N-[2-(2-Piperdine)ethyl]-N -[2-(thiazo-
ꢀ
N-[3-(Pyrrolidinone)propyl]-N -[2-(thiazolyl)]thiourea
ꢀ
(12):
205, 256,
lyl)]thiourea (9): yield 50%; mp 163±164 C; UV (MeOH) l
yield 56%; mp 123.5±126 C; UV (MeOH) l
max
max
2
04, 207, 211, 258, 290 nm; IR n 3169, 3019, 2931, 1556, 1512,
290 nm; IR n 3199, 3054, 2964, 2863, 1660, 1550, 1508,
À1
1
À1
1
1
J=3.3 Hz), 6.82 (d, 1H, J=3.6 Hz), 3.78 (t, 2H), 2.59 (t, 2H),
6
181 cm ; H NMR (DMSO-d ) d 10.75 (s, 2H), 7.33 (d, 1H,
1315, 1166, 692 cm
;
6
H NMR (DMSO-d ) d 11.61 (s,
1H), 9.56 (s, 1H), 7.37 (d, 1H, J=3.6 Hz), 7.08 (d, 1H,
J=3.6 Hz), 3.48 (q, 2H), 3.21 (t, 4H), 2.19 (t, 2H), 1.90 (t,
1
3
2
.45 (s, 5H), 1.60 (t, 3H), 1.45 (d, 3H); C NMR (DMSO-d6)
1
3
d 177.1, 161.9, 137.8, 111.4, 107.5, 56.4, 54.5, 43.2, 26.5, 24.8;
MALDI-TOF 272.1. N-[2-(4-Hydroxyphenyl)ethyl]-N -[2-
6
2H), 1.75 (t, 2H); C NMR (DMSO-d ) d 173.9, 161.9,
0
136.4, 122.8, 112.0, 102.7, 46.4, 41.9, 30.7, 26.3, 17.8;
0
ꢀ
(
(
thiazolyl)]thiourea (10): yield 47%; mp 160±161 C; UV
MeOH) lmax 209, 219, 225, 260, 289 nm; IR n 3437, 3050,
MALDI-TOF:
lyl)]thiourea (13): yield 44%; mp 149±151 C; UV (MeOH)
282.6.
N-[ꢀ-Ethylbenzyl]-N -[2-(thiazo-
ꢀ
À1
1
1
9
6
581, 1556, 1518 cm ; H NMR (DMSO-d
6
) d 11.57 (s, 1H),
.66 (s, 1H), 9.22 (s, 1H), 7.33 (d, 1H, J=3.6 Hz), 7.06 (t, 3H),
.68 (d, 2H, J=8.1 Hz), 3.68 (q, 2H), 2.76 (t, 2H); C NMR
l
max 210, 258, 291 nm; IR n 3166, 3022, 2931, 1576, 1511,
À1
1
1189, 1054, 698 cm
7.36±7.31 (m, 6H), 6.80 (d, 1H, J=3.6 Hz), 5.52±5.45 (m,
1H), 2.10±1.92 (m, 2H), 0.97 (t, 3H); C NMR (CDCl ) d
3
3
; H NMR (CDCl ) d 11.18 (s, 2H),
1
3
1
3
(
DMSO-d
6
) d 178.5, 162.3, 156.4, 137.3, 130.3, 129.5, 115.9,
0
1
12.7, 46.9, 34.1; MALDI-TOF 280.6. N-[2-Pyridylethyl]-N -
ꢀ
177.0, 162.3, 141.3, 137.8, 128.8, 127.5, 111.5, 61.0, 29.9,
10.9; MALDI-TOF: 279.5.
[
2-(thiazolyl)]thiourea (11): yield 60%; mp 140±141 C;
UV(MeOH) lmax 209, 262, 269, 288 nm; IR n 3176, 3047,
30. Sudbeck, E. A.; Venkatachalam, T. K.; Uckun, F. M.
Acta Cryst. 1999, C55, 2122.
3
1
002, 2937, 1581, 1558, 1514, 1475, 1433, 1342, 1304, 1246,
1
À1
167, 1147, 1068, 1020, 989, 869, 789, 752, 690 cm ; H NMR
31. Zarling, J. M.; Moran, P. A.; Ha€ar, O.; Sias, J.; Rich-
man, D. D.; Spina, C. A.; Myers, D. E.; Kuebelbeck, V.;
Ledbetter, J. A.; Uckun, F. M. Nature 1990, 347, 92.
32. Erice, A.; Lieler, C. L.; Meyers, D. E.; Sannerund, K. J.;
Irvin, J. D.; Balfour, H. H.; Uckun, F. M. Antimicrob. Agents
Chemother. 1993, 37, 835.
(
DMSO-d ) d 11.59 (bs, 1), 9.77 (bs, 1H), 8.51±8.49 (d, 1H),
6
7
7
.72±7.67 (m, 1H), 7.31±7.26 (m, 2H), 7.23±7.19 (m, 1H),
1
3
.06±7.05 (m, 1H), 3.95±3.89 (m, 2H), 3.07±3.02 (m, 2H);
) d 178.1, 161.8, 158.7, 149.2, 136.7, 129.4,
23.5, 121.8, 112.2, 43.9, 36.2; MALDI-TOF: 266.3 (M+2).
C
NMR (DMSO-d
1
6