Discovery of 1-[3-(4-Bromo-2-methyl-2H-pyrazol-3-yl)-4-methoxyphenyl]-3-(2, 4-difluorophenyl)urea (Nelotanserin) and Related 5-Hydroxytryptamine 2A Inverse Agonists for the Treatment of Insomnia

Article abstract of DOI:10.1021/jm9007328

Insomnia affects a growing portion of the adult population in the U.S. Most current therapeutic approaches to insomnia primarily address sleep onset latency. Through the 5-hydroxytryptamine_2A (5-HT_2A) receptor, serotonin (5-HT) plays a role in the regulation of sleep architecture, and antagonists/ inverse-agonists of 5-HT_2A have been shown to enhance slow wave sleep (SWS). We describe here a series of 5-HT_2A inverse-agonists that when dosed in rats, both consolidate the stages of NREM sleep, resulting in fewer awakenings, and increase a physiological measure of sleep intensity. These studies resulted in the discovery of 1-[3-(4-bromo-2- methyl-2i/-pyrazol-3-yl)-4-methoxyphenyl]-3-(2,4-difluorophenyl)urea (Nelotanserin), a potent inverse-agonist of 5-HT_2A that was advanced into clinical trials for the treatment of insomnia.

Full text of DOI:10.1021/jm9007328

J. Med. Chem. 2010, 53, 1923–1936 1923
DOI: 10.1021/jm9007328
Discovery of 1-[3-(4-Bromo-2-methyl-2H-pyrazol-3-yl)-4-methoxyphenyl]-3-(2,4-difluorophenyl)urea
(Nelotanserin) and Related 5-Hydroxytryptamine2A Inverse Agonists for the Treatment of Insomnia
Bradley R. Teegarden,*,† Hongmei Li,† Honnappa Jayakumar,† Sonja Strah-Pleynet,† Peter I. Dosa,† Susan D. Selaya,†
Naomi Kato,† Katie H. Elwell,† Jarrod Davidson,† Karen Cheng,† Hazel Saldana,† John M. Frazer,† Kevin Whelan,†
Jonathan Foster,† Stephan Espitia,† Robert R. Webb,† Nigel R. A. Beeley,† William Thomsen,† Stephen R. Morairty,‡
Thomas S. Kilduff,‡ and Hussien A. Al-Shamma†
†Arena Pharmaceuticals, Inc., 6166 Nancy Ridge Drive, San Diego, California 92121 and
‡Biosciences Division, SRI International, Menlo Park, California 94025
Received May 28, 2009
Insomnia affects a growing portion of the adult population in the U.S. Most current therapeutic
approaches to insomnia primarily address sleep onset latency. Through the 5-hydroxytryptamine2A
(5-HT2A) receptor, serotonin (5-HT) plays a role in the regulation of sleep architecture, and antagonists/
inverse-agonists of 5-HT2A have been shown to enhance slow wave sleep (SWS). We describe here a
series of 5-HT2A inverse-agonists that when dosed in rats, both consolidate the stages of NREM sleep,
resulting in fewer awakenings, and increase a physiological measure of sleep intensity. These studies
resulted in the discovery of 1-[3-(4-bromo-2-methyl-2H-pyrazol-3-yl)-4-methoxyphenyl]-3-(2,4-difluor-
ophenyl)urea (Nelotanserin), a potent inverse-agonist of 5-HT2A that was advanced into clinical trials
for the treatment of insomnia.
Introduction
Sleep is a physiological state that is crucial for the main-
tenance of physical, mental, and emotional health. For opti-
mum well being, an adult will spend approximately one-third
of his/her life asleep. Insomnia, the most common sleep
disorder, significantly impairs the ability of an individual to
function effectively.1,2 An indication of the prevalence of
insomnia comes from the results of a poll released by the
National Sleep Foundation in 2005.3 This poll suggested that
Figure 1. Some known 5-HT2A antagonists.
approximately one-half of the adult population in the U.S.
Serotonin (5-hydroxytryptamine, 5-HT) is an endogenous
experienced at least one symptom of insomnia a few nights a
small molecule neuromodulator regulating diverse biological
week, with one-third experiencing at least one symptom every
functions such as mood, aggression, cognition, satiety, sleep,
night or almost every night.
locomotion, pain perception, sexual behavior, and body
Therapeutically, acute insomnia may be treated with
temperature and peripheral functions such as platelet aggre-
γ-aminobutyric acid (GABAa) agonists. GABA is a primary
gation and vascular tone.9 The effects of 5-HT in the CNS are
inhibitory neurotransmitter in the central nervous system
mediated by multiple receptor subtypes that have been classi-
(CNS), and such agonists bind to specific sites on postsynaptic
fied into seven subfamilies (5-HT1 to 5-HT7).10 The 5-HT2
GABAA receptors, potentiate GABA signaling, and thereby
subfamily comprises three subtypes: 5-HT2A, 5-HT2B, and
cause sedation and sleep.4 Unfortunately, most GABA ago-
5-HT2C. Evidence from both clinical and preclinical studies
nists are associated with several adverse effects including
suggests that 5-HT2 receptors modulate slow wave sleep
dizziness, hypotension, and respiratory depression.5,6 Further-
(SWS).11-15 For example, the 5-HT2 receptor antagonist,
more, longer acting compounds are associated with next-
ritanserin (Figure 1), promotes sleep and enhances slow wave
day hangover effects including sedation, psychomotor, and
activityinhumansandrats.16,17 Thisactivityislikelymediated
cognitive impairment,7 while shorter acting compounds are
through the 5-HT2A receptor,18,19 as similar increases in SWS
associated with rebound insomnia and anterograde amnesia.8
and slow wave activity are observed with more selective
5-HT2A receptor antagonists such as eplivanserin.20,21
*To whom correspondence should be addressed. Phone: 858-453-
Utilizing a 5-HT2A functional assay based on [3H]inositol
7200. Fax: 858-453-7210. E-mail: bradteegarden@ymail.com.
aAbbreviations: 5-HT, 5-hydroxytryptamine; SWS, slow wave sleep;
NREM, nonrapid eye movement; GABA, γ-aminobutyric acid; CNS,
central nervous system; IP, inositol phosphate; CYP, cytochome P450
enzyme; Bu, butyl; DMSO, dimethyl sulfoxide; DMF, dimethylforma-
mide; THF, tetrahydrofuran; NBS, n-bromosuccinimide; DOI, 2,5-
dimethoxy-4-iodoamphetamine
phosphate (IP) release, we identified a starting point for
=
120 nM), an inverse-agonist of 5-HT2A (Figure 2). The early
SAR work was centered on improving potency at the 5-HT2A
receptor and provided inverse-agonists with excellent low
our structure-activity relationship (SAR), 1 (5-HT2A IC50
r
2010 American Chemical Society
Published on Web 02/09/2010
pubs.acs.org/jmc

1924 Journal of Medicinal Chemistry, 2010, Vol. 53, No. 5
Teegarden et al.
Figure 2. Early stage SAR development.
Scheme 1. Pyrazole Elaboration via Suzuki Couplinga
a Reagents: (a) n-BuLi, THF at -78°C; (b) B(Oi-Pr)3; (c) 2-methoxy 5-nitrophenyltriflate, Pd(PPh3)4, various conditions; (d) (X = Br, NBS or
X = Cl, NCS or X = F, Selectfluor), CH2Cl2; (e) iron dust, HOAc, CH2Cl2; (f) aryl isocyanate, CH2Cl2.
nanomolar functional activity such as 2 (5-HT2A IC50
=
n-BuLi, followed by quenching with triisopropoxyborane
to form, after workup, the boronate 4 in 60% yield
(Scheme 1).23,24 Palladium mediated Suzuki coupling25 with
2-methoxy 5-nitrophenyltriflate furnished intermediate 5a.
Selective halogenation of the pyrazole ring was achieved at
the nitro stage using N-halosuccinimide in CH2Cl2 to form
chloro- and bromopyrazoles 5b and 5c, respectively, in
89-93% yield. Fluoro substitution of the pyrazole ring was
accomplished through selective fluorination of 5a, which
provided 5d in 33% yield. Reduction of the nitro functionality
of 5a-d with elemental iron readily provided the anilines
6a-d in 86-88% yield. Condensation of 6a-d with a suitable
aryl isocyanate provided the desired ureas 7a-d in 50-92%
yield.
In order to further investigate the ether moiety of the B ring
(Figure 2), an alternative method was used to synthesize
phenylpyrazoles (Scheme 2). Methylhydrazine was condensed
with 6-nitrochromone (8) in DMSO at 70 °C, providing 9 in
44% yield. Treatment of 9 with NaH in DMF/THF, followed
by the addition of an alkyl halide, furnished 10, giving access
to a wide range of ethers. Selective bromination of the
pyrazole with NBS in CH2Cl2 provided 11. Reduction of the
nitro functionality with SnCl2 in ethanol provided the penul-
timate aniline, 12, in 40-80% yield over three steps. Finally,
condensation with 4-chlorophenyl isocyanate furnished the
target compounds, 13, in 60-80% yield.
19 nM, 150-fold selective against 5-HT2C).22 These pyrazoles
are unique 5-HT2A compounds in that they contain no ioniz-
able amine functionality. These early compounds, however,
were associated with significant hepatotoxicity. Specifically,
daily dosing of 2 in Sprague-Dawley rats at 100-250 mg/kg
for 10 days showed a 15-30% increase in liver weight. In
addition, inhibition of several human CYP subtypes was
observed at low micromolar levels for 2. This potential hepa-
totoxicity was seen with many closely related analogues in this
series. Hence, an expansion of the SAR was undertaken in
order to alleviate these significant issues. One of the areas of
interest was the B phenyl ring (Figure 2). One of the B ring
modifications prepared, containing a methoxy group ortho to
the pyrazole, was found to be a highly potent 5-HT2A inverse-
agonist (3, 5-HT2A IC50 = 0.7 nM). Furthermore, 3 showed no
increase in liver weight in Sprague-Dawley rats at doses up to
500 mg/kg daily for 10 days. In that same study, 3 did not
induce CYP enzyme production. Human CYP inhibition
studies showed 3 did not inhibit these important liver enzymes.
Further hepatic studies on compounds in this new class were
devoid of liver weight increase and major CYP enzyme (1A2,
2D6, 3A4, 2C9, and 2C19) induction/inhibition. Herein, we
describe the optimization of this series of phenylpyrazoleureas,
leading to the identification of a clinical candidate for the
treatment of insomnia, nelotanserin (APD125).
Chemistry
Primary Biological Evaluation
Preparation of the 1-N-alkyl-5-phenylpyrazole ring system
proceeded through lithiation of N-methylpyrazole with
The relative affinity of the compounds for h5-HT2A and h5-
HT2C receptorswas determined in a competitivebindingassay

Article
Journal of Medicinal Chemistry, 2010, Vol. 53, No. 5 1925
Scheme 2. Generation of Phenyl Ethersa
a Reagents: (a) methylhydrazine, DMSO, 70°C; (b) RCH2X, NaH, DMF/THF; (c) NBS, CH2Cl2; (d) SnCl2, EtOH, reflux; (e) 4-chlorophenyl
isocyanate, CH2Cl2.
Table 1. Functional Activity and Binding for 5-HT2A and 5-HT2C Receptors
pKi (n) binding
pIC50 (n) IP
5-HT2A
compd
R1
R2
R3
X
5-HT2A
5-HT2C
selectivitya
3
4-Cl
3-Cl
4-F
3-F
2-F
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
H
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
i-Pr
Br
Br
Br
Br
Br
Br
Br
Br
Br
Br
Br
Br
Br
Br
Br
Br
Br
Br
Br
Br
Br
Br
Cl
H
9.1 ( 0.3 (14)
9.4 (1)
9.3 ( 0.2 (3)
9.6 ( 0.2 (3)
9.6 ( 0.1 (3)
9.5 ( 0.1 (3)
9.0 ( 0.1 (3)
9.6 ( 0.2 (3)
9.4 ( 0.3 (3)
9.5 ( 0.2 (3)
8.6 ( 0.1 (4)
9.3 ( 0.2 (3)
8.8 ( 0.2 (4)
9.5 ( 0.1 (3)
9.3 ( 0.1 (3)
9.3 ( 0.1 (3)
9.6 ( 0.1 (3)
9.4 ( 0.2 (3)
9.1 ( 0.2 (3)
9.6 ( 0.1 (3)
9.5 ( 0.2 (3)
8.3 ( 0.3 (3)
7.7 ( 0.1 (3)
8.2 ( 0.2 (3)
9.8 ( 0.1 (3)
8.8 ( 0.1 (3)
9.7 ( 0.1 (3)
9.5 ( 0.1 (3)
9.2 ( 0.3 (4)
9.2 ( 0.1 (3)
9.6 ( 0.1 (3)
8.9 ( 0.1 (3)
9.4 ( 0.3 (3)
9.0 ( 0.3 (3)
9.3 ( 0.2 (3)
9.5 ( 0.2 (3)
8.0 ( 0.1 (3)
7.8 ( 0.2 (3)
7.5 ( 0.1 (3)
7.4 ( 0.2 (3)
6.4 ( 0.1 (3)
8.4 ( 0.3 (3)
7.8 ( 0.2 (3)
8.4 ( 0.1 (3)
6.6 ( 0.1 (3)
6.9 ( 0.2 (3)
6.4 ( 0.1 (3)
7.6 ( 0.3 (3)
7.2 ( 0.2 (3)
8.6 ( 0.3 (3)
8.4 ( 0.3 (3)
7.3 ( 0.3 (3)
7.8 ( 0.3 (3)
8.7 ( 0.3 (3)
8.0 ( 0.2 (3)
6.8 ( 0.1 (3)
6.6 ( 0.2 (3)
6.1 ( 0.1 (3)
8.0 ( 0.2 (3)
6.8 ( 0.1 (3)
7.6 ( 0.1 (3)
7.8 ( 0.2 (3)
6.8 ( 0.1 (4)
6.5 ( 0.2 (3)
7.6 ( 0.3 (3)
6.4 ( 0.1 (3)
7.5 ( 0.1 (3)
7.2 ( 0.2 (3)
6.9 ( 0.1 (3)
8.5 ( 0.2 (3)
1.3
1.8
2.1
2.1
2.6
1.2
1.6
1.1
2.0
2.4
2.4
1.9
2.1
0.7
1.2
2.1
1.3
0.9
1.5
1.5
1.1
2.1
1.8
2.0
2.1
1.7
2.4
2.7
2.3
2.5
1.9
1.8
2.4
1.0
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
9.6 ( 0.1 (6)
9.1 (1)
8.8 (1)
4-Br
9.3 (1)
3-CF3
4-CF3
3-Ac
9.4 ( 0.7 (2)
8.8 ( 0.2 (2)
8.4 ( 0.3 (4)
9.4 (1)
4-OMe
4-NMe2
4-iPr
7.3 ( 0.3 (3)
8.6 (1)
8.2 (1)
3-CN
4-Cl
8.9 ( 0.1 (2)
9.0 (1)
4-F
4-Cl
i-Pr
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
8.8 ( 0.2 (4)
7.8 ( 0.1 (3)
8.8 (1)
4-Cl
4-Cl
CF3
CH2CH3
i-Pr
4-Cl
4-Cl
8.8 (1)
8.1 (1)
CH2Ph
4-ClPhCH2
CH2CH2Ph
CH3
4-Cl
4-Cl
7.9 (1)
7.3 (1)
4-Cl
4-Cl
9.3 ( 0.2 (3)
9.0 (1)
8.9 (1)
CH3
CH3
2,6-diCl
3,5-diF
2,4-diF
2,4-diF
3,4-diF
3,4-diF
3,5-diCF3
3,5-diCF3
4-Cl-2-CF3
4-Cl-3-CF3
Br
Br
Br
Cl
Cl
F
CH3
CH3
8.9 (1)
9.2 ( 0.3 (8)
9.0 ( 0.4 (3)
9.3 ( 0.3 (2)
8.6 (1)
CH3
CH3
CH3
CH3
Br
Cl
Br
Br
8.7 (1)
8.4 (1)
CH3
CH3
8.6 (1)
9.1 (1)
CH3
a Fold-selectivity (in log units) is expressed as the difference in 5-HT2A and 5-HT2C binding pKi values.
using [125I]DOI in stably transfected HEK-293 cells. Func-
tional activity of the compounds was determined for h5-HT2A
and h5-HT2C receptors by measuring [3H] IP turnover in
transiently transfected HEK-293 cells.26
Results
The in vitro screening results for the compounds, show-
ing the inverse-agonist pIC50 and the binding pKi on both

1926 Journal of Medicinal Chemistry, 2010, Vol. 53, No. 5
Teegarden et al.
h5-HT2A and h5-HT2C receptors, are shown in Table 1.
Structural modification of this series began through substitu-
tion on aryl ring A, and a wide range of monosubstitutions
were evaluated (Figure 2). We observed excellent binding
affinity with halo and -CF3 substitutions with 5-HT2A pKi
values ranging from 9.0 to 9.6. As illustrated with the mono-
fluoro substitutions (15, 16, and 17), there was an observed
rank order of activity against the 5-HT2A receptor of para =
meta>ortho. However, for chloro substitution, meta was
marginally better than para (i.e., 14 vs 3). The more hydro-
phobic CF3 moiety was also equipotent for meta vs para
substitution (i.e., 19 vs 20). Overall, hydrophobic substitu-
tions were more favorable for aryl ring A. The monosubsti-
tuted analogues were 10- to 150-fold more selective for the
5-HT2A receptor verses the 5-HT2C receptor, with the greatest
selectivity being observed with 2-position substitutions (i.e.,
17 was 400-fold more selective for 5-HT2A). All compounds in
this series maintained functional inverse-agonism pIC50 va-
lues similar to the binding pKi values, as determined by the IP
accumulation assay (Table 1).
Table 2. Oral Pharmacokinetic Parameters in Male Wistar Rats
dose Cmax AUC0-inf
(mg/kg) tmax (h)a (ng/mL)a t1/2 (h)a (h ng/mL)a
compd
n
3
3
2
2
2
2
1.0
1.4
1.5
1.4
3 ( 1
4 ( 0
6 ( 3
3 ( 1
45 ( 19
85 ( 57
41 ( 11
44 ( 5
3 ( 2
2 ( 0
5 ( 4
3 ( 1
281 ( 10
507 ( 356
478 ( 282
298 ( 95
15
35
39
a Mean ( SD.
Table 3. Rat Receptor in Vitro Binding and in Vivo Effect in the of
DOI-Induced Behavior Model in Rats
in vitro binding (125I-DOI)
in vivo
DOI ED50
a
compd
h5-HT2A pKi (n)
rHT2A pKi (n)
3
9.3 ( 0.2 (3)
9.6 ( 0.1 (3)
9.8 ( 0.1 (3)
9.2 ( 0.3 (4)
8.4 ( 0.3 (4)
8.4 ( 0.3 (4)
8.7 ( 0.5 (3)
8.3 ( 0.3 (17)
0.5
0.7
0.7
0.7
15
35
39
a ED50 expressed in mg/kg.
Addressing the N-methylpyrazole moiety, we chose to look
at N-isopropylpyrazole as a possible substitute. Direct com-
parison of two pairs of analogues (3, 26 and 15, 27) showed
that the binding affinity for the 5-HT2A receptor in each of
these pairs was identical. The methyl substituted analogues,
however, proved to be more selective over the 5-HT2C recep-
tor. It was for this reason that we concentrated our further
efforts on N-methyl analogues.
Binding affinity for 5-HT2A remained essentially constant
when we addressed the halogen on the pyrazole ring. The
selectivity over 5-HT2C, however, was inversely proportional
to the substituent size (3 < 35 e 36).
We next addressed modifications of the B ring ether
(Scheme 2). This series of compounds was tolerant of small
alkyl substitutions (3, 30, and 31) but less tolerant of the larger
hydrophobic groups (32, 34, and 33) or the electron with-
drawing character of -OCF3 (29).
During the fine-tuning stage of our SAR we were looking
to maximize 5-HT2A selectivity. As noted earlier, although
2-position substitutions on the A ring were not necessarily the
most potent analogues against 5-HT2A, these substitutions in
combination with the two optimal substituents on the pyra-
zole as described above resulted in an improvement in 5-HT2A
selectivity. We therefore assessed a series of disubstituted
analogues to look for the best combination of binding affinity
and selectivity. Binding affinity was maximized for molecules
having at least one of the substituents in the 3- or 4-position
(e.g., 38, 39, and 41). Although selectivity was very good when
at least one substituent was in the ortho position (e.g., 39, 40,
and 37), a 3,4-substitution pattern also provided excellent
selectivity (e.g., 41 and 42).
this screening model,28 we chose four compounds (3, 15, 35,
and 39) that represented an adequate cross-section of acti-
vity, selectivity, and some structural diversity for further
evaluation. Oral pharmacokinetics were assessed for these
compounds in male Wistar rats (Table 2). All compounds
had reasonable AUCs, with plasma half-lives of 2-5 h.
However, 3 and 39 each had a shorter tmax of 3 h, which
was thought to be of interest in the intended therapeutic area
of sleep maintenance.
Although the compounds evaluated showed somewhat
lower affinity for the rat-5-HT2A receptor than its human
counterpart, we were able to determine an ED50 in our
in vivo 5HT2 antagonism model for each of the four com-
pounds (Table 3). In this model, each of the selected com-
pounds had an ED50 of less than 1 mg/kg when dosed orally.
Rat Sleep Studies. Individual doses were selected for each
of the four compounds to measure their effects in rat sleep
pharmacology studies that were 2-fold higher than the
compound’s ED50 in the DOI model. Each compound was
tested in a minimum of five rats by oral gavage with admini-
stration occurring in the middle of the inactive period, 6 h
after light onset. The delta power during non-REM sleep
(NREMS) was significantly different between all the analo-
gues tested and the vehicle control (Figure 3). Compounds 3
and 35 significantly increased delta power during the second
hour following dosing. Compound 15 significantly increased
delta power during the first and second hour following
dosing. Compound 39 produced significant increases in delta
power that persisted for the first 4 h following dosing.
No significant effects were found on either waking bout
length or number of waking bouts. Significant differences
were found, however, in NREMS bout length. Compound
39 significantly increased NREMS bout length during the
first hour following dosing, and 3 did so during the second
hour. In conjunction with this increased NREM bout dura-
tion, the number of NREM bouts decreased during the first
hour for compound 39 (p < 0.01) as well as for compound 15
(p<0.05).
In Vivo Experiments
DOI Screen. At this stage we needed to choose several
compounds to assess for both pharmacokinetics (PK) and in
vivo efficacy. Compounds of interest were identified using a
preliminary assessment of in vivo activity in a 2,5-di-
methoxy-4-iodoamphetamine (DOI) behavioral model in
rats following oral administration of compound.27 Attenua-
tion of the DOI-induced inhibition of rearing with 5-HT2A
inverse-agonists is strongly suggestive of the compounds’
ability to antagonize activity at 5-HT2A receptors located in
the CNS. Of the compounds that demonstrated activity in
Discussion
Several compounds of this series were very potent and
selective for the 5-HT2A receptor. Noted selectivity is for the
5-HT2A receptor verses the 5-HT2C receptor. The compounds

Article
Journal of Medicinal Chemistry, 2010, Vol. 53, No. 5 1927
Experimental Section
Biological Assays. [125I]DOI Binding to Recombinant Human
5-HT2A and 5-HT2C Receptors. Radioligand binding assays for
human 5-HT2A and 5-HT2C receptors were developed using
crude plasma membranes prepared from HEK293 cells stably
expressing these receptors (Thomsen et al.,26 2008). The 5-HT2
agonist [125I]DOI (0.5nM) was used as radioligand, and non-
specific radioligand binding was determined in the presence of
10 μM cold DOI. Competition experiments consisted of addi-
tion of 95 μL of assay buffer (20 mM HEPES, pH 7.4, 10 mM
MgCl2), 50 μL of membranes (5-25 μg of protein), 50 μL of
[
125I]DOI (0.5 nM final assay concentration), and 5 μL of test
compound diluted in assay buffer (final concentrations ranging
from 1 pM to 10 μM) to 96-well Perkin-Elmer GF/C microtiter
plates, and incubations were performed for 1 h at room tem-
perature. Each radioligand competition study consisted of
testing eight different concentrations in which triplicate deter-
minations were performed for each test compound concentra-
tion. Assay incubations were terminated by rapid filtration of
microtiter plates under vacuum pressure using a Brandell cell
harvestor, followed by washing filter plates several times with
ice-cold wash buffer (50 mM Tris-HCl, pH 7.4). Plates were then
dried at 45 °C in an oven for a minimum of 2 h, 25 μL of
BetaScint scintillation cocktail was added to each well, and
microtiter plates were counted in a Packard TopCount scintilla-
tion counter.
Inositol Phosphate (IP3) Assay Protocol. A mutated consti-
tutively active h5-HT2A receptor was used for this assay. This
constitutively active receptor was made by replacing the third
intracellular loop and cytoplasmic tail of the wild type h5-HT2A
receptor with those same portions of the wild type h5-HT2C
receptor. The constitutive activity of this construct provides a
sufficient window to measure 5-HT2A inverse agonism in the IP3
assay. For this assay, HEK-293 cells, transiently transfected
with mutated constitutively active h5-HT2A, were added to
96-well microtiter plates and labeled with 0.4 mCi/mL [3H]myoi-
nositol in serum and myoinositol-free DMEM for 18 h. Unin-
corporated [3H]myoinositol was removed and replaced with
fresh myoinositol-free HBSS supplemented with LiCl (10 mM
final), pargyline (10 mM final), and various concentrations of
test compound. Plates were then incubated for 3 h at 37 °C.
Incubations were terminated by lysing cells with ice-cold 0.1 M
formic acid followed by freezing at -80 °C. After the samples
were thawed, total [3H]IP was resolved from unincorporated
[3H]myoinositol using AG1-X8 ion-exchange resin and [3H]IP
was measured by scintillation counting using a Wallac Micro-
beta scintillation counter.
Rat Pharmacokinetics. Male Wistar rats were dosed orally at
10 to 1.5 mg/kg, in 80% Tween-80/20% water. Animals were
fasted overnight prior to oral dose administration. Whole blood
samples were collected from the jugular vein over a 24 h period
postdose. Plasma was prepared from sodium heparin-treated
whole blood and separated by centrifugation. Plasma samples
were frozen and stored at -70 °C until assayed using a specific
and sensitive HPLC/MS/MS method. The method provided a
lower limit of quantitation of 1 ng/mL and an upper limit of
quantitation of 2000 ng/mL. Serial sampling [at 0.017 (iv only),
0.1 (iv only), 0.25, 0.5, 1, 2, 4, 6, 8, 12, 18 and 21hrs post dosing]
was used to define the plasma concentration vs time profile
(n = 2-3 animals/administration route). Noncompartmental
pharmacokinetic analysis was performed with a commercial
software package (WinNonlin Professional, version 4.1.b.,
Pharsight, Mountain View, CA).
Figure 3. Effects on non-REM sleep parameters of male Wistar
rats. Compounds were dosed 6 h after the beginning of the inactive
period (lights on). All rats were dosed one time, po, with the
following doses: 3, 1 mg/kg; 15, 1.4 mg/kg; 35, 1.4 mg/kg; 39, 1.4
mg/kg.
of this series generally showed poor affinity for the 5-HT2B
receptor. For instance, compounds 15 and 35 had 5-HT2B
pKi<5 on repeated measure. Compound 3 and 39 had a
5-HT2B pKi = 6.1 ( 0.2 and 5.4 ( 0.3, respectively. These four
compounds (3, 15, 35, and 39) were chosen for evaluation in a
sleep study in rats. Rat sleep is naturally fragmented and is
ideal for the evaluation of compounds with the potential to
induce sleep consolidation.29 If sleep consolidation is in-
creased while total sleep quantity remains the same, then an
increase in sleep bout length would be accompanied by a
corresponding decrease in bout number. Indeed, all four
compounds tested in this assay showed a trend toward
increasingNREMSbout length and decreasing NREMSbout
number. This trend was statistically significant for 39. These
5-HT2A inverse-agonists also caused an increase in delta
power during NREMS, suggesting that these compounds
promote “deeper” sleep in addition to their effects on sleep
consolidation. As a result of the positive sleep effects observed
in rodents, compound 39 was advanced into clinical trials.30
DOI in Vivo Screen. 5-HT2A inverse-agonism of the test
compounds was evaluated in vivo in an acute DOI screen. In
short, compounds were administered to adult, male Sprague-
Dawley rats 45 min prior to administration of the 5-HT2A
agonist DOI (0.3 mg/kg; Sigma/Aldrich, St. Louis, MO), which
decreases rearing behavior in rats. Fifteen minutes later the
animals were placed in photocell monitored locomotor activity

1928 Journal of Medicinal Chemistry, 2010, Vol. 53, No. 5
Teegarden et al.
cages. For each compound, a dose response curve was generated
for reversal of DOI induced decreases in rearing and an ED50
calculated for later evaluation in sleep studies.
system controller, Shimadzu Inc. SPD-10A VP UV detector,
monitoring at 214 and 280 nm, Leap Scientific CTC HTS, PAL
autosampler, Analyst 1.2 software and either (a) Supelco Dis-
covery C18 (5 cm ꢀ 2.1 mm), using a gradient of 5% v/v CH3CN
(containing 0.05% v/v TFA) in H2O (containing 0.05% v/v
TFA) (t = 0.0 min) gradient to 95% v/v CH3CN in H2O (t =
4.0 min), 0.6 mL/min or (b) Grace Prevail C18 column (5 μm,
5 cm ꢀ 4.6 mm), using a gradient of 5% v/v CH3CN (containing
0.05% v/v TFA) in H2O (containing 0.05% v/v TFA) (t =
0.0 min) gradient to 95% v/v CH3CN in H2O (t = 4.0 min),
3.5 mL/min. All final compounds were assessed via the above-
described analytical method and found to be g95% in purity.
Preparative HPLC was conducted on a Varian Prostar re-
verse phase HPLC using a Phenomenex Luna C18 column
(10 μm, 250 mm ꢀ 50 mm; and 10 μm, 250 mm ꢀ 21.2 mm),
5% (v/v) CH3CN (containing 0.1% v/v TFA) in H2O (containing
0.1% v/v TFA) gradient to 100% H2O, 60 or 20 mL/min, λ =
220 nM. HRMS were analyzed using an Acquity BEH C18 2.1
mm ꢀ 50 mm, 1.7 microns column (Waters) on an UPLC (Waters)
and QTOF micro (þve mode) mass spectrometer. All chemicals and
reagents were purchased from Aldrich or TCI America or Fluka.
Elemental analysis was conducted by West Coast Analytical
Service Inc., 9240 Santa Fe Springs Road, Santa Fe Springs, CA
90670.
Rat Sleep Study. All experimental procedures complied with
institutional animal care and use committee regulations at SRI
International and National Institutes of Health guidelines for
the care and use of experimental animals. To this end, eight male
Wistar rats (300 ( 25 g; Charles River, Wilmington, MA) were
prepared with chronic recording implants for continuous
electroencephalograph (EEG) and electromyograph (EMG)
recordings and allowed 1 week of recovery prior to treatment.
The compounds were compared to vehicle treatment (80%
Tween-80, Sigma, St. Louis, MO) and administered in a
repeated measures design, wherein each rat received each
treatment in random order via oral gavage. Rats were dosed
during the middle of the normal inactive period (6 h following
lights on).
For sleep recordings, animals were connected via a cable and
a counter-balanced commutator to a Neurodata model 15 data
collection system (Grass-Telefactor, West Warwick, RI). The
animals were allowed an acclimation period of at least 48 h
before the start of the experiment and were connected to the
recording apparatus continuously throughout the experimental
period except to replace damaged cables. The amplified EEG
and EMG signals were digitized and stored on a computer using
SleepSign software (Kissei Comtec, Irvine CA).
EEG and EMG data were scored visually in 10 s epochs for
waking (W), REMS, and NREMS. Scored data were analyzed
and expressed as time spent in each state per half hour. Sleep
bout length and number of bouts for each state were calculated
in hourly bins. A “bout” consisted of a minimum of two
consecutive epochs of a given state. EEG delta power (0.5-
3.5 Hz) within NREMS was also analyzed in hourly bins. The
EEG spectra during NREMS were obtained offline with a fast
Fourier transform algorithm on all epochs without artifact. The
delta power was normalized to the average δ power in NREMS
during the fifth and sixth hour following lights off, a time when
delta power is low.
Data were analyzed using repeated measures ANOVA follo-
wed by post hoc analysis using t tests where appropriate. Light
phase and dark phase data were analyzed separately. Since we
predicted a treatment effect that changed (decreased) over time,
we analyzed both the treatment effect within each rat and the
time by treatment effect within each rat. Since two comparisons
were made, a minimum value of P < 0.025 was used for post hoc
analysis. When statistical significance was found from our
ANOVAs, t-tests were performed comparing all compounds
to vehicle.
Chemistry. All reagents were commercially available and used
without further purification. Proton nuclear magnetic reso-
nance (1H NMR) spectra were recorded on a Varian Mercury
Vx-400 equipped with a four nucleus autoswitchable probe and
z-gradient or a Bruker Avance-400 equipped with a QNP (quad
nucleus probe) or a BBI (broad-band inverse) and z-gradient.
Chemical shifts are given in parts per million (ppm) with the
residual solvent signal used as reference. NMR abbreviations
are used as follows: s = singlet, d = doublet, t = triplet, q =
quartet, m = multiplet, br = broad. Microwave irradiations
were carried out using the Emyrs synthesizer (Personal
Chemistry). Thin-layer chromatography (TLC) was performed
on silica gel 60 F254 (Merck), and column chromatography was
carried out on silica gel columns using Kieselgel 60, 0.063-
0.200 mm (Merck), and on prepacked silica gel columns using
KP-Sil, supplied by Biotage. Evaporation was done under
reduced pressure in a Buchi rotary evaporator. Celite 545 was
used during palladium filtrations. Analytical HPLC/MS was
conducted on an Applied Biosystem MDS Sciex API 150EX
mass spectrometer with an atmospheric pressure ionization
source and an APCI probe assembly, using a Shimadzu Inc.
LC-10AD VP HPLC pump, Shimadzu Inc. SCL10A VP HPLC
Preparation of Intermediates. 2-Methyl-2H-pyrazole-3-boro-
nic Acid (4). N-Methylpyrazole (25 mL, 0.3 mol) was dissolved
in 500 mL of tetrahydrofuran. The solution was cooled to
-78 °C in a dry ice/isopropanol bath, and n-BuLi (140 mL of
2.5 M in hexanes, 0.35 mol) was added dropwise by cannula. The
reaction mixture was stirred at -78 °C for 1.5 h. Then triiso-
propyl borate (280 mL, 1.2 mol) was added via cannula. While
being stirred overnight, the reaction temperature was gradually
increased from -78 to 0 °C. The pH of the mixture was adjusted
to 6 with 1 N HCl. Tetrahydrofuran was removed under reduced
pressure, and the resulting residue was triturated with ethyl
acetate/dichloromethane (1:1). The solid suspension was then
filtered and the solid was dried in vacuo to yield 60 g (60%) of
2-methyl-2H-pyrazole-3-boronic acid (4) as a light-yellow solid.
1
LCMS m/z (%) = 127 M þ Hþ, (100). H NMR (400 MHz,
DMSO-d6) δ: 8.24 (s, 2H), 7.2 (s, 1H), 6.5 (s, 1H), 3.75 (s, 3H).
Trifluoromethanesulfonic Acid 2-Methoxy-5-nitrophenyl
Ester. To a stirred solution of 2-methoxy-5-nitrophenol (5.092 g,
30 mmol) in a mixture of methylene chloride (3 mL) and pyridine
(20 mL) was added triflic anhydride (16.478 g, 9.8 mL) dropwise
at 0 °C. The mixture was warmed to room temperature and
stirred for 2 h. The pyridine was removed under vacuum. The
residue was diluted with ethyl acetate, washed with 1 N HCl and
water, and the aqueous phase was then extracted with ethyl
acetate (3 ꢀ 100 mL). The combined organic phase was washed
with brine, dried over MgSO4, filtered, and evaporated. The
crude reaction mixture was purified by flash chromatography
(SiO2, eluent ethyl acetate/hexane = 1/3 then 1/2) to give
trifluoromethanesulfonic acid 2-methoxy-5-nitrophenyl ester
(8.943 g, 30 mmol, 100%) as a yellow solid. LCMS m/z (%) =
302 (M þ H, 100). 1H NMR (400 MHz, CDCl3) δ: 8.30 (dd, J =
4.0, 8.0 Hz, 1H), 8.16 (d, J = 4.0 Hz, 1H), 7.15 (d, J = 8.0 Hz,
1H), 4.06 (s, 3H).
5-(2-Methoxy-5-nitrophenyl)-1-methyl-1H-pyrazole (5a). Tri-
fluoromethanesulfonic acid 2-methoxy-5-nitrophenyl ester
(2.561 g, 8.50 mmol), 2-methyl-2H-pyrazole-3-boronic acid
(4) (4.283 g, 34.01 mmol, 4.0 equiv), and sodium carbonate
(10.816 g, 102.04 mmol, 12.0 equiv) were suspended in a mixture
of tetrahydrofuran (200 mL) and water (100 mL). The resulting
mixture was degassed with argon for 5 min, followed by the
addition of Pd(PPh3)4 (0.486 g, 0.42 mmol, 0.05 equiv). After
degassing for another 5 min, the reaction mixture was heated to
70 °C overnight. Once the reaction was complete, tetrahydro-
furan was removed under reduced pressure and the aqueous
phase was extracted with ethyl acetate (4 ꢀ 100 mL). The
combined organic phase was dried over MgSO4, filtered, and

Article
Journal of Medicinal Chemistry, 2010, Vol. 53, No. 5 1929
evaporated. The crude reaction mixture was purified by flash
chromatography (SiO2, eluent ethyl acetate/hexane = 1/1) to afford
5-(2-methoxy-5-nitrophenyl)-1-methyl-1H-pyrazole (5a) (1.799 g,
7.71 mmol, 91%) as a white solid. LCMS m/z (%) = 234 (M þ H,
100). 1H NMR (400 MHz, CDCl3) δ:8.34(dd,J=2.8, 9.2Hz, 1H),
8.19 (d, J = 2.8 Hz, 1H), 7.56 (d, J = 2.0 Hz, 1H), 7.08 (d, J =
9.2 Hz, 1H), 6.31 (d, J = 1.6 Hz, 1H), 3.96 (s, 3H), 3.74 (s, 3H).
4-Chloro-5-(2-methoxy-5-nitrophenyl)-1-methyl-1H-pyrazole
(5b). 5-(2-Methoxy-5-nitrophenyl)-1-methyl-1H-pyrazole (5a)
(2.37 g, 10.17 mmol) was dissolved in DMF (100 mL). The
solution was then heated to 80 °C. N-Chlorosuccinimide (1.49 g,
11.1 mmol) was added at 80 °C under argon gas. After 2 h of
continuous stirring, the reaction was checked by TLC and
LCMS and found to be incomplete. An additional aliquot of
N-chlorosuccinimide (0.5 g, 3.7 mmol) was added, bringing the
reaction to completion after 1.5 h. While the sample was being
stirred, a portion of water (200 mL) was added to force the
product to precipitate out of solution. After the precipitation
was complete, the flask containing the solid was cooled in an
ice-water bath for 10 min. The solid was then filtered under
vacuum, rinsed with water, and dried to afford 2.4 g (89%) of
4-chloro-5-(2-methoxy-5-nitrophenyl)-1-methyl-1H-pyrazole
(5b) as a light-yellow solid. LCMS m/z (%) = 268 (M þ H, 100).
1H NMR (400 MHz, CDCl3) δ: 8.41 (dd, J1 = 8 Hz, J2 = 4 Hz,
1H), 8.22 (d, J = 4 Hz, 1H), 7.53 (s, 1H), 7.14 (d, J = 12 Hz, 1H),
3.97 (s,3H), 3.72 (s, 3H).
acetate (100 mL) and 1 N sodium hydroxide, neutralizing the
reaction to a pH of approximately 7. The mixture was then
filtered through Celite. The organic layer was separated, and the
aqueous layer was extracted with ethyl acetate (2 ꢀ 50 mL). The
organic layers were combined, dried over sodium sulfate, fil-
tered, and the solvent was removed under reduced pressure. The
residue was then purified by flash chromatography (SiO2,
hexanes/ethyl acetate) to afford 1.73 g (86%) of 3-(4-chloro-
2-methyl-2H-pyrazol-3-yl)-4-methoxyphenylamine (6b) as alight-
brown solid. LCMS m/z (%) = 238 (M þ H35Cl, 100), 240 (M þ
H37Cl, 37). 1H NMR (400 MHz, CDCl3) δ: 7.48 (s, 1H), 6.87 (d,
J = 8, 1H), 6.81 (dd, J1 = 8, J2 = 4, 1H), 6.63 (d, J = 4, 1H), 3.72
(s, 3H), 3.70 (s, 3H).
3-(4-Bromo-2-methyl-2H-pyrazol-3-yl)-4-methoxyphenylamine
(6c). To a stirred solution of 4-bromo-5-(2-methoxy-5-nitro-
phenyl)-1-methyl-1H-pyrazole (5c) (1.799 g, 5.76 mmol) in
ethanol (20 mL) was added tin(II) chloride dihydrate (5.306 g,
23.05 mmol). The mixture was stirred at reflux for 2 h, and then
the solvent was removed under vacuum. The resulting solid was
dissolved in ethyl acetate, 1 N sodium hydroxide (30 mL) was
added, and the mixture was stirred overnight. The white pre-
cipitate was filtered off through Celite, and the aqueous phase
was extracted with ethyl acetate (3 ꢀ 80 mL). The combined
organic phase was dried over MgSO4, filtered, and evaporated.
The crude residue was purified by flash chromatography (SiO2,
eluent ethyl acetate/hexane=1/3 and then 1/1) to give 3-(4-
bromo-2-methyl-2H-pyrazol-3-yl)-4-methoxyphenylamine (6c)
(1.430 g, 5.07 mmol, 88%) as a white solid. LCMS m/z (%) =
282 (M þ H79Br, 98), 284 (M þ H81Br, 100). 1H NMR
(400 MHz, CDCl3) δ: 7.52 (s, 1H), 6.86 (d, J = 8.8 Hz, 1H),
6.80 (dd, J = 2.8, 8.8 Hz, 1H), 6.22 (d, J = 2.4 Hz, 1H), 4.25
(broad s, 2H), 3.72 (s, 3H), 3.71 (s, 3H).
3-(4-Fluoro-2-methyl-2H-pyrazol-3-yl)-4-methoxyphenylamine
(6d). 4-Fluoro-5-(2-methoxy-5-nitrophenyl)-1-methyl-1H-pyr-
azole (5d) (109 mg, 0.434 mmol) in ethanol (10 mL) was treated
with Pd/C (10 wt %, Degussa), and H2 was allowed to bubble
through the slurry. The reaction mixture was filtered through
Celite and the solvent was removed under reduced pressure to
afford 93 mg (97%) of 3-(4-fluoro-2-methyl-2H-pyrazol-3-yl)-
4-methoxyphenylamine (6d) as a light-brown oil. LCMS m/z
(%) = 222 (M þ H, 100). 1H NMR (400 MHz, CDCl3) δ: 7.38
(d, JH,F = 4.4 Hz, 1H), 6.86 (d, J = 8.8 Hz, 1H), 6.78 (dd, J1 =
8.8 Hz, J2 = 2.8 Hz, 1H), 6.63 (d, J = 2.8 Hz, 1H), 3.74 (s, 3H),
3.68 (s, 3H), 3.53 (s, 2H). 19F NMR (376 MHz, CDCl3) δ:
-175.50 (d, JH,F = 5.3 Hz, 1F).
1-Isopropyl-1H-pyrazole. To a solution of pyrazole (50.0 g,
735.3 mmol) in aqueous sodium hydroxide (123.5 g of sodium
hydroxide/200 mL of water) was added isopropyl bromide
(180.0 g, 1470.1 mmol), and the mixture was then heated to
reflux for 7 days. The reaction mixture was cooled and extracted
with ethyl acetate (3 ꢀ 300 mL). The combined organic layers
were dried over MgSO4. Removal of the volatiles in vacuum
provided a light-yellow oil, which was distilled via Kugelrohr at
140 °C and 10 Torr to provide 1-isopropyl-1H-pyrazole as a
colorless oil (43 g, 53%). LCMS m/z (%) = 111 (M þ Hþ, 100).
1H NMR (400 MHz, DMSO-d6) δ: 7.72 (d, J = 2.3 Hz, 1H), 7.41
(t, 1H), 6.21 (t, 1H), 4.5 (q, 1H), 1.41-1.37 (d, J = 11.1 Hz).
2-Isopropyl-2H-pyrazole-3-boronic Acid. n-BuLi (110 mL,
275 mmol, 2.5 M in hexanes) was slowly added over 30 min at
-78 °C to a tetrahydrofuran solution of 1-isopropyl-1H-pyra-
zole (25.0 g, 227 mmol). The reaction mixture was stirred at
-78 °C for 2 h. A solution of cooled triisopropoxy boronate
(170.0 g, 909 mmol) was added slowly via cannula over 45 min.
The reaction mixture was allowed to warm to room temperature
and stirred overnight. The reaction mixture was adjusted to
pH 7 with HCl (1 M, 170 mL). The solvent was evaporated
to dryness, and the resulting residue was triturated with 1:1
ethyl acetate/dichloromethane. The suspension was filtered and
the solvent was evaporated in vacuum to yield 2-isopropyl-2H-
pyrazole-3-boronic acid as a colorless solid (20.0 g, 58%).
4-Bromo-5-(2-methoxy-5-nitrophenyl)-1-methyl-1H-pyrazole
(5c). To a stirred solution of 5-(2-methoxy-5-nitrophenyl)-1-
methyl-1H-pyrazole (5a) (1.787 g, 7.66 mmol) in DMF (20 mL)
was added N-bromosuccinimide (1.515 g, 8.43 mmol) in DMF
(5 mL) dropwise at 0 °C. After the mixture was stirred at 0 °C for
3 h, TLC showed completion of the reaction. The mixture was
diluted with ethyl acetate (300 mL) and washed with water
(3 ꢀ 100 mL) and brine. The ethyl acetate phase was dried
with MgSO4, filtered, and evaporated. The crude reaction
mixture was purified by flash chromatography (SiO2, eluent
ethyl acetate/hexane = 1/3 and then 1/1) to give the product
4-bromo-5-(2-methoxy-5-nitrophenyl)-1-methyl-1H-pyrazole
(5c) (2.214 g, 7.09 mmol, 93%) as a light-yellow solid. LCMS
1
m/z (%) = 312 (M þ H79Br, 100), 314 (M þ H81Br, 100). H
NMR (400 MHz, CDCl3) δ: 8.40 (dd, J = 2.4, 6.9 Hz, 1H), 8.22
(m, 1H), 7.57 (s, 1H), 7.14 (d, J = 9.2 Hz, 1H), 3.98 (s, 3H), 3.74
(s, 3H).
4-Fluoro-5-(2-methoxy-5-nitrophenyl)-1-methyl-1H-pyrazole
(5d). 5-(2-Methoxy-5-nitrophenyl)-1-methyl-1H-pyrazole (5a)
(300.0 mg, 1.29 mmol) was dissolved in acetonitrile (15 mL) in
a polypropylene 20 mL scintillation vial. To this solution,
Selectfluor (913.9 mg, 2.58 mmol) was added, and the mixture
was degassed with argon and heated to 80 °C for 6 h. The solvent
was removed under reduced pressure, and the residue was
dissolved in ethyl acetate (50 mL) and 3 N HCl (30 mL). The
organic layer was separated, and the aqueous layer was ex-
tracted with ethyl acetate (2 ꢀ 50 mL). The organic layers were
combined, dried over sodium sulfate, filtered, and the solvent
was removed under reduced pressure. The residue was then
purified by flash chromatography (SiO2, eluent hexanes (0.01%
TEA)/ethyl acetate) to afford 108 mg (33%) of 4-fluoro-5-(2-
methoxy-5-nitrophenyl)-1-methyl-1H-pyrazole (5d) as a white
solid. LCMS m/z (%) = 252 (M þ H, 100). 1H NMR (400 MHz,
CDCl3) δ: 8.39 (d, J = 9.2 Hz, 1H), 8.22 (s, 1H), 7.44 (d, JH,F
=
4.4 Hz, 1H), 7.12 (d, J = 9.2 Hz, 1H) 3.98 (s, 3H), 3.77 (s, 3H).
19F NMR (376 MHz, CDCl3) δ: -175.50 (d, JH,F = 5.3 Hz, 1F).
3-(4-Chloro-2-methyl-2H-pyrazol-3-yl)-4-methoxyphenylamine
(6b). 4-Chloro-5-(2-methoxy-5-nitrophenyl)-1-methyl-1H-pyr-
azole (5b) (2.27 g, 8.5 mmol) was dissolved in dry ethanol
(150 mL) and heated to 75 °C. The heated solution was then
treated with tin(II) chloride dihydrate (9.6 g, 42.5 mmol) and
stirred at 75 °C. After 3 h, the reaction was found to be complete
by TLC and LCMS. The solvent was removed under reduced
pressure. The residue was subsequently diluted with ethyl

1930 Journal of Medicinal Chemistry, 2010, Vol. 53, No. 5
Teegarden et al.
1
LCMS m/z (%) = 155 (M þ Hþ, 100). H NMR (400 MHz,
was then quenched with saturated ammonium chloride, diluted
with ethyl acetate, washed with water, and the aqueous phase
was extracted with ethyl acetate (3 ꢀ 50 mL). The combined
organic phase was washed with brine, dried over MgSO4,
filtered, and evaporated, providing crude 5-(2-ethoxy-5-
nitrophenyl)-1-methyl-1H-pyrazole. LCMS m/z = 248 (M þ H).
1H NMR (400 MHz, CDCl3) δ: 8.33 (dd, J = 2.5, 9.1 Hz, 1H),
8.21 (d, J = 2.5 Hz, 1H), 7.57 (d, J = 1.3 Hz, 1H), 7.07 (d, J =
9.1 Hz, 1H), 6.34 (s, 1H), 4.22 (dd, J = 7.0, 13.9 Hz, 2H), 3.78 (s,
3H), 1.44 (t, J = 6.8 Hz, 3H).
Step 2. The crude mixture of 5-(2-ethoxy-5-nitrophenyl)-
1-methyl-1H-pyrazole was treated dropwise at 0 °C with
N-bromosuccinimide in dimethylformamide. After the mixture
was stirred at 0 °C for 3 h, TLC showed completion of the
reaction. The mixture was diluted with ethyl acetate (300 mL)
and washed with water (3 ꢀ 100 mL) and brine. The ethyl acetate
phase was dried over anhydrous MgSO4, filtered, and evapo-
rated. The crude reaction mixture was purified by flash chro-
matography (SiO2, eluent ethyl acetate/hexane = 1/3 and then
1/1), providing 4-bromo-5-(2-ethoxy-5-nitrophenyl)-1-methyl-
1H-pyrazole as a colorless solid. LCMS m/z (%) = 326 (M þ
H79Br, 88), 328 (M þ H81Br, 100). 1H NMR (400 MHz, CDCl3)
δ: 8.38 (dd, J = 2.7, 9.2 Hz, 1H), 8.22 (d, J = 2.7 Hz, 1H), 7.59
(s, 1H), 7.11 (d, J = 9.2 Hz, 1H), 4.14-4.32 (m, 2H), 3.76 (s,
3H), 1.43 (t, J = 6.8 Hz, 3H).
Step 3. To a stirred solution of 4-bromo-5-(2-ethoxy-5-
nitrophenyl)-1-methyl-1H-pyrazole in ethanol was added tin(II)
chloride dihydrate. After the mixture was stirred at reflux for
2 h, the solvent was removed under reduced pressure. The result-
ing solid was dissolved in ethyl acetate, 1 N sodium hydroxide
(30 mL) was added, and the mixture was stirred overnight. The
white precipitate was filtered off through Celite, and the aqu-
eous phase was extracted with ethyl acetate (3 ꢀ 80 mL). The
combined organic phase was dried over anhydrous MgSO4,
filtered, and evaporated. The crude residue was purified by flash
chromatography (SiO2, eluent ethyl acetate/hexane) to afford
(0.225 g, 0.76 mmol, 81% over three steps) 3-(4-bromo-
2-methyl-2H-pyrazol-3-yl)-4-ethoxyphenylamine as a white solid.
LCMS m/z (%) = 296 (M þ H79Br, 100), 298 (M þ H81Br, 98).
1H NMR (400 MHz, CDCl3) δ: 7.52 (s, 1H), 6.86 (d, J = 8.7 Hz,
1H), 6.77 (dd, J = 2.2, 8.5 Hz, 1H), 6.62 (d, J = 2.3 Hz, 1H),
3.82-4.00 (m, 2H), 3.73 (s, 3H), 3.24-3.58 (broad s, 2H), 1.24
(t, J = 6.8 Hz, 3H).
4-Benzyloxy-3-(4-bromo-2-methyl-2H-pyrazol-3-yl)phenylamine.
Step 1. 2-(2-Methyl-2H-pyrazol-3-yl)-4-nitrophenol (0.124 g,
0.57 mmol) was treated with sodium hydride (60%, 0.049 g,
1.13 mmol) and benzyl bromide (0.21 mL, 1.70 mmol) in a
mixture of DMF (2 mL) and THF (4 mL) at 0 °C. The mixture
was warmed to 70 °C and stirred until the starting material was
consumed. The reaction was quenched with saturated ammo-
nium chloride, diluted with ethyl acetate, washed with water,
and the aqueous phase was extracted with ethyl acetate (3ꢀ
50 mL). The combined organic phase was washed with brine,
dried over MgSO4, filtered and the solvent evaporated, provid-
ing crude 5-(2-benzyloxy-5-nitrophenyl)-1-methyl-1H-pyrazole.
LCMS m/z = 310 (M þ H). 1H NMR (400 MHz, CDCl3) δ: 8.32
(dd, J = 2.8, 9.1 Hz, 1H), 8.24 (d, J = 2.8 Hz, 1H), 7.59 (d, J =
1.7 Hz, 1H), 7.22-7.45 (m, 5H), 7.16 (d, J = 9.1 Hz, 1H), 6.37
(d, J = 1.7 Hz, 1H), 5.25 (s, 2H), 3.77 (s, 3H).
DMSO-d6) δ: 8.14 (s, 2H), 7.2 (s, 1H), 6.5 (s, 1H), 5.05 (m, 1H),
1.2 (d, J = 9.0 Hz, 6H).
1-Isopropyl-5-(2-methoxy-5-nitrophenyl)-1H-pyrazole. To a
mixture of trifluoromethanesulfonic acid 2-methoxy-5-nitro-
phenyl ester (4.1 g, 13.6 mmol), 2-isopropyl-2H-pyrazole-
3-boronic acid (5.2 g, 34.1 mmol), and cesium carbonate (17.7 g,
54.4 mmol) in dimethoxyethane under argon was added Pd-
(PPh3)4 (0.79 g, 0.68 mmol), and the mixture was heated at 80 °C
for 16 h. The reaction mixture was cooled, filtered through
Celite, and evaporated to dryness. The residue was taken up in
ethyl acetate, and the solution was washed with water. The
organic layer was dried over MgSO4 and evaporated to afford a
crude product as a brown solid. The crude material was purified
via flash chromatography (SiO2, hexane/ethyl acetate, 3/1)
to yield 1-isopropyl-5-(2-methoxy-5-nitrophenyl)-1H-pyrazole
(1.88 g, 52%) as a colorless solid. LCMS m/z (%) = 262 (M þ
Hþ, 100). 1H NMR (400 MHz, CDCl3) δ: 8.36 (dd, J1 = 9.09 Hz,
J2 = 2.5 Hz, 1H), 8.18 (d, J = 8.18 Hz, 1H), 7.65 (s, 1H), 7.09 (d,
J = 8.08 Hz, 1H), 6.25 (s, 1H), 4.16 (dd, J1 = 13.14 Hz, J2 =
6.57 Hz, 1H), 3.95 (s, 3H), 1.45 (d, J = 6.82 Hz, 6H).
4-Bromo-1-isopropyl-5-(2-methoxy-5-nitrophenyl)-1H-pyrazole.
To a stirred, ice-cooled solution of 1-isopropyl-5-(2-methoxy-
5-nitrophenyl)-1H-pyrazole (1.0 g, 3.83 mmol) in DMF (10 mL)
was added N-bromosuccinimide (0.75 g, 4.22 mmol) slowly over
a period of 10 min. The reaction mixture was warmed to room
temperature and stirred for 2 h. The reaction mixture was
poured into an ice-water mixture with vigorous stirring to form
a white solid, which was filtered and washed with cold water
until free of DMF. The solid was dried in vacuum to give
colorless solid 4-bromo-1-isopropyl-5-(2-methoxy-5-nitrophenyl)-
1H-pyrazole (1.25 g, 96%). LCMS m/z (%) = 340 M þ Hþ
(79Br, 100), 342 (81Br, 96.5). 1H NMR (400 MHz, CDCl3) δ: 8.4
(dd, J1 = 9.09 Hz, J2 = 2.78 Hz, 1H), 8.19 (d, J = 2.78), 7.6
(s, 1H), 7.14 (d, J = 9.35 Hz, 1H), 4.11 (m, 1H), 3.96 (s, 3H), 1.49
(d, J = 6.52 Hz, 3H), 1.36 (d, J = 6.52 Hz, 3H).
3-(4-Bromo-2-isopropyl-2H-pyrazol-3-yl)-4-methoxyphenyla-
mine. To a solution of 4-bromo-1-isopropyl-5-(2-methoxy-
5-nitrophenyl)-1H-pyrazole (0.50 g, 1.47 mmol) in ethanol
(5.0 mL) was added tin(II) chloride dihydrate (1.3 g, 5.88 mmol),
and the mixture was heated at 55 °C overnight. The ethanol was
evaporated, and the residue was taken up in ethyl acetate
(50 mL) and washed with 10% sodium hydroxide (10 mL).
The organic layer was dried over MgSO4 and evaporated to
yield a light-yellow solid. The crude material was purified via
flash chromatography (SiO2, hexane/ethyl acetate, 3/1) to yield
of 3-(4-bromo-2-isopropyl-2H-pyrazol-3-yl)-4-methoxypheny-
lamine (0.38 g, 85%) as a pale-yellow solid. LCMS m/z (%) =
310 M þ Hþ, (79 Br, 100), 312 M þ Hþ (81Br, 96.5). 1H NMR
(400 MHz, CDCl3) δ: 7.47 (s, 1H), 6.78 (d, J = 8.08 Hz, 1H),
6.72 (dd, J1 = 8.01 Hz, J2 = 2.78 Hz, 1H), 6.54 (d, J = 2.78 Hz,
1H), 4.14 (m, 1H), 3.63 (s, 3H), 1.4 (d, J = 6.57 Hz, 3H), 1.23 (d,
J = 6.57 Hz, 3H).
2-(2-Methyl-2H-pyrazol-3-yl)-4-nitrophenol. To methylhy-
drazine (1.106 g, 1.3 mL, 23.5 mmol) was added 6-nitrochro-
mone (1.159 g, 5.88 mmol) in DMSO (40 mL) dropwise via
syringe pump at 70 °C. The crude reaction mixture was purified
by HPLC to afford 2-(2-methyl-2H-pyrazol-3-yl)-4-nitrophenol
(0.567 g, 2.59 mmol, 44%) as a white solid. LCMS m/z = 220
(M þ H). 1H NMR (400 MHz, acetone-d6) δ: 8.24 (dd, J = 2.9,
9.0 Hz, 1H), 8.13 (d, J = 2.8 Hz, 1H), 7.46 (d, J = 1.8 Hz, 1H),
7.26 (d, J = 9.0 Hz, 1H), 6.36 (d, J = 1.8 Hz, 1H), 3.77 (s, 3H).
3-(4-Bromo-2-methyl-2H-pyrazol-3-yl)-4-ethoxyphenylamine.
Step 1. To a stirred solution of 2-(2-methyl-2H-pyrazol-3-yl)-
4-nitrophenol (0.206 g, 0.94 mmol) in a mixture of dimethylfor-
mamide/tetrahydrofuran (1 mL/5 mL) was added sodium hy-
dride (60%, 0.082 g, 1.88 mmol) at 0 °C. After the mixture was
stirred for 30 min, iodoethane (0.444 g, 0.23 mL, 3.0 equiv) was
added, and the mixture was warmed up to 70 °C and stirred until
the starting material was completely consumed. The reaction
Step 2. Crude 5-(2-benzyloxy-5-nitrophenyl)-1-methyl-1H-
pyrazole was treated dropwise at 0 °C with N-bromosuccinimide
(0.113 g, 0.63 mmol) in DMF. After being stirred at 0 °C for 3 h,
the mixture was cooled to room temperature, diluted with ethyl
acetate (300 mL), and washed with water (3ꢀ100 mL) and
brine. The ethyl acetate phase was dried over anhydrous
MgSO4, filtered, and evaporated. The crude reaction mixture
was purified by flash chromatography (SiO2, eluent ethyl acet-
ate/hexane), providing 5-(2-benzyloxy-5-nitrophenyl)-4-bromo-
1-methyl-1H-pyrazole. LCMS m/z (%)=388 (M þ H79Br,
100), 390 (M þ H81Br, 94). 1H NMR (400 MHz, CDCl3) δ: 8.36

Article
Journal of Medicinal Chemistry, 2010, Vol. 53, No. 5 1931
(dd, J = 2.8, 9.2 Hz, 1H), 8.23 (d, J = 2.8 Hz, 1H), 7.59 (s, 1H),
7.25-7.42 (m, 5H), 7.19 (d, J = 9.2 Hz, 1H), 5.24 (s, 2H), 3.73
(s, 3H).
7.54 (s, 1H), 7.28 (d, J = 8.2 Hz, 2H), 7.11 (d, J = 8.2 Hz, 2H), 6.90
(d, J = 8.7 Hz, 1H), 6.76 (dd, J = 2.7, 8.7 Hz, 1H), 6.63 (d, J =
2.7 Hz, 1H), 4.86 (AB quartet, J = 12.1, 20.9 Hz, 2H), 3.71 (s, 3H).
3-(4-Bromo-2-methyl-2H-pyrazol-3-yl)-4-phenethyloxypheny-
lamine. Step 1. 2-(2-Methyl-2H-pyrazol-3-yl)-4-nitrophenol
(0.125 g, 0.57 mmol) was treated with sodium hydride
(0.049 g, 1.14 mmol, 2.0 equiv) and (2-bromoethyl)benzene
(0.323 g, 0.24 mL, 1.71 mmol, 3.0 equiv) in a mixture of DMF
(0.9 mL) and THF (2.5 mL) at 0 °C. The mixture was warmed to
70 °C and stirred until the starting material was consumed. The
reaction was quenched with saturated ammonium chloride,
diluted with ethyl acetate, washed with water, and the aqueous
phase was extracted with ethyl acetate (3 ꢀ 50 mL). The
combined organic phase was washed with brine, dried over
MgSO4, filtered and the solvent evaporated, providing crude
1-methyl-5-(5-nitro-2-phenethyloxyphenyl)-1H-pyrazole (0.137 g,
0.42 mmol, 74%) as an oil. LCMS m/z (%) = 324 (M þ H). 1H
NMR (400 MHz, CDCl3) δ: 8.31 (dd, J = 2.8, 9.1 Hz, 1H), 8.17
(d, J = 2.8 Hz, 1H), 7.59 (s, 1H), 7.20-7.36 (m, 3H), 7.09 (d,
J = 7.1 Hz, 2H), 7.05 (d, J = 9.2 Hz, 1H), 6.26 (s, 1H), 4.33 (t,
J = 6.6 Hz, 2H), 3.55 (s, 3H), 3.05 (t, J = 6.6 Hz, 2H).
Step 3. To a stirred solution of 5-(2-benzyloxy-5-nitro-
phenyl)-4-bromo-1-methyl-1H-pyrazole in ethanol was added
tin(II) chloride dihydrate. After the mixture was stirred at reflux
for 2 h, the solvent was removed under reduced pressure. The
resulting solid was dissolved in ethyl acetate, 1 N sodium hydro-
xide (30 mL) was added, and the mixture was stirred overnight.
The white precipitate was filtered off through Celite, and the
aqueous phase was extracted with ethyl acetate (3 ꢀ 80 mL). The
combined organic phase was dried over MgSO4, filtered, and
evaporated. The crude residue was purified by flash chroma-
tography (SiO2, eluent ethyl acetate/hexane), providing 4-ben-
zyloxy-3-(4-bromo-2-methyl-2H-pyrazol-3-yl)phenylamine
(0.079 g, 0.22 mmol, 39% over three steps). LCMS m/z (%) =
358 (M þ H79Br, 98), 360 (M þ H81Br, 100). 1H NMR
(400 MHz, CDCl3) δ: 7.45 (s, 1H), 7.15-7.26 (m, 3H), 7.10
(d, J = 6.6 Hz, 2H), 6.83 (d, J = 8.7 Hz, 1H), 6.66 (dd, J = 2.8,
8.6 Hz, 1H), 6.55 (d, J = 2.8 Hz, 1H), 4.83 (AB quartet, J=
12.0, 17.2 Hz, 2H), 3.62 (s, 3H).
3-(4-Bromo-2-methyl-2H-pyrazol-3-yl)-4-(4-chlorobenzyloxy)-
phenylamine. Step 1. 2-(2-Methyl-2H-pyrazol-3-yl)-4-nitro-
phenol (0.143 g, 0.65 mmol) was treated with sodium hydride
(0.057 g, 1.30 mmol) and 4-chlorobenzyl bromide (0.332 g,
1.96 mmol) in a mixture of DMF (0.9 mL) and THF (2.5 mL)
(2.5 mL) at 0 °C. The mixture was warmed to 70 °C and stirred
until the starting material was consumed. The reaction was
quenched with saturated ammonium chloride, diluted with ethyl
acetate, washed with water, and the aqueous phase was ex-
tracted with ethyl acetate (3 ꢀ 50 mL). The combined organic
phase was washed with brine, dried over MgSO4, filtered and the
solvent evaporated, providing crude 5-[2-(4-chlorobenzyloxy)-
5-nitrophenyl]-1-methyl-1H-pyrazole (0.142 g, 0.41 mmol,
63%) as an oil. LCMS m/z (%) = 344 (M þ H35Cl, 100), 346
(M þ H37Cl, 39). 1H NMR (400 MHz, CDCl3) δ: 8.33 (dd, J =
2.8, 9.1 Hz, 1H), 8.23 (d, J = 9.1 Hz, 1H), 7.58 (d. J = 1.7 Hz,
1H), 7.36 (d, J = 8.3 Hz, 2H), 7.21 (d, J = 8.3 Hz, 1H), 7.13 (d,
J= 9.1 Hz, 1H), 6.36 (d, J= 1.7 Hz, 1H), 5.20 (s, 2H), 3.75 (s, 3H).
Step 2. Crude 5-[2-(4-chlorobenzyloxy)-5-nitrophenyl]-1-
methyl-1H-pyrazole was treated dropwise 0 °C with N-bromo-
succinimide (0.082 g, 0.45 mmol, 1.05 equiv) in DMF. After
being stirred at 0 °C for 3 h, the mixture was diluted with ethyl
acetate (300 mL) and washed with water (3 ꢀ 100 mL) and then
brine. The ethyl acetate phase was dried over anhydrous
MgSO4, filtered and the solvent evaporated. The crude reaction
mixture was purified by flash chromatography (SiO2, eluent
ethyl acetate/hexane), providing 4-bromo-5-[2-(4-chlorobenzy-
loxy)-5-nitrophenyl]-1-methyl-1H-pyrazole. LCMS m/z (%) =
422 (M þ H79Br35Cl, 85), 424 (M þ H81Br35Cl, 100), 426 (M þ
Step 2. 1-Methyl-5-(5-nitro-2-phenethyloxyphenyl)-1H-pyr-
azole (0.137 g, 0.42 mmol) was treated with N-bromosuccini-
mide (0.084 g, 0.46 mmol, 1.05 equiv) in DMF (5 mL). After
being stirred at 0 °C for 3 h, the mixture was diluted with ethyl
acetate (300 mL) and washed with water (3 ꢀ 100 mL) and then
brine. The ethyl acetate phase was dried over MgSO4, filtered
and the solvent evaporated. The crude reaction mixture was
purified by flash chromatography (SiO2, eluent ethyl acetate/
hexane), providing 4-bromo-1-methyl-5-(5-nitro-2-phenethyl-
oxyphenyl)-1H-pyrazole. LCMS m/z (%) = 402 (M þ H79Br,
100), 404 (M þ H81Br, 97). 1H NMR (400 MHz, CDCl3) δ: 8.27
(dd, J = 2.8, 9.2 Hz, 1H), 8.10 (d, J = 2.8 Hz, 1H), 7.52 (s, 1H),
7.16-7.24 (m, 3H), 6.94-7.03 (m, 3H), 4.18-4.28 (m, 2H), 3.37
(s, 3H), 2.88-3.02 (m, 2H).
Step 3. To a stirred solution of 4-bromo-1-methyl-5-(5-nitro-
2-phenethyloxyphenyl)-1H-pyrazole in ethanol was added tin-
(II) chloride dihydrate (0.387 g, 1.68 mmol, 4.0 equiv) in
ethanol. After the mixture was stirred at reflux for 2 h, the
solvent was removed under reduced pressure. The resulting solid
was dissolved in ethyl acetate, 1 N sodium hydroxide (30 mL)
was added, and the mixture was stirred overnight. The white
precipitate was filtered off through Celite, and the aqueous
phase was extracted with ethyl acetate (3 ꢀ 80 mL). The com-
bined organic phase was dried over MgSO4, filtered, and
evaporated. The crude residue was purified by flash chroma-
tography (SiO2, eluent ethyl acetate/hexane), providing 3-(4-
bromo-2-methyl-2H-pyrazol-3-yl)-4-phenethyloxyphenylamine
(0.124 g, 0.33 mmol, 80% over the final two steps) as an oil.
LCMS m/z (%) = 372 (M þ H79Br, 94), 374 (M þ H81Br, 100).
1H NMR (400 MHz, CDCl3) δ: 7.54 (s, 1H), 7.18-7.33 (m, 3H),
7.08 (d, J = 7.7 Hz, 2H), 6.85 (d, J = 8.7 Hz, 1H), 6.77 (dd, J =
2.7, 8.7 Hz, 1H), 6.61 (d, J = 2.6 Hz, 1H), 3.99-4.15 (m, 2H),
3.53 (s, 3H), 3.10-3.40 (broad s, 2H), 2.83-3.00 (m, 2H).
3-(4-Bromo-2-methyl-2H-pyrazol-3-yl)-4-isopropoxyphenyla-
mine. Step 1. To a stirred solution of 2-(2-methyl-2H-pyrazol-3-
yl)-4-nitrophenol (0.061 g, 0.28 mmol) in DMF (3 mL) was
added potassium carbonate (0.077 g, 0.56 mmol) at room
temperature. The reaction mixture was stirred for 30 min, and
isopropyl bromide (110 μL, 1.16 mmol) was added. The mixture
was heated to 50 °C until the consumption of starting material
was complete. The reaction mixture was diluted with ethyl ace-
tate, washed with water, and the aqueous phase was extracted
with ethyl acetate. The combined organic phase was washed
with brine, dried over MgSO4, filtered, and evaporated to pro-
vide crude 5-(2-isopropoxy-5-nitrophenyl)-1-methyl-1H-pyra-
zole. LCMS m/z = 262 (M þ H). 1H NMR (400 MHz, CDCl3)
δ: 8.31 (dd, J = 2.8, 9.2 Hz, 1H), 8.20 (d, J = 2.8 Hz, 1H), 7.56
(s, 1H), 7.06 (d, J = 9.2 Hz, 1H), 6.3 (s, 1H), 4.74 (ddd, J = 6.1,
6.1, 12.1 Hz, 1H), 1.37 (s, 3H), 1.36 (s, 3H)
1
H81Br37Cl, 26). H NMR (400 MHz, CDCl3) δ: 8.37 (dd, J =
2.7, 9.2 Hz, 1H), 8.22 (d, J = 2.7 Hz, 1H), 7.59 (s, 1H), 7.34 (d,
J = 8.3 Hz, 2H), 7.21 (d, J = 8.3 Hz, 2H), 7.16 (d, J = 9.2 Hz,
1H), 5.20 (AB quartet, J = 12.1, 15.2 Hz, 2H), 3.72 (s, 3H).
Step 3. To a stirred solution of 4-bromo-5-[2-(4-chlorobenzy-
loxy)-5-nitrophenyl]-1-methyl-1H-pyrazole in ethanol was added
tin(II) chloride dihydrate (0.378 g, 1.64 mmol) in ethanol (5 mL).
After the mixture was stirred at reflux for 2 h the solvent was
removed under reduced pressure. The resulting solid was dis-
solved in ethyl acetate, 1 N sodium hydroxide (30 mL) was
added, and the mixture was stirred overnight. The white pre-
cipitate was filtered off through Celite, and the aqueous phase
was extracted with ethyl acetate (3 ꢀ 80 mL). The combined
organic phase was dried over anhydrous MgSO4, filtered, and
evaporated. The crude residue was purified by flash chroma-
tography (SiO2, eluent ethyl acetate/hexane), providing 3-(4-
bromo-2-methyl-2H-pyrazol-3-yl)-4-(4-chlorobenzyloxy)phen-
ylamine (0.114 g, 0.29 mmol, 71% over the final two steps).
LCMSm/z (%)=393(M þ H79Br35Cl, 70), 395 (M þ H81Br35Cl,
100), 397 (M þ H81Br37Cl, 23). 1H NMR (400 MHz, CDCl3) δ:

1932 Journal of Medicinal Chemistry, 2010, Vol. 53, No. 5
Teegarden et al.
Step 2. Crude 5-(2-isopropoxy-5-nitrophenyl)-1-methyl-1H-
pyrazole from step 1 was treated with N-bromosuccinimide in
DMF (5 mL). After being stirred at 0 °C for 3 h, the mixture was
diluted with ethyl acetate (300 mL) and washed with water (3ꢀ
100 mL) and then brine. The organic phase was dried over
MgSO4, filtered and the solvent evaporated. The crude reac-
tion mixture was purified by flash chromatography (SiO2,
eluent ethyl acetate/hexane), providing 4-bromo-5-(2-iso-
propoxy-5-nitrophenyl)-1-methyl-1H-pyrazole. LCMS m/z
(%) = 340 (M þ H79Br, 85), 342 (M þ H81Br, 100). 1H NMR
(400 MHz, CDCl3) δ: 8.36 (dd, J = 2.8, 9.2 Hz, 1H), 8.20 (d,
J = 2.8 Hz, 1H), 7.57 (s, 1H), 7.10 (d, J = 9.2 Hz, 1H), 4.73 (ddd,
J = 6.1, 6.1, 12.1 Hz, 1H), 1.39 (d, J = 6.1 Hz, 3H), 1.32 (d,
J = 6.0 Hz, 3H).
Step 3. To a stirred solution of 4-bromo-5-(2-isopropoxy-
5-nitrophenyl)-1-methyl-1H-pyrazole in ethanol from step 2
was added tin(II) chloride dihydrate in ethanol. After the
mixture was stirred at reflux for 2 h, the solvent was removed
under reduced pressure. The resulting solid was dissolved in
ethyl acetate, 1 N sodium hydroxide (30 mL) was added, and the
mixture was stirred overnight. The white precipitate was filtered
off through Celite, and the aqueous phase was extracted with
ethyl acetate (3 ꢀ 80 mL). The combined organic phase was
dried over anhydrous MgSO4, filtered, and evaporated. The
crude residue was purified by flash chromatography (SiO2,
eluent ethyl acetate/hexane), providing 3-(4-bromo-2-methyl-
2H-pyrazol-3-yl)-4-isopropoxyphenylamine (0.043 g, 0.14 mmol,
50% over three steps). LCMS m/z (%) = 310 (M þ H79Br, 99),
312 (M þ H81Br, 100). 1H NMR (400 MHz, CDCl3) δ: 7.51 (s,
1H), 6.89 (d, J = 8.8 Hz, 1H), 6.76 (dd, J = 2.7, 8.6 Hz, 1H), 6.62
(d, J = 2.7 Hz, 1H), 4.08 (ddd, J = 6.1, 6.1, 12,2 Hz, 1H), 3.74 (s,
3H), 1.21 (d, J = 6.1 Hz, 3H), 1.01 (d, J = 6.1 Hz, 3H).
(3-Bromo-4-trifluoromethoxyphenyl)carbamic Acid tert-Butyl
and washed with brine and water. The organic layer was
separated, dried over anhydrous sodium sulfate, filtered, and
concentrated to give a yellow oily residue that was subjected to
purification by flash chromatography (SiO2, hexanes/ethyl
acetate gradient elution) to afford [3-(4-bromo-2-methyl-2H-
pyrazol-3-yl)-4-trifluoromethoxyphenyl]carbamic acid tert-bu-
tyl ester as a white solid (70 mg, 0.16 mmol, 89% yield). LCMS
1
m/z (%) = 436 (M þ H 79Br, 100), 438 (M þ H 81Br, 98). H
NMR (400 MHz, CD3OD) δ: 7.79 (d, J = 8.90 Hz, 1H), 7.61
(s, 1H), 7.55 (s, 1H), 7.43 (d, J = 8.94 Hz, 1H), 3.73 (s, 3H), 1.55
(s, 9H).
N-[4-Hydroxy-3-(2-methyl-2H-pyrazol-3-yl)phenyl]acetamide.
A solution of N-[4-methoxy-3-(2-methyl-2H-pyrazol-3-yl)phe-
nyl]acetamide (2.0 g, 8.65 mmol) in anhydrous 1,2-dichlor-
oethane (60 mL) was cooled to 0 °C in an ice bath and stirred
for 10 min. Anhydrous aluminum chloride (4.35 g, 32.6 mmol)
was added and the reaction mixture stirred at 0 °C for 20 min,
then stirred at 80 °C for 1 h. Ethyl acetate was added, and the
organic was washed with 10% aqueous potassium sodium
tartrate (2 ꢀ 50 mL). The organic layer was separated, dried
over anhydrous sodium sulfate, filtered, and concentrated to
give a crude product that was purified via preparative HPLC.
The fractions containing product were collected and lyophilized
to afford N-[4-hydroxy-3-(2-methyl-2H-pyrazol-3-yl)phenyl]-
acetamide (1.5 g, 6.1 mmol, 70% yield) as a white solid. LCMS
m/z (%) = 232 (M þ H, 100). 1H NMR (400 MHz, DMSO-d6)
δ: 7.39 (s,1H), 6.86 (d, J = 8.74 Hz, 1H), 6.62 (d, J = 8.70 Hz,
1H), 6.47 (s, 1H), 6.15 (s, 1H), 4.80 (bs, 2H), 3.87(t, J = 5.80 Hz,
2H), 3.63 (s, 3H), 2.44 (t, J = 5.80 Hz, 2H), 2.08 (s, 6H).
Preparation of Final Products. 1-[3-(4-Bromo-2-methyl-2H-
pyrazol-3-yl)-4-methoxyphenyl]-3-(4-chlorophenyl)urea (3). To a
stirred solution of 3-(4-bromo-2-methyl-2H-pyrazol-3-yl)-4-
methoxyphenylamine (0.260 g, 0.92 mmol) in methylene chlor-
ide (5 mL) was added 4-chlorophenyl isocyanate (0.144 g,
0.92 mmol). After the TLC showed the consumption of the
starting material, the crude product was purified by preparative
thin layer chromatography (TLC) (eluent ethyl acetate/
hexane = 1/1) to afford 1-[3-(4-bromo-2-methyl-2H-pyrazol-3-
yl)-4-methoxyphenyl]-3-(4-chlorophenyl)urea, 3 (0.340 g, 0.78
mmol, 84%) as a white solid. LCMS m/z (%) = 435 (M þ
H79Br35Cl, 77), 437 (M þ H81Br35Cl, 100), 439 (M þ H81Br37Cl,
25). 1H NMR (400 MHz, CDCl3) δ: 7.56 (s, 1H), 7.44 (dd, J =
2.7, 8.9 Hz, 1H), 7.34 (d, J = 9.0 Hz, 1H), 7.29 (d, J = 9.0 Hz,
1H), 7.19 (d, J = 2.7 Hz, 1H), 6.59 (s, 1H), 6.47 (s, 1H), 3.84 (s,
3H), 3.74 (s, 3H).
1-[3-(4-Bromo-2-methyl-2H-pyrazol-3-yl)-4-methoxyphenyl]-
3-(3-chlorophenyl)urea (14). To a stirred solution of 3-(4-bromo-
2-methyl-2H-pyrazol-3-yl)-4-methoxyphenylamine (0.015 g,
0.051 mmol) in methylene chloride (1 mL) was added 3-chlor-
ophenyl isocyanate (7 μL, 0.054 mol). After TLC showed the
consumption of the starting material, the crude material was
purified by preparative thin layer chromatography (TLC)
(eluent ethyl acetate/hexane = 1/1) to afford (14) (0.020 g,
0.047 mmol, 92%) as a colorless solid film. LCMS m/z (%) =
435 (M þ H79Br, 68), 437 (M þ H81Br, 100). 1H NMR
(400 MHz, acetone-d6) δ: 8.29 (s, 1H), 8.19 (s, 1H), 7.80 (t,
J = 1.9 Hz, 1H), 7.29 (dd, J = 2.7, 9.0 Hz, 1H), 7.49 (s, 1H), 7.43
(d, J = 2.7 Hz, 1H), 7.34 (d, J = 8.4 Hz, 1H), 7.26 (t, J = 8.0 Hz,
1H), 7.14 (d, J = 9.0 Hz, 1H), 7.00 (d, J = 7.8 Hz, 1H), 3.82 (s,
3H), 3.68 (s, 3H).
Ester.
A solution of 3-bromo-4-(trifluoromethoxy)aniline
(3.84 g, 15 mmol) in dioxane (15 mL) was treated with di-tert-
butyl dicarbonate (4.91 g, 22.5 mmol), and the reaction mixture
was heated to 80 °C overnight. The solvent was removed under
reduced pressure to give an oily residue that was triturated with
hexanes. The resulting solid was collected by filtration to give
(3-bromo-4-trifluoromethoxyphenyl)carbamic acid tert-butyl
ester as a white solid (3.26 g, 9.2 mmol, 61.0% yield). 1H
NMR (400 MHz, DMSO-d6) δ: 9.78 (bs, 1H), 7.87 (s, 1H),
7.54-7.43 (m, 2H),1.51 (s, 9H).
[3-(2-Methyl-2H-pyrazol-3-yl)-4-trifluoromethoxyphenyl]car-
bamic Acid tert-Butyl Ester. A 25-mL round-bottom flask was
charged with (3-bromo-4-trifluoromethoxyphenyl)carbamic
acid tert-butyl ester (230.0 mg, 0.65 mmol), 1-methylpyrazole-
5-boronic acid (392.9 mg, 1.93 mmol), sodium carbonate
(137.8 mg, 1.3 mmol), dimethoxyethane (5 mL), and water
(0.5 mL) under argon atmosphere. Pd(PPh3)4 (75.1 mg,
0.065 mmol) was added and the reaction mixture again purged
with argon. The mixture was heated to 80 °C overnight, then
cooled to room temperature. Ethyl acetate (10 mL) was added
and the mixture washed with brine and water. The organic layer
was separated, dried over anhydrous sodium sulfate, filtered,
and concentrated to give a residue that was subjected to
purification by flash chromatography (SiO2, eluent hexanes/
ethyl acetate) to afford [3-(2-methyl-2H-pyrazol-3-yl)-4-tri-
fluoromethoxyphenyl]carbamic acid tert-butyl ester as an off-
white solid (84 mg, 0.24 mmol, 37% yield). LCMS m/z (%) =
358 (M þ H, 100). 1H NMR (400 MHz, DMSO-d6) δ: 9.83 (bs,
1H), 7.77 (d, J = 8.95 Hz, 1H), 7.69 (s, 1H), 7.63 (s, 1H), 7.57 (d,
J = 8.84 Hz, 1H), 6.45 (s, 1H), 3.78 (s, 3H), 1.60 (s, 9H).
[3-(4-Bromo-2-methyl-2H-pyrazol-3-yl)-4-trifluoromethoxy-
phenyl]carbamic Acid tert-Butyl Ester. To a solution of [3-(2-
methyl-2H-pyrazol-3-yl)-4-trifluoromethoxyphenyl]carbamic
acid tert-butyl ester (65 mg, 0.18 mmol) in DMF (1.5 mL) at
0 °C, N-bromosuccinimide (35.6 mg, 0.2 mmol) was added, and
then the reaction mixture was stirred at room temperature
overnight. The resulting mixture was diluted with ethyl acetate
1-[3-(4-Bromo-2-methyl-2H-pyrazol-3-yl)-4-methoxyphenyl]-
3-(4-fluorophenyl)urea (15). 3-(4-Bromo-2-methyl-2H-pyrazol-
3-yl)-4-methoxyphenylamine (2.965 g, 10.5 mmol) was treated
with 4-fluorophenyl isocyanate (1.31 mL, 11.6 mmol) in methy-
lene chloride (20 mL) in a similar manner as described for 3 to
afford 15 (3.755 g, 8.94 mmol, 85%) as a white solid. LCMS m/z
(%) = 419 (M þ H79Br, 99), 421 (M þ H81Br, 100). 1H NMR
(400 MHz, acetone-d6) δ: 8.49 (broad s, 2H), 7.77 (d, J = 9.0 Hz,
1H), 7.50-7.58 (m, 2H), 7.50 (s, 1H), 7.43 (s, 1H), 7.12 (d, J =
8.9 Hz, 1H), 6.98-7.06 (m, 2H), 3.81 (s, 3H), 3.68 (s, 3H).

Article
1-[3-(4-Bromo-2-methyl-2H-pyrazol-3-yl)-4-methoxyphenyl]-
Journal of Medicinal Chemistry, 2010, Vol. 53, No. 5 1933
with 4-methoxyphenyl isocyanate (0.016 g, 14.2 μL, 0.11 mmol,
1.0 equiv) in methylene chloride (2 mL) in a similar manner as
described for 3 to afford 22 (0.037 g, 0.086 mmol, 78%) as a white
solid. LCMS m/z (%) = 431 (M þ H79Br, 89), 433 (M þ H81Br,
100). 1H NMR (400 MHz, acetone-d6) δ: 8.02 (s, 1H), 7.89 (s, 1H),
7.67 (dd, J = 2.7, 9.0 Hz, 1H), 7.49 (s, 1H), 7.43 (s, 1H), 7.42 (d,
J = 9.0 Hz, 2H), 7.12 (d, J= 9.0 Hz, 1H), 6.85 (d, J= 9.0 Hz, 2H),
3.81 (s, 3H), 3.75 (s, 3H), 3.68 (s, 3H).
1-[3-(4-Bromo-2-methyl-2H-pyrazol-3-yl)-4-methoxyphenyl]-
3-(4-dimethylaminophenyl)urea (23). To 3-(4-bromo-2-methyl-
2H-pyrazol-3-yl)-4-methoxyphenylamine (34.9 mg, 0.124 mmol)
in methylene chloride (3 mL) was added 4-(dimethylamino)-
phenyl isocyanate (21 mg, 0.129 mmol), and the mixture was
stirred for 2 days. The resulting material was purified by HPLC.
The product was dried in vacuum to afford 23 as a waxy solid
(13.5 mg, 25%). LCMS m/z (%) = 444 (M þ H79Br, 100), 446
(M þ H81Br, 95). 1H NMR (400 MHz, DMSO-d6) δ: 8.51 (bs,
1H), 8.26 (bs, 1H), 7.61 (s, 1H), 7.53 (dd, J = 8.97, 2.71 Hz, 1H),
7.34 (d, J = 2.70 Hz, 1H), 7.24 (d, J = 9.03 Hz, 2H), 7.12 (d, J =
9.05 Hz, 1H), 6.68 (d, J = 9.07 Hz, 2H), 3.75 (s, 3H), 3.63 (s, 3H),
2.82 (s, 6H).
3-(3-fluorophenyl)urea (16). 3-(4-Bromo-2-methyl-2H-pyrazol-
3-yl)-4-methoxyphenylamine (0.033 g, 0.12 mmol) was treated
with 3-fluorophenyl isocyanate (0.017 g, 14.3 μL, 0.12 mmol) in
methylene chloride (1 mL) in a similar manner as described for
3 to afford 16 (0.040 g, 0.09 mmol, 82%) as a white solid. LCMS
1
m/z (%) = 419 (M þ H79Br, 100), 421 (M þ H81Br, 91). H
NMR (400 MHz, acetone-d6) δ: 8.31 (s, 1H), 8.17 (s, 1H), 7.69
(dd, J = 2.7, 9.0 Hz, 1H), 7.59 (dt, J = 2.2, 12.0 Hz, 1H), 7.50 (s,
1H), 7.43 (d, J = 2.6 Hz, 1H), 7.27 (dd, J = 8.1, 15.0 Hz, 1H),
7.11-7.19 (m, 2H), 6.73 (ddd, J = 2.4, 8.4 Hz, 1H), 3.82 (s, 1H),
3.69 (s, 1H).
1-[3-(4-Bromo-2-methyl-2H-pyrazol-3-yl)-4-methoxyphenyl]-
3-(2-fluorophenyl)urea (17). 3-(4-Bromo-2-methyl-2H-pyrazol-
3-yl)-4-methoxyphenylamine (0.034 g, 0.12 mmol) was treated
with 2-fluorophenyl isocyanate (0.018 g, 14.4 μL, 0.12 mmol,
1.05 equiv) in methylene chloride (1 mL) in a similar manner as
described for 3 to afford 17 (0.045 g, 0.11 mmol, 91%) as a solid
film. LCMS m/z (%) = 419 (M þ H79Br, 99), 421 (M þ H81Br,
100). 1H NMR (400 MHz, CDCl3) δ: 8.08 (t, J = 8.1 Hz, 1H),
7.59 (s, 1H), 7.54 (s, 1H), 7.53-7.59 (m, 1H), 7.40 (s, 1H), 7.12
(d, J = 1.5 Hz, 1H), 6.95-7.12 (m, 3H), 6.94 (d, J = 5.7 Hz, 1H),
3.77 (s, 3H), 3.70 (s, 3H).
1-[3-(4-Bromo-2-methyl-2H-pyrazol-3-yl)-4-methoxyphenyl]-
3-(4-bromophenyl)urea (18). 3-(4-Bromo-2-methyl-2H-pyrazol-
3-yl)-4-methoxyphenylamine (0.032 g, 0.11 mmol) was treated
with 4-bromophenyl isocyanate (0.022 g, 0.11 mmol, 1.0 equiv)
in methylene chloride (2 mL) in a similar manner as described
for 3 to afford 18 (0.040 g, 0.08 mmol, 75%) as a white
solid. LCMS m/z (%) = 479 (M þ H79Br79Br, 51), 481 (M þ
H79Br81Br, 100), 483 (M þ H81Br81Br, 50). 1H NMR (400 MHz,
acetone-d6) δ: 8.22 (s, 1H), 8.14 (s, 1H), 7.68 (dd, J = 2.7, 9.0 Hz,
1H), 7.48-7.54 (m, 3H), 7.39-7.46 (m, 3H), 7.14 (d, J = 9.0 Hz,
1H), 3.82 (s, 3H), 3.68 (s, 3H).
1-[3-(4-Bromo-2-methyl-2H-pyrazol-3-yl)-4-methoxyphenyl]-
3-(3-trifluoromethylphenyl)urea (19). 3-(4-Bromo-2-methyl-2H-
pyrazol-3-yl)-4-methoxyphenylamine (0.035 g, 0.12 mmol)
was treated with R,R,R-trifluoro-m-tolyl isocyanate (0.025 g,
18.0 μL, 0.13 mmol) in methylene chloride (1 mL) in a similar
manner as described for 3 to afford 19 (0.038 g, 0.080 mmol,
65%) as a white solid. LCMS m/z (%) = 469 (M þ H79Br, 91),
471 (M þ H81Br, 100). 1H NMR (400 MHz, acetone-d6) δ: 8.42
(s, 1H), 8.23 (s, 1H), 8.07 (s, 1H), 7.64-7.73 (m, 2H), 7.45-
7.53 (m, 2H), 7.44 (s, 1H), 7.30 (d, J = 7.6 Hz, 1H), 7.15 (d, J =
8.9 Hz, 1H), 3.82 (s, 3H), 3.69 (s, 3H).
1-[3-(4-Bromo-2-methyl-2H-pyrazol-3-yl)-4-methoxyphenyl]-
3-(4-isopropylphenyl)urea (24). 3-(4-Bromo-2-methyl-2H-pyra-
zol-3-yl)-4-methoxyphenylamine (0.035 g, 0.12 mmol) was trea-
ted with 4-isopropylphenyl isocyanate (0.022 g, 21.0 μL,
0.13 mmol, 1.05 equiv) in methylene chloride (1 mL) in a similar
manner as described for 3 to afford 24 (0.028 g, 0.06 mmol, 50%)
as a solid film. LCMS m/z (%) = 443 (M þ H79Br, 100), 445
1
(M þ H81Br, 99). H NMR (400 MHz, acetone-d6) δ: 8.08 (s,
1H), 8.00 (s, 1H), 7.68 (dd, J = 2.6, 8.9 Hz, 1H), 7.49 (s, 1H),
7.40-7.46 (m, 3H), 7.09-7.17 (m, 3H), 3.81 (s, 3H), 3.68 (s, 3H),
2.78-2.92 (m, 1H), 1.21 (s, 3H), 1.20 (s, 3H).
1-[3-(4-Bromo-2-methyl-2H-pyrazol-3-yl)-4-methoxyphenyl]-
3-(3-cyanophenyl)urea (25). 3-(4-Bromo-2-methyl-2H-pyrazol-
3-yl)-4-methoxyphenylamine (0.037 g, 0.13 mmol) was treated
with 3-cyanophenyl isocyanate (0.020 g, 0.14 mol, 1.05 equiv) in
methylene chloride (1 mL) in a similar manner as described for 3
to afford 25 (0.032 g, 0.08 mmol, 58%) as a white powder.
LCMS m/z (%) = 426 (M þ H79Br, 99), 428 (M þ H81Br, 100).
1H NMR (400 MHz, acetone-d6) δ: 8.45 (s, 1H), 8.26 (d, J = 9.6
Hz, 1H), 8.05 (t, J = 1.7 Hz, 1H), 7.74 (dd, J = 1.5, 8.2 Hz, 1H),
7.70 (dd, J = 2.7, 9.0 Hz, 1H), 7.50 (s, 1H), 7.48 (t, J = 8.1 Hz,
1H), 7.43 (d, J = 2.7 Hz, 1H), 7.36 (d, J = 7.6 Hz, 1H), 7.15 (d,
J = 9.0 Hz, 1H), 3.83 (s, 3H), 3.69 (s, 3H).
1-[3-(4-Bromo-2-isopropyl-2H-pyrazol-3-yl)-4-methoxyphenyl]-
3-(4-chlorophenyl)urea (26). To a solution of 3-(4-bromo-2-
isopropyl-2H-pyrazol-3-yl)-4-methoxyphenylamine (0.08 g,
0.258 mmol) in methylene chloride was added 4-chlorophenyl
isocyanate (0.041 g, 0.263 mmol), and the mixture was stirred
overnight. The resulting precipitate was filtered and washed
with methylene chloride/hexane (1:1) and dried in vacuum to
provide 26 as a colorless solid (0.052 g, 42%). LCMS m/z (%) =
463 (M þ H þ 79Br, 35Cl, 41), 465 M þ H þ (81Br 35Cl 88), 467
Hþ (81Br 37Cl, 21). 1H NMR (400 MHz, acetone-d6) δ: 8.30 (bs,
1H), 8.24 (bs, 1H), 7.69 (d, J = 2.7 Hz, 1H), 7.58 (d, J = 1.9 Hz,
2H), 7.74 (d, J = 2.7, 1H), 7.29 (d, J = 1.9 Hz, 2H), 7.28 (d, J =
1.6 Hz, 1H), 7.135 (d, J = 9.0 Hz, 1H), 4.26 (m, 1H), 3.81 (s, 3H),
1.45 (d, J = 6.6 Hz, 3H), 1.29 (d, J = 6.6 Hz, 3H).
1-[3-(4-Bromo-2-methyl-2H-pyrazol-3-yl)-4-methoxyphenyl]-
3-(4-trifluoromethylphenyl)urea (20). 3-(4-Bromo-2-methyl-2H-
pyrazol-3-yl)-4-methoxyphenylamine (0.035 g, 0.12 mmol) was
treated with R,R,R-trifluoro-p-tolyl isocyanate (0.024 g, 19.0 μL,
0.13 mmol) in methylene chloride (1 mL) in a similar manner as
described for 3 to afford 20 (0.048 g, 0.102 mmol, 83%) as a
white solid. LCMS m/z (%) = 469 (M þ H79Br, 92), 471 (M þ
1
H81Br, 100). H NMR (400 MHz, acetone-d6) δ: 8.51 (s, 1H),
8.27 (s, 1H), 7.76 (d, J = 8.3 Hz, 2H), 7.71 (dd, J = 2.3, 9.0 Hz,
1H), 7.62 (d, J = 8.4 Hz, 2H), 7.52 (s, 1H), 7.46 (d, J = 2.3 Hz,
1H), 7.16 (d, J = 8.9 Hz, 1H), 3.84 (s, 3H), 3.70 (s, 3H).
1-(3-Acetylphenyl)-3-[3-(4-bromo-2-methyl-2H-pyrazol-3-yl)-
4-methoxyphenyl]urea (21). 3-(4-Bromo-2-methyl-2H-pyrazol-
3-yl)-4-methoxyphenylamine (0.031 g, 0.11 mmol) was treated
with 3-acetylphenyl isocyanate (0.019 g, 15.8 μL, 0.11 mmol) in
methylene chloride (1 mL) in a similar manner as described for 3
to afford 21 (0.038 g, 0.09 mmol, 79%) as a white solid. LCMS
1-[3-(4-Bromo-2-isopropyl-2H-pyrazol-3-yl)-4-methoxyphenyl]-
3-(4-fluorophenyl)urea (27). To a solution of 3-(4-bromo-2-
isopropyl-2H-pyrazol-3-yl)-4-methoxyphenylamine (0.08 g,
0.258 mmol) in methylene chloride was added 4-fluorophenyl
isocyanate (0.036 g, 0.263 mmol), and the mixture was stirred
overnight. The resulting precipitate was filtered and washed
with methylene chloride/hexane (1:1) and dried in vacuum to
provide 27 as a colorless solid (0.037 g, 32%). LCMS m/z (%) =
1
m/z (%) = 443 (M þ H79Br, 99), 445 (M þ H81Br, 100). H
NMR (400 MHz, acetone-d6) δ: 8.30 (s, 1H), 8.19 (s, 1H), 8.13 (t,
J = 1.8 Hz, 1H), 7.80 (dd, J = 1.4, 8.1 Hz, 1H), 7.70 (dd, J =
2.7, 9.0 Hz, 1H), 7.62 (d, J = 7.7 Hz, 1H), 7.49 (s, 1H), 7.44 (d,
J = 2.7 Hz, 1H), 7.41 (t, J = 7.9 Hz, 1H), 7.15 (d, J = 9.0 Hz, 1H).
1-[3-(4-Bromo-2-methyl-2H-pyrazol-3-yl)-4-methoxyphenyl]-
3-(4-methoxyphenyl)urea (22). 3-(4-Bromo-2-methyl-2H-pyrazol-
3-yl)-4-methoxyphenylamine (0.031 g, 0.11 mmol) was treated
1
447 M þ Hþ (79Br, 100), 449 M þ Hþ (81Br, 95). H NMR
(400 MHz, CDCl3) δ: 7.5 (s, 1H), 7.35 (d, 2.0 Hz, 2H), 7.33 (9bs,
1H), 7.15 (d, J = 4.8 Hz, 1H), 7.12 (t, 1H), 7.00 (d, J = 1.9 Hz,
2H), 6.879 (d, J = 5.4 Hz, 1H), 6.85 (d, J = 4.7 Hz, 1H), 4.05

1934 Journal of Medicinal Chemistry, 2010, Vol. 53, No. 5
Teegarden et al.
(m, 1H), 3.65 (s, 3H), 1.33 (d, J = 6.6 Hz, 3H), 1.16 (d, J =
6.6 Hz, 3H).
methylene chloride (1 mL) in a similar manner as described for 3
to afford 32 (0.019 g, 0.04 mmol, 42%) as a white solid. LCMS
m/z (%) = 511 (M þ H79Br35Cl, 82), 513 (M þ H81Br35Cl, 100),
1-[3-(4-Bromo-2-methyl-2H-pyrazol-3-yl)-4-hydroxyphenyl]-
3-(4-chlorophenyl)urea (28). To 3 (1.170 g, 2.68 mmol) in methy-
lene chloride was added anhydrous aluminum chloride (1.432 g,
10.74 mmol) slowly at 0 °C. The mixture was stirred under reflux
overnight and then quenched with saturated sodium carbonate.
The mixture was then extracted with ethyl acetate, and the com-
bined organic phase was washed with water, 10% potassium
sodium tartrate and brine, dried over MgSO4, filtered and the
solvent evaporated. The crude solid was first purified with flash
chromatography (SiO2, eluent ethyl acetate/hexane = 1/3 to 1/1),
and the fractions containing 28 were then purified by HPLC. The
pure fractions were neutralized with saturated sodium bicarbonate,
extracted with ethyl acetate, dried with MgSO4, filtered and the
solvent was removed in vacuo to provide 28 as a white solid. LCMS
m/z (%) = 421 (M þ H79Br35Cl, 69), 423 (M þ H81Br35Cl, 100),
425 (M þ H81Br37Cl, 21). 1H NMR (400 MHz, acetone-d6) δ: 8.47
(s, 1H), 8.16 (s, 1H), 8.04 (s, 1H), 7.44 (d, J = 8.9 Hz, 2H), 7.38-
7.43 (m, 1H), 7.35 (s, 1H), 7.26 (d, J = 2.6 Hz, 1H), 7.15 (d,
J = 8.9 Hz, 2H), 6.87 (d, J = 8.8 Hz, 1H), 3.62 (s, 3H).
1
515 (M þ H81Br37Cl, 33). H NMR (400 MHz, acetone-d6) δ:
8.22 (s, 1H), 8.16 (s, 1H), 7.66 (dd, J = 2.4, 8.9 Hz, 1H), 7.55 (d,
J = 8.7 Hz, 2H), 7.50 (s, 1H), 7.46 (d, J = 2.5 Hz, 1H),
7.28-7.35 (m, 5H), 7.28 (d, J = 8.7 Hz, 2H), 7.22 (d, J = 8.9
Hz, 1H), 5.13 (AB quartet, J = 12.0, 24.3 Hz, 2H), 3.69 (s, 3H).
1-[3-(4-Bromo-2-methyl-2H-pyrazol-3-yl)-4-(4-chlorobenzyloxy)-
phenyl]-3-(4-chlorophenyl)urea (33). 3-(4-Bromo-2-methyl-
2H-pyrazol-3-yl)-4-(4-chlorobenzyloxy)phenylamine (0.029 g,
0.08 mmol) was treated with 4-chlorophenyl isocyanate
(0.014 g, 0.09 mmol) in methylene chloride (1 mL) in a similar
manner as described for 3 to afford 33 (0.027 g, 0.05 mmol, 65%)
as a white solid. LCMS m/z (%) = 545 (M þ H79Br35Cl35Cl,
65), 547 (M þ H79Br35Cl37Cl 81Br35Cl35Cl, 100), 549 (M þ
H81Br35Cl37Cl79Br37Cl37Cl, 45), 551 (M þ H81Br37Cl37Cl, 6). 1H
NMR (400 MHz, acetone-d6) δ: 8.23 (s, 1H), 8.17 (s, 1H), 7.66
(dd, J = 2.7, 9.0 Hz, 1H), 7.56 (d, J = 8.9 Hz, 2H), 7.50 (s, 1H),
7.46 (d, J = 2.7 Hz, 1H), 7.37 (d, J = 8.7 Hz, 2H), 7.33 (d,
J = 8.7 Hz, 2H), 7.28 (d, J = 8.9 Hz, 2H), 7.22 (d, J = 9.0 Hz,
1H), 5.14 (AB quartet, J = 12.3, 24.8 Hz, 2H), 3.69 (s, 3H).
1-[3-(4-Bromo-2-methyl-2H-pyrazol-3-yl)-4-phenethyloxy-
phenyl]-3-(4-chlorophenyl)urea (34). 3-(4-Bromo-2-methyl-2H-
pyrazol-3-yl)-4-phenethyloxyphenylamine (0.028 g, 0.07 mmol)
was treated with 4-chlorophenyl isocyanate (0.014 g, 0.09 mmol)
in methylene chloride (1 mL) in a similar manner as described
for 3 to afford 34 (0.025 g, 0.05 mmol, 66%) as a solid film.
LCMS m/z (%) = 525 (M þ H79Br35Cl, 85), 527 (M þ
H81Br35Cl, 100), 529 (M þ H81Br37Cl, 31). 1H NMR (400
MHz, acetone-d6) δ: 8.34 (s, 1H), 8.26 (s, 1H), 7.65 (dd, J =
2.7, 8.9 Hz, 1H), 7.56 (d, J = 8.9 Hz, 2H), 7.53 (s, 1H), 7.43 (d,
J = 2.7 Hz, 1H), 7.16-7.31 (m, 5 H), 7.09-7.16 (m, 3H),
4.11-4.30 (m, 2H), 3.51 (s, 3H), 2.86-3.06 (m, 2H).
1-[3-(4-Chloro-2-methyl-2H-pyrazol-3-yl)-4-methoxyphenyl]-
3-(4-chlorophenyl)urea (35). 3-(4-Chloro-2-methyl-2H-pyrazol-
3-yl)-4-methoxyphenylamine was treated with 4-chlorophenyl
isocyanate in methylene chloride in a similar manner as de-
scribed for 3, providing 12 mg (30%) of 35. LCMS m/z (%) =
393 (MþH37Cl, 60), 391 (MþH35Cl, 100). 1H NMR (400 MHz,
DMSO-d6) δ: 8.80 (s, 1H), 8.71 (s, 1H), 7.62 (s, 1H), 7.57 (dd,
J1 = 8 Hz, J2 = 4 Hz, 1H), 7.49 (dd, J1 = 8 Hz, J2 = 2 Hz, 2H),
7.39 (d, J = 4 Hz, 1H), 7.33 (dd, J1 = 8 Hz, J2 = 2 Hz, 2H), 7.17
(d, J = 8 Hz, 1H), 3.77 (s, 3H), 3.62 (s, 3H).
1-(4-Chlorophenyl)-3-[4-methoxy-3-(2-methyl-2H-pyrazol-3-yl)-
phenyl]urea. (36). 4-Methoxy-3-(2-methyl-2H-pyrazol-3-yl)pheny-
lamine (0.291 g, 1.43 mmol) was treated with 4-chlorophenyl iso-
cyanate (0.247 g, 1.57 mmol) in methylene chloride (5 mL) in a
similar manner as described for 3, providing 36 (0.415 g, 1.16 mmol,
81%) as a white solid. LCMS m/z (%) = 357 (M þ H). 1H NMR
(400 MHz, acetone-d6) δ:8.21(s,1H),8.07(s,1H),7.58(dd,J=2.8,
8.9 Hz, 1H), 7.56 (d, J = 8.8 Hz, 2H), 7.44 (d, J = 2.7 Hz, 1H), 7.39
(d, J = 1.8 Hz, 1H), 7.28 (d, J = 8.8 Hz, 2H), 7.08 (d, J = 8.9 Hz,
1H), 6.20 (d, J = 1.8 Hz, 1H), 3.81 (s, 3H), 3.68 (s, 3H).
1-[3-(4-Bromo-2-methyl-2H-pyrazol-3-yl)-4-trifluoromethoxy-
phenyl]-3-(4-chlorophenyl)urea (29). To a solution of [3-(2-meth-
yl-2H-pyrazol-3-yl)-4-trifluoromethoxyphenyl]carbamic acid
tert-butyl ester (21.8 mg, 0.05 mmol) in methylene chloride
(0.5 mL), trifluoroacetic acid (0.5 mL) was added. The reaction
mixture stirred at room temperature for 20 min. The solvent was
removed under reduced pressure to afford 3-(4-bromo-2-meth-
yl-2H-pyrazol-3-yl)-4-trifluoromethoxyphenylamine trifluoro-
acetate as a colorless oil. LCMS m/z (%) = 336 (M þ H79Br,
100), 338 (M þ H81Br, 95). This intermediate was dissolved in
methylene chloride (0.8 mL) and then treated with N,N-diiso-
propylethylamine until pH 7-8 was obtained. 4-Chlorophenyl
isocyanate (8.5 mg, 0.055 mmol) was added and reaction
mixture stirred at room temperature overnight and concen-
trated to give a residue that was subjected to a purification by
flash chromatography (SiO2, hexanes/ethyl acetate) to afford 29
as a white solid in 62.0% yield. LCMS m/z (%) = 489 (M þ
H79Br35Cl, 93), 491 (M þ H81Br35Cl, 100), 493 (M þ H 81Br37Cl,
1
34). H NMR (400 MHz, CD3OD) δ: 7.71 (dd, J = 9.0 Hz,
2.7 Hz, 1H), 7.64-7.62 (m, 2H), 7.49-7.45 (m, 3H), 7.33-7.30
(m, 2H), 3.76 (s, 3H).
1-[3-(4-Bromo-2-methyl-2H-pyrazol-3-yl)-4-ethoxyphenyl]-3-
(4-chlorophenyl)urea (30). 3-(4-Bromo-2-methyl-2H-pyrazol-3-
yl)-4-ethoxyphenylamine (0.040 g, 0.13 mmol) was treated with
4-chlorophenyl isocyanate (0.023 g, 0.15 mmol, 1.1 equiv) in
methylene chloride (1 mL) in a similar manner as described for 3
to afford 30 (0.034 g, 0.08 mmol, 56%) as a white solid. LCMS
m/z (%) = 449 (M þ H79Br35Cl, 72), 451 (M þ H81Br35Cl, 100),
1
453 (M þ H81Br37Cl, 26). H NMR (400 MHz, acetone-d6) δ:
8.22 (s, 1H), 8.14 (s, 1H), 7.66 (dd, J = 2.7, 9.0 Hz, 1H), 7.56 (d,
J = 8.8 Hz, 2H), 7.49 (s, 1H), 7.43 (d, J = 2.7 Hz, 1H), 7.28 (d,
J = 8.8 Hz, 2H), 7.12 (d, J = 9.0 Hz, 1H), 3.98-4.18 (m, 2H),
3.71 (s, 3H), 1.28 (t, J = 7.1 Hz, 3H).
1-[3-(4-Bromo-2-methyl-2H-pyrazol-3-yl)-4-methoxyphenyl]-
3-(2,4-dichlorophenyl)urea (37). 3-(4-Bromo-2-methyl-2H-pyra-
zol-3-yl)-4-methoxyphenylamine (0.031 g, 0.11 mmol) was trea-
ted with 2,4-dichlorophenyl isocyanate (0.021 g, 0.11 mmol) in
methylene chloride (2 mL) in a similar manner as described for 3
to afford 37 (0.036 g, 0.076 mmol, 69%) as a white solid. LCMS
m/z (%) = 469 (M þ H79Br35Cl35Cl, 60), 471 (M þ H79Br35Cl37-
Cl and 81Br35Cl35Cl, 100), 473 (M þ H81Br35Cl37Cl79Br37Cl37Cl,
54), 475 (M þ H81Br37Cl37Cl, 4). 1H NMR (400 MHz, acetone-
d6) δ: 8.81 (s, 1H), 8.36 (d, J = 9.0 Hz, 1H), 7.91 (s, 1H), 7.69 (dd,
J = 2.7, 9.0 Hz, 1H), 7.50 (s, 1H), 7.48 (d, J = 2.4 Hz, 1H), 7.45
(d, J = 2.7 Hz, 1H), 7.34 (dd, J = 2.4, 9.0 Hz, 1H), 7.15 (d, J =
9.0 Hz, 1H), 3.83 (s, 3H), 3.69 (s, 3H).
1-[3-(4-Bromo-2-methyl-2H-pyrazol-3-yl)-4-isopropoxyphenyl]-
3-(4-chlorophenyl)urea (31). 3-(4-Bromo-2-methyl-2H-pyrazol-
3-yl)-4-isopropoxyphenylamine (0.024 g, 0.08 mmol) was trea-
ted with 4-chlorophenyl isocyanate (0.014 g, 0.09 mmol) in
methylene chloride (1 mL) in a similar manner as described
for 3 to afford 31 (0.034 g, 0.07 mmol, 91%) as a white solid.
LCMS m/z (%) = 463 (M þ H79Br35Cl, 82), 465 (M þ H81-
1
Br35Cl, 100), 467 (M þ H81Br37Cl, 29). H NMR (400 MHz,
acetone-d6) δ: 8.24 (s, 1H), 8.17 (s, 1H), 7.65 (dd, J = 2.5, 8.9 Hz,
1H), 7.55 (d, J = 8.6 Hz, 2H), 7.49 (s, 1H), 7.42 (d, J = 2.5 Hz,
1H), 7.28 (d, J = 8.6 Hz, 2H), 4.42-4.52 (m, 1H), 3.70 (s, 3H),
1.26 (d, J = 6.0 Hz, 3H), 1.11 (d, J = 6.0 Hz, 3H).
1-[4-Benzyloxy-3-(4-bromo-2-methyl-2H-pyrazol-3-yl)phenyl]-
3-(4-chlorophenyl)urea (32). 4-Benzyloxy-3-(4-bromo-2-methyl-
2H-pyrazol-3-yl)-phenylamine (0.023 g, 0.09 mmol) was
treated with 4-chlorophenyl isocyanate (0.016 g, 0.10 mmol) in
1-[3-(4-Bromo-2-methyl-2H-pyrazol-3-yl)-4-methoxyphenyl]-
3-(3,5-difluorophenyl)urea (38). 3-(4-Bromo-2-methyl-2H-pyra-
zol-3-yl)-4-methoxyphenylamine (0.032 g, 0.11 mmol) was

Article
Journal of Medicinal Chemistry, 2010, Vol. 53, No. 5 1935
treated with 3,5-difluorophenyl isocyanate (14 μL, 0.11 mmol)
in methylene chloride (2 mL) in a similar manner as described
for 3 to afford 37 (0.038 g, 0.09 mmol, 77%) as a white solid.
LCMS m/z (%) = 437 (M þ H79Br, 100), 439 (M þ H81Br, 100).
1H NMR (400 MHz, acetone-d6) δ: 8.47 (s, 1H), 8.23 (s, 1H),
7.68 (dd, J = 2.7, 9.0 Hz, 1H), 7.50 (s, 1H), 7.42 (d, J = 2.7 Hz,
1H), 7.18-7.27 (m, 2H), 7.15 (d, J = 9.0 Hz, 1H), 6.59 (ttt, J =
2.3, 9.1, 9.1 Hz, 1H), 3.82 (s, 3H), 3.68 (s, 3H).
1-[3-(4-Bromo-2-methyl-2H-pyrazol-3-yl)-4-methoxyphenyl]-
3-(2,4-difluorophenyl)urea (39). 3-(4-Bromo-2-methyl-2H-pyra-
zol-3-yl)-4-methoxyphenylamine (0.027 g, 0.095 mmol) was
treated with 2,4-difluorophenyl isocyanate (11.5 μL, 0.095 mmol)
in methylene chloride (2 mL) in a similar manner as described
for 3 to afford 39 (0.030 g, 0.069 mmol, 71%) as a white solid.
LCMS m/z (%) = 437 (M þ H79Br, 100), 439 (M þ H81Br, 91).
1H NMR (400 MHz, acetone-d6) δ: 8.45 (s, 1H), 8.23 (dt, J =
6.1, 9.2 Hz, 1H), 7.93 (s, 1H), 7.68 (dd, J = 2.6, 9.0 Hz, 1H), 7.49
(s, 1H), 7.44 (d, J = 2.6 Hz, 1H), 7.14 (d, J = 9.0 Hz, 1H), 7.07
(ddd, J = 2.7, 8.7, 11.3 Hz, 1H), 6.93-7.02 (m, 1H), 3.82 (s, 3H),
3.69 (s, 3H).
1-[3-(4-Chloro-2-methyl-2H-pyrazol-3-yl)-4-methoxyphenyl]-
3-(2,4-difluorophenyl)urea (40). 3-(4-Chloro-2-methyl-2H-pyra-
zol-3-yl)-4-methoxyphenylamine was treated with 2,4-difluor-
ophenyl isocyanate in methylene chloride (2 mL) in a similar
manner as described for 3, providing 26.7 mg (36%) of 40 as a
white solid. LCMS m/z (%) = 393 (M þ H35Cl, 100), 395 (M þ
H37Cl, 35). 1H NMR (400 MHz, DMSO-d6) δ: 9.00 (s, 1H), 8.43
(s, 1H), 8.03 (m, J1 = 12 Hz, J2 = 4 Hz, 1H), 7.56 (s, 1H), 7.50
(dd, J1 = 8 Hz, J2 = 4 Hz, 1H), 7.34 (d, J = 4 Hz, 1H), 7.28 (m,
J1 = 12 Hz, J2 = 4 Hz, 1H), 7.12 (d, J = 8 Hz, 1H), 7.01 (m,
J1 = 8 Hz, J2 = 2 Hz, 1H), 3.72 (s, 3H), 3.56 (s, 3H).
(32%) of 44 as a white solid. LCMS m/z (%) = 493 (M þ H35Cl,
1
100), 495 (M þ H37Cl, 41). H NMR (400 MHz, DMSO-d6) δ:
9.58 (s, 1H), 9.18 (s, 1H), 8.31 (s, 2H), 7.80 (s, 1H), 7.79 (s, 1H),
7.79 (dd, J1 = 8 Hz, J2 = 4 Hz, 1H), 7.59 (d, J = 2 Hz, 1H), 7.36
(d, = 8 Hz, 1H), 3.96 (s, 3H), 3.80 (s, 3H).
1-[3-(4-Bromo-2-methyl-2H-pyrazol-3-yl)-4-methoxyphenyl]-
3-(4-chloro-2-trifluoromethylphenyl)urea (45). To a stirred solu-
tion of 3-(4-bromo-2-methyl-2H-pyrazol-3-yl)-4-methoxyphe-
nylamine (0.034 g, 0.12 mol) in methylene chloride (1 mL) was
added 4-chloro-2-(trifluoromethyl)phenyl isocyanate (20.0 μL,
0.13 mmol) at room temperature. White precipitated solid was
filtered and washed with cold methylene chloride to afford
(45) (0.037 g, 0.074 mmol, 60%) as a white solid. LCMS m/z
(%) = 503 (M þ H79Br, 77), 505 (M þ H81Br, 100). 1H NMR
(400 MHz, acetone-d6) δ: 8.82 (s, 1H), 8.22 (d, J = 9.6 Hz, 1H),
7.62-7.72 (m, 4H), 7.49 (s, 1H), 7.43 (d, J = 2.6 Hz, 1H), 7.15
(d, J = 9.0 Hz, 1H), 3.83 (s, 3H), 3.68 (s, 3H).
1-[3-(4-Bromo-2-methyl-2H-pyrazol-3-yl)-4-methoxyphenyl]-
3-(4-chloro-3-trifluoromethylphenyl)urea (46). 3-(4-Bromo-2-
methyl-2H-pyrazol-3-yl)-4-methoxyphenylamine (0.035 g, 0.12
mmol) was treated with 4-chloro-3-(trifluoromethyl)phenyl iso-
cyanate (0.027 g, 0.12 mmol) in methylene chloride (2 mL) in
a similar manner as described for 3 to afford (46) (0.051 g,
0.10 mmol, 81%) as a white solid. LCMS m/z (%) = 503 (M þ
H79Br35Cl, 78), 505 (M þ H81Br35Cl, 100), 507 (M þ H81Br37Cl,
28). 1H NMR (400 MHz, acetone-d6) δ: 8.52 (s, 1H), 8.27 (s, 1H),
8.13 (s, 1H), 7.74 (d, J = 8.7 Hz, 1H), 7.68 (d, J = 9.0 Hz, 1H),
7.53 (d, J = 8.7 Hz, 1H), 7.49 (s, 1H), 7.43 (s, 1H), 7.14 (d, J =
9.0 Hz, 1H), 3.82 (s, 3H), 3.68 (s, 3H).
References
1-[3-(4-Chloro-2-methyl-2H-pyrazol-3-yl)-4-methoxyphenyl]-
3-(3,4-difluorophenyl)urea (41). 3-(4-Chloro-2-methyl-2H-pyra-
zol-3-yl)-4-methoxyphenylamine (30 mg, 0.13 mmol) was trea-
ted with 3,4-difluorophenyl isocyanate (17 μL, 0.14 mmol) in
methylene chloride (2 mL) in a similar manner as described for 3,
providing 18.6 mg (34%) of 41 as a white solid. LCMS m/z
(%) = 393 (M þ H35Cl, 100), 395 (M þ H37Cl, 38). 1H NMR
(400 MHz, acetone-d6) δ: 8.18 (s, 1H), 8.05 (s, 1H), 7.65 (m, 1H),
7.57 (dd, J1 = 8 Hz, J2 = 4 Hz, 1H), 7.36 (s, 1H), 7.33 (d, J =
2 Hz, 1H), 7.09 (d, J = 4 Hz, 1H), 7.06 (d, J = 2 Hz, 1H), 7.04 (d,
J = 8 Hz, 1H), 3.72 (s, 3H), 3.55 (s, 3H).
(1) Coleman, R. M.; Roffwarg, H. P.; Kennedy, S. J.; Guilleminault, C.;
Cinque, J.; Cohn, M. A.; Karacan, I.; Kupfer, D. J.; Lemmi, H.;
Miles, L. E.; Orr, W. C.; Phillips, E. R.; Roth, T.; Sassin, J. F.;
Schmidt, H. S.; Weitzman, E. D.; Dement, W. C. Sleep-wake
disorders based on a polysomnography diagnosis. A National
Cooperative Study. JAMA, J. Am. Med. Assoc. 1982, 247, 997–1003.
(2) Alberto, J.; Silva, C. E. Sleep disorders in psychiatry. Metab., Clin.
Exp. 2006, 55, S40–S44.
(3) 2005 Sleep in America Poll; National Sleep Foundation: Washington,
DC, 2005.
(4) De Settimo, F.; Taliani, S.; Trincavelli, M. L.; Montali, M.;
Martini, C. GABA A/Bz receptor subtypes as targets for selective
drugs. Curr. Med. Chem. 2007, 14, 2680–2701.
1-(3,4-Difluorophenyl)-3-[3-(4-fluoro-2-methyl-2H-pyrazol-3-
yl)-4-methoxyphenyl]urea (42). 3-(4-Fluoro-2-methyl-2H-pyra-
zol-3-yl)-4-methoxyphenylamine was treated with 3,4-difluor-
ophenyl isocyanate in methylene chloride (2 mL) in a similar
manner as described for 3, providing 27 mg (63% yield) of 42 as
(5) Mendelson, W. B.; Roth, T.; Cassella, J.; Roehrs, T.; Walsh, J. K.;
Woods, J. H.; Buysse, D. J.; Meyer, R. E. The treatment of chronic
insomnia: drug indications, chronic use and abuse liability. Sum-
mary of a 2001 New Clinical Drug Evaluation Unit meeting
symposium. Sleep Med. Rev. 2004, 8, 7–17.
1
(6) Krystal, A. D. The changing perspective on chronic insomnia
a white solid. LCMS m/z (%) = 377 (M þ H, 100). H NMR
management. J. Clin. Psychiatry 2004, 65, S20–S25.
(400 MHz, acetone-d6) δ: 8.28 (s, 1H), 8.12 (s, 1H), 7.74 (ddd,
J1 = 13.5 Hz, J2 = 7.3 Hz, J3 = 2.5 Hz, 1H), 7.63 (ddd, J1 = 8.8
(7) Roth, T.; Roehrs, T. A. A review of the safety profiles of benzo-
diazepine hypnotics. J. Clin. Psychiatry 1991, 52, 38–41.
(8) Mendelson, W. B. Clinical distinctions between long-acting and
short-acting benzodiazepines. J. Clin. Psychiatry 1992, 53, 8–9.
(9) Sanders-Bush, E.; Fentress, H.; Hazelwood, L. Serotonin 5-HT2
receptors: molecular and genomic diversity. Mol. Interventions
2003, 3, 319–330.
(10) Hoyer, D.; Clarke, D. E.; Fozard, J. R.; Hartig, P. R.; Martin,
G. R.; Mylecharane, E. J.; Saxena, P. R.; Humphery, P. P. Inter-
national Union of Pharmacology classification of receptors for
5-hydroxytryptamine (serotonin). Pharmacol. Rev. 1994, 46, 157–203.
(11) Sharpley, A. L.; Solomon, R. A.; Fernando, J. M.; Da Roza Davis,
J. M.; Cowen, P. J. Dose-related effects of selective 5-HT2 receptor
antagonists on slow wave sleep in humans. Psychopharmacology
1990, 101, 568–569.
Hz, J2 = 2.8 Hz, 1H), 7.47 (d, J = 2.8 Hz, 1H), 7.38 (d, JH,F
=
4.4 Hz, 1H), 7.16 (m, 3H), 3.84 (s, 3H), 3.65 (s, 3H). 19F NMR
(376 MHz, acetone-d6) δ: -138.89 (m, 1F), -148.38 (m, 1F),
-177.40 (d, JH,F = 5.3 Hz, 1F).
1-(3,5-Bis-trifluoromethylphenyl)-3-[3-(4-bromo-2-methyl-2H-
pyrazol-3-yl)-4-methoxyphenyl]urea (43). 3-(4-Bromo-2-methyl-
2H-pyrazol-3-yl)-4-methoxyphenylamine (0.037 g, 0.13 mmol)
was treated with 3,5-bis(trifluoromethyl)phenyl isocyanate
(24.0 μL, 0.14 mmol) in methylene chloride (1 mL) in a similar
manner as described for 3 to afford 43 (0.030 g, 0.06 mmol, 43%)
as a white solid. LCMS m/z (%) = 537 (M þ H79Br, 99), 539
(M þ H81Br, 100). 1H NMR (400 MHz, acetone-d6) δ: 8.77 (s,
1H), 8.42 (s, 1H), 8.22 (s, 2H), 7.73 (dd, J = 2.5, 9.0 Hz, 1H),
7.51 (s, 1H), 7.46 (d, J = 2.5 Hz, 1H), 7.18 (d, J = 9.0 Hz, 1H),
3.85 (s, 3H), 3.71 (s, 3H).
1-(3,5-Bis-trifluoromethylphenyl)-3-[3-(4-chloro-2-methyl-2H-
pyrazol-3-yl)-4-methoxyphenyl]urea (44). 3-(4-Chloro-2-methyl-
2H-pyrazol-3-yl)-4-methoxyphenylamine was treated with
3,5-bis(trifluoromethyl)phenyl isocyanate in methylene chloride
(2 mL) in a similar manner as described for 3, providing 21.5 mg
(12) Dugovic, C.; Wauquier, A. 5-HT2 receptors could be primarily
involved in the regulation of slow wave sleep in the rat. Eur.
J. Pharmacol. 1987, 137, 145–146.
(13) Bacon, E. R.; Chatterjee, S.; Williams, M. Sleep. Compr. Med.
Chem. II 2006, 6, 139–167.
(14) Palomer, A.; Princep, M.; Guglietta, A. Recent advances in the
treatment of insomnia. Annu. Rep. Med. Chem. 2007, 42, 63–80.
(15) Teegarden, B. R.; Al-Shamma, H.; Xiong, Y. 5-HT2A inverse-
agonists for the treatment of insomnia. Curr. Top. Med. Chem.
2008, 8, 969–976.

1936 Journal of Medicinal Chemistry, 2010, Vol. 53, No. 5
Teegarden et al.
(16) Idzikowski, C.; Mills, F. J.; Glennard, R. 5-Hydroxytryptamine-
2 antagonist increases human slow wave sleep. Brain Res. 1986,
378, 164–168.
1-alkyl-1H-pyrazol-4-ylboronic acids. J. Heterocycl. Chem. 2004,
41, 931–939.
(24) Teegarden, B.; Jayakumar, H.; Li, H.; Strah-Pleynet, S.; Dosa, P.
Diaryl and Arylheteroaryl Urea Derivatives as Modulators of
the 5-HT2A Serotonin Receptor Useful for the Prophylaxis and
Treatment of Disorders Related Thereto. Pct Int. Appl. WO/
2005012254, 2005.
ꢀ
(17) Borbely, A. A.; Trachsel, L.; Tobler, I. Effect of ritanserin on sleep
stages and sleep EEG in the rat. Eur. J. Pharmacol. 1988, 156, 275–
278.
(18) Popa, D.; Lena, C.; Fabre, V.; Prenat, C.; Gingrich, J.; Escourrou,
ꢀ
P.; Hamon, M.; Adrien, J. Contribution of 5-HT2 receptor sub-
types to sleep-wakefulness and respiratory control, and functional
adaptations in knock-out mice lacking 5-HT2A receptors. J. Neu-
rosci. 2005, 25 (49), 11231–11238.
(25) Miyaura, N.; Akira Suzuki, A. Palladium-catalyzed cross-coupling
reactions of organoboron compounds. Chem. Rev. 1995, 95, 2457–
2483.
(26) Thomsen, W. J.; Grottick, A. J.; Menzaghi, F.; Reyes-Saldana, H.;
Espitia, S.; Yuskin, D.; Whelan, K.; Martin, M.; Morgan, M.;
Chen, W.; Al-Shamma, H.; Smith, B.; Chalmers, D.; Behan, D.
Lorcaserin, a novel selective human 5-hydroxytryptamine2C ago-
nist: in vitro and in vivo pharmacological characterization.
J. Pharmacol. Exp. Ther. 2008, 325 (2), 577–587.
(27) Hillegaart, V.; Estival, A.; Ahlenius, S. Evidence for specific
involvement of 5-HT1A and 5-HT2A/C receptors in the expression
of patterns of spontaneous motor activity of the rat. Eur.
J. Pharmacol. 1996, 295, 155–161.
(28) Reversal of DOI-induced reductions in rearing in rats after a single
high dose (50 mg/kg po) of each analogue (unpublished results).
(29) Vivaldi, E. A.; Ocampo, A.; Wyneken, U.; Roncagliolo, M.; Zapata,
A. M. Short-term homeostasis of active sleep and the architecture of
sleep in the rat. J Neurophysiol. 1994, 72 (4), 1745–1755.
(30) Rosenberg, R.; Seiden, D. J.; Hull, S. G.; Erman, M.; Schwartz, H.;
Anderson, C.; Prosser, W.; Shanahan, W.; Sanchez, M.; Chuang,
E.; Roth, T. APD125, a selective serotonin 5-HT2A receptor inverse
agonist, significantly improves sleep maintenance in primary in-
somnia. Sleep 2008, 31, 1663–1671.
(19) Morairty, S. R.; Hedley, L; Flores, J.; Martin, R.; Kilduff, T. S.
Selective 5HT2A and 5HT6 receptor antagonists promote sleep in
rats. Sleep. 2008, 31 (1), 34–44.
(20) Landolt, H. P.; Meier, V.; Burgess, H. J.; Finelli, L. A.; Cattelin, F.;
Achermann, P.; Borbely, A. A. Serotonin-2 receptors and human
sleep: effect of a selective antagonist on EEG power spectra.
Neuropsychopharmacology 1999, 21, 455–466.
(21) Francon, D.; Decobert, M.; Herve, B.; Richard, A.; Griebel, G.;
Avenet, P.; Scatton, B.; Fur, G. L. Eplivanserin promotes sleep
maintenance in rats. Sleep Biol. Rhythms 2007, 5, A3.
(22) Jayakumar, H.; Teegarden, B. R.; Li, H.; Strah-Pleynet, S.; Dosa,
P. I.; Selaya, S. D.; Kato, N.; Elwell, K.; Davidson, J.; Cheng, K.;
Foster, J.; Espitia, S.; Chen, X.; Thomsen, W.; Reyes, H. Synthesis
and SAR of Alkoxyphenyl Pyrazole as 5-HT2A Inverse Agonists.
Abstracts of Papers, 232nd National Meeting of the American Che-
mical Society, San Francisco, CA, 2006; American Chemical Society:
Washington, DC, 2006; MEDI-430.
(23) Ivachtchenko, A. V.; Kravchenko, D. V.; Zheludeva, V. I.; Pershin,
D. G. Synthesis of pinacol esters of 1-alkyl-1H-pyrazol-5-yl- and