Synthesis, Biological Properties, and Molecular Modeling Investigations of Novel 3,4-Diarylpyrazolines as Potent and Selective CB1 Cannabinoid Receptor Antagonists

Article abstract of DOI:10.1021/jm031019q

A series of novel 3,4-diarylpyrazolines was synthesized and evaluated in cannabinoid (hCB₁ and hCB₂) receptor assays. The 3,4-diarylpyrazolines elicited potent in vitro CB₁ antagonistic activities and in general exhibited high CB₁ vs CB₂ receptor subtype selectivities. Some key representatives showed potent pharmacological in vivo activities after oral dosing in both a CB agonist-induced blood pressure model and a CB agonist-induced hypothermia model. Chiral separation of racemic 67, followed by crystallization and an X-ray diffraction study, elucidated the absolute configuration of the eutomer 80 (SLV319) at its C₄ position as 4S. Bioanalytical studies revealed a high CNS-plasma ratio for the development candidate 80. Molecular modeling studies showed a relatively close three-dimensional structural overlap between 80 and the known CB₁ receptor antagonist rimonabant (SR141716A). Further analysis of the X-ray diffraction data of 80 revealed the presence of an intramolecular hydrogen bond that was confirmed by computational methods. Computational models and X-ray diffraction data indicated a different intramolecular hydrogen bonding pattern in the in vivo inactive compound 6. In addition, X-ray diffraction studies of 6 revealed a tighter intermolecular packing than 80, which also may contribute to its poorer absorption in vivo. Replacement of the amidine -NH₂ moiety with a -NHCH₃ group proved to be the key change for gaining oral biovailability in this series of compounds leading to the identification of 80.

Full text of DOI:10.1021/jm031019q

J . Med. Chem. 2004, 47, 627-643
627
Syn th esis, Biologica l P r op er ties, a n d Molecu la r Mod elin g In vestiga tion s of
Novel 3,4-Dia r ylp yr a zolin es a s P oten t a n d Selective CB1 Ca n n a bin oid Recep tor
An ta gon ists
J os H. M. Lange,* Hein K. A. C. Coolen, Herman H. van Stuivenberg, J essica A. R. Dijksman,
Arnoud H. J . Herremans, Eric Ronken, Hiskias G. Keizer, Koos Tipker, Andrew C. McCreary, Willem Veerman,
Henri C. Wals, Bob Stork, Peter C. Verveer, Arnold P. den Hartog, Natasja M. J . de J ong, Tiny J . P. Adolfs,
J an Hoogendoorn, and Chris G. Kruse
Solvay Pharmaceuticals, Research Laboratories, C. J . van Houtenlaan 36, 1381 CP Weesp, The Netherlands
Received September 4, 2003
A series of novel 3,4-diarylpyrazolines was synthesized and evaluated in cannabinoid (hCB1
and hCB2) receptor assays. The 3,4-diarylpyrazolines elicited potent in vitro CB1 antagonistic
activities and in general exhibited high CB1 vs CB2 receptor subtype selectivities. Some key
representatives showed potent pharmacological in vivo activities after oral dosing in both a
CB agonist-induced blood pressure model and a CB agonist-induced hypothermia model. Chiral
separation of racemic 67, followed by crystallization and an X-ray diffraction study, elucidated
the absolute configuration of the eutomer 80 (SLV319) at its C4 position as 4S. Bioanalytical
studies revealed a high CNS-plasma ratio for the development candidate 80. Molecular
modeling studies showed a relatively close three-dimensional structural overlap between 80
and the known CB1 receptor antagonist rimonabant (SR141716A). Further analysis of the X-ray
diffraction data of 80 revealed the presence of an intramolecular hydrogen bond that was
confirmed by computational methods. Computational models and X-ray diffraction data
indicated a different intramolecular hydrogen bonding pattern in the in vivo inactive compound
6. In addition, X-ray diffraction studies of 6 revealed a tighter intermolecular packing than
80, which also may contribute to its poorer absorption in vivo. Replacement of the amidine
-NH2 moiety with a -NHCH3 group proved to be the key change for gaining oral biovailability
in this series of compounds leading to the identification of 80.
In tr od u ction
In this paper, the discovery of a novel class of
diarylpyrazolines of general formula 1 as potent and
CB1-subtype selective receptor antagonists is described.
Cannabinoids are present in the Indian hemp Can-
nabis sativa L. and have been used as medicinal agents
for centuries.1-4 However, only within the past 10 years
the research in the cannabinoid area has revealed
pivotal information on the endocannabinoid system, its
receptor subtypes5,6 (CB1 and CB2), and their (endog-
enous) agonists.7 Recent data suggest there may be a
third cannabinoid receptor8 (“CB3”). The CB1 cannab-
inoid receptor is expressed at high levels in several brain
areas including hippocampus, cortex, cerebellum, and
basal ganglia as well as in some peripheral tissues
including urinary bladder, testis, and ileum. The CB2
cannabinoid receptor is principally found in the immune
system. CB1 receptor antagonists may have potential
in the treatment of a number of diseases such as
neuroinflammatory disorders,9 cognitive disorders,10
septic shock,10 obesity,10,11 psychosis,10,12 addiction,13
and gastrointestinal disorders.14
Ch em istr y
A set of proprietary compounds based on structural
resemblance with rimonabant was screened and re-
sulted in the initial discovery of the lead compound 5
as a CB1 receptor antagonist. A synthesis program
based on 5 was devised and carried out.
Several types of CB1 receptor antagonists are known
and have recently been reviewed,9 including the potent
and selective15 rimonabant, which is currently undergo-
ing clinical phase III development for obesity treatment.
Reaction of 3-(4-chlorophenyl)-4-phenylpyrazoline16
2
* To whom correspondence should be addressed: Dr. J . H. M. Lange,
Solvay Pharmaceuticals, Chemical Design & Synthesis Unit, C. J . van
Houtenlaan 36, 1381 CP Weesp, The Netherlands. Telephone: +31
(0)294 479731. Fax +31 (0)294 477138. E-mail: jos.lange@solvay.com.
with 3 gave the amidine 4. This amidine was reacted
with various arylsulfonyl halides to furnish the target
molecules 5-9 in good yields (Scheme 1).
10.1021/jm031019q CCC: $27.50 © 2004 American Chemical Society
Published on Web 12/30/2003

628 J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 3
Lange et al.
Sch em e 1a
a
Reagents and conditions: (a) pyridine, 110 °C; (b) 2 N NaOH; (c) R6ArSO2Cl, CH3CN, DMAP, Et3N, room temp.
Sch em e 2a
a
Reagents and conditions: (a) m-CPBA, reflux; (b) N2H4‚H2O, EtOH, 35 °C; (c) H2NC(SMe)dNH. 0.5 H2SO4, pyridine, 110 °C; (d) 2 N
NaOH; (e) p-Cl-PhSO2Cl, Et3N, CH3CN, room temp.
The synthesis of the target molecule having an
additional hydroxy group at the 4-position of the pyra-
zoline ring started with an epoxidation reaction (using
m-chloroperbenzoic acid) of 4′-chloro-2-phenylacrylophe-
none16 10 to give the oxirane derivative 11. Subsequent
cyclization of 11 with hydrazine hydrate gave the
4-hydroxypyrazoline congener 12. The reaction of 12
with methyl imidothiocarbamate delivered the amidated
product 13. The target molecule 14 was obtained from
the reaction of 13 with p-chlorophenylsulfonyl chloride
(Scheme 2).
For the synthesis of the target molecules having one
or two additional methyl groups on their carboxamidine
moiety, a more convergent approach was devised,
wherein the NR3R4 moiety is introduced in the last step.
The arylsulfonyldithioimidocarbonic acid methyl esters
15-19 were prepared17 from the corresponding aryl-
sulfonamides, methyl iodide and CS2 and subsequently
coupled to the 3,4-diarylpyrazoline 2 to furnish the
compounds 20-24. Nucleophilic attack by either meth-
ylamine or dimethylamine gave the target molecules
25-29 in reasonable to good yields (Scheme 3).
To expand the scope of phenyl group substituents on
the 3- and 4-position of the 4,5-dihydropyrazole ring,
the synthesis of 34 and 35 was undertaken. Compounds
32 and 33 were obtained from 30 and 31, respectively,
using a Mannich reaction/ elimination sequence and
further cyclocondensed16 into 34 and 35 (Scheme 4).
The described synthetic route to compounds 25-29
is straightforward but is adversely affected by liberation
of the smelly methyl sulfide in the final step. Therefore,
an additional synthetic route was developed to avoid
this environmental issue. The synthetic strategy is
based on the coupling of diarylpyrazolines of general
formula A with sulfonylated carbamic acid methyl esters
of general formula B, which were obtained from the
corresponding arylsulfonamide and methyl chlorofor-
mate, to furnish the products C. Chlorination of C using
phosphorus pentachloride in chlorobenzene yielded the
intermediate imidoyl chlorides D. The target molecules
E were obtained from the reaction of D with methyl-
amine (Scheme 5). It is interesting to note that the high
reactivity of the intermediate imidoyl chlorides D
enables their quick conversion with a broad range of
amines, which makes this route particularly amenable
to combinatorial chemistry purposes.
As the 3,4-diarylpyrazoline moiety contains a chiral
center at its 4-position, the prepared target compounds
of general formula 1 are racemates. To further inves-
tigate the stereochemical requirements for binding to
the CB1 receptor in this chiral pyrazoline series in more
detail, the key compounds 29 and 67 were separated
into their enantiomers by applying chiral preparative
HPLC to furnish two optically pure sets of compounds
78/79 and 80/81, respectively (Scheme 6).

CB1 Cannabinoid Receptor Antagonists
J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 3 629
Sch em e 3a
a
Reagents and conditions: (a) Et3N, CH3CN, reflux; (b) R3R4NH, MeOH, CH2Cl2, room temp.
Sch em e 4a
a
Reagents and conditions: (a) 37% aq. CH2O, piperidine, reflux; (b) N2H4‚H2O, EtOH, reflux.
An intriguing modification in our target molecules
was the replacement of their sulfonyl group by a
carbonyl group (Scheme 7). 4-Chlorobenzoylisothiocy-
anate 82 was prepared18 from 4-chlorobenzoyl chloride
and ammonium isothiocyanate. Nucleophilic addition of
pyrazoline 2 to 82 yielded the adduct 83. The target
molecule 84 was obtained from the reaction of 83 with
methylamine in the presence of HgCl2 in moderate yield.
The CB1 receptor binding data in the amidine -N-
HCH3 series 67-70 wherein the substituents R1 and
R2 were varied clearly elicit the CB1 affinity optimum
in the R1 ) Cl and R2 ) H substitution pattern, whereas
the other variations, including 68 wherein R2 represents
4-F, were markedly less tolerated. Comparison of 67
with 27-29 and 71-77 further clarified the role of the
substituent R6. Replacement of 4-Cl in 67 by H (71), F
(72), or methyl (73) and CF3 (29) all resulted in reduced
affinity. Replacement of 4-Cl in 67 by 2-Cl (27), 3-CF3
(74), and 2,4,6-trimethyl (75) gave a small reduction of
affinity. The 3-Cl (28), 4-OMe (76), and the bulky
2-naphthyl substituted analogue 77 elicited a high CB1
receptor affinity. Compound 84 in which the sulfonyl
group is replaced by a carbonyl group showed ∼3-fold
less affinity than 67. The negligible affinity of interme-
diate 45 wherein the amidine group is substituted by
an amide moiety underlines the importance of the
amidine moiety in the CB1 pharmacophore. It is inter-
esting to note that the intermediate 24 wherein the
amidine NH2 group is replaced by the SMe group
showed also considerable CB1 receptor affinity. Appar-
ently, limited structural variations are allowed in the
carboxamidine part of the pharmacophore. As 29 and
67 are racemates their enantiomerically pure constitu-
ents were also tested. In both cases the levorotatory
enantiomers 78 and 80, respectively, had significantly
higher CB1 affinities than their dextrorotatory coun-
terparts 79 and 81. The highest CB1 receptor affinity
(7.8 nM) was found in the eutomer 80. This value is in
the same order of magnitude as that reported15 for
rimonabant (11.5 nM). The distomer 81 showed ∼ 100-
Resu lts a n d Discu ssion
The target compounds 5-9, 14, 24-29, 45, 67-81,
and 84 were evaluated in vitro at the human CB1 and
CB2 receptor, stably expressed into Chinese hamster
ovary (CHO) cells,19,20 utilizing radioligand binding
studies. CB1 receptor antagonism21 was measured using
an arachidonic acid release-based functional assay,
using the same recombinant cell line. The results are
reported in Table 1. The CB1 receptor binding data in
the amidine -NH2 series (compounds 5-9, 14, and 25-
27) revealed that replacement of the 4-Me group in 5
by Cl (6) or F (9) gave a substantial gain in affinity,
whereas OMe substitution (7) did not elicit a clear effect
on affinity. 2,4,6-Trimethyl substituted 8 also showed
considerably higher affinity than the 4-methyl substi-
tuted 5. Incorporation of a 4-OH group in the dihydro-
pyrazole moiety (14) reduced affinity as compared to 6.
Relocation of the 4-Cl atom in 6 to the 3-position (28)
had little effect on affinity, whereas Cl relocation to the
2-position (27) reduced CB1 receptor affinity. Substitu-
tion of the 4-methyl group in 5 by the strongly electron
withdrawing -CF3 group (29) had little effect on affinity.
Both compounds 25 and 26 from the amidine N(CH3)2
series had reduced CB1 affinity as compared to their
-NH2 counterparts 6 and 9.

630 J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 3
Lange et al.
Sch em e 5a
a
Reagents and conditions: (a) toluene, reflux; (b) PCl5, chlorobenzene, reflux; (c) MeNH2, CH2Cl2, room temp.
Sch em e 6a
a
Reagents and conditions: (a) chiral preparative HPLC.
fold less affinity than the eutomer 80, indicating that
these chiral ligands bind stereoselectively to the CB1
receptor.
based functional assay. Interestingly, the 4-trifluoro-
methylphenyl substituted 29 revealed strong CB1 an-
tagonistic properties (pA2 ) 9.3), despite its moderate
receptor affinity. In line with the CB1 receptor affinity
results the eutomers 78 and 80 both showed consider-
ably more potent CB1 antagonistic properties than their
distomers 79 and 81.
It was encouraging to note that a considerable CB1/2
receptor selectivity was already observed in the original
lead 5. The results from Table 1 reveal that CB1/CB2
receptor subtype selectivity is apparent throughout the
The results from the arachidonic acid release-based
functional assay (Table 1) clearly reveal the CB1 recep-
tor antagonistic properties of our target compounds 5-9,
24-29, 67-81, and 84. In general, the compounds
having the highest CB1 receptor affinities also show
strong antagonistic activity. Eight compounds (6, 8, 24,
29, 74-75, 78, and 80) exhibited subnanomolar CB1
antagonistic potencies in the arachidonic acid release-

CB1 Cannabinoid Receptor Antagonists
J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 3 631
Sch em e 7a
a
Reagents: (a) CH3CN, 0 °C; (b) CH3NH2, HgCl2, CH3CN, room temp.
Ta ble 1. In Vitro Results of the Pyrazoline Derivatives 5-9, 14, 24-29, 45, 67-81, 84 and Rimonabant
compound
Ki(CB1),a nM
pA2(CB1)b
Ki(CB2),c nM
compound
Ki(CB1),a nM
pA2(CB1)b
Ki(CB2),c nM
rimonabant
25 ( 15
8.6 ( 0.1
1580 ( 150
(1640)15
> 1,000
> 1,000
> 1,000
> 1,000
> 1,000
68
584 ( 220
(11.5)15
5
6
7
8
197 ( 152
16.1 ( 6.6
196 ( 107
24.2 ( 13.0
52.6 ( 10.5
713 ( 268
16.6 ( 11.6
280 ( 178
> 1,000
8.4 ( 0.2
9.5 ( 0.3
8.3 ( 0.2
9.4 ( 0.3
9.0 ( 0.3
69
70
71
72
73
74
75
76
77
78
79
80
81
84
214 ( 55
7.6 ( 0.1
255 ( 105
170 ( 44
7.5 ( 0.2
8.5 ( 0.3
8.6 ( 0.3
9.1 ( 0.2
9.4 ( 0.5
8.0 ( 0.3
8.5 ( 0.2
9.0 ( 0.3
7.5 ( 0.1
9.9 ( 0.6
< 7.4
338 ( 170
119 ( 40
> 1,000
> 1,000
9
14
24
25
26
27
28
29
45
67
36.5 ( 21.7
54.2 ( 17.7
22.9 ( 11.0
21.8 ( 3.4
35.9 ( 10.8
293 ( 120
7.8 ( 1.4
9.7 ( 0.5
8.5 ( 0.3
< 7.5
8.3 ( 0.1
8.6 ( 0.2
9.3 ( 0.2
> 1,000
> 1,000
> 1,000
> 1,000
> 1,000
> 1,000
75.4 ( 12.3
13.9 ( 7.9
221 ( 130
> 1000
3,515 ( 1085
> 1,000
7,943 ( 126
> 1,000
894 ( 324
70.6 ( 12.7
25.2 ( 7.4
8.7 ( 0.3
> 1,000
8.7 ( 0.2
a
Displacement of specific CP-55,940 binding in CHO cells stably transfected with human CB1 receptor, expressed as Ki ( SEM (nM).
[3H]-Arachidonic acid release in CHO cells expressed as pA2 ( SEM values. c Displacement of specific CP-55,940 binding in CHO cells
b
stably transfected with human CB2 receptor, expressed as Ki ( SEM (nM). The values represent the mean result based on at least three
independent experiments.
presented dihydropyrazole series. The highest CB1/CB2
receptor selectivity (∼1000) was found in the develop-
ment candidate 80, which is ∼7-fold higher than the
reported15 CB1/CB2 receptor selectivity (143) for rimona-
bant.
Ta ble 2. in Vivo Results of Compounds 5-6, 25, 29, 67,
78-81, and Rimonabant
ED50, hypotension,
rata
LED, hypothermia,
compound
mouseb
rimonabant
3.2
3
5
6
> 30
> 30
> 30
8.9
15
2.0
> 30
5.5
> 30
> 30
> 30
10
3
3
The in vivo activity of some key dihydropyrazoles was
investigated in two mechanistic pharmacological mod-
els, viz. a CB1 agonist (CP-55,940) induced hypoten-
sion22 rat model and a CB1 agonist (WIN-55,212)
induced hypothermia23 mouse model. Their activities
were compared with those of rimonabant. The results
indicated that both the initial lead 5 and its congener 6
are devoid of in vivo cannabinoid antagonistic activity
after oral administration in both models. Therefore,
further optimization efforts were directed to improve the
bioavailability after oral administration. It was discov-
ered that the test compound 25 from the series wherein
the polar -NH2 group of the carboxamidine group is
substituted by an -N(CH3)2 group, showed improved in
vivo activity in the hypothermia model after oral
administration. This result prompted a further subtle
structural carboxamidine modification from the -N(CH3)2
to the -NHCH3 moiety (compounds 27-29 and 67-77).
This variation proved to be particularly worthwhile and
provided a number of potent in vivo compounds. It was
most gratifying to see that the compounds 29 and 67,
which contain a 4-CF3 substituent and 4-Cl substituent,
respectively, at their arylsulfonyl moiety, exhibited
strong activities after oral administration in both the
CB-agonist induced hypotension and hypothermia model
25
29
67
78
79
80
81
1
> 30
3
> 30
a
Antagonism of CB agonist (CP55,940) induced hypotension,
b
rat expressed asED50 (mg/kg, po administration). Antagonism of
CB agonist (WIN-55,212) induced hypothermia, mouse expressed
as least effective dose (LED) (mg/kg, po administration).
(Table 2). In line with the reported in vitro results (vide
supra), the levorotatory enantiomers 78 and 80 were
active in vivo, whereas no activity was found for the
distomers 79 and 81. Apparently, the CB1 receptor
strongly discriminates between both mirror images
indicating that the orientation of the 4-phenyl substitu-
ent is strongly involved in CB1 receptor-ligand interac-
tion. To obtain a better understanding of the structural
moieties being critically involved in the CB1 receptor-
ligand interaction in our pyrazoline series additional
studies were undertaken. The absolute configuration of
the eutomer 80 was assessed by means of an X-ray

632 J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 3
Lange et al.
F igu r e 1. Stereoview of the X-ray diffraction result of 80.
Recently, a model for the binding of rimonabant in
the CB1 receptor has been described in the literature,25
based on the X-ray structure26 of bovine rhodopsin
(Rho). The original template was modified to the puta-
tive inactive R-state with a pronounced proline kink at
Pro358 in transmembrane helix 6 (TMH6) as the most
remarkable feature.27,28 It enables a stabilizing salt
bridge between Lys214 and Asp338 at the intracellular
end of TMHs 3 and 6. It has been postulated,25 sup-
ported by biological data, that rimonabant in its Tg
conformation has an interaction with this Lys214, which
is only possible when the latter is bridged to Asp338.
This implies that rimonabant has a higher affinity for
the R-state. Binding of rimonabant is further described
by aromatic stacking interactions between the two
aromatic rings of rimonabant and an aromatic residue-
rich region in TMH 3-4-5-6.
F igu r e 2. Intramolecular hydrogen bonding in 80. The
intramolecular H-bond is indicated as a dashed line.
diffraction study. The absolute configuration of 80 was
found to be 4S from the X-ray diffraction data analysis
(Figure 1).
The X-ray diffraction result of 80 revealed the pres-
ence of an intramolecular hydrogen bond between the
hydrogen atom at its amidine moiety and the N atom
at the 2-position of the dihydropyrazole ring (Figure 2).
The presence of this particular intramolecular hydrogen
bond was also found in the modeled lowest energy
conformation of 80. It is remarkable to notice that this
H-bond is preferred above the alternative binding to one
of the SO2 oxygen atoms. Furthermore, the delocaliza-
tion of the double bond electrons of the amidine moiety
in 80 is clearly demonstrated by the identical inter-
atomic distances (Figure 2).
The receptor model was reconstructed.25 Giving the
best fit with rimonabant, the Tg, conformation 80D was
used as starting conformation for manual docking into
the receptor, followed by simulated annealing and
minimization. In Figure 4 the resulting receptor-based
alignment of rimonabant and 80 is given.
Conformational analysis by molecular modeling stud-
ies has revealed four low energy conformations of
rimonabant,24 determined by the amide bond (cis [C]
or trans [T] configuration) and the conformation of its
N-piperidinyl moiety (gauche [g] or skew [s]). Compa-
rable studies on the more flexible 80 gave several easily
accessible conformations, mutually differing in the
positioning of the sulfonyl carboxamidine chain with
respect to the pyrazoline ring. Interestingly, the differ-
ent MOPAC-minimization methods gave remarkable
differences with respect to the angle in the -CdN-SO2
moiety of the side-chain. The PM3 method appeared to
give the best approximation of the angle in comparison
with the X-ray structure (AM1: 149.7°; PM3: 138.6°;
X-ray: 123.3°). Ten representative conformations of 80
are depicted in Figure 3 and their corresponding ener-
gies are summarized in Table 3, all lying within 4 kcal/
mol as compared to the minimum energy conformation.
This calculated result demonstrates the flexibility of the
molecule. Conformation H most closely resembles the
X-ray structure.
One of the SO2 oxygen atoms in 80 forms a hydrogen
bond with the Asp366-Lys192 salt bridge. Compared
to rimonabant, binding of 80 is further enhanced by an
additional hydrogen bond via its other SO2 oxygen atom
with Ser383. This is also in line with the 3-fold less CB1
receptor affinity of 84, wherein the SO2 moiety is
replaced with a carbonyl group that cannot accom-
modate this additional hydrogen bond, as compared
with 67. The end group of the chain fits well in a pocket
formed by various lipophilic residues. In the case of 80,
a stacking interaction between the p-chlorophenyl ring
and Phe170 is possible. The two aromatic rings attached
to the pyrazoline core are enclosed by an arrangement
of stacked aromatic residues. The p-chlorophenyl ring
is bound in a pocket formed by Trp279/Phe200/Trp356
while the other ring fits in a cavity created by Tyr275/
Trp255/Phe278. The stereoselectivity in the binding
(Table 2) can be rationalized by the latter interaction.
In the enantiomer 78, the aromatic ring points in the
wrong direction, away from the lipophilic pocket thereby
loosing the favorable stacking interactions.

CB1 Cannabinoid Receptor Antagonists
J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 3 633
F igu r e 3. Orthographic drawing (left: front view, right: side view) of 10 representative low energy conformations of 80, aligned
with respect to the pyrazoline core. (The core is grayed out for clarity).
Ta ble 3. Heats of Formation of the Conformations Depicted in
Ta ble 4. ADME Parameters of 6, 25, and 80
Figure 3
P-glycoprotein membrane
heat of
heat of
compound ACD log Pa
affinityb
passagec
cPSAd
conformation formation (kcal) conformation formation (kcal)
6
25
80
4.3e
4.8
4.8
1.7 ( 0.5
1.4 ( 0.1
1.4 ( 0.1
7.0 ( 0.7
15.2 ( 0.6
14.8 ( 2.2
122.5
62.7
89.3
A
B
C
D
E
52.53
53.30
54.70
51.98
51.50
F
51.91
51.27
51.39
52.67
51.16
G
H
K
L
a
Calculated log P: ACD log P, version 7; Advanced Chemistry
Development, 90 Adelaide St. W. Suite 702, Toronto, ON, Canada
b
M5H 3V9. P-glycoprotein transport ratio, expressed as the mean
percentage of compound transported. c Membrane passage, ex-
d
pressed as the mean percentage of compound transported. Cal-
culated polar surface area of the presumed binding conformation.
e Mean value of calculated results from two tautomers.
(Table 1). However, compound 6 showed no in vivo CB1
receptor mediated activity after oral administration
(Table 2). The intriguing phenomenon that the structur-
ally so closely related compounds 6 and 80 showed
markedly different potencies in vivo was investigated
in more detail. To this purpose, the most important
ADME parameters were determined, which are sum-
marized in Table 4.
The common Lipinski parameters30 (log P, mol weight,
number of H-bond donors and acceptors) are in the same
order of magnitude as the only difference between the
structures 6, 25, and 67 (80) is the presence of one or
two additional methyl groups. In addition, the log P
value of compound 80 was determined by RP-HPLC and
was found in the same order of magnitude (log P (80) )
5.1) as compared to its calculated log P value of 4.8
(Table 4).
It has been described that the P-glycoprotein pump
is present in the gut wall and is involved in intestinal
absorption. In addition, the P-glycoprotein pump lowers
the CNS levels of certain compounds by actively extrud-
ing them from the brain.31 Therefore, the affinities of
6, 25, and 80 for this efflux pump were examined. All
compounds were shown to be devoid of significant
P-glycoprotein pump substrate affinity (Table 4).
F igu r e 4. Receptor-based alignments of 80 and rimonabant.
As can be seen in Table 1, the dimethyl derivative 25
is considerably less active than 80. The binding cavity
of the receptor can easily accommodate this additional
methyl group. Moreover, conformational studies on 25
showed that the required conformation for binding is
only slightly higher (0.83 kcal/mol) than the lowest
energy conformation. A possible explanation for the
observed reduced CB1 receptor affinity (Table 1) can be
found in the presence of the intramolecular hydrogen
bond in 80 (see Figure 2). This interaction conceivably
directs the carboxamidine chain toward the binding
pocket. In the dimethyl derivative 25, this directing
effect by hydrogen bonding is impossible, which might
cause loss of entropy during binding, thereby resulting
in a lower binding affinity.29 In the desmethyl derivative
6, the above-mentioned preorganizing intramolecular
hydrogen bond is also possible. This is in nice agreement
with the comparable CB1 receptor affinities of 6 and 67
The molecular polar surface area (PSA) has been
shown to correlate well with drug transport properties,
such as intestinal absorption or blood-brain barrier

634 J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 3
Lange et al.
F igu r e 5. Orthogonal representations of the crystal packing of (a) 6 along the xy-diagonal of the unit cell, columns with
S-configuration colored orange and those with R-configuration blue/green and (b) of 80 along the x-axis of the unit cell.
penetration.32,33 PSA thus represents, at least in part,
the energy involved in the membrane transport of a
compound.34 Compounds having a PSA value > 120 Å2
have generally been shown to have a low oral bioavail-
ability. It was anticipated that attachment of apolar
methyl groups to the polar amidine moiety of 6 would
result in compounds with a lower PSA, showing higher
bioavailability after oral dosing. The substantially
higher calculated PSA value for 6 as compared to the
PSA values for 25 and 80 supports this hypothesis
(Table 4). Furthermore, the high PSA value of 6 is in
line with its observed lower membrane passage rate and
diminished in vivo potency after oral administration as
compared to its N-methylated congeners 25 and 80.
lattice energy have an impact on the rate of dissolution
in solvents, including water. Water solubility and dis-
solution rate constitute critical determinants for the
degree of uptake in the GI tract after oral administra-
tion.35
An X-ray diffraction study of compound 6 was carried
out to assess potential differences in crystal packing
between crystalline 6 and 80.
Remarkably, both enantiomers are present in the unit
cell of the X-ray structure of 6. In the crystal packing
of 6 (see Figure 5a), the dihydropyrazole core almost
lies in a plane with the sulfonyl carboxamidine substit-
uents and the core p-chlorophenyl ring. These units are
aligned in a straight sheet kept together by a progres-
sion of intramolecular hydrogen bonds between the SO2
oxygen atoms and the -NH2 groups. The two remaining
phenyl rings are positioned nearly perpendicular with
respect to the sheet. Two of these sheets are attached
to each other via a network of π-π stacking interactions
forming a columnar packing of two opposite sheets.
Interestingly, in the packing the columns exist alter-
nately of molecules having the R- and S-configuration,
Before any absorption can take place, a drug needs
to be in solution and therefore dissolution and solubility
are important properties to consider. It was found that
both compound 6 and 80 are very poorly soluble in water
(<1 mg/L at pH ) 7). However, the solubility of 6 in
the polar organic solvents acetonitrile and ethanol at
reflux conditions is moderate, whereas 80 readily dis-
solved under these conditions. It is known that physical
properties of solids such as crystal packing and crystal

CB1 Cannabinoid Receptor Antagonists
J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 3 635
F igu r e 6. Stereoview of the S-enantiomer of the X-ray structure of 6.
Con clu sion
The lead optimization of the CB1 cannabinoid receptor
antagonist 5 has led to the development candidates 78
(SLV326) and 80. Both 78 and 80 are novel subtype
selective CB1 receptor antagonists exhibiting potent
pharmacological activity in vitro as well as in vivo after
oral administration. It has been demonstrated that the
interactions of the enantiomers 78-81 with the CB1
receptor are highly stereoselective. Mono- and dimeth-
ylation of the polar carboxamidine moiety in 6 resulted
in the compounds 80 and 25 having substantially lower
calculated PSA values. These methylations are pivotal
in governing the oral bioavailability in the pyrazoline
series, conceivably by subtly affecting the degree of
dissolution rate in the gastrointestinal tract, as the
result of a different intramolecular hydrogen bonding
pattern and crystal packing.
F igu r e 7. Intramolecular and intermolecular hydrogen bond-
ing in the S-enantiomer of 6. The intermolecular H-bonds are
indicated as a dashed arrow.
respectively. These columns are mutually transformable
via centers of inversion between them.
The crystal packing of 80 also reveals a columnar
orientation along the x-axis of the unit cell (Figure 5b).
However, as can be clearly seen, this packing is not as
tight as with 6. This is also expressed by the higher
melting point of 6 compared to 80 (235 and 170 °C,
respectively). A predictive model for solubility has been
reported36,37 based on the log P and the melting point
of the compound, wherein in general higher melting
points correlate with lower water solubilities. The lower
water solubility and dissolution rate of 6 might result
in an insufficient dissolution rate in the GI tract to
enable in vivo activity.
Exp er im en ta l Section
Ch em istr y. 1H and 13C NMR spectra were recorded on a
Bruker Avance DRX600 instrument (600 MHz), Varian UN400
instrument (400 MHz), or a Varian VXR200 instrument (200
MHz) using DMSO-d6 or CDCl3 as solvents with tetrameth-
ylsilane as an internal standard. Chemical shifts are given in
ppm (δ scale) downfield from tetramethylsilane. Coupling
constants (J ) are expressed in hertz. Thin-layer chromatog-
raphy was performed on Merck precoated 60 F254 plates, and
spots were visualized with UV light. Flash chromatography
was performed using silica gel 60 (0.040-0.063 mm, Merck).
Column chromatography was performed using silica gel 60
(0.063-0.200 mm, Merck). Chiral preparative HPLC was
conducted by using a LC80 column (250 × 80 mm). Melting
points were recorded on a Bu¨chi B-545 melting point apparatus
and are uncorrected. Mass spectra were recorded on a Micro-
mass QTOF-2 instrument with MassLynx application software
for acquisition and reconstruction of the data. Exact mass
measurement was done of the quasimolecular ion [M+H]+.
Optical rotations ([R]D) were measured on an Optical Activity
polarimeter. Specific rotations are given as deg/dm, the
concentration values are reported as g/100 mL of the specified
solvent and were recorded at 23 °C. Elemental analyses were
In Figure 6 the S-enantiomer out of the X-ray
structure of 6 is shown. Basically, the difference in the
packing between 6 and 80 can be explained by the
bridging ability of the NH2 group of 6 forming intramo-
lecular hydrogen bonds with both the dihydropyrazole
core and the sulfonyl group. In this constellation, the
side-chain is directed in a planar orientation with
respect to the core, thereby enabling a strong intermo-
lecular H-bond of one of the SO2 oxygen atoms with a
hydrogen atom of the NH2 group of another molecule 6
(see Figure 7).
To estimate the CNS availability of our development
candidate 80 a bioanalytical study was undertaken to
assess its CNS/plasma ratio. The CNS/plasma ratio of
80 was found 1.7, which is in nice agreement with its
potent CB1 receptor mediated activity in the CB agonist-
induced hypothermia assay and its negligible P-glyco-
protein pump substrate affinity.
performed on
a Vario EL elemental analyzer by Solvay
Pharmaceuticals, Hanover, Germany, and were within (0.4%
of theoretical values, unless otherwise stated. Yields refer to
isolated pure products and were not maximized.
3-(4-Ch lor op h en yl)-4-p h en yl-4,5-d ih yd r o-1H-p yr a zole
(2). 2 was prepared according to the literature procedure.16

636 J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 3
Lange et al.
3-(4-Ch lor op h en yl)-4-p h en yl-4,5-d ih yd r o-1H-p yr a zole-
1-ca r boxa m id in e (4). A magnetically stirred mixture of 2
(5.13 g, 20.0 mmol), 3 (5.00 g, 23.0 mmol), and pyridine (10
mL) was heated at 110 °C for 1 h. After one night standing at
room temperature, Et2O was added and the precipitate was
collected by filtration and washed three times with Et2O
portions to afford a solid (9.0 g): mp 230 °C. The obtained solid
was dissolved in MeOH (20 mL) and a 2 N NaOH solution (12
mL) and water (200 mL) were successively added. The formed
precipitate was collected by filtration, washed two times with
Et2O and with diisopropyl ether, and dried in vacuo to yield 4
(5.1 g, 88% yield), mp 187-189 °C; 1H NMR (400 MHz, DMSO-
d6) δ 3.79 (dd, J ) 11 and 4.5 Hz, 1H), 4.19 (t, J ) 11 Hz, 1H),
4.89 (dd, J ) 11 and 4.5 Hz, 1H), 5.65 (br s, 3H), 7.20-7.25
(m, 3H), 7.28-7.35 (m, 2H), 7.37 (dt, J ) 8 and 2 Hz, 2H),
7.65 (dt, J ) 8 and 2 Hz, 2H); 13C NMR (100 MHz, DMSO-d6)
δ 50.0, 56.6, 127.5 (2C), 128.3, 128.9, 129.4, 130.6, 133.6, 141.5,
151.1, 155.8.
135.2, 136.1, 140.5, 153.1, 157.6, 161.9; HRMS (C23H22-
ClN4O3S) [M+H]+: found m/z 469.1122, calcd 469.1101. Anal.
(C23H21ClN4O3S) C, H, N.
3-(4-Ch lor oph en yl)-4-ph en yl-N-[(2,4,6-tr im eth ylph en yl)-
su lfon yl]-4,5-d ih yd r o-1H-p yr a zole-1-ca r boxa m id in e (8).
8 was prepared from 4 and 2,4,6-trimethylphenylsulfonyl
chloride in 82% yield by the same procedure as described for
1
9, mp 228-229 °C; H NMR (400 MHz, DMSO-d6) δ 2.22 (s,
3H), 2.59 (s, 6H), 3.74 (dd, J ) 11 and 4 Hz, 1H), 4.31 (t, J )
11 Hz, 1H), 5.01 (dd, J ) 11 and 4 Hz, 1H), 6.94 (s, 2H), 7.16-
7.34 (m, 5H), 7.42 (dt, J ) 8 and 2 Hz, 2H), 7.50-7.70 (m,
2H), 7.74 (dt, J ) 8 and 2 Hz, 2H); 13C NMR (100 MHz, DMSO-
d6) δ 20.7, 22.7, 50.0, 56.0, 127.5, 127.9, 129.1, 129.3, 129.4,
129.6, 131.5, 135.2, 137.5, 138.6, 140.5, 140.6, 152.8, 157.4;
HRMS (C25H26ClN4O2S) [M+H]+: found m/z 481.1467, calcd
481.1465. Anal. (C25H25ClN4O2S) C, H, N.
(4-Ch lor op h en yl)(2-p h en yloxir a n -2-yl)m eth a n on e (11).
To a magnetically stirred solution of 1016 (31.8 g, 0.131 mol)
in CH2Cl2 (300 mL) was added MCPBA (40 g; 70% solution,
0.162 mol) and the resulting mixture was refluxed for 16 h to
give a suspension. After cooling of the sample to room
temperature, the mixture was washed with an aqueous
NaHCO3 solution (3×) and water. The organic layer was dried
over Na2SO4, filtered, and concentrated in vacuo to give 11
(37.6 g, quantitative yield) as an oil. 1H NMR (400 MHz,
DMSO-d6) δ 3.36 (d, J ) 5 Hz, 1H), 3.39 (d, J ) 5 Hz, 1H),
7.34-7.40 (m, 5H), 7.57 (d, J ) 8 Hz, 2H), 7.94 (d, J ) 8 Hz,
2H); 13C NMR (100 MHz, DMSO-d6) δ 54.2, 63.4, 126.7, 129.5,
129.6, 129.8, 131.8, 133.4, 135.7, 139.7, 194.2.
3-(4-Ch lor oph en yl)-N-[(4-flu or oph en yl)su lfon yl]-4-ph en -
yl-4,5-d ih yd r o-1H-p yr a zole-1-ca r boxa m id in e (9). To a
magnetically stirred mixture of 4 (0.50 g, 1.68 mmol) and
4-fluorophenylsulfonyl chloride (0.34 g, 1.75 mmol) in CH3CN
(10 mL) were added N,N-dimethyl-4-aminopyridine (0.020 g,
0.175 mmol) and Et3N (1 mL). The resulting solution was
stirred at room temperature for 30 min. After addition of a 2
N NaOH solution and extraction with EtOAc (400 mL), the
EtOAc layer was concentrated in vacuo. The resulting crude
residue was further purified by flash chromatography (petro-
leum ether (40-60)/Et2O ) 1/1 (v/v), followed by EtOAc) and
recrystallized from CH3CN to afford 9 (0.55 g, 72% yield), mp
3-(4-Ch lor op h en yl)-4-h yd r oxy-4-p h en yl-4,5-d ih yd r o-
1H-p yr a zole (12). 11 (112 g, 0.43 mol) was dissolved in EtOH
(650 mL) at 35 °C. To the resulting stirred solution was added
N2H4‚H2O (42 mL) and the formed 12 slowly precipitated. After
standing for 16 h the crystalline material was collected by
filtration and successively washed with EtOH, water, and
EtOH and subsequently dried to give pure 12 (92 g, 78% yield).
1
214-215 °C; H NMR (400 MHz, DMSO-d6) δ 3.79 (dd, J )
12 and 4 Hz, 1H), 4.35 (t, J ) 12 Hz, 1H), 5.03 (dd, J ) 12 and
4 Hz, 1H), 7.16-7.36 (m, 9H), 7.43 (d, J ) 8 Hz, 2H), 7.76 (d,
J ) 8 Hz, 2H), 7.89-7.94 (m, 2H); 13C NMR (100 MHz, DMSO-
d6) δ 50.0. 56.0, 116.2 (d, J CF ) 22 Hz), 127.6, 127.9, 128.98
(d, J CF ) 10 Hz), 129.05, 129.2, 129.5, 129.6, 135.3, 140.4, 140.6
(d, J CF ) 3 Hz), 153.2, 157.9, 164.0 (d, J CF ) 249 Hz); HRMS
(C22H19ClFN4O2S) [M+H]+: found m/z 457.0924, calcd 457.0901.
Anal. (C22H18ClFN4O2S) C, H, N.
1
mp 195-196 °C; H NMR (400 MHz, DMSO-d6) δ 3.53 (dd, J
) 10 and 2 Hz, 1H), 3.73 (dd, J ) 10 and 4 Hz, 1H), 6.41 (s,
1H), 7.19-7.42 (m, 8H), 7.62 (dt, J ) 8 and 2 Hz, 2H); 13C
NMR (100 MHz, DMSO-d6) δ 65.7, 84.8, 124.8, 127.2, 127.9,
128.4, 128.6, 131.1, 132.2, 144.8, 151.3.
3-(4-Ch lor op h en yl)-N-[(4-m et h ylp h en yl)su lfon yl]-4-
p h en yl-4,5-d ih yd r o-1H-p yr a zole-1-ca r boxa m id in e (5). 5
was prepared from 4 and p-tolylsulfonyl chloride in 93% yield
by the same procedure as described for 9, mp 206-208 °C; 1H
NMR (400 MHz, DMSO-d6) δ 2.35 (s, 3H), 3.78 (dd, J ) 12
and 4 Hz, 1H), 4.33 (t, J ) 12 Hz, 1H), 5.12 (dd, J ) 12 and 4
Hz, 1H), 7.15-7.33 (m, 7H), 7.42 (d, J ) 8 Hz, 2H), 7.72 (d, J
) 8 Hz, 2H), 7.76 (d, J ) 8 Hz, 2H), 7.82-7.92 (m, 2H); 13C
NMR (100 MHz, DMSO-d6) δ 21.3, 50.0, 56.0, 126.1, 127.6,
127.9, 129.0, 129.3, 129.4, 129.6 (2C), 135.2, 140.5, 141.3,
142.0, 153.1, 157.7; HRMS (C23H22ClN4O2S) [M+H]+: found
m/z 453.1163, calcd 453.1152. Anal. (C23H21ClN4O2S) C, H, N.
3-(4-Ch lor op h en yl)-4-h yd r oxy-4-p h en yl-4,5-d ih yd r o-
1H-p yr a zole-1-ca r boxa m id in e (13). 13 was prepared from
12 and methyl imidothiocarbamate hemisulfate in 29% yield
by the same procedure as described for 4, mp 203-205 °C; 1H
NMR (400 MHz, DMSO-d6) δ 2.90-3.80 (m, 3H), 3.93 (d, J )
12 Hz, 1H), 4.12 (d, J ) 12 Hz, 1H), 7.22-7.40 (m, 8H), 7.70
(dt, J ) 8 and 2 Hz, 2H); 13C NMR (100 MHz, DMSO-d6) δ
64.8, 84.6, 124.7, 127.7, 128.6, 128.7, 128.9, 129.6, 133.4, 143.9,
151.5, 155.2 (broad).
3-(4-Ch lor op h en yl)-N-[(4-ch lor op h en yl)su lfon yl]-4-h y-
d r oxy-4-p h en yl-4,5-d ih yd r o-1H -p yr a zole-1-ca r b oxa m i-
d in e (14). 14 was prepared from 13 and p-chlorophenylsul-
fonyl chloride in 68% yield by the same procedure as described
3-(4-Ch lor oph en yl)-N-[(4-ch lor oph en yl)su lfon yl]-4-ph en -
yl-4,5-d ih yd r o-1H-p yr a zole-1-ca r boxa m id in e (6). 6 was
prepared from 4 and p-chlorophenylsulfonyl chloride in 75%
yield by the same procedure as described for 9, mp 212-213
1
for 9, mp 222-223 °C; H NMR (400 MHz, DMSO-d6) δ 3.96
1
(d, J ) 12 Hz, 1H), 4.17 (d, J ) 12 Hz, 1H), 7.12 (s, 1H), 7.25-
7.40 (m, 7H), 7.60 (dt, J ) 8 and 2 Hz, 2H) 7.78 (dt, J ) 8 and
2 Hz, 2H) 7.88 (dt, J ) 8 and 2 Hz, 2H), 8.10 (br s, 1H); 13C
NMR (100 MHz, DMSO-d6) δ 63.9, 84.3, 124.9, 128.0, 128.1,
128.3, 128.8, 129.0, 129.3, 129.7, 135.0, 136.8, 142.7, 142.8,
152.9, 157.3; HRMS (C22H19Cl2N4O3S) [M+H]+: found m/z
489.0569, calcd 489.0555. Anal. (C22H18Cl2N4O3S) C, H, N.
[(4-Ch lor op h en yl)su lfon yl]d ith ioim id oca r bon ic Acid
Dim eth yl Ester (15). 15 was prepared from 4-chlorophenyl-
sulfonamide, MeI, and CS2 according to the literature proce-
dure.17 1H NMR (600 MHz, DMSO-d6) δ 3.35 (s, 6H), 7.69 (d,
J ) 8 Hz, 2H), 7.93 (d, J ) 8 Hz, 2H); 13C NMR (150 MHz,
DMSO-d6) δ 16.6, 129.0, 129.7, 138.4, 139.6, 187.4.
°C; H NMR (400 MHz, DMSO-d6) δ 3.79 (dd, J ) 11 and 4
Hz, 1H), 4.36 (t, J ) 11 Hz, 1H), 5.54 (dd, J ) 11 and 4 Hz,
1H), 7.17 (d, J ) 8 Hz, 2H), 7.21-7.27 (m, 1H), 7.28-7.34 (m,
2H), 7.43 (d, J ) 8 Hz, 2H), 7.58 (d, J ) 8 Hz, 2H), 7.76 (d, J
) 8 Hz, 2H), 7.86 (d, J ) 8 Hz, 2H), 7.90 (br s, 2H); 13C NMR
(100 MHz, DMSO-d6) δ 50.0, 56.0, 127.6, 127.9, 128.1, 129.1,
129.2, 129.3, 129.5, 129.6, 135.3, 136.7, 140.4, 143.0, 153.2,
158.0; HRMS (C22H19Cl2N4O2S) [M+H]+: found m/z 473.0612,
calcd 473.0606. Anal. (C22H18Cl2N4O2S) C, H, N.
3-(4-Ch lor op h en yl)-N-[(4-m eth oxyp h en yl)su lfon yl]-4-
p h en yl-4,5-d ih yd r o-1H-p yr a zole-1-ca r boxa m id in e (7). 7
was prepared from 4 and p-methoxyphenylsulfonyl chloride
in 79% yield by the same procedure as described for 9, mp
1
191-192 °C; H NMR (400 MHz, DMSO-d6) δ 3.77 (dd, J )
[(2-Ch lor op h en yl)su lfon yl]d ith ioim id oca r bon ic Acid
Dim eth yl Ester (16). To a magnetically stirred solution of
2-chlorophenylsulfonamide (11.54 g, 0.0603 mol) in DMF (60
mL) was added CS2 (4.0 mL, 0.0663 mol). KOH (11.2 mL of a
45% aqueous solution) was slowly added while keeping the
temperature <15 °C. The resulting red solution was stirred
12 and 4 Hz, 1H), 3.81 (s, 3H), 4.33 (t, J ) 12 Hz, 1H), 5.02
(dd, J ) 12 and 4 Hz, 1H), 7.03 (dt, J ) 8 and 2 Hz, 2H), 7.14-
7.32 (m, 5H), 7.42 (dt, J ) 8 and 2 Hz, 2H), 7.72-7.80 (m,
4H), 7.82 (br s, 2H); 13C NMR (100 MHz, DMSO-d6) δ 50.0,
55.9, 56.0, 114.3, 127.6, 127.9, 128.1, 129.0, 129.3, 129.4, 129.6,

CB1 Cannabinoid Receptor Antagonists
J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 3 637
for 1 h and MeI was slowly added (7.4 mL, 0.119 mol) to give
a yellow solution which was stirred for 2 h. Water (300 mL)
was added and the resulting precipitate was collected by
filtration, washed with petroleum ether (40-60), and recrys-
tallized from EtOH (125 mL) to give 16 (12.24 g, 69% yield),
(m, 1H), 4.76 (t, J ) 11 Hz, 1H), 5.22 (dd, J ) 11 and 4 Hz,
1H), 7.20-7.28 (m, 3H), 7.31-7.39 (m, 4H), 7.47 (d, J ) 8 Hz,
2H), 7.70 (d, J ) 8 Hz, 2H), 7.92-7.97 (m, 2H).
3-(4-Ch lor op h en yl)-N-{[4-(tr iflu or om eth yl)p h en yl]su l-
fon yl}-4-p h en yl-4,5-d ih yd r o-1H -p yr a zole-1-ca r b oxim i-
d oth ioic Acid Meth yl Ester (24). 24 was prepared from 2
and 19 in 89% yield by the same procedure as described for
1
mp 128 °C; H NMR (400 MHz, CDCl3) δ 2.56 (s, 6H), 7.39-
7.45 (m, 1H), 7.48-7.55 (m, 2H), 8.20 (dd, J ) 8 and 2 Hz,
1H). 13C NMR (150 MHz, DMSO-d6) δ 16.6, 127.9, 130.2, 131.6,
132.3, 135.0, 138.3, 187.3.
1
20, mp 173 °C; H NMR (400 MHz, DMSO-d6) δ 2.42 (s, 3H),
4.29 (br d, J ) 11, 1H), 4.80 (t, J ) 11 Hz, 1H), 5.26 (dd, J )
11 and 4 Hz, 1H), 7.24-7.30 (m, 3H), 7.33-7.38 (m, 2H), 7.48
(d, J ) 8 Hz, 2H), 7.73 (d, J ) 8 Hz, 2H), 7.94 (d, J ) 8 Hz,
2H), 8.13 (d, J ) 8 Hz, 2H); 13C NMR (100 MHz, DMSO-d6) δ
16.4 (broad), 50.9, 60.1 (broad), 123.9 (q, J CF ) 273 Hz), 126.5
(q, J CF ) 4 Hz), 127.1, 127.7, 128.2, 128.4, 129.4, 129.75,
129.82, 132.0 (q, J CF ) 32 Hz), 136.3, 139.7, 149.9 (broad),
161.9 (broad), 163.0 (broad); HRMS (C24H20ClF3N3O2S2) [M+H]+:
found m/z 538.0668, calcd 538.0638. Anal. (C24H19ClF3N3O2S2)
C, H, N.
[(3-Ch lor op h en yl)su lfon yl]d ith ioim id oca r bon ic Acid
Dim eth yl Ester (17). 17 was prepared from m-chlorophenyl-
sulfonamide, CS2, and MeI in 63% yield by the same procedure
1
as described for 16, mp 80 °C; H NMR (200 MHz, CDCl3) δ
2.55 (s, 6H), 7.40-7.60 (m, 2H), 7.85-7.92 (m, 1H), 7.97-8.00
(m, 1H); 13C NMR (150 MHz, DMSO-d6) δ 16.6, 125.8, 126.5,
131.7, 133.5, 134.1, 142.6, 188.0.
[(4-F lu or op h en yl)su lfon yl]d ith ioim id oca r bon ic Acid
Dim eth yl Ester (18). 18 was prepared from p-fluorophenyl-
sulfonamide, CS2, and MeI in 89% yield by the same procedure
N1-Dim et h yl-N2-[(4-ch lor op h en yl)su lfon yl]-3-(4-ch lo-
r op h en yl)-4,5-d ih yd r o-4-p h en yl-1H-p yr a zole-1-ca r boxa -
m id in e (25). To a magnetically stirred mixture of 20 (4.20 g,
8.30 mmol) in MeOH (75 mL) was added cold dimethylamine
(10 mL, 40% aqueous solution, 160 mmol) and CH2Cl2 (75 mL)
and the resulting solution was stirred at room temperature
for 6 h. Evaporation in vacuo and subsequent flash chromato-
graphic purification (Et2O/petroleum ether (40-60) ) 1/1 (v/
v), followed by Et2O) gave a crude solid which was further
purified by recrystallization from diisopropyl ether to yield 25
(2.63 g, 63% yield), mp 189-190 °C; 1H NMR (400 MHz,
DMSO-d6) δ 3.15 (s, 6H), 3.71 (dd, J ) 11 and 4 Hz, 1H), 4.46
(t, J ) 11 Hz, 1H), 4.96 (dd, J ) 11 and 4 Hz, 1H), 7.21-7.34
(m, 5H), 7.41 (d, J ) 8 Hz, 2H), 7.52 (d, J ) 8 Hz, 2H), 7.62 (d,
J ) 8 Hz, 2H), 7.79 (d, J ) 8 Hz, 2H); 13C NMR (100 MHz,
DMSO-d6) δ 41.5, 49.4, 58.5, 127.4, 127.85, 127.88, 129.1 (2C),
129.2, 129.4, 129.5, 135.2, 135.8, 140.2, 145.3, 154.4, 157.4;
HRMS (C24H23Cl2N4O2S) [M+H]+: found m/z 501.0911, calcd
501.0919. Anal. Calcd. for (C24H22Cl2N4O2S: C, H, N.
N1-Dim et h yl-N2-[(4-flu or op h en yl)su lfon yl]-3-(4-ch lo-
r op h en yl)-4,5-d ih yd r o-4-p h en yl-1H-p yr a zole-1-ca r boxa -
m id in e (26). 26 was prepared from 23 and dimethylamine in
74% yield by the same procedure as described for 25, mp 176-
177 °C; 1H NMR (400 MHz, DMSO-d6) δ 3.15 (s, 6H), 3.72 (dd,
J ) 11 and 4 Hz, 1H), 4.47 (t, J ) 11 Hz, 1H), 4.97 (dd, J ) 11
and 4 Hz, 1H), 7.21-7.35 (m, 7H), 7.42 (d, J ) 8 Hz, 2H), 7.64
(d, J ) 8 Hz, 2H), 7.82-7.88 (m, 2H); 13C NMR (100 MHz,
DMSO-d6) δ 41.5, 49.3, 58.5, 116.0 (d, J CF ) 22 Hz), 127.83,
127.87, 128.3 (d, J CF ) 9 Hz), 129.1, 129.2, 129.4, 129.5, 135.1,
140.2, 142.8 (d, J CF ) 3 Hz), 154.3, 157.4, 163.5 (d, J CF ) 248
Hz); HRMS (C24H23ClFN4O2S) [M+H]+: found m/z 485.1222,
calcd 485.1214. Anal. (C24H22ClFN4O2S) C, H, N.
1
as described for 16, mp 116 °C; H NMR (400 MHz, CDCl3) δ
2.54 (s, 6H), 7.14-7.20 (m, 2H), 7.97-8.03 (m, 2H). 13C NMR
(150 MHz, DMSO-d6) δ 16.5, 116.7 (d, J CF ) 23 Hz), 130.2 (d,
J CF ) 10 Hz), 137.2 (d, J CF ) 3 Hz), 164.8 (d, J CF ) 251 Hz),
186.9.
[(4-(Tr iflu or om eth yl)p h en yl)su lfon yl]d ith ioim id oca r -
bon ic Acid Dim eth yl Ester (19). 19 was prepared from
p-(trifluoromethyl)phenylsulfonamide, CS2, and MeI in 93%
yield by the same procedure as described for 16, mp 116-117
°C; 1H NMR (400 MHz, DMSO-d6) δ 2.60 (s, 6H), 8.00 (d, J )
8 Hz, 2H), 8.15 (d, J ) 8 Hz, 2H); 13C NMR (100 MHz, DMSO-
d6) δ 16.6, 123.8 (d, J CF ) 273 Hz), 126.8 (d, J CF ) 4 Hz), 128.0,
133.0 (d J CF ) 33 Hz), 144.7, 188.4.
3-(4-ch lor oph en yl)-N-[(4-ch lor oph en yl)su lfon yl]-4-ph en -
yl-4,5-d ih yd r o-1H -p yr a zole-1-ca r b oxim id ot h ioic Acid
Meth yl Ester (20). A magnetically stirred mixture of 2 (12.0
g, 46.8 mmol), diester 15 (9.20 g, 31.1 mmol), and Et3N (15
mL) in CH3CN (200 mL) was refluxed for 20 h under dry N2.
An additional portion of 2 (12.0 g, 46.8 mmol) was added and
the resulting mixture was refluxed for another 16 h. After
concentration in vacuo, CH2Cl2 was added and the resulting
solution was washed twice with water and dried over Na2SO4.
After filtration and concentration, the residue was further
purified by flash chromatography (Et2O/ petroleum ether (40-
60) ) 1/1 (v/v)) to give 20 (12.5 g, 80% yield based on 15), mp
1
139 °C; H NMR (200 MHz, CDCl3) δ 2.17 (s, 3H), 4.48-4.56
(m, 1H), 4.81 (dd, J ) 12 and 4 Hz, 1H), 4.94 (br t, J ) 12 Hz,
1H), 7.16 (d, J ) 8 Hz, 2H), 7.24-7.36 (m, 5H), 7.44 (dt, J )
8 and 2 Hz, 2H), 7.60 (d, J ) 8 Hz, 2H), 7.90 (dt, J ) 8 and 2
Hz, 2H).
3-(4-Ch lor op h e n yl)-N -[(2-ch lor op h e n yl)su lfon yl]-4-
ph en yl-4,5-dih ydr o-1H-pyr azole-1-car boxim idoth ioic Acid
Meth yl Ester (21). 21 was prepared from 2 and 16 in 76%
yield by the same procedure as described for 20, mp 153-155
3-(4-Ch lor op h en yl)-N-[(2-ch lor op h en yl)su lfon yl]-N′-
m eth yl-4-p h en yl-4,5-d ih yd r o-1H-p yr a zole-1-ca r boxa m i-
d in e (27). 27 was prepared from 21 and methylamine in 65%
yield by the same procedure as described for 25, mp 191-192
1
°C; H NMR (400 MHz, CDCl3) δ 2.39 (s, 3H), 4.48-4.56 (m,
1
°C; H NMR (400 MHz, DMSO-d6) δ 2.95 (d, J ) 4 Hz, 3H),
1H), 4.81 (dd, J ) 11 and 4 Hz, 1H), 5.02 (br t, J ) 11 Hz,
1H), 7.16 (br d, J ) 8 Hz, 2H), 7.25-7.36 (m, 5H), 7.38 (dd, J
) 8 and 2 Hz, 1H), 7.44 (td, J ) 8 and 2 Hz, 1H), 7.50 (dd, J
) 8 and 2 Hz, 1H), 7.61 (br d, J ) 8 Hz, 2H), 8.16 (dd, J ) 8
and 2 Hz, 1H).
4.00 (dd, J ) 11 and 4 Hz, 1H), 4.48 (t, J ) 11 Hz, 1H), 7.20-
7.35 (m, 5H), 7.41-7.56 (m, 5H), 7.77 (dt, J ) 8 and 2 Hz,
2H), 8.02 (dd, J ) 8 and 2 Hz, 1H), 8.19 (br d, J ) 4 Hz, 2H);
13C NMR (100 MHz, DMSO-d6) δ 30.6 (broad), 50.0, 58.0, 127.5,
127.6, 127.9, 128.7, 129.1, 129.2, 129.55, 129.57, 130.8, 131.7,
3-(4-Ch lor op h e n yl)-N -[(3-ch lor op h e n yl)su lfon yl]-4-
ph en yl-4,5-dih ydr o-1H-pyr azole-1-car boxim idoth ioic Acid
Meth yl Ester (22). 22 was prepared from 2 and 17 in 75%
yield by the same procedure as described for 20, mp 162-163.5
132.8, 135.4, 140.3, 143.1 (broad), 152.6, 157.9; HRMS (C23H21
-
Cl2N4O2S) [M+H]+: found m/z 487.0752, calcd 487.0762. Anal.
(C23H20Cl2N4O2S) C, H, N.
3-(4-Ch lor op h en yl)-N-[(3-ch lor op h en yl)su lfon yl]-N′-
m eth yl-4-p h en yl-4,5-d ih yd r o-1H-p yr a zole-1-ca r boxa m i-
d in e (28). 28 was prepared from 22 and methylamine in 85%
yield by the same procedure as described for 25, mp 167-168
°C; NMR (400 MHz, CDCl3) δ 3.24 (d, J ) 4 Hz, 3H), 4.12 (dd,
J ) 11 and 4 Hz, 1H), 4.54 (t, J ) 11 Hz, 1H), 4.65 (dd, J ) 11
and 4 Hz, 1H), 7.12 (br d, J ) 8 Hz, 2H), 7.18 (br s, 1H), 7.24-
7.34 (m, 5H), 7.37 (d, J ) 8 Hz, 1H), 7.40-7.44 (m, 1H), 7.52
(dt, J ) 8 and 2 Hz, 2H), 7.80 (br d, J ) 8 Hz, 1H), 7.92 (br t,
J ) 2 Hz, 1H). HRMS (C23H21Cl2N4O2S) [M+H]+: found m/z
487.0762, calcd 487.0762. Anal. (C23H20Cl2N4O2S) C, H, N.
1
°C; H NMR (400 MHz, CDCl3) δ 2.34 (s, 3H), 4.52 (br d, J )
11 Hz, 1H), 4.82 (dd, J ) 11 and 4 Hz, 1H), 4.96 (br t, J ) 11
Hz, 1H), 7.15 (br d, J ) 8 Hz, 2H), 7.25-7.36 (m, 5H), 7.41 (t,
J ) 8 Hz, 1H), 7.46-7.50 (m 1H), 7.61 (dt, J ) 8 and 2 Hz,
2H), 7.85 (dt, J ) 8 and 2 Hz, 1H) 7.97 (t, J ) 2 Hz, 1H).
3-(4-Ch lor oph en yl)-N-[(4-flu or oph en yl)su lfon yl]-4-ph en -
yl-4,5-d ih yd r o-1H -p yr a zole-1-ca r b oxim id ot h ioic Acid
Meth yl Ester (23). 23 was prepared from 2 and 18 in 75%
yield by the same procedure as described for 20, mp 176-178
1
°C; H NMR (400 MHz, DMSO-d6) δ 2.38 (s, 3H), 4.24-4.30

638 J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 3
Lange et al.
3-(4-Ch lor op h en yl)-N-{[(4-tr iflu or om eth yl)p h en yl]su l-
fon yl}-N′-m eth yl-4-ph en yl-4,5-dih ydr o-1H-pyr azole-1-car -
boxa m id in e (29). 29 was prepared from 24 and methylamine
in 76% yield by the same procedure as described for 25, mp
143-145 °C; 1H NMR (400 MHz, CDCl3) δ 2.90-2.97 (m, 3H),
3.95 (dd, J ) 11 and 4 Hz, 1H), 4.48 (t, J ) 11 Hz, 1H), 5.05
(dd, J ) 11 and 4 Hz, 1H), 7.17-7.32 (m, 5H), 7.45 (dt, J ) 8
and 2 Hz, 2H), 7.74 (dt, J ) 8 and 2 Hz, 2H), 7.84 (d, J ) 8
Hz, 1H), 8.04 (d, J ) 8 Hz, 1H) 8.24-8.30 (m, 1H); 13C NMR
(100 MHz, DMSO-d6)) δ 30.6 (broad), 50.1, 57.9, 124.0 (q, J CF
) 273 Hz), 126.3 (q, J CF ) 3 Hz), 126.4, 127.6, 127.9, 129.2,
129.3, 129.55, 129.58, 131.1 (q, J CF ) 32 Hz), 135.4, 140.3,
150.2 (broad), 152.5, 158.1; HRMS (C24H21ClF3N4O2S) [M+H]+:
found m/z 521.1005, calcd 521.1026. Anal. (C24H20ClF3N4O2S)
C, H, N.
1-(4-Ch lor op h en yl)-2-(4-flu or op h en yl)p r op -2-en -1-on e
(32). To a magnetically stirred solution of 1-(4-chlorophenyl)-
2-(4-fluorophenyl)ethanone (30) (31.9 g, 0.128 mol) in MeOH
(500 mL) was successively added piperidine (1.2 mL, 12.1
mmol), AcOH (1.2 mL, 20.8 mmol), and formaline (40 mL: 37%
aqueous solution, 0.532 mol), and the resulting mixture was
refluxed for 4 h, followed by concentration in vacuo. Water was
added to the residue and the mixture was extracted with
CH2Cl2. The organic layer was separated, washed with water
(3×), dried over Na2SO4, filtered, and concentrated to give 32
(33.4 g, quantitative yield), mp 77 °C; 1H NMR (200 MHz,
CDCl3) δ 5.63 (s, 1H), 6.05 (s, 1H), 6.97-7.10 (m, 2H), 7.35-
7.47 (m, 4H), 7.83 (dt, J ) 8 and 2 Hz, 2H).
3-(4-Ch lor op h en yl)-4-(4-flu or op h en yl)-4,5-d ih yd r o-1H-
p yr a zole (34). A solution of 32 (33.4 g, 0.128 mol), hydrazine
hydrate (630 mL) in EtOH (300 mL) was refluxed for 3 h under
dry N2. After cooling of the sample to room temperature the
mixture was concentrated in vacuo, water was added, and
extraction was performed with CH2Cl2. The organic layer was
twice washed with water, dried over Na2SO4, and concentrated.
The residue was crystallized from EtOH to give 34 (20.0 g,
59% yield), mp 115 °C; 1H NMR (200 MHz, CDCl3) δ 3.51 (dd,
J ) 11 and 4.5 Hz, 1H), 3.93 (t, J ) 11 Hz, 1H), 4.47 (dd, J )
11 and 4.5 Hz, 1H), 5.65 (br s, 1H), 6.92-7.03 (m, 2H), 7.15-
7.27 (m, 4H), 7.83 (dt, J ) 8 and 2 Hz, 2H).
1-(4-F lu or op h en yl)-2-p h en ylp r op -2-en -1-on e (33). 33
was prepared from 1-(4-fluorophenyl)-2-phenylethanone 31 in
quantitative yield by the same procedure as described for 32.
1H NMR (200 MHz, CDCl3) δ 5.62 (s, 1H), 6.05 (s, 1H), 7.03-
7.13 (m, 2H), 7.30-7.45 (m, 5H), 7.90-8.00 (m, 2H).
in 75% yield by the same procedure as described for 40, mp )
1
132 °C; H NMR (200 MHz, CDCl3) δ 3.72 (s, 3H), 7.53 (dt, J
) 8 and 2 Hz, 2H), 8.00 (dt, J ) 8 and 2 Hz, 2H). 13C NMR
(150 MHz, DMSO-d6) δ 53.4, 129.77, 129.79, 138.3, 139.0,
152.0.
N-(P h en ylsu lfon yl)ca r ba m ic Acid Meth yl Ester (38).
38 was prepared according to the literature procedure.38
N-[(4-F lu or op h en yl)su lfon yl]ca r ba m ic Acid Meth yl
Ester (39). 39 was prepared from p-fluorophenylsulfonamide
in 53% yield by the same procedure as described for 40, mp )
1
102 °C; H NMR (200 MHz, CDCl3) δ 3.72 (s, 3H), 5.00 (br s,
1H), 7.17-7.30 (m, 2H), 8.04-8.14 (m, 2H).
N-{[3-(Tr iflu or om eth yl)ph en yl]su lfon yl}car bam ic Acid
Meth yl Ester (41). 41 was prepared from m-(trifluoromethyl)-
phenylsulfonamide in 69% yield by the same procedure as
described for 40, mp 105-108 °C; 1H NMR (200 MHz, CDCl3)
δ 3.73 (s, 3H), 7.67-7.77 (m, 1H), 7.93 (br d, J ) 8 Hz, 1H),
8.24-8.33 (m, 2H), NH proton invisible.
N-[(2,4,6-Tr im et h ylp h en yl)su lfon yl]ca r b a m ic
Acid
Meth yl Ester (42). 42 was prepared from 2,4,6-trimethylphen-
ylsulfonamide in 44% yield by the same procedure as described
1
for 40, mp 169 °C; H NMR (200 MHz, CDCl3) δ 2.33 (s, 3H),
2.70 (s, 6H), 3.70 (s, 3H) 7.01 (s, 2H), NH proton invisible.
N-[(4-Meth oxyp h en yl)su lfon yl]ca r ba m ic Acid Meth yl
Ester (43). 43 was prepared from p-methoxyphenylsulfona-
mide in 53% yield by the same procedure as described for 40,
1
mp ) 108 °C; H NMR (200 MHz, CDCl3) δ 3.70 (s, 3H), 3.88
(s, 3H), 5.00 (br s, 1H), 7.00 (dt, J ) 8 and 2 Hz, 2H), 7.97 (dt,
J ) 8 and 2 Hz, 2H).
N-[(2-Na p h th yl)su lfon yl]ca r ba m ic Acid Meth yl Ester
(44). 44 was prepared from 2-naphthylsulfonamide in 62%
yield by the same procedure as described for 40, mp 140-142
1
°C; H NMR (600 MHz, DMSO-d6) δ 3.66 (s, 3H), 7.68-7.72
(m, 1H), 7.73-7.77 (m, 1H), 7.90 (dd, J ) 8 and 2 Hz, 1H),
8.07 (d, J ) 8 Hz, 1H), 8.17 (d, J ) 8 Hz, 1H), 8.24 (d, J ) 8
Hz, 1H), 8.62 (br s, 1H), 12.20 (br s, 1H); 13C NMR (150 MHz,
DMSO-d6) δ 53.3, 122.5, 128.16, 128.23, 129.4, 129.73, 129.77,
129.8, 131.8, 135.0, 136.4, 152.0.
3-(4-Ch lor op h e n yl)-N -[(4-ch lor op h e n yl)su lfon yl]-4-
p h en yl-4,5-d ih yd r o-1H-p yr a zole-1-ca r boxa m id e (45). To
a solution of 37 (29.94 g, 0.120 mmol) in toluene (600 mL) was
added 2 (33.86 g, 0.132 mmol), and the resulting mixture was
refluxed for 4 h. After cooling of the sample to room temper-
ature 45 slowly crystallized. The crystals were collected and
washed with MTBE (2×) to yield pure 45 (55.67 g, 98% yield),
1
3-(4-F lu or op h en yl)-4-p h en yl-4,5-d ih yd r o-1H-p yr a zole
(35). 35 was prepared from 33 in 84% yield by the same
procedure as described for 34, mp 110 °C; 1H NMR (200 MHz,
CDCl3) δ 3.52 (dd, J ) 11 and 4.5 Hz, 1H), 3.97 (t, J ) 11 Hz,
1H), 4.49 (dd, J ) 11 and 4.5 Hz, 1H), 5.70 (br s, 1H), 6.85-
7.00 (m, 2H), 7.20-7.35 (m, 5H), 7.49-7.60 (m, 2H); 13C NMR
(100 MHz, DMSO-d6) δ 50.4, 57.7, 116.0 (d, J CF ) 21 Hz),
127.4, 128.1, 128.4 (d, J CF ) 8 Hz), 129.4, 129.8 (d, J CF ) 3
Hz), 142.2, 151.9, 162.4 (d, J CF ) 245 Hz).
mp 210-212 °C; H NMR (400 MHz, DMSO-d6) δ 3.68 (dd, J
) 12 and 4 Hz, 1H), 4.28 (t, J ) 12 Hz, 1H), 4.98 (dd, J ) 12
and 4 Hz, 1H), 7.16-7.34 (m, 5H), 7.43 (dt, J ) 8 and 2 Hz,
2H), 7.72 (dt, J ) 8 and 2 Hz, 2H), 7.82 (dt, J ) 8 and 2 Hz,
2H), 8.02 (dt, J ) 8 and 2 Hz, 2H), 11.55 (br s, 1H); 13C NMR
(100 MHz, DMSO-d6) δ 49.8, 54.9, 127.6, 127.9, 129.0, 129.4,
129.54 (2C), 129.56, 130.0, 135.1, 138.7, 139.2, 140.5, 148.9,
156.3; HRMS (C22H18Cl2N3O3S) [M+H]+: found m/z 474.0436,
calcd 474.0446. Anal. Calcd. for C22H17Cl2N3O3S; H, N: C:
calcd., 55.70; found, 55.24.
3,4-Bis-(4-ch lor op h en yl)-4,5-d ih yd r o-1H-p yr a zole (36).
36 was prepared according to the literature procedure.16
N-[(4-Meth ylp h en yl)su lfon yl]ca r ba m ic Acid Meth yl
Ester (40). To a magnetically stirred solution of p-toluene-
sulfonamide (6.48 g, 0.040 mol) and Et3N (10.12 g, 0.100 mol)
in anhydrous CH3CN (40 mL) was slowly added methyl
chloroformate (4.43 mL, 0.060 mol), and the resulting solution
was stirred at room temperature for 6 h and evaporated in
vacuo. The residue was dissolved in EtOAc and aqueous
NaHCO3 was added. The water layer was separated and
acidified with a mixture of ice and concentrated HCl to give
an oily precipitate which slowly crystallized upon standing.
The crystals were collected by filtration, washed with water,
and dried to give 40 (4.09 g, 45% yield), mp ) 107-109 °C; 1H
NMR (200 MHz, CDCl3) δ 2.45 (s, 3H), 3.71 (s, 3H), 7.35 (d, J
N-[(4-Ch lor op h en yl)su lfon yl]-3-(4-ch lor op h en yl)-4-(4-
flu or op h en yl)-4,5-d ih yd r o-1H -p yr a zole-1-ca r b oxa m id e
(46). 46 was prepared from 34 and 37 in 78% yield by the same
procedure as described for 45, mp 250 °C; 1H NMR (400 MHz,
DMSO-d6) δ 3.68 (dd, J ) 11 and 4 Hz, 1H), 4.26 (t, J ) 11
Hz, 1H), 5.02 (dd, J ) 11 and 4 Hz, 1H), 7.10-7.16 (m, 2H),
7.21-7.26 (m, 2H), 7.44 (dt, J ) 8 and 2 Hz, 2H), 7.73 (dt, J
) 8 and 2 Hz, 2H), 7.81 (dt, J ) 8 and 2 Hz, 2H), 8.01 (dt, J
) 8 and 2 Hz, 2H), 11.55 (br s, 1H); 13C NMR (100 MHz,
DMSO-d6) δ 48.9, 54.8, 116.3 (d, J CF ) 21 Hz), 129.0, 129.3,
129.5, 129.6, 129.7 (d, J CF ) 8 Hz), 130.0, 135.1, 136.7 (d, J CF
) 3 Hz), 138.6, 139.3, 149.0, 156.1, 161.7 (d, J CF ) 244 Hz).
N-[(4-Ch lor oph en yl)su lfon yl]-3-(4-flu or oph en yl)-4-ph en -
yl-4,5-d ih yd r o-1H-p yr a zole-1-ca r boxa m id e (47). 47 was
prepared from 35 and 37 in 60% yield by the same procedure
as described for 45, mp 114 °C (dec); 1H NMR (400 MHz,
DMSO-d6) δ 3.68 (dd, J ) 12 and 4 Hz, 1H), 4.26 (t, J ) 12
Hz, 1H), 4.98 (dd, J ) 12 and 4 Hz, 1H), 7.17-7.34 (m, 7H),
7.72 (dt, J ) 8 and 2 Hz, 2H), 7.83-7.88 (m, 2H), 8.02 (dt, J
) 8 Hz, 2H), 7.93 (d, J ) 8 Hz, 2H), 7.40-7.65 (br s, 1H); 13
C
NMR (150 MHz, DMSO-d6) δ 21.4, 53.2, 127.8, 129.9, 136.7,
144.6, 152.0.
N-[(4-Ch lor op h en yl)su lfon yl]ca r ba m ic Acid Meth yl
Ester (37). 37 was prepared from p-chlorophenylsulfonamide

CB1 Cannabinoid Receptor Antagonists
J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 3 639
) 8 and 2 Hz, 2H), 11.55 (br s, 1H); 13C NMR (100 MHz,
procedure as described for 45, mp 243-244 °C; 1H NMR (400
MHz, DMSO-d6) δ 3.67 (dd, J ) 11 and 4 Hz, 1H), 3.85 (s,
3H), 4.35 (t, J ) 11 Hz, 1H), 4.96 (dd, J ) 11 and 4 Hz, 1H),
7.12-7.32 (m, 7H), 7.43 (dt, J ) 8 and 2 Hz, 2H), 7.82 (dt, J
) 8 and 2 Hz, 2H), 7.95 (dt, J ) 8 and 2 Hz, 2H), 11.40 (br s,
1H); 13C NMR (100 MHz, DMSO-d6) δ 49.7, 54.9, 56.1, 114.5,
127.6, 127.8, 128.9, 129.5 (3C), 130.3, 131.9, 135.0, 140.6,
149.1, 155.9, 163.2.
3-(4-Ch lor op h en yl)-4-p h en yl-N-[(2-n a p h th yl)su lfon yl]-
4,5-d ih yd r o-1H-p yr a zole-1-ca r boxa m id e (55). 55 was pre-
pared from 2 and 44 in 81% yield by the same procedure as
described for 45, mp 216-220 °C; 1H NMR (400 MHz, DMSO-
d6) δ 3.66 (dd, J ) 11 and 4 Hz, 1H), 4.24 (t, J ) 11 Hz, 1H),
4.96 (dd, J ) 11 and 4 Hz, 1H), 7.15-7.30 (m, 5H), 7.43 (d, J
) 8 Hz, 2H), 7.69-7.78 (m, 2H), 7.82 (d, J ) 8 Hz, 2H), 8.01-
8.23 (m, 4H), 8.35 (br s, 1H), 11.60 (br s, 1H); 13C NMR (100
MHz, DMSO-d6) δ 49.7, 54.9, 123.1, 127.6, 127.8, 128.0, 128.2,
128.9, 129.42, 129.45, 129.52 (2C), 129.56 (2C), 129.8, 131.8,
134.9, 135.0, 137.4, 140.5, 149.0, 156.1.
DMSO-d6) δ 49.9, 54.9, 115.9 (d, J CF ) 22 Hz), 127.1 (d, J CF
)
3 Hz), 127.6, 127.8, 129.50, 129.53, 129.9, 130.2 (d, J CF ) 9
Hz), 138.6, 139.3, 140.6, 149.0, 156.3, 163.4 (d, J CF ) 249 Hz).
3,4-Bis-(4-ch lor op h en yl)-N-[(4-ch lor op h en yl)su lfon yl]-
4,5-d ih yd r o-1H-p yr a zole-1-ca r boxa m id e (48). 48 was pre-
pared from 36 and 37 in 71% yield by the same procedure as
described for 45, mp 260 °C; 1H NMR (400 MHz, DMSO-d6) δ
3.70 (dd, J ) 11 and 4 Hz, 1H), 4.27 (t, J ) 11 Hz, 1H), 5.02
(dd, J ) 11 and 4 Hz, 1H), 7.22 (dt, J ) 8 and 2 Hz, 2H), 7.37
(dt, J ) 8 and 2 Hz, 2H), 7.45 (dt, J ) 8 and 2 Hz, 2H), 7.73
(dt, J ) 8 and 2 Hz, 2H), 7.81 (dt, J ) 8 and 2 Hz, 2H), 8.02
(dt, J ) 8 and 2 Hz, 2H), 11.55 (br s, 1H); 13C NMR (100 MHz,
DMSO-d6) δ 49.0, 54.7, 129.0, 129.3, 129.50, 129.54 (2C), 129.6,
130.0, 132.5, 135.2, 138.7, 139.2, 139.4, 149.0, 155.9.
3-(4-Ch lor op h en yl)-4-p h en yl-N-(p h en ylsu lfon yl)-4,5-
d ih yd r o-1H-p yr a zole-1-ca r boxa m id e (49). 49 was prepared
from 2 and 38 in 81% yield by the same procedure as described
1
for 45, mp 250 °C; H NMR (400 MHz, DMSO-d6) δ 3.67 (dd,
J ) 11 and 4 Hz, 1H), 4.26 (t, J ) 11 Hz, 1H), 4.96 (dd, J ) 11
and 4 Hz, 1H), 7.15-7.33 (m, 5H), 7.42 (dt, J ) 8 and 2 Hz,
2H), 7.82 (dt, J ) 8 and 2 Hz, 2H), 8.02 (dt, J ) 8 and 2 Hz,
2H), 11.50 (br s, 1H);
3-(4-Ch lor op h en yl)-N′-[(4-ch lor op h en yl)su lfon yl]-N-
m eth yl-4-p h en yl-4,5-d ih yd r o-1H-p yr a zole-1-ca r boxa m i-
d in e (67). A mixture of 45 (3.67 g, 7.75 mmol) and PCl5 (1.69
g, 8.14 mmol) in chlorobenzene (40 mL) was refluxed for 1 h.
After thorough concentration in vacuo, the formed 56 was
suspended in CH2Cl2 and reacted with cold methylamine (1.5
mL). After stirring of the sample at room temperature for 1
h, the mixture was concentrated in vacuo. The residue was
crystallized from EtOH to give 67 (2.29 g, 61% yield): mp 96-
13C NMR (100 MHz, DMSO-d6) δ 49.7, 54.9, 127.6, 127.85,
127.9, 128.9, 129.3, 129.50, 129.54, 129.56, 133.7, 135.0, 140.4,
140.6, 149.0, 156.1.
3-(4-Ch lor oph en yl)-N-[(4-flu or oph en yl)su lfon yl]-4-ph en -
yl-4,5-d ih yd r o-1H-p yr a zole-1-ca r boxa m id e (50). 50 was
prepared from 2 and 39 in 96% yield by the same procedure
1
98 °C (dec); H NMR (400 MHz, DMSO-d6) δ 2.94 (d, J ) 4
1
Hz, 3H), 3.96 (dd, J ) 11 and 4 Hz, 1H), 4.46 (t, J ) 11 Hz,
1H), 5.05 (dd, J ) 11 and 4 Hz, 1H), 7.20-7.35 (m, 5H), 7.45
(dt, J ) 8 and 2 Hz, 2H), 7.53 (dt, J ) 8 and 2 Hz, 2H), 7.77
(dt, J ) 8 and 2 Hz, 2H), 7.82 (dt, J ) 8 and 2 Hz, 2H), 8.19
(br d, J ) 4 Hz, 1H); 13C NMR (100 MHz, DMSO-d6) δ 30.6
(broad), 50.1, 57.9, 127.5, 127.6, 127.9, 129.1 (2C), 129.2, 129.5,
129.6, 135.4, 135.8, 140.3, 145.4 (broad), 152.5, 157.9; HRMS
(C23H21Cl2N4O2S) [M+H]+: found m/z 487.0745, calcd 487.0762.
Anal. (C23H20Cl2N4O2S) C, H, N.
as described for 45, mp 220 °C; H NMR (400 MHz, DMSO-
d6) δ 3.68 (dd, J ) 12 and 4 Hz, 1H), 4.28 (t, J ) 12 Hz, 1H),
4.98 (dd, J ) 12 and 4 Hz, 1H), 7.16-7.52 (m, 9H), 7.82 (d, J
) 8 Hz, 2H), 8.06-8.12 (m, 2H), 11.55 (br s, 1H); 13C NMR
(100 MHz, DMSO-d6) δ 49.7, 54.9, 116.3 (d, J CF ) 22 Hz),
127.6, 127.8, 128.9, 129.46, 129.54, 129.56, 131.2 (d, J CF ) 10
Hz), 135.1, 136.7 (d, J CF ) 3 Hz), 140.5, 149.0, 156.2, 165.0 (d,
J CF ) 252 Hz).
3-(4-Ch lor op h en yl)-N-[(4-m et h ylp h en yl)su lfon yl]-4-
p h en yl-4,5-d ih yd r o-1H-p yr a zole-1-ca r boxa m id e (51). 51
was prepared from 2 and 40 in 72% yield by the same
procedure as described for 45, mp 219-221 °C; 1H NMR (400
MHz, DMSO-d6) δ 2.40 (s, 3H), 3.67 (dd, J ) 12 and 4 Hz,
1H), 4.25 (t, J ) 12 Hz, 1H), 4.96 (dd, J ) 12 and 4 Hz, 1H),
7.16-7.32 (m, 5H), 7.43 (d, J ) 8 Hz, 4H), 7.82 (dt, J ) 8 and
2 Hz, 2H), 7.90 (d, J ) 8 Hz, 2H), 11.40 (br s, 1H); 13C NMR
(100 MHz, DMSO-d6) δ 21.3, 49.7, 54.9, 127.6, 127.8, 128.0
(2C), 128.9, 129.5 (2C), 129.7, 135.0, 137.6, 140.5, 144.2, 149.0,
156.0.
3-(4-Ch lor op h en yl)-N′-[(4-ch lor op h en yl)su lfon yl]-4-(4-
flu or op h en yl)-N-m eth yl- 4,5-d ih yd r o-1H-p yr a zole-1-ca r -
boxa m id in e (68). 68 was prepared from 46 via 57 in 68%
yield by the same procedure as described for 67, mp 93-94
1
°C (dec); H NMR (400 MHz, DMSO-d6) δ 2.92 (br d, J ) 4.5
Hz, 3H), 3.90 (dd, J ) 11 and 4 Hz, 1H), 4.41 (t, J ) 11 Hz,
1H), 5.05 (dd, J ) 11 and 4 Hz, 1H), 7.10-7.16 (m, 2H), 7.20-
7.25 (m, 2H), 7.42 (d, J ) 8 Hz, 2H), 7.50 (dt, J ) 8 and 2 Hz,
2H), 7.72 (d, J ) 8 Hz, 2H), 7.79 (dt, J ) 8 and 2 Hz, 2H),
8.16-8.21 (m, 1H); 13C NMR (100 MHz, DMSO-d6) δ 31.0
(broad), 49.5, 58.1, 116.7 (d, J CF ) 21 Hz), 127.8, 129.40,
129.44, 129.8, 130.0 (d, J CF ) 8 Hz), 135.8, 136.1, 136.8 (d,
J CF ) 3 Hz), 145.7 (broad), 152.8, 158.1, 162.1 (d, J CF ) 244
Hz); HRMS (C23H20Cl2FN4O2S) [M+H]+: found m/z 471.1054,
calcd 471.1058.
3-(4-Ch lor op h en yl)-4-p h en yl-N-{3-[(t r iflu or om et h yl)-
p h en yl]su lfon yl}-4,5-d ih yd r o-1H-p yr a zole-1-ca r b oxa m -
id e (52). 52 was prepared from 2 and 41 in 71% yield by the
same procedure as described for 45, mp 187-190 °C; 1H NMR
(400 MHz, DMSO-d6) δ 3.69 (dd, J ) 11 and 4 Hz, 1H), 4.29
(t, J ) 11 Hz, 1H), 4.99 (dd, J ) 11 and 4 Hz, 1H), 7.16-7.33
(m, 4H), 7.44 (dt, J ) 8 and 2 Hz, 2H), 7.80 (dt, J ) 8 and 2
Hz, 2H), 7.90-7.94 (m, 1H), 8.10-8.14 (m, 1H), 8.28-8.34 (m,
2H), 11.60 (br s, 1H); 13C NMR (100 MHz, DMSO-d6) δ 49.8,
54.9, 123.8 (q, J CF ) 272 Hz), 124.6 (q, J CF ) 4 Hz), 127.6,
127.9, 128.9, 129.4, 129.5, 129.6, 129.9 (q, J CF ) 23 Hz), 130.49,
130.52, 131.1, 132.1, 135.1, 140.5, 141.5, 148.9, 156.5.
3-(4-Ch lor oph en yl)-4-ph en yl-N-[(2,4,6-tr im eth ylph en yl)-
su lfon yl]-4,5-d ih yd r o-1H-p yr a zole-1-ca r boxa m id e (53).
53 was prepared from 2 and 42 in 80% yield by the same
procedure as described for 45, mp 245-250 °C; 1H NMR (400
MHz, DMSO-d6) δ 2.26 (s, 3H), 2.66 (s, 6H), 3.66 (dd, J ) 11
and 4 Hz, 1H), 4.24 (t, J ) 11 Hz, 1H), 4.95 (dd, J ) 11 and 4
Hz, 1H), 7.04 (s, 2H), 7.15-7.34 (m, 5H), 7.42 (dt, J ) 8 and
N′-[(4-Ch lor op h en yl)su lfon yl]-3-(4-flu or op h en yl)-N-
m eth yl-4-p h en yl-4,5-d ih yd r o-1H-p yr a zole-1-ca r boxa m i-
d in e (69). 69 was prepared from 47 via 58 in 43% yield by
1
the same procedure as described for 67, mp 146-148 °C; H
NMR (400 MHz, DMSO-d6) δ 2.93 (d, J ) 4 Hz, 3H), 3.96 (dd,
J ) 11 and 4 Hz, 1H), 4.45 (t, J ) 11 Hz, 1H), 5.05 (dd, J ) 11
and 4 Hz, 1H), 7.20-7.36 (m, 7H), 7.53 (dt, J ) 8 and 2 Hz,
2H), 7.77-7.84 (m, 4H), 8.17 (br d, J ) 4 Hz, 1H); 13C NMR
(100 MHz, DMSO-d6) δ 30.6 (broad), 50.2, 57.9, 116.1 (d, J CF
) 22 Hz), 126.9 (d, J CF ) 3 Hz), 127.5, 127.6, 127.9, 129.1,
129.6, 130.2 (d, J CF ) 9 Hz), 135.8, 140.4, 145.4 (broad), 152.5,
158.1, 163.5 (d, J CF ) 249 Hz); HRMS (C23H21ClFN4O2S)
[M+H]+: found m/z 471.1065, calcd 471.1058. Anal. (C23H20
ClFN4O2S) C, H, N.
-
2 Hz, 2H), 7.87 (dt, J ) 8 and 2 Hz, 2H), 11.55 (br s, 1H); 13
C
3,4-Bis-(4-ch lor op h en yl)-N′-[(4-ch lor op h en yl)su lfon yl]-
N-m eth yl-4,5-d ih yd r o-1H-p yr a zole-1-ca r boxa m id in e (70).
70 was prepared from 48 via 59 in 55% yield by the same
procedure as described for 67, mp 107-108 °C; 1H NMR (400
MHz, DMSO-d6) δ 2.95 (br d, J ) 4 Hz, 3H), 3.94 (dd, J ) 11
and 4 Hz, 1H), 4.45 (t, J ) 11 Hz, 1H), 5.08 (dd, J ) 11 and 4
Hz, 1H), 7.24 (dt, J ) 8 and 2 Hz, 2H), 7.53 (dt, J ) 8 and 2
NMR (100 MHz, DMSO-d6) δ 20.8, 22.5, 49.7, 54.8, 127.6,
127.8, 128.9, 129.53, 129.56, 129.7, 131.9, 134.9, 139.8 (2C),
140.6, 142.8, 149.6, 155.9.
3-(4-Ch lor op h en yl)-N-[(4-m eth oxyp h en yl)su lfon yl]-4-
p h en yl-4,5-d ih yd r o-1H-p yr a zole-1-ca r boxa m id e (54). 54
was prepared from 2 and 43 in 71% yield by the same

640 J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 3
Lange et al.
Hz, 2H), 7.40 (dt, J ) 8 and 2 Hz, 2H), 7.46 (dt, J ) 8 and 2
Hz, 2H), 7.53 (dt, J ) 8 and 2 Hz, 2H), 7.75 (dt, J ) 8 and 2
Hz, 2H), 7.82 (dt, J ) 8 and 2 Hz, 2H), 8.22 (br d, J ) 4 Hz,
1H); 13C NMR (100 MHz, DMSO-d6) δ 30.6 (broad), 49.3, 57.7,
127.5, 129.0, 129.1, 129.2, 129.5, 129.6 (2C), 132.5, 135.5,
129.3, 129.5, 129.6, 131.3, 132.0, 135.3, 136.7, 139.7, 140.3,
152.3, 157.5; HRMS (C26H28ClN4O2S) [M+H]+: found m/z
495.1592, calcd 495.1622.
3-(4-Ch lor op h en yl)-N-m eth yl-4-p h en yl-N′-[(4-m eth oxy-
phenyl)sulfonyl]-4,5-dihydro-1H-pyrazole-1-carboxamidine
(76). 76 was prepared from 54 via 65 in 39% yield by the same
procedure as described for 67, mp 180-181 °C; 1H NMR (400
MHz, DMSO-d6) δ 2.97 (d, J ) 4 Hz, 3H), 3.78 (s, 3H), 3.97
(dd, J ) 11 and 4 Hz, 1H), 4.46 (t, J ) 11 Hz, 1H), 5.03 (dd, J
) 11 and 4 Hz, 1H), 6.98 (dt, J ) 8 and 2 Hz, 2H), 7.19-7.27
(m, 3H), 7.30-7.35 (m, 2H), 7.44 (dt, J ) 8 and 2 Hz, 2H),
7.73 (dt, J ) 8 and 2 Hz, 2H), 7.76 (dt, J ) 8 and 2 Hz, 2H),
8.05 (br d, J ) 4 Hz, 1H); 13C NMR (100 MHz, DMSO-d6) δ
30.8 (broad), 49.3, 55.8, 58.0, 114.0, 127.5, 127.6, 127.9, 129.1,
129.3, 129.5, 129.6, 135.3, 138.5 (broad), 140.4, 152.4, 157.5,
161.3; HRMS (C24H24ClN4O3S) [M+H]+: found m/z 483.1289,
calcd 483.1258. Anal. (C24H23ClN4O3S) C, H, N.
135.9, 139.1, 145.3 (broad), 152.5, 157.5; HRMS (C23H20
-
Cl3N4O2S) [M+H]+: found m/z 521.0353, calcd 521.0373.
3-(4-Ch lor op h en yl)-N-m eth yl-4-p h en yl-N′-(p h en ylsu l-
fon yl)-4,5-d ih yd r o-1H-p yr a zole-1-ca r boxa m id in e (71). 71
was prepared from 49 via 60 in 53% yield by the same
procedure as described for 67, mp 130-132 °C; 1H NMR (400
MHz, DMSO-d6) δ 2.95 (d, J ) 4 Hz, 3H), 3.98 (dd, J ) 11 and
4 Hz, 1H), 4.47 (t, J ) 11 Hz, 1H), 5.04 (dd, J ) 11 and 4 Hz,
1H), 7.20-7.28 (m, 3H), 7.30-7.35 (m, 2H), 7.42-7.50 (m, 5H),
7.77 (dt, J ) 8 and 2 Hz, 2H), 7.80-7.84 (m, 2H), 8.13 (br d,
J ) 4 Hz, 1H); 13C NMR (100 MHz, DMSO-d6) δ 30.7 (broad),
50.0, 58.0, 125.5, 127.6, 127.9, 129.0, 129.1, 129.3, 129.5, 129.6,
131.2, 135.3, 140.3, 146.4, 152.5, 157.7; (C23H22ClN4O2S)
3-(4-Ch lor op h e n yl)-N -m e t h yl-4-p h e n yl-N ′-[(2-n a p h -
t h yl)su lfon yl]-4,5-d ih yd r o-1H -p yr a zole -1-ca r b oxa m i-
d in e (77). 77 was prepared from 55 via 66 in 29% yield
by the same procedure as described for 67, mp 162-164
°C; 1H NMR (400 MHz, DMSO-d6) δ 2.96 (br d, J ) 4
[M+H]+: found m/z 453.1158, calcd 453.1152. Anal. (C23H21
ClN4O2S) C, H, N.
-
3-(4-Ch lor op h en yl)-N′-[(4-flu or op h en yl)su lfon yl]-N-
m eth yl-4-p h en yl-4,5-d ih yd r o-1H-p yr a zole-1-ca r boxa m i-
d in e (72). 72 was prepared from 50 via 61 in 39% yield by
Hz, 3H), 4.02 (dd, J ) 11 and 4 Hz, 1H), 4.50 (t, J
)
1
11 Hz, 1H), 5.03 (dd, J ) 11 and 4 Hz, 1H), 7.19-7.27
(m, 3H), 7.28-7.33 (m, 2H), 7.43 (dt, J ) 8 and 2 Hz,
2H), 7.59-7.66 (m, 2H), 7.75 (dt, J ) 8 and 2 Hz, 2H),
7.88 (dd, J ) 8 and 2 Hz, 1H), 7.95-8.02 (m, 2H) 8.07-8.10
(m, 1H), 8.14-8.20 (m, 1H), 8.42 (br s, 1H); 13C NMR
(100 MHz, DMSO-d6) δ 30.7 (broad), 50.0, 58.0, 122.7, 125.0,
127.5, 127.6, 127.9, 128.0, 128.2, 129.0, 129.1, 129.2, 129.4,
129.5, 129.6, 132.1, 133.9, 135.4, 140.3, 143.6 (broad), 152.5,
157.7. HRMS (C27H24ClN4O2S) [M+H]+: found m/z 503.1280,
calcd. 503.1309. Anal. Calcd. for C27H23ClN4O2S: C, H, N.
the same procedure as described for 67, mp 147-149 °C; H
NMR (400 MHz, DMSO-d6) δ 2.95 (d, J ) 4 Hz, 3H), 3.97 (dd,
J ) 11 and 4 Hz, 1H), 4.46 (t, J ) 11 Hz, 1H), 5.05 (dd, J ) 11
and 4 Hz, 1H), 7.20-7.35 (m, 7H), 7.45 (dt, J ) 8 and 2 Hz,
2H), 7.76 (dt, J ) 8 and 2 Hz, 2H), 7.84-7.90 (m, 2H), 8.16
(br d, J ) 4 Hz, 1H); 13C NMR (100 MHz, DMSO-d6) δ 30.7
(broad), 50.0, 58.0, 116.1 (d, J CF ) 22 Hz), 127.6, 127.9, 128.3
(d, J CF ) 9 Hz), 129.1, 129.2, 129.5, 129.6, 135.4, 140.3, 142.9
(broad), 152.4, 157.8, 163.4 (d, J CF ) 249 Hz); HRMS (C23H21
-
ClFN4O2S) [M+H]+: found m/z 471.1054, calcd 471.1058. Anal.
(C23H20ClFN4O2S) C, H, N.
(4S)-(-)-3-(4-Ch lor oph en yl)-N-m eth yl-N′-[(4-ch lor oph en -
yl)sulfonyl]-4-phenyl-4,5-dihydro-1H-pyrazole-1-carboxamidine
(80) and (4R)-(+)-3-(4-ch lor op h en yl)-N-m et h yl-N′-[(4-
ch lor oph en yl)su lfon yl]-4-ph en yl-4,5-dih ydr o-1H-pyr azole-
1-ca r boxa m id in e (81). Chiral preparative HPLC separation
of racemic 67 (18 g, 0.037 mol) using a Chiralpak AD, 20 µm
chiral stationary phase yielded 80 (7.16 g, 0.0147 mol) and 81
(7.46 g, 0.0153 mol), respectively. The mobile phase consisted
of a mixture of n-hexane/ethanol (80/20 (v/v)) and 0.1% NH4OH
(25% aqueous solution). 80: [R2D5] ) -150°, c ) 0.01, MeOH;
mp 171-172 °C; 1H NMR (400 MHz, DMSO-d6) δ 2.94 (d, J )
4 Hz, 3H), 3.96 (dd, J ) 11 and 4 Hz, 1H), 4.46 (t, J ) 11 Hz,
1H), 5.05 (dd, J ) 11 and 4 Hz, 1H), 7.20-7.35 (m, 5H), 7.45
(dt, J ) 8 and 2 Hz, 2H), 7.53 (dt, J ) 8 and 2 Hz, 2H), 7.77
(dt, J ) 8 and 2 Hz, 2H), 7.82 (dt, J ) 8 and 2 Hz, 2H), 8.19
(br d, J ) 4 Hz, 1H); HRMS (C23H21Cl2N4O2S) [M+H]+: found
m/z 487.0768, calcd 487.0762. Anal. (C23H20Cl2N4O2S) C, H,
3-(4-Ch lor op h en yl)-N-m eth yl-N′-[(4-m eth ylp h en yl)su l-
fon yl]-4-p h en yl-4,5-d ih yd r o-1H -p yr a zole-1-ca r b oxa m i-
d in e (73). 73 was prepared from 51 via 62 in 50% yield by
1
the same procedure as described for 67, mp 170-172 °C; H
NMR (400 MHz, DMSO-d6) δ 2.32 (s, 3H), 2.95 (d, J ) 4 Hz,
3H), 3.95 (dd, J ) 11 and 4 Hz, 1H), 4.45 (t, J ) 11 Hz, 1H),
5.03 (dd, J ) 11 and 4 Hz, 1H), 7.19-7.27 (m, 5H), 7.30-7.35
(m, 2H), 7.45 (dt, J ) 8 and 2 Hz, 2H), 7.69 (d, J ) 8 Hz, 2H),
7.75 (dt, J ) 8 and 2 Hz, 2H), 8.09 (br d, J ) 4 Hz, 1H); 13C
NMR (100 MHz, DMSO-d6) δ 21.2, 30.7 (broad), 50.0, 58.0,
125.5, 127.6, 127.9, 129.1, 129.3, 129.4, 129.5, 129.6, 135.3,
140.4, 141.1, 143.6, 152.4, 157.6. HRMS (C24H24ClN4O2S)
[M+H]+: found m/z 467.1337, calcd. 467.1309. Anal. Calcd.
for C24H23ClN4O2S: C, H, N.
3-(4-Ch lor op h en yl)-N-m eth yl-N′-{[3-(tr iflu or om eth yl)-
p h en yl]su lfon yl}-4-p h en yl-4,5-d ih yd r o-1H -p yr a zole-1-
ca r boxa m id in e (74). 74 was prepared from 52 via 63 in 44%
yield by the same procedure as described for 67, mp 167-168
N. 81: [R2D5] ) + 150°, c ) 0.01, MeOH; mp 171-172 °C; H
1
NMR (400 MHz, DMSO-d6) δ 2.94 (d, J ) 4 Hz, 3H), 3.96 (dd,
J ) 11 and 4 Hz, 1H), 4.46 (t, J ) 11 Hz, 1H), 5.05 (dd, J ) 11
and 4 Hz, 1H), 7.20-7.35 (m, 5H), 7.45 (dt, J ) 8 and 2 Hz,
2H), 7.53 (dt, J ) 8 and 2 Hz, 2H), 7.77 (dt, J ) 8 and 2 Hz,
2H), 7.82 (dt, J ) 8 and 2 Hz, 2H), 8.19 (br d, J ) 4 Hz, 1H);
HRMS (C23H21Cl2N4O2S) [M+H]+: found m/z 487.0749, calcd
487.0762. Anal. (C23H20Cl2N4O2S) C, H, N.
1
°C; H NMR (400 MHz, DMSO-d6) δ 2.93 (d, J ) 4 Hz, 3H),
3.98 (dd, J ) 11 and 4 Hz, 1H), 4.49 (t, J ) 11 Hz, 1H), 5.07
(dd, J ) 11 and 4 Hz, 1H), 7.20-7.28 (m, 3H), 7.30-7.36 (m,
2H), 7.45 (dt, J ) 8 and 2 Hz, 2H), 7.72-7.77 (m, 3H), 7.90
(br d, J ) 8 Hz, 1H), 8.06 (br s, 1H), 8.14 (br d, J ) 8 Hz, 1H),
8.23-8.29 (m, 1H); 13C NMR (100 MHz, DMSO-d6) δ 30.5
(broad), 50.1, 57.9, 121.9 (q, J CF ) 4 Hz), 123.9 (q, J CF ) 272
Hz),127.6, 127.88, 127.95, 129.09, 129.15, 129.54, 129.58,
129.63 (q, J CF ) 22 Hz), 129.64, 130.7, 135.4, 140.3, 147.6,
152.5, 158.1; HRMS (C24H21ClF3N4O2S) [M+H]+: found m/z
521.1041, calcd. 521.1026. Anal. Calcd. for C24H20ClF3N4O2S:
C, H, N.
(-)-3-(4-Ch lor op h e n yl)-N -m e t h yl-N ′-{[4-(t r iflu or o-
methyl)phenyl]sulfonyl)}-4-phenyl-4,5-dihydro-1H-pyrazole-1-
ca r boxa m id in e (78) and (+)-3-(4-ch lor op h en yl)-N-m eth yl-
N′-{[4-(tr iflu or om eth yl)p h en yl]su lfon yl}-4-p h en yl-4,5-d i-
h yd r o-1H-p yr a zole-1-ca r b oxa m id in e (79). Racemic ami-
dine 29 was analogously separated by chiral preparative HPLC
as described for 67 using a mixture of heptane/2-propanol (85/
15 (v/v)) as the mobile phase and Chiralcel OD as the
stationary phase to give optically pure 78 and 79, respectively.
78: [R2D5] ) -131°, c ) 0.01, CHCl3; mp: 160-162 °C; 1H
NMR (400 MHz, CDCl3) δ 2.90-2.97 (m, 3H), 3.95 (dd, J ) 11
and 4 Hz, 1H), 4.48 (t, J ) 11 Hz, 1H), 5.05 (dd, J ) 11 and 4
Hz, 1H), 7.17-7.32 (m, 5H), 7.45 (dt, J ) 8 and 2 Hz, 2H),
7.74 (dt, J ) 8 and 2 Hz, 2H), 7.84 (d, J ) 8 Hz, 1H), 8.04 (d,
J ) 8 Hz, 1H) 8.24-8.30 (m, 1H); HRMS (C24H21ClF3N4O2S)
3-(4-Ch lor op h en yl)-N-m eth yl-N′-[(2,4,6-tr im eth ylp h en -
yl)sulfonyl]-4-phenyl-4,5-dihydro-1H-pyrazole-1-carboxamidine
(75). 75 was prepared from 53 via 64 in 35% yield by the same
procedure as described for 67, mp 171-172 °C; 1H NMR (400
MHz, DMSO-d6) δ 2.19 (s, 3H), 2.53 (s, 6H), 2.91 (br d, J ) 4
Hz, 3H), 3.85 (dd, J ) 11 and 4 Hz, 1H), 4.41 (t, J ) 11 Hz,
1H), 5.00 (dd, J ) 11 and 4 Hz, 1H), 6.89 (br s, 2H), 7.16-
7.34 (m, 5H), 7.43 (dt, J ) 8 and 2 Hz, 2H), 7.74 (dt, J ) 8
and 2 Hz, 2H), 8.14 (br d, J ) 4 Hz, 1H); 13C NMR (100 MHz,
DMSO-d6) δ 20.6, 22.8, 30.6, 49.9, 58.0, 127.5, 127.9, 129.1,
[M+H]+: found m/z 521.1016, calcd 521.1026. Anal. (C24H20
-

CB1 Cannabinoid Receptor Antagonists
J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 3 641
ClF3N4O2S) C, H, N. 79: [R25] ) +131°, c ) 0.01, CHCl3, mp
combined and converted to Ki values using the assumptions
D
of Cheng and Prusoff.39
160-162 °C; 1H NMR (400 MHz, CDCl3) δ 2.90-2.97 (m, 3H),
3.95 (dd, J ) 11 and 4 Hz, 1H), 4.48 (t, J ) 11 Hz, 1H), 5.05
(dd, J ) 11 and 4 Hz, 1H), 7.17-7.32 (m, 5H), 7.45 (dt, J ) 8
and 2 Hz, 2H), 7.74 (dt, J ) 8 and 2 Hz, 2H), 7.84 (d, J ) 8
Hz, 1H), 8.04 (d, J ) 8 Hz, 1H), 8.24-8.30 (m, 1H); HRMS
In Vitr o P h a r m a cology. Mea su r em en t of Ar a ch id on ic
Acid Relea se. CB1 receptor antagonism21 was assessed with
the human CB1 receptor cloned in Chinese hamster ovary
(CHO) cells. CHO cells were grown in a Dulbecco’s modified
Eagle’s medium (DMEM) culture medium, supplemented with
10% heat-inactivated fetal calf serum. Medium was aspirated
and replaced by DMEM, without fetal calf serum, but contain-
ing [3H]-arachidonic acid and incubated overnight in a cell
culture stove (5% CO2/95% air; 37 °C; water-saturated atmo-
sphere). During this period [3H]-arachidonic acid was incor-
porated in membrane phospholipids. On the test day, medium
was aspirated and cells were washed three times using 0.5
mL of DMEM, containing 0.2% bovine serum albumin (BSA).
Stimulation of the CB1 receptor by WIN 55,212-2 led to
activation of PLA2 followed by release21 of [3H]-arachidonic acid
into the medium. This WIN 55,212-2-induced release was
concentration dependently antagonized by CB1 receptor an-
tagonists. The CB1 antagonistic potencies of the test com-
pounds were expressed as pA2 values.
(C24H21ClF3N4O2S)
calcd 521.1026. Anal. (C24H20ClF3N4O2S) C, H, N.
[M+H]+:
found
m/z
521.1033,
4-Ch lor oben zoylisoth iocya n a te (82). 82 was prepared
according to the literature procedure18 from 4-chlorobenzoyl
chloride and NH4NCS and immediately reacted with 2.
N-(4-Ch lor oben zoyl)-3-(4-ch lor op h en yl)-4-p h en yl-4,5-
d ih yd r o-1H-p yr a zole-1-th ioca r boxa m id e (83). 2 (2.57 g,
0.01 mol) was added to a magnetically stirred and cooled (0
°C) solution of 82 (2.07 g, 0.0105 mol) in anhydrous CH3CN
(40 mL), and the resulting mixture was stirred at room
temperature for 1 h. The formed precipitate (NH4Cl) was
removed by filtration and thoroughly washed with CH3CN.
The filtrate was concentrated in vacuo and the formed solid
material was collected and further purified by column chro-
matography (CH2Cl2), followed by recrystallization from CH3CN
1
to give pure 83 (2.07 g, 46% yield), mp 173-175 °C; H NMR
In Vivo P h a r m a cology. 1. CP -55,940 In d u ced Hy-
p oten sion in Ra t. Male normotensive rats (225-300 g;
Harlan, Horst, The Netherlands) were anaesthetized with
pentobarbital (80 mg/kg ip). Blood pressure was measured, via
a cannula inserted into the left carotid artery, by means of a
Spectramed DTX-plus pressure transducer (Spectramed B. V.,
Bilthoven, The Netherlands). After amplification by a Nihon
Kohden Carrier amplifier (Type AP-621G; Nihon Kohden B.
V., Amsterdam, The Netherlands), the blood pressure signal
was registered on a personal computer (Compaq Deskpro
386s), by means of a Po-Ne-Mah data-acquisition program
(Po-Ne-Mah Inc., Storrs, USA). Heart rate was derived from
the pulsatile pressure signal. All compounds were adminis-
tered orally as a microsuspension in 1% methylcellulose 30
min before induction of the anesthesia which was 60 min prior
to administration of the CB1 receptor agonist CP-55,940. The
injection volume was 10 mL kg-1. After haemodynamic sta-
bilization the CB1 receptor agonist CP-55,940 (0.1 mg kg-1 i.v.)
was administered and the hypotensive effect22 established.
Typical blood pressure after administration of CP-55,940 was
approximately 60% as compared to vehicle treated animals.
2. WIN 55,212-2 In d u ced Hyp oth er m ia in Isola ted
Mou se. Male NMRI mice (Charles River, Sulzfeld, Germany)
weighing ca. 12-14 g upon arrival in the laboratory, were
housed in groups of five animals per cage (dimensions: 34 ×
22 × 15 cm) under nonreversed 12 h light-12 h dark cycle
conditions (lights on from 07.00 to 19.00 h). The animals were
housed at constant room temperature (21 ( 2 °C) and relative
humidity (60 ( 10%) with food and water freely available.
Experiments were carried out between 9.00 a.m. and 3 p.m.
The day preceding the experiment, the mice were individually
housed with free access to food and water. According to a
balanced design mice were allocated to times of day and
treatments in each experiment. The number of animals per
treatment group was eight. The experiments were performed
with a dose range of the test compound administered in a
volume of 10 mL/kg orally. Simultaneously, WIN 55,212-2 (5
mg/kg, suspended in 1% methyl cellulose with 5% mannitol)
was administered in a volume of 10 mL/kg s.c. After 60 min,
the temperature was measured by inserting a thermistor probe
for a length of 2 cm into the rectum of the mice. Digital
recordings of the temperature were determined with an
accuracy of 0.1 °C by means of a Keithley 871A digital
thermometer (NiCr-NiAl thermocouple). The body tempera-
tures of all groups were compared to the 1 h saline pretreated
group (n ) 24). Effects on body temperature were analyzed
using ANOVA statistics. Hypothermia23 was determined by
the difference in temperature between the control group and
the WIN 55,212-2 test group. The lowest effective dose (LED)
was defined as the dose of the administered test compound
(in the presence of WIN 55,212-2) giving a significant increase
of the body temperature as compared with the WIN 55,212-2
treated animals. Typical temperature measurements in vehicle
(400 MHz, DMSO-d6) δ 4.17 (dd, J ) 11 and 4 Hz, 1H), 4.71
(t, J ) 11 Hz, 1H), 5.10 (dd, J ) 11 and 4 Hz, 1H), 7.24-7.37
(m, 5H), 7.42 (d, J ) 8 Hz, 2H), 7.60-7.66 (m, 4H), 8.05 (d, J
) 8 Hz, 2H), 11.30 (br s, 1H); 13C NMR (100 MHz, DMSO-d6)
δ 49.5, 60.3, 127.7, 128.0, 128.9, 129.1, 129.3, 129.6 (2C), 130.7,
132.6, 136.0, 137.8, 140.3, 161.0, 164.4, 173.7.
N′-(4-Ch lor ob en zoyl)-3-(4-ch lor op h en yl)-N-m et h yl-4-
p h en yl-4,5-d ih yd r o-1H-p yr a zole-1-ca r boxa m id in e (84).
To a stirred suspension of 83 (1.82 g, 4.0 mmol) in CH3CN (20
mL) was added excess cold methylamine (3 mL) to give a clear
green colored solution. A solution of HgCl2 (1.20 g, 4.40 mmol)
in CH3CN (20 mL) was slowly added, and the resulting dark
suspension was stirred for 3 h. The precipitate was removed
by filtration over Hyflo super cel (Fluka). The filtrate was
successively concentrated in vacuo, dissolved in EtOAc, washed
with a 2 N NaOH solution, dried over Na2SO4, filtered, and
concentrated in vacuo. The residue was further purified by
column chromatography (petroleum ether (40-60)/EtOAc )
1/1 (v/v)) and recrystallized from EtOH to yield 84 (0.57 g, 32%
yield), mp 164-165 °C; 1H NMR (400 MHz, DMSO-d6) δ 2.90
(br s, 3H), 3.84 (br s, 1H), 4.40 (br s, 1H), 5.05 (dd, J ) 11 and
4 Hz, 1H), 7.20-7.26 (m, 3H), 7.30-7.35 (m, 2H), 7.42 (d, J )
8 Hz, 2H), 7.46 (d, J ) 8 Hz, 2H), 7.78 (d, J ) 8 Hz, 2H), 8.02
(d, J ) 8 Hz, 2H), 8.22 (br s, 1H); 13C NMR (100 MHz, DMSO-
d6) δ 29.5 (broad), 50.2 (broad), 56.9 (broad), 127.6, 127.8,
128.1, 129.1, 129.4, 129.5, 129.8, 130.2 (2C), 135.1, 135.6
(broad), 137.5, 140.7, 157.0, 157.3. HRMS (C24H21Cl2N4O)
[M+H]+: found m/z 451.1109, calcd. 451.1092. Anal. Calcd.
for C24H20Cl2N4O: C, H, N.
Recep tor Bin d in g Assa ys. 1. CB1 Assa y. CB1 receptor
affinities were determined using membrane preparations of
Chinese hamster ovary (CHO) cells in which the human
cannabinoid CB1 receptor is stably transfected19 in conjunction
with [3H]CP-55,940 as radioligand. After incubation of a
freshly prepared cell membrane preparation with the [3H]-
radioligand, with or without addition of test compound,
separation of bound and free ligand was performed by filtration
over glassfiber filters. Radioactivity on the filter was measured
by liquid scintillation counting. The IC50 values from at least
three independent measurements were combined and con-
verted to Ki values using the assumptions of Cheng and
Prusoff.39
CB2 Assa y. CB2 receptor affinities were determined using
membrane preparations of Chinese hamster ovary (CHO) cells
in which the human cannabinoid CB2 receptor is stably
transfected20 in conjunction with [3H]CP-55,940 as radioli-
gand.40 After incubation of a freshly prepared cell membrane
preparation with the [3H]-radioligand, with or without addition
of test compound, separation of bound and free ligand was
performed by filtration over glassfiber filters. Radioactivity on
the filter was measured by liquid scintillation counting. The
IC50 values from at least two independent measurements were

642 J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 3
Lange et al.
treated animals were of the range of 37.5-38.5 °C and
administration of WIN-55,212-2 reduced the temperature to
33-34 °C.
dosing, two animals per time point. A group of 12 animals
received 10 mg/kg per os, blood and brain samples were taken
at 60, 120, 360, and 1440 min in triplicate. Plasma samples
were analyzed after liquid-liquid extraction on a reversed
phase liquid chromatographic system with ultraviolet detection
at 314 nm. Brain samples were analyzed on the same system
after homogenization and solid-phase extraction. Levels in the
samples were calculated from a concentration versus response
curve obtained from spiked blanc matrix samples which were
processed and analyzed in the same way as the samples
(extracted calibration curve). The CNS/plasma ratio was
estimated using the plasma (ng/mL) over brain (ng/g) concen-
tration over the entire oral dosing time range. The average
value found was 1.7 (smean ) 0.14, n ) 12).
Molecu la r Mod elin g. All modeling studies were carried
out on a Silicon Graphics Octane workstation running Sybyl
V6.9.1.42 Confort was used to generate a collection of maxi-
mally diverse low energy conformations of 80, followed by
MOPAC minimization using the PM3 method. The protein
model was created using the 2.8-Å crystal structure of bovine
rhodopsin.26 The residues were mutated according to the amino
acid sequences alignment made with ClustalX.43 The loops
were omitted. Standard geometries for the side-chains were
given by the Biopolymer module. This rough model was
minimized with Kolmann charges in the Kollmann All-atom
force field, holding the TMH backbones fixed. Subsequently,
the kink in TMH6 at Pro358 was introduced25 to enable the
salt bridge between Lys192 and Asp366 and the model was
further minimized. The ligands were manually docked into the
receptor, followed by minimization with the Tripos force-field
using the charges obtained by earlier calculations, with a
range-constraint of 2.5-3.0 Å on the N-atom of Lys192 and
the O-atom of the ligand to which it is bound. Finally, the
complex was subjected to a simulated annealing procedure of
five cycles (starting at 500 K for 500 fs annealing to 200 K via
exponential ramping during 1000 fs) with the same constraints
as mentioned above.
P -Glycop r otein Assa y. The capability of the human MDR1
P-glycoprotein pump to translocate compounds over a cellular
monolayer of PK1 LLC MDR cells was assessed. The transport
method essentially described in the literature31 was used.
Compounds were added at the start of the experiment at 1
µg/mL to one side of the cellular layer. The bottom to top
transport was measured as well as the top to bottom transport.
The P-glycoprotein (Pgp) factor was expressed as the ratio of
the bottom to top transport and top to bottom transport. The
membrane passage was expressed as the mean percentage of
compound transported from bottom to top and from top to
bottom at 3 h after adding the compound. Compound detection
was performed using a LC/MS method.
X-r a y Cr ysta llogr a p h ic An a lysis of 6. Crystallographic
analyses and the structure determination of compound 6 were
performed by Dr. H. Kooijman and A. L. Spek, Bijvoet Centre
for Biomolecular Research, Utrecht University, Utrecht, The
Netherlands. Suitable crystals were obtained by recrystalli-
zation of 6 from EtOH. A colorless, plate shaped crystal was
fixed to the tip of a glass fiber and transferred into the cold
nitrogen stream on a rotating anode X-ray diffractometer. The
structure was solved by automated direct methods. Non-
hydrogen atoms were refined with anisotropic atomic displace-
ment parameters. The hydrogen atoms were refined with fixed
isotropic displacement parameters related to the value of the
equivalent isotropic displacement parameters of their carrier
atoms by a factor 1.2. All calculations were performed on a
DEC Alpha station 255 (UNIX). Relevant data collection
parameters: temperature: 150 K, wavelength: 0.71073 Å (Mo
Ka), X-ray exposure time: 5.5 h, crystal size: 0.05 × 0.12 ×
0.15 mm, crystal system: monoclinic, space group: P21/c: unit
cell dimensions: a ) 17.1654; b ) 5.759; c ) 24.882 Å,
calculated density: 1.535 g cm-3, completeness: 100%, total
number of reflections: 47244, number of unique reflections:
3748, number of refined parameters: 334.
Ack n ow led gm en t. Mr. Karel Stegman and Mr. J an
J eronimus are gratefully acknowledged for supplying
and interpreting the spectral data. Dr. Mia Pras-Raves
is acknowledged for supplying the X-ray diffraction data.
Dr. Anneke Mu¨hlebach and Mrs. Ingrid Gehrmann are
gratefully acknowledged for supplying the elemental
analysis data. Mr. Piet Hoogkamer is acknowledged for
supplying the RP-HPLC lipophilicity data.
X-r a y Cr ysta llogr a p h ic An a lysis of 80. Crystallographic
analyses and the structure determination of compound 80 were
performed by Dr. H. Kooijman and A. L. Spek, Bijvoet Centre
for Biomolecular Research, Utrecht University, Utrecht, The
Netherlands. Suitable crystals were obtained by recrystalli-
zation of 80 from EtOH. A colorless, block-shaped crystal, cut
from a larger crystal, was glued to the tip of a glass fiber and
transferred into the cold nitrogen stream on a rotating anode
X-ray diffractometer. The structure was solved by automated
direct methods. Hydrogen atoms were located on an electron-
density map and their coordinates were included as param-
eters in the refinement. All non-hydrogen atoms were refined
with anisotropic atomic displacement parameters. Relevant
data collection parameters: Temperature: 150 K, wave-
length: 0.71073 Å (Mo Ka), X-ray exposure time: 3 h, crystal
size: 0.25 × 0.25 × 0.35 mm, crystal system: orthorhombic,
space group: P212121: unit cell dimensions: a ) 9.018; b )
Su ppor tin g In for m ation Available: Microanalytical data.
This material is available free of charge via the Internet at
http://pubs.acs.org.
Refer en ces
(1) Robson, P. Therapeutic aspects of cannabis and cannabinoids.
Br. J . Psychiatry 2001, 178, 107-115.
15.084; c ) 16.073 Å, calculated density: 1.481 g cm-3
,
(2) Croxford, J . L. Therapeutic potential of cannabinoids in CNS
disease. CNS Drugs 2003, 17, 179-202.
completeness: 99.9%, total number of reflections: 49341,
number of unique reflections: 5006, number of refined pa-
rameters: 350. Flack x-parameter: - 0.02.
(3) Glass, M. The role of cannabinoids in neurodegenerative dis-
eases. Progr. Neuro-Psychopharmacol., Biol. Psychiat. 2001, 25,
743-765.
(4) Consroe, P. Brain cannabinoid systems as targets fore the
therapy of neurological disorders. Neurobiol. Dis. 1998, 5, 534-
551.
Exp er im en ta l Lip op h ilicity Deter m in a tion by RP -
HP LC. Partition coefficients (n-octanol/water) were measured
by a high-performance liquid chromatographic (HPLC) method
based on an Organization for Economic Cooperation and
Development (OECD) method,41 using a mobile phase buffered
at pH > 11 and an aluminum-based octadecyl modified
stationary phase. The retention factor k of a compound was
correlated with its partition coefficient using a calibration
graph based on 10 reference compounds with well-known log
Pow in the range 2.1-5.7.
CNS/P la sm a Ra tio of Com p ou n d 80. Preliminary kinetic
data in rats were gathered by administration of 1 mg/kg
intravenously and 10 mg/kg orally to Wistar rats. A group of
10 animals received 1 mg/kg intravenously; blood samples
were taken at time points 10, 30, 60, 180, and 420 min after
(5) Matsuda, L. A.; Lolait, S. J .; Brownstein, B. J .; Young, A. C.;
Bonner. T. I. Structure of a cannabinoid receptor and functional
expression of the cloned cDNA. Nature 1990, 356, 561-564.
(6) Munro, S.; Thomas, K. L.; Abu-Shaar, M. Molecular character-
ization of a peripheral receptor for cannabinoids. Nature 1993,
365, 61-62.
(7) Wilson, R.; Nicoll, R. A. Endocannabinoid signaling in the brain.
Science 2002, 296, 678-682.
(8) Breivogel, C. S.; Griffin, G.; Di Marzo, V.; Martin, B. R. Evidence
for a new G protein-Coupled Cannabinoid receptor in mouse
brain. Mol. Pharmacol. 2001, 60, 155-163.
(9) Adam, J .; Cowley, P. Recent advances in the cannabinoids.
Expert Opin. Ther. Pat. 2002, 12, 1475-1489.
(10) Pertwee, R. G. Neuropharmacology and therapeutic potential
of cannabinoids. Addict, Biol. 2000, 5, 37-46.

CB1 Cannabinoid Receptor Antagonists
J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 3 643
(11) Gomez, R.; Navarro, M.; Ferrer, B.; Trigo, J . M.; Bilbao, A.; Del
Arco, I.; Cippitelli, A.; Nava, F.; Piomelli, D.; De Fonseca, F. R.
A peripheral mechanism for CB1 cannabinoid receptor-depend-
ent modulation of feeding. J . Neurosci. 2002, 22, 9612-9617.
(12) Hall, W. Cannabis and psychosis. Drug Alcohol Rev. 1998, 17,
433-444.
(13) Hungund, B. L.; Basavarajappa, B. S.; Vadasz, C.; Kunos, G.;
de Fonseca, F. R.; Colombo, G.; Serra, S.; Parsons, L.; Koob, G.
F. Ethanol, endocannabinoids, and the cannabinoidergic signal-
ing system. Alcohol Clin. Exp. Res. 2002, 26, 565-574.
(14) Pertwee, R. G. Cannabinoids and the gastrointestinal tract. Gut
2001, 48, 859-867.
(15) Lan, R.; Liu, Q.; Fan, P.; Lin, S.; Fernando, S. R.; McCallion,
D.; Pertwee, R.; Makriyannis, A. Structure-activity relation-
ships of pyrazole derivatives as cannabinoid receptor antago-
nists. J . Med. Chem. 1999, 42, 769-776.
(16) Grosscurt, A. C.; Van Hes, R.; Wellinga, K. 1-Phenylcarbamoyl-
2-pyrazolines, a new class of insecticides. 3. Synthesis and
insecticidal properties of 3,4-diphenyl-1-phenylcarbamoyl-2-
pyrazolines. J . Agric. Food Chem. 1979, 27, 406-409.
(17) Gompper, R.; Ha¨gele, W. N-Sulfonyl-iminodithiokohlensa¨u-
reester und N-Sulfonyl-dithiourethane. Chem. Ber. 1966, 99,
2885-2899.
(18) Cho, N. S.; Shon, H. I. Synthesis of 5-(aroylamino)-2-methyl-
2H-1,2,4-thiadiazol-3-ones by oxidative cyclisation of 1-aroyl-5-
methyl-2-thiobiurets. J . Heterocycl. Chem. 1991, 28, 1645-1649.
(19) Gerard, C. M.; Mollereau, C.; Vassart, G.; Parmentier, M.
Molecular cloning of a human cannabinoid receptor which is also
expressed in testis. Biochem J . 1991, 279, 129-134.
(20) Showalter, V. M.; Compton, D. R.; Martin, B. R.; Abood, M. E.
Evaluation of binding in a transfected cell line expressing a
peripheral cannabinoid receptor (CB2): Identification of can-
nabinoid receptor subtype selective ligands. J . Pharmacol. Exp.
Ther. 1996, 278, 989-999.
(21) Bayewitch, M.; Rhee, R. H.; Avidorreis, T.; Breuer, A.; Mechou-
lam, R.; Vogel, Z. (-)-Delta(9)-Tetrahydrocannabinol antagonizes
the peripheral cannabinoid receptor-mediated inhibition of
adenylyl cyclase. J . Biol. Chem. 1996, 271, 9902-9905.
(22) Wagner, J . A.; J arai, Z.; Batkai, S.; Kunos, G. Hemodynamic
effects of cannabinoids: coronary and cerebral vasodilation
mediated by cannabinoid CB1 receptors. Eur. J . Pharmacol.
2001, 423, 203-210.
(23) Rawls, S. M.; Cabassa, J .; Geller, E. B.; Adler, M. W. CB1
receptors in the preoptic anterior hypothalamus regulate WIN
55,212-2 [(4,5-dihydro-2-methyl-4(4-morpholinylmethyl)-1-(1-
naphthalenyl-carbonyl)-6H-pyrrolo[3,2,1ij]quinolin-6-one]-in-
duced hypothermia. J . Pharmacol. Exp. Ther. 2002, 301, 963-
968.
(24) Shim, J .; Welsh, W. J .; Cartier, E.; Edwards, J . L.; Howlett, A.
C. Molecular interaction of the antagonist N-piperidin-1-yl-5-
(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-
carboxamide with the CB1 cannabinoid receptor. J . Med. Chem.
2002, 45, 1447-1459.
(27) Barnet-Norris, J .; Hurst, D. P.; Buehner, K.; Ballesteros, J . A.;
Guarnieri, F.; Reggio P. H. Agonist alkyl tail interaction with
Cannabinoid CB1 receptor V6.43/I6.46 groove induces a Helix
6 active conformation. Int. J . Quantum. Chem. 2002, 88, 76-
86.
(28) J ensen, A. D.; Guarnieri, F.; Rasmussen, S. G. F.; Asmar, F.;
Ballesteros, J . A.; Gether, U. Agonist-induced conformational
changes at the cytoplasmic side of transmembrane segment 6
in â2 adrenergic receptor mapped by site-selective Fluorescent
Labeling. J . Biol. Chem. 2001, 276, 9279-9290.
(29) Klebe, G.; Bo¨hm, H.-J . Energetic and entropic factors determin-
ing binding affinity in protein-ligand complexes. J . Receptor
Signal Transduct. Res. 1997, 17, 459-473.
(30) Lipinski, C. A.; Lombardo, F.; Dominy, B. W.; Feeney, P. J .
Experimental and computational approaches to estimate solubil-
ity and permeability in drug discovery and development settings.
Adv. Drug Delivery Rev. 1997, 23, 3-25.
(31) Schinkel, A. H.; Wagenaar, E.; van Deemter, L.; Mol, C. A. A.
M.; Borst, P. Absence of the mdr1a P-glycoprotein in mice affects
tissue distribution and pharmacokinetics of dexamethasone,
digoxin and cyclosporin A. J . Clin. Invest. 1995, 96, 1698-1705.
(32) Palm; K.; Stenberg, P.; Luthman, K.; Artursson, P. Polar
molecular surface properties predict the intestinal absorption
of drugs in humans. Pharm. Res. 1997, 14, 568-571.
(33) Kelder, J .; Grootenhuis, P. D. J .; Bayada, D. M.; Delbressine, L.
P. C.; Ploemen, J .-P. Polar molecular surface as a dominating
determinant for oral absorption and brain penetration of drugs.
Pharm. Res. 1999, 16, 1514-1519.
(34) Van de Waterbeemd, H.; J ones, B. C. Predicting oral absorption
and bioavailability. In Progress in Medicinal Chemistry; King,
F. D.; Oxford, A. W., Eds.; Elsevier Science B. V.: Amsterdam,
2003; Vol. 41, pp 1-59.
(35) Halbert, G. W. Pharmaceutical Development. In The Textbook
of Pharmaceutical Medicine, 3rd ed.; Griffin, J . P., O’Grady, J .,
D’Arcy, P. F., Eds.; The Queen’s University of Belfast: Belfast,
1998; pp 33-35.
(36) Yalkowsky, S. H.; Valvani, S. C.; Solubility and partitioning. I.
Solubility of nonelectrolytes in water. J . Pharm. Sci. 1980, 69,
912-922.
(37) J ain, N.; Yalkowsky, S. H.; Estimation of the aqueous solubility
I. Application to organic nonelectrolytes. J . Pharm. Sci. 2001,
90, 234-252.
(38) Franz, J . E.; Osuch, C. The reactions of sulfonamides with oxalyl
chloride. J . Org. Chem. 1964, 29, 2592-2595.
(39) Cheng, Y.; Prusoff, W. H. Relationship between the inhibition
constant (Ki) and the concentration of inhibitor which causes
50% (IC50) of an enzymatic reaction. Biochem. Pharmacol. 1973,
22, 3099-3108.
(40) Reggio, P. H.; Basu-Dutt, S.; Barnett-Norris, J .; Castro, M. T.;
Hurst, D. P.; Seltzman, H. H.; Roche, M. J .; Gilliam, A. F.;
Thomas, B. F.; Stevenson, L. A.; Pertwee, R. G.; Abood, M. E.
The bioactive conformation of aminoalkylindoles at the cannab-
inoid CB1 and CB2 receptors: Insights gained from (E)- and
(Z)-naphylidene indenes J . Med. Chem. 1998, 41, 5177-5187.
(41) OECD Guideline for Testing of Chemicals no. 117, adopted at
30-03-1989.
(25) Hurst, D. P.; Lynch, D. L.; Barnett-Norris, J .; Hyatt, S. M.;
Seltzman, H. H.; Zhong, M.; Song, Z.-H.; Nie, J .; Lewis, D.;
Reggio, P. H. N-(Piperidin-1-yl)-5-(4-chlorophenyl)-1-(2,4-dichlo-
rophenyl)-4-methyl-1H-pyrazole-3-carboxamide (SR141716A) In-
teraction with LYS 3.28(192) is crucial for its inverse agonism
at the Cannabinoid CB1 receptor. Mol. Pharmacol. 2002, 62,
1274-1287.
(26) Palczewski, K.; Kumasaka, T.; Hori, T.; Behnke, C. A.; Mo-
toshima, H. B. A.; Fox, B. A.; LeTron, I.; Teller, D. C.; Okada,
T.; Stenkamp, R. E. Crystal structure of Rhodopsin: a G-protein-
coupled receptor. Science 2000, 289, 739-745.
(42) Tripos Inc., St. Louis, MO 63144.
(43) Thompson, J . D.; Gibson, T. J .; Plewniak, F.; J eanmougin, F.;
Higgins, D. G. The ClustalX windows interface: flexible strate-
gies for multiple sequence alignment aided by quality analysis
tools. Nucleic Acids Res. 1997, 24, 4876-4882.
J M031019Q