Design of 2,5-dimethyl-3-(6-dimethyl-4-methylpyridin-3-yl)-7-dipropylamino- pyrazolo[1,5-a]pyrimidine (NBI 30775/R121919) and structure-activity relationships of a series of potent and orally active corticotropin-releasing factor receptor antagonists

Article abstract of DOI:10.1021/jm040058e

We previously shown that 3-phenylpyrazolo[1,5-a]pyrimidines exemplified by 8 were potent antagonists of the human corticotropin-releasing factor-1 receptor. A series of 3-pyridylpyrazolo-[1,5-a]pyrimidines 15, 25-30, 34, and 35 containing a weakly basic pyridine ring at the 3-position of the bicyclic nucleus was designed to reduce lipophilicity from the initial leads such as 7. Here, we showed that these 3-pyridyl compounds exhibited potent antagonists at the human CRF₁ receptor. Moreover, the hydrophilic and weakly basic pyridine moiety increased the water solubility of some analogues. Compound 26h exhibited good binding affinity at the human CRF₁ receptor with a K_i value of 3.5 nM. As a functional antagonist, it dose-dependently inhibited CRF-stimulated cAMP production in cells expressing the CRF₁ receptor (IC₅₀ = 50 nM), and CRF-stimulated ACTH release from cultured rat pituitary cells (IC₅₀ = 20 nM). 26h had a log P value of 4.9 and water solubility of greater than 10 mg/mL. Pharmacokinetic studies in rats showed that 26h was orally bioavailable and able to penetrate into the brain. 26h has been demonstrated in vivo efficacy in animal behavioral models that measure anxiolytic activity. These results suggest that analogues from this series were potent CRF₁ receptor antagonists with proper physicochemical properties and good pharmacokinetic profiles. 26h was developed into a clinical compound and exhibited efficacy in patients with major depression.

Full text of DOI:10.1021/jm040058e

J . Med. Chem. 2004, 47, 4787-4798
4787
Design of 2,5-Dim eth yl-3-(6-d im eth yl-4-m eth ylp yr id in -3-yl)-7-d ip r op yla m in o-
p yr a zolo[1,5-a ]p yr im id in e (NBI 30775/R121919) a n d Str u ctu r e-Activity
Rela tion sh ip s of a Ser ies of P oten t a n d Or a lly Active Cor ticotr op in -Relea sin g
F a ctor Recep tor An ta gon ists
Chen Chen,* Keith M. Wilcoxen, Charles Q. Huang, Yun-Feng Xie, J ames R. McCarthy, Thomas R. Webb,
Yun-Fei Zhu, J ohn Saunders, Xin-J un Liu, Ta-Kung Chen, Haig Bozigian, and Dimitri E. Grigoriadis
Neurocrine Biosciences, Inc., 10555 Sciences Center Drive, San Diego, California 92121
Received March 3, 2004
We have previously shown that 3-phenylpyrazolo[1,5-a]pyrimidines exemplified by 8 were potent
antagonists of the human corticotropin-releasing factor-1 receptor. A series of 3-pyridylpyrazolo-
[1,5-a]pyrimidines 15, 25-30, 34, and 35 containing a weakly basic pyridine ring at the
3-position of the bicyclic nucleus was designed to reduce lipophilicity from the initial leads
such as 7. Here, we showed that these 3-pyridyl compounds exhibited potent antagonists at
the human CRF1 receptor. Moreover, the hydrophilic and weakly basic pyridine moiety increased
the water solubility of some analogues. Compound 26h exhibited good binding affinity at the
human CRF1 receptor with a Ki value of 3.5 nM. As a functional antagonist, it dose-dependently
inhibited CRF-stimulated cAMP production in cells expressing the CRF1 receptor (IC50 ) 50
nM), and CRF-stimulated ACTH release from cultured rat pituitary cells (IC50 ) 20 nM). 26h
had a log P value of 4.9 and water solubility of greater than 10 mg/mL. Pharmacokinetic studies
in rats showed that 26h was orally bioavailable and able to penetrate into the brain. 26h has
been demonstrated in vivo efficacy in animal behavioral models that measure anxiolytic activity.
These results suggest that analogues from this series were potent CRF1 receptor antagonists
with proper physicochemical properties and good pharmacokinetic profiles. 26h was developed
into a clinical compound and exhibited efficacy in patients with major depression.
In tr od u ction
pounds possess excellent in vitro activities as CRF1
antagonists, and several of them have exhibited in vivo
efficacy in anxiety models when dosed orally, most of
the compounds reported earlier suffer from high lipo-
philicity and poor water solubility.15 Therefore, it is very
difficult to develop these compounds into pharmaceuti-
cal agents for clinical usage. For example, 1 has a very
long half-life (51 h) associated with high volume distri-
bution (105 L/kg) in rats.16 Recent efforts on discovery
of more hydrophilic CRF1 antagonists have resulted in
compounds such as 8-10 with proper lipophilicity.17 In
our efforts to identify potent CRF1 antagonists with
drug-like properties, we synthesized 3-phenylpyrazolo-
[1,5-a]pyrimidines such as 8 (NBI 30545)17a by incor-
poration of polar alkoxy groups into the highly lipophilic
molecules such as 7.18 By using ACD/LogP software,19
we calculated log P values of some small molecule CRF1
antagonists to assess the relative lipophilicities of these
compounds. For example, the C log P values of 1 and 3
were 8.43 and 9.71. However, 8 had a C log P of 3.18, a
desirable value for CNS agents,20 which was much lower
than that of 7 (C log P ) 5.86). As an alternative,
replacement of the 3-phenyl group of the 3-phenylpyra-
zolo[1,5-a]pyrimidine with a hydrophilic and weakly
basic pyridine moiety should reduce the lipophilicity of
this series of compounds. In addition, alternation of
substituents at the pyridine ring will also change the
basicity and hydrophilicity of the target molecules. In
this paper we report the design, synthesis, and struc-
ture-activity relationships of a series of 3-pyridylpyra-
zolo[1,5-a]pyrimidines as potent CRF1 receptor antago-
Corticotropin-releasing factor (CRF, also known as
corticotropin-releasing hormone), a neuropeptide iso-
lated from mammalian brain,1 is the prime regulator
of the hypothalamus-pituitary-adrenocortical (HPA)
axis.2 It has broad extrahypothalamic distribution in the
central nervous system and produces a wide spectrum
of autonomic, electrophysiological, and behavioral effects
consistent with a neurotransmitter or neuromodulator
role in the brain.3 CRF has been implicated as the
mediator for the integrated physiological response to
stress,4 and it mediates its actions through high affinity
binding to its receptors, CRF1-R and CRF2-R, both of
which are members of the class B G-protein-coupled
receptor superfamily.5 Inhibition of CRF1 receptor has
been shown to reduce ACTH level in plasma of stressed
animals.6 Antagonists of the CRF1 receptor are expected
to have utility in treatment of stress-related diseases
such as anxiety/depression and diseases involving the
HPA axis.7
Since the first small molecule CRF1 receptor antago-
nist CP-154,526 was reported in 1996,8 many com-
pounds from different chemical classes have appeared
in the literature.9 Potent CRF1 antagonists such as 1
(CP-154,526), 2 (Antalarmin),10 3 (NBI 27914),11
4
(DMP904),12 5 (CRA1000),13 and 6 (SRA125543A)14
(Figure 1) have been widely studied in different animal
models for CRF related behavior. Although these com-
* Corresponding author. Phone: 1-858-658-7634. Fax: 1-858-658-
7619. E-mail: cchen@neurocrine.com.
10.1021/jm040058e CCC: $27.50 © 2004 American Chemical Society
Published on Web 08/06/2004

4788 J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 19
Chen et al.
F igu r e 1. Some small molecule CRF1 receptor antagonists.
Sch em e 1. Synthesis of 3-(Pyridin-2-yl)pyrazolo[1,5-a]pyrimidine 15a
a
Reagents and conditions: (a) MeC(ONa)dCHCN/DMSO; (b) (i) NH2NH2HBr/H2O/EtOH/reflux; (c) ethyl acetoacetate/dioxane/reflux;
(d) POCl3/reflux; (e) Pr2NH/acetonitrile/reflux; (f) H2/Pd-C/EtOH; (g) CH2O/NaBCNH3/AcOH.
nists.21 In particular, the discovery, in vitro activities,
and pharmacokinetic properties of 26h (NBI 30775/
R121919), which has exhibited anxiolytic effects in
vivo22 and clinical efficacy in patients with major
depression,23 will be discussed.
corresponding 7-chloropyrazolo[1,5-a]pyrimidine 12 was
accomplished with POCl3 in refluxing acetonitrile (91%
yield). Compound 13 was synthesized by reaction of 12
with dipropylamine in refluxing acetonitrile in 69%
yield. This nitro compound 13 was reduced under
palladium-catalyzed hydrogenation conditions to give
the corresponding analine 14 in 80% yield, which was
further modified to 15 by using a standard reductive
alkylation protocol with formaldehyde.26
Ch em istr y
The 3-(pyridin-2-yl)pyrazolo[1,5-a]pyrimidine 15 was
synthesized as showed in Scheme 1. Thus, reaction of
2-chloro-3-methyl-5-nitropyridine with acetoacetonitrile
sodium salt, obtained from 2-methylisoxazole and so-
dium ethoxide,24 afforded 2-(3-methyl-5-nitropyridin-2-
yl)acetoacetonitrile in 61% yield,25 which was cyclized
with hydrazine hydrobromide in a mixture of ethanol-
water (10:1) at reflux to give 3-amino-4-(3-methyl-5-
nitropyridin-2-yl)-5-methylpyrazole in 41% yield. This
compound was subjected to a second cyclization with
ethyl acetoacetate in refluxing dioxane to provide the
3-(pyridin-2-yl)pyrazolo[1,5-a]pyrimidone 11 as a white
solid (26%). Conversion of the pyrimidone 11 to the
The 3-(pyridin-3-yl)pyrazolo[1,5-a]pyrimidines 25-30
were prepared by the procedures outlined in Schemes
3-5 and illustrated below. Commercially available
2-aminopyridines 16a -d were converted to the corre-
sponding dimethylaminopyridines 17a -d using a stan-
dard reductive alkylation protocol with formaldehyde
and sodium cyanoborohydride.26 The pyridines 17a -d
were brominated in dichloromethane to give the corre-
sponding 2-dimethylamino-5-bromopyridines 18a -d as
the major products.27 The regioisomeric structures were
1
assigned on the basis of the coupling constants of H

Design of NBI 30775/ R121919
J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 19 4789
Sch em e 2. Synthesis of 6-Dimethylaminopyridin-3-ylacetonitriles 20a -d a
a
Reagents and conditions: (a) 37% aqueous CH2O/NaCNBH3/AcOH; (b) Br2/aqueous Na2CO3/CH2Cl2/room temperature; (c) Mg/THF,
then DMF/0 °C to room temperature; (d) TosMIC/t-BuOK/DME/-50 °C, then MeOH/reflux.
Sch em e 3. Synthesis of 3-(Pyridin-3-yl)pyrazolo[1,5-a]pyrimidines 25-30a
a
Reagents and conditions: (a) NaH/THF/EtOAc/room temperature; (b) NH2NH2HBr/EtOH-H2O/reflux; (c) ethyl acetoacetate/dioxane/
reflux; (d) POCl3/ACN/reflux; (e) R5R6NH/ACN/reflux.
Sch em e 4. Synthesis of 2-Desmethyl-3-(pyridin-3-yl)pyrazolo[1,5-a]pyrimidine 34a
a
Reagents and conditions: (a) NaH/CHOOEt/THF; (b) NH2NH2‚HBr/EtOH/reflux; (c) MeCOCH2COOEt/dioxane/reflux; (d) POCl3/
reflux; (e) Pr2NH/ACN/reflux.
NMR spectra. The bromopyridines 18a -d were reacted
with butyllithium at -78 °C and the anions were
quenched with dry DMF28 to give the 3-pyridylcarbox-
aldehydes 19a -d , which were converted to the aceto-
nitriles 20a -d using the TosMIC protocol (Scheme 2).29
The pyridylacetonitriles 20e,f were synthesized from
substituted nicotinic esters.30 Thus, 6-methylnicotinic
acids were reduced using lithium aluminum hydride in
THF to give the corresponding alcohols, which were
converted to the chloromethylpyridines with thionyl
chloride. Reaction of chloromethylpyridines with NaCN
in DMF afforded 20e,f.
Finally, substitution of 24 with an alkylamine in aceto-
nitrile at reflux provided the desired compounds 25-
30.
The 2-desmethyl analogue (34) of 28 was synthesized
from the acetonitrile 20d following a procedure de-
scribed in Scheme 4. Formylation of 20d with ethyl
formate in the presence of sodium hydride in THF gave
31, which was cyclized with hydrazine hydrobromide,
followed by a second cyclization with ethyl acetoacetate
to afford the 2-desmethylpyrazolo[1,5-a]pyrimidone 32.
34 was obtained from the chloro intermediate 33 using
dipropylamine.
Halogenation of compound 26h with N-fluorobenze-
nesulfonimide, N-chlorosuccinimide, or N-bromosuccin-
imide in chloroform at room temperature gave the
corresponding 6-halopyrazolo[1,5-a]pyrimidines 35a -
c, respectively (Scheme 5).
Acetylation of the acetonitriles 20a -f was accom-
plished in THF in the presence of sodium hydride and
ethyl acetate to give the corresponding acetoacetonitriles
21a -f (Scheme 3), which were cyclized to the aminopy-
razoles 22a -f with hydrazine hydrobromide in aqueous
ethanol. For this cyclization reaction, the hydrazine salt
gave better yields of the desired products than free
hydrazine.31 The aminopyrazoles 22a -f were then
subjected to a second cyclization with ethyl acetoacetate
in refluxing dioxane, and the corresponding pyrazolo-
[1,5-a]pyrimidones 23a -f precipitated out from the
reaction solution. Conversion of 23a -f to the 7-chloro-
pyrazolo[1,5-a]pyrimidines 24a -f was accomplished in
refluxing acetonitrile with phosphorus oxychloride.
Resu lts a n d Discu ssion
The synthesized compounds were tested for their
binding affinities at the cloned human CRF1 receptor
expressed in CHO cells using [125I]o-CRF as the radio-
labeled ligand, and the Ki values were determined from
dose-response curves using concentrations ranging
from 1 nM to 10 µM as described.32,38 The binding
affinities of 3-pyridin-2-yl compounds are depicted in
Table 1. The structure-activity relationships of substi-

4790 J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 19
Chen et al.
Sch em e 5. Synthesis of 6-Halo-3-(pyridin-3-yl)pyrazolo[1,5-a]pyrimidines 35a -ca
a
Reagents and conditions: (a) NBFS/CHCl3/room temperature 2 days; (b) NCS/CHCl3/room temperature 2 h; (c) NBS/CHCl3/room
temperature, overnight.
by several groups.12,18,34 Although many compounds
from this series were identified to possess excellent in
Ta ble 1. SAR of
7-Dipropylamino-3-(2-pyridyl)pyrazolopyrimidines 13-15
vitro CRF1 receptor binding affinities, like many other
compounds reported earlier, most of them suffer from
high lipophilicity and poor water solubility (for 7, Ki )
1.3 nM, C log P ) 5.86; the hydrochloride or mesylate
salt of 7 was largely insoluble in water). By incorpora-
tion of polar alkoxy groups into these molecules we
successfully identified potent CRF1 receptor antagonists
Ki (nM)a
such as 8 (Ki ) 3.4 nM, C log P ) 3.18, measured log P
) 2.78 at pH of 7.4) with proper lipophilicity and
adequate water solubility (>10 mg/mL, mesylate salt).17a
Alternatively, we designed a series of 3-pyridylpyrazolo-
[1,5-a]pyrimidines 15, 25-30, and 34 by utilizing a
hydrophilic and weakly basic pyridine35 to replace the
highly lipophilic phenyl group.
compound
W
7
8
13
14
15
1.6
3.4
9.1
85
NO2
NH2
NMe2
10
a
Receptor binding was conducted as described previously. Data
are average of two or more independent determinations. Typical
The 2-(pyridin-2-yl)pyrazolo[1,5-a]pyrimidine 15 pos-
sessed a Ki value of 10 nM and a C log P of 4.76, while
the 5-nitro- 13 and the 5-aminopyridin-2-yl analogue 14
had Ki values of 9.1 and 85 nM, respectively. Appar-
ently, one advantage of 15 over 7 was its lower lipophi-
licity. This initial success prompted us to study a series
of 3-(pyridine-3-yl)pyrazolo[1,5-a]pyrimidines since 2-ami-
nopyridine (pKa ) 6.8) is slightly more basic than
3-aminopyridine (pKa ) 6.2).
standard errors were e30%.
Ta ble 2. Binding Affinity of CRF Antagonists 25-30, 34, and
35
Compound 25, which had a 6-dimethylaminopyridin-
3-yl group at the 3-position of the pyrazolo[1,5-a]-
pyrimidine core and possessed a C log P value of 4.36,
had a Ki value of 4.2 nM in the competitive binding
assay. We then studied the effect of methyl substitution
at the “ortho” position of the pyridine ring, on which a
substituent may change the orthogonal relationship
between the 3-aromatic ring and the bicyclic core.11,36
Thus, introduction of a methyl group at the 6′-position
of 25 resulted in compound 26h , which had a Ki value
of 3.5 nM. This result is somewhat unexpected since this
methylation could cause some changes at the dihedral
angle between the two aromatic rings. A methyl group
at the 2′-position improved the binding slightly (27, Ki
) 2.2 nM). Incorporating two methyl groups at both 2′-
and 6′-positions also had little effect on the receptor
binding (28, Ki ) 5.2 nM). On the contrary, the 6′-methyl
group increased the binding affinity of the 4′-methylpy-
ridin-1′-yl compound 29 (Ki ) 21 nM) about 3-fold (30,
Ki ) 7.3 nM). However, deletion of the methyl group at
the 2-position of pyrazolo[1,5-a]pyrimidine 28 resulted
in a 4-fold decrease in binding affinity (34, Ki ) 20 nM).
compound
R1
R2
R3
R4
Y
Ki (nM)a
25
26h
27
28
34
29
30
35a
35b
35c
H
H
Me
Me
Me
H
H
H
H
H
H
Me
H
Me
Me
H
Me
Me
Me
Me
Me2N
Me2N
Me2N
Me2N
Me2N
Me
Me
Me
Me
Me
H
Me
Me
Me
Me
Me
H
4.2
3.5
2.2
5.2
20
H
H
H
H
H
H
F
21
Me
7.3
5.6
39
Me2N
Me2N
Me2N
Cl
Br
240
a
Receptor binding was conducted as described previously. Data
are average of two or more independent determinations. Typical
standard errors were e30%.
tutions at the 3-pyridyl moiety and the 6-position of
pyrazolopyrimidine core are summarized in Table 2. The
results from variation of 7-alkylamino groups are tabu-
lated in Table 3. Selected compounds were also mea-
sured for their abilities to inhibit CRF-stimulated cAMP
production in the same cell line as that used in the
binding studies above, however, utilizing a live whole
cell preparation to assess their functional antagonism
(Table 4). 26 was further determined in a functional
assay based on its ability to inhibit CRF-stimulated
ACTH release in cultured rat pituitary cells.33
Next we examined the structure-activity relation-
ships of the 7-substitution of 3-(pyridin-3-yl)-pyrazolo-
[1,5-a]pyrimidines 26. A small lipophilic side chain, such
as dipropylamino (26h ), N-ethyl-N-butylamino (26g),
N-propyl-N-cyclopropanemethylamino (26i), or N-ben-
zyl-N-ethylamino (26k , 26l, 26m , 26n , 26o, 26p ),
The 3-phenylpyrazolo[1,5-a]pyrimidines exemplified
by 7 have been discovered as potent CRF1 antagonists

Design of NBI 30775/ R121919
J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 19 4791
Ta ble 3. SAR of 7-Alkylamino- or 7-Dialkylaminopyrazolopyrimidines 26a -v
a
Receptor binding was conducted as described previously. Data are average of two or more independent determinations. Typical standard
errors were e30%.
Ta ble 4. Inhibition of CRF-Stimulated cAMP Production for
to a hydrogen atom, and the Ki value of 35a was similar
Selected Compounds
to that of 26h , the large change in chemical shift was
compound
Ki (nM)a
IC50 (nM)a
most likely caused by strong electronic negativity of the
fluorine. Thus, these results suggest that the 6-position
of this core is limited to substitution of bulky group, due
to a requirement of the receptor binding pocket.
Selected compounds such as 15, 25, 26h , 27, 28, and
35a were tested in the CRF-stimulated cAMP release
assay to assess their functional antagonism. Compounds
26h , 28, and 35a inhibited the accumulation of cAMP
concentration with an IC50 values of 50, 40, and 50 nM,
respectively, and these numbers were comparable to
those of 8 (IC50 ) 76 nM) and 7 (IC50 ) 29 nM).
Compounds 25 and 27 were slightly less potent in this
assay (IC50 values of 110 and 190, respectively). These
results demonstrated that compounds from this class
were functional CRF1 antagonists.
Compound 26h was weakly basic with a pKa value of
6.9. It possessed moderate lipophilicity with a log P
value of 4.9, which closely matched with the calculated
value (C log P ) 4.76) using ACD/LogP software. Its
hydrochloride salt was readily soluble in water (>10 mg/
mL, pH ∼4). This compound had little affinity to the
CRF2 receptor expressed in CHO cells at 10 µM con-
centration.37 26h showed no significant binding at 10
µM to over 60 different receptors, ion channels, and
transporters including benzodiazepin and dopaminergic
and VIP receptors.
7
8
1.6
3.4
9.1
10
4.2
3.5
2.2
5.2
7.3
5.6
29
76
13
15
25
26h
27
28
30
35a
180b
160
110
50
190
40
300b
50
a
Receptor binding and function antagonism were conducted as
described previously. Data are average of two or more independent
determinations. Typical standard errors were e30%. Single
determination.
b
resulted in compounds with good binding affinity (Ki
value < 5 nM). Derivatives from some primary amines
also exhibited good binding (i.e. 4-heptylamino analogue
26d ).
The 6-halogenated analogues of 26h displayed very
interesting results. While the fluorinated analogue of
26h had a binding affinity (35a , Ki ) 5.6 nM) very
similar to that of the parent, the chloro (35b, Ki ) 39
nM) and the bromo analogue 35c (Ki ) 240 nM)
exhibited reduced binding affinities. The proton NMR
spectra of these four compounds were almost identical
except a singlet at 2.45-2.72 ppm (35a , 2.76; 35b, 2.72;
35c, 2.62; 26h , 2.46 ppm), which was assigned to the
5-methyl group of the pyrazolo[1,5-a]pyrimidine. Since
the fluorine, which possesses the strongest electron
negativity among these halogens, was similar in size
In h ibition of CRF -Stim u la ted ACTH Relea se
26h was further evaluated in a functional assay based
on its ability to inhibit CRF-stimulated ACTH release

4792 J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 19
Chen et al.
licity and water solubility of some analogues. A repre-
sentative from this series, compound 26h , possessed
proper lipophilicity as a CNS agent, good in vitro
biological activities, and a good pharmacokinetic profile.
26h not only inhibited CRF-stimulated adrenocorticopin
hormone (ACTH) release in vitro but also dose-depen-
dently attenuated peak plasma ACTH in stressed rats
in vivo.42 Compound 26h has demonstrated oral activity
in several animal models in rodents.22 These results
suggest that orally active CRF1 receptor antagonists
have the potential to treat stress-related anxiety/
depression in humans. Because of these desirable
profiles, 26h was evaluated in clinical trials and dem-
onstrated efficacy in patients with major depression,23a
although the clinical development of this compound has
been discontinued due to reversible elevations of liver
enzymes in two healthy subjects.23b
F igu r e 2. Inhibition of CRF stimulated ACTH release from
rat pituitary cells by 26h .
from cultured rat pituitary cells.33 The result showed
that 26h was a highly potent inhibitor with an IC50
value of 20 nM (Figure 2).
Exp er im en ta l Section
P h a r m a cok in ectics
Gen er a l. 1H NMR spectra were recorded on a Varian
Spectrometer (Mercury 300 Hz) using TMS as the internal
standard and CDCl3 as solvent except where indicated. HPLC
purification and purity analyses of final compounds were
performed on a reversed phase HPLC-MS system (HP-4500
series with APCI mode for mass detection), and purity was
determined to be at least 95% based on absorbance of two UV
wavelengths (220 nm, 254 nm) and total ion current (TIC)
monitoring the mass spectrometer. GC-MS was performed on
a Hewlett-Packard 5890 series II system equipped with a 5972
series mass detector. The results from elemental analysis are
indicated by atom symbols and within 0.4% of theoretical
values.
3-(3-Meth yl-5-d im eth yla m in op yr id in -2-yl)-2,5-d im eth -
yl-7-d ip r op yla m in op yr a zolo[1,5-a ]p yr im id in e H yd r o-
ch lor ide (15). 3-(3-Meth yl-5-n itr opyr idin -2-yl)-2,5-dim eth -
yl-7-h yd r oxyp yr a zolo[1,5-a ]p yr im id in e (11). To a solution
of cyanoacetone sodium salt43 (25.24 g, 240 mmol) in DMSO
(160 mL) was added 2-chloro-3-methyl-5-nitropyridine44 (27.6
g, 160 mmol) in DMSO (20 mL) at -10 °C under nitrogen
atmosphere. The mixture was stirred at room temperature
overnight and poured into saturated aqueous NH4Cl. The solid
was collected, washed with water, and dried in vacuo to give
2-cyano-2-(3-methyl-5-nitropyridin-2-yl)acetone (21.5 g, 61%),
which was used for the next step without further purifica-
tion: 1H NMR 2.51 (s, 3H), 2.77 (s, 3H), 8.22 (s, 1H), 8.78 (s,
1H); MS (EI) 218 (MH+).
A mixture of the above compound (6.16 g, 30 mmol) and
hydrazine hydrobromide (6.78 g, 60 mmol), acetic acid (30 mL)
in ethanol (60 mL), dioxane (30 mL), and water (5 mL) was
heated at reflux for 16 h. The reaction mixture was then
concentrated in vacuo, and the residue was partitioned be-
tween ethyl acetate and saturated aqueous sodium bicarbon-
ate. The organic phase was separated, washed with brine,
dried over MgSO4, filtered, and concentrated in vacuo. The
crude oil was treated with ether to precipitate 3-amino-4-(3-
methyl-5-nitropyridin-2-yl)-5-methyl-1H-pyrazole as a pale
yellow solid, which was collected by filtration (2.9 g, 41%
yield): 1H NMR 2.54 (s, 6H), 8.35 (s, 1H), 9.27 (s, 1H); MS
(EI) 234 (MH+).
A pharmacokinetic profile of 26h was determined in
male Sprague-Dawley rats following intravenous and
oral administrations at 10 mg/kg. After an iv injection,
the results indicated that 26h had a high plasma
clearance (CL ) 112 mL/min kg) and a large volume of
distribution (Vd ) 16.7 L/kg) in this species, which
resulted in a terminal half-life of 1.7 h. After oral
administration, the Cmax in plasma and brain occurred
at 0.25 and 0.5 h post dosing, respectively. The mean
maximal concentrations (Cmax) in plasma and brain
tissue via oral administration were 296 ng/mL and 290
ng/g, respectively. Oral bioavailability was estimated to
be 34%, and, on the basis of the AUC (0-6 h) ratio, the
brain tissue was exposed to approximately 67% of the
plasma concentration of 26h at this dosage.38
Effects on Str ess-In d u ced An xiogen ic-lik e
Beh a vior in Mice
Ability to attenuate stress-induced anxiogenic-like
behavior in mice has been used as an animal model to
evaluate anxiolytic and antianxiety compounds, and
activation of CRF secretion by stress has been exten-
sively documented.39 When mice are subjected to re-
straint stress and then placed in a novel environment,
they tend to assume a frozen posture and spend little
time to explore the surroundings.40 Compound 26h ,
given orally, dose-dependently reversed swim stress
induced reduction of time spent in the open arms in the
elevated plus-maze paradigm in mice. The time spent
in the lighted area in the light/dark exploration para-
digm was also significantly reduced among the 26h (2.5
and 10 mg/kg, po) treated animals after they had been
subjected to forced swim stress compared with the non-
swim-stressed mice.41
A solution of the above compound (2.9 g, 12.4 mmol) and
ethyl acetoacetate (3.2 g, 24.9 mmol) in dioxane (20 mL) was
heated at reflux overnight. A white solid was formed, which
was collected by filtration (0.98 g, 26% yield), to give the title
compound 11: 1H NMR (DMSO-d6) 2.33 (s, 3H), 2.41 (s, 3H),
5.68 (s, 1H), 8.41 (d, J ) 2.7 Hz, 1H), 9.32 (d, J ) 2.7 Hz, 1H),
11.35 (brs, 1H); MS (EI) 300 (MH+). Anal. (C14H13N5O3) C, H,
N.
3-(3-Meth yl-5-n itr op yr id in -2-yl)-2,5-d im eth yl-7-d ip r o-
p yla m in op yr a zolo[1,5-a ]p yr im id in e (13). A mixture of 11
(800 mg, 2.67 mmol) and phosphorus oxychloride (5 mL) was
heated at reflux for 1 h. The reaction mixture was poured into
Con clu sion s
In the present study, we showed that pyrazolo[1,5-a]-
pyrimidines bearing a 2- or 3-pyridyl group at the
3-position of the core structure were potent CRF1
antagonists. The antagonistic activities of these com-
pounds were demonstrated by their high affinities in
binding to the CRF1 receptor and inhibition of CRF-
stimulated cAMP production. The presence of a weakly
basic and hydrophilic pyridine group confers good phys-
icochemical properties, in particular, adequate lipophi-

Design of NBI 30775/ R121919
J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 19 4793
ice water and basified with sodium bicarbonate. The product
was extracted with ethyl acetate. The extract was washed with
brine, dried over MgSO4, filtered through a silica gel pad, and
concentrated in vacuo to yield 7-chloro-3-(3-methyl-5-nitropy-
ridin-2-yl)-2,5-dimethylpyrazolo[1,5-a]pyrimidine (12) as a
pale yellow oil (770 mg, 91% yield): GC-MS (100%, tR )13.7
min, m/e 317); 1H NMR 2.46 (s, 3H), 2.59 (s, 6H), 6.89 (s, 1H),
8.43 (d, J ) 2.1 Hz, 1H), 9.37 (d, J ) 2.1 Hz, 1H); MS (EI) 318
(MH+).
A solution of 12 (518 mg, 1 mmol) and dipropylamine (2 mL)
in acetonitrile (10 mL) was heated at reflux for 2 h. The
reaction mixture was cooled to room temperature and concen-
trated in vacuo. The crude product was purified on silica gel
with ethyl acetate-hexanes (1:5) to yield the title compound
from above) in THF (100 mL). The reaction was initiated with
5 drops of 1,2-dibromoethane with slight heating. The reaction
became vigorous after initiation and 10 mL of THF was added.
The rest of the bromo compound was added dropwise to
maintain a gentle reflux. After addition the red mixture was
stirred at room temperature for 0.5 h before DMF (27.5 mL,
1.5 equiv) was slowly injected at 0 °C. The resultant mixture
was stirred at room temperature overnight and quenched with
saturated aqueous NH4Cl. The product was extracted with
ether (2 × 500 mL), and the combined extract was washed
with brine, dried over MgSO4, filtered, and concentrated in
vacuo. The product was purified by chromatography on silica
gel with 1:5 ethyl acetate/hexanes to give 2-dimethylamino-
4-methyl-5-formylpyridine (19b) as a tan solid (77% yield). The
analytic sample was obtained by crystallization from ether/
hexanes: 1H NMR 2.57 (s, 3H), 3.11 (s, 6H), 6.28 (s, 1H), 8.43
(s, 1H), 9.87 (s, 1H); MS (EI) 165 (MH+).
Into a suspension of KOBu-t (12.5 g) in DME (70 mL) at
-50 °C was added dropwise a solution of TosMIC (15.6 g) in
DME (70 mL). The brown solution was stirred at -50 °C for
10 min before a solution of 19b (11 g, 68 mmol) in DME (70
mL) was added dropwise. The resultant mixture was stirred
at -50 °C for 0.5 h and quenched with methanol (70 mL). This
mixture was heated to reflux for 1 h, the solvent was
evaporated, and the residue was partitioned in ethyl acetate-
water. The organic layer was washed with brine, dried over
MgSO4, and filtrated through a silica gel pad with ethyl
acetate. This workup gave 2-dimethylamino-4-methyl-5-(cya-
nomethyl)pyridine as a yellow solid (20b, 9.5 g, 80%): 1H NMR
2.31(s, 3H), 3.08 (s, 6H), 3.54 (s, 2H), 6.36 (s, 1H), 7.99 (s, 1H);
MS (EI) 176 (MH+). Anal. (C10H13N3) C, H, N.
3-(4-Meth yl-6-d im eth yla m in op yr id in -3-yl)-2,5-d im eth -
yl-7-h yd r oxyp yr a zolo[1,5-a ]p yr im id in e (23b). Into a sus-
pension of 20b (40 g, 0.23 mol) and NaH (2.5 equiv) in THF
(100 mL) was added about 5 mL of ethyl acetate. The mixture
was stirred at room temperature until an exothermic reaction
started and hydrogen evolved vigorously. Fifty milliliters of
ethyl acetate was then added dropwise to maintain a gentle
reflux. The mixture was stirred at room temperature for 2 h
before it was quenched with water (100 mL). The organic phase
was separated and the aqueous phase was washed several
times with ethyl ether. The aqueous phase was then acidified
with acetic acid and the product extracted with ethyl acetate
(5 × 800 mL). The combined extract was washed with brine
(50 mL) and dried over MgSO4. Concentration in vacuo gave
1-cyano-1-(6-dimethylamino-4-methylpyridin-3-yl)acetone as a
brown solid (21b, 40 g, 80% yield): 1H NMR (1:1 mixture of
enol and ketone forms) 2.24 (s, 1.5 × 3H), 2.32 (s, 0.5 × 3H),
2.88 (s, 0.5 × 6H), 3.09 (s, 0.5 × 6H), 4.50 (brs, 0.5 × 1H),
4.62 (s, 0.5 × 1H), 6.13 (s, 0.5 × 1H), 6.35 (s, 0.5 × 1H), 7.60
(s, 0.5 × 1H), 8.05 (s, 0.5 × 1H); MS (EI) 218 (MH+).
13 as a colorless oil (420, 69% yield): GC-MS (100%, tR
)
19.6 min, m/e 382); 1H NMR 0.96 (t, J ) 7.1 Hz, 6H), 1.75 (m,
4H), 2.44 (s, 3H), 2.47 (s, 3H), 2.50 (s, 3H), 3.74 (m, 4H), 5.84
(s, 1H), 8.36 (s 1H), 9.32 (s, 1H); MS (EI) 383 (MH+).
3-(3-Meth yl-5-d im eth yla m in op yr id in -2-yl)-2,5-d im eth -
yl-7-d ip r op yla m in op yr a zolo[1,5-a ]p yr im id in e d ih yd r o-
ch lor id e (15). A mixture of 13 (400 mg, 0.52 mmol) and Pd/C
(10%, 80 mg) in ethanol (30 mL) was hydrogenated at 32 psi
for 2 h. The mixture was filtered through a pad of Celite, and
the filtrate was concentrated in vacuo to yield 3-(5-amino-3-
methylpyridin-2-yl)-2,5-dimethyl-7-dipropylaminopyrazolo[1,5-
a]pyrimidine (14) as an orange solid (320 mg, 80% yield): 1H
NMR 0.92 (t, J ) 7.4 Hz, 6H), 1.70 (m, 4H), 2.19 (s, 3H), 2.39
(s, 3H), 2.42 (s, 3H), 3.62 (brs, 2H), 3.70 (m, 4H), 5.78 (s, 1H),
6.92 (d, J ) 2.1 Hz, 1H), 8.04 (d, J ) 2.1 Hz, 1H); MS (EI) 353
(MH+).
Into a solution of 14 (31.2 mg, 0.09 mmol) and formaldehyde
(37%, 1 mL) in acetonitrile (1 mL) was added sodium cy-
anoborohydride (17 mg, 0.267 mmol), followed by three drops
of acetic acid. The mixture was stirred at room temperature
for 2 h. The mixture was then partitioned between ethyl
acetate and saturated NaHCO3. The organic layer was washed
with brine, dried over MgSO4, filtered, and concentrated in
vacuo. The crude material was purified on silica gel with CH2-
Cl2-MeOH-NH4OH (150:10:1) to give the title compound
(15): 1H NMR 0.93 (t, J ) 7.2 Hz, 6H), 1.70 (m, 4H), 2.24 (s,
3H), 2.39 (s, 3H), 2.42 (s, 3H), 2.99 (s, 6H), 3.71 (m, 4H), 5.79
(s, 1H), 6.95 (s, 1H), 8.12 (s, 1H); MS (EI) 381 (MH+).
15 (200 mg) was dissolved in ether (2 mL) and treated with
excess 1 N HCl in ether. The yellow solid was collected by
filtration (160 mg). Anal. (C22H32N6‚2HCl) C, H, N.
3-(6-Dim eth yla m in o-4-m eth ylp yr id in -3-yl)-2,5-d im eth -
yl-7-dipr opylam in opyr azolo[1,5-a ]pyr im idin e (26h ). 2-Di-
m et h yla m in o-4-m et h yl-5-(cya n om et h yl)p yr id in e (20b).
To a mixture of 2-amino-4-picoline (16b, 33 g, 0.3 mol), NaBH3-
CN (57 g, 3 equiv), formaldehyde (37% aqueous solution, 240
mL) in acetonitrile (1 L) and water (200 mL) was added
dropwise acetic acid (60 mL) at 0 °C in 2 h. The resultant
solution was stirred at room temperature for 7 days and then
concentrated in vacuo. The residue was basified with solid
NaOH to pH 10, and the product extracted with hexanes (3 ×
700 mL). The combined extract was washed with 1 N NaOH
and brine, dried over Na2SO4, and evaporated in vacuo to give
2-dimethylamino-4-methylpyridine (17b)45 as a colorless oil:
1H NMR 2.26 (s, 3H), 3.07 (s, 6H), 6.33 (s, 1H), 6.40 (d, J )
8.1 Hz, 1H), 8.02 (d, J ) 8.1 Hz, 1H); MS (EI) 137 (MH+).
A mixture of 17b (32 g, 0.235 mol), Na2CO3 (30 g, 1.2 equiv)
in dichloromethane (50 mL), and water (400 mL) was treated
dropwise with a solution of bromine (13 mL, 1.05 equiv) in
dichloromethane (50 mL) at 0 °C in 0.5 h. The resultant light
brown suspension was stirred at 0 °C for another half hour.
The product was extracted with hexanes (2 × 600 mL), and
the combined extract was washed with brine, dried over Na2-
SO4, and evaporated in vacuo. The crude product was purified
by chromatography on silica gel with 1:5 ethyl acetate/hexanes
to give 5-bromo-2-dimethylamino-4-methylpyridine (18b) as
a tan solid (78% yield): 1H NMR 2.30 (s, 3H), 3.04 (s, 6H),
6.38 (s, 1H), 8.14 (s, 1H); MS (EI) 216 (MH+).
A mixture of 21b (30 g, 0.14 mol) and hydrazine hydrobro-
mide (62 g, 4 equiv) in ethanol (150 mL) and water (20 mL)
was heated to reflux for 1 h. Ethanol was removed in vacuo,
and the residue was diluted with water (50 mL). This aqueous
phase was basified with solid Na2CO3, and the product was
extracted with ethyl acetate. The extract was dried over
MgSO4, filtered, and concentrated in vacuo to give 3-amino-
4-(6-dimethylamino-4-methylpyridin-3-yl)-5-methylpyrazole 22b
as a brownish oil (30 g, 93% yield), which was crystallized from
ether-hexanes: 1H NMR 2.07 (s, 3H), 2.14 (s, 3H), 3.10 (s,
6H), 4.10 (brs, 3H), 6.45 (s, 1H), 7.92 (s, 1H); MS (EI) 232
(MH+).
A solution of 22b (29.5 g, 128 mmol) and ethyl acetoacetate
(2.5 equiv) in dioxane (100 mL) was heated to reflux for 20 h.
The suspension was cooled, and ether (200 mL) was added.
The solid was collected by vacuum filtration, and the title
compound 23b was obtained as a tan solid (23.5 g, 62% yield):
1H NMR 2.10 (s, 3H), 2.20 (s, 3H), 2.33 (s, 3H), 2.91 (s, 6H),
5.64 (s, 1H), 6.24 (s, 1H), 7.65 (s, 1H); MS (EI) 298 (MH+).
Anal. (C16H19N5O) C, H, N.
2,5-Dim et h yl-3-(6-d im et h yla m in o-4-m et h ylp yr id in -3-
yl)-7-d ip r op yla m in op yr a zolo[1,5-a ]p yr im id in e H yd r o-
ch lor id e (26h .HCl). A suspension of 23b (11 g, 37 mmol) and
Into a suspension of magnesium (11.3 g, 2 equiv) in THF
(20 mL) was added a quarter of the solution of 18b (48.5 g

4794 J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 19
Chen et al.
POCl3 (2 equiv) in acetonitrile (50 mL) was heated to reflux
for 8 h. The reaction was quenched with ice and basified with
Na2CO3. The product was extracted with ethyl acetate (2 ×
200 mL). The extract was dried over MgSO4, filtered through
a silica gel pad, and concentrated in vacuo to give 2,5-dimethyl-
3-(6-dimethylamino-4-methylpyridin-3-yl)-7-chloropyrazolo-
[1,5-a]pyrimidine 24b as a yellowish solid (11.5 g, 99% yield):
1H NMR 2.13 (s, 3H), 2.43 (s, 3H), 2.53 (s, 3H), 3.11 (s, 6H),
6.49 (s, 1H), 6.78 (s, 1H), 8.01 (s, 1H); MS (EI) 316 (MH+).
A solution of 24b (11.5 g, 36.5 mmol) and dipropylamine (4
equiv) in acetonitrile (50 mL) was heated to reflux for 3 h.
The mixture was concentrated in vacuo, the residue was
dissolved in ethyl acetate and filtered through a short silica
gel column with ethyl acetate, and the filtrate was concen-
trated in vacuo to give the title compound 26h as a yellowish
powder, which was recrystallized from ether-hexanes to give
an off-white solid (10 g, 72% yield): 1H NMR 0.96 (t, J ) 7.1
Hz, 6H), 1.72 (m, 4H), 2.17 (s, 6H), 2.33 (s, 3H), 2.41 (s, 3H),
3.11 (s, 6H), 3.70 (m, 4H), 5.78 (s, 1H), 6.49 (s, 1H), 8.03 (s,
1H); MS (EI) 381 (MH+). Anal. (C22H32N6) C, H, N.
Hyd r och lor id e Sa lt F or m a tion . 26h (10 g, 26 mmol) was
dissolved in dichloromethane (50 mL) and treated with HCl
in ether (1 M solution, 26.5 mL) at room temperature. The
solution was diluted with ether (about 200 mL) to precipitate
2,5-dimethyl-3-(6-dimethylamino-4-methylpyridin-3-yl)-7-dipro-
pylaminopyrazolo[1,5-a]pyrimidine hydrochloride as an off-
white solid, which was collected by vacuum filtration (10 g,
96% yield).
2,5-Dim et h yl-3-(6-d im et h yla m in o-4-m et h ylp yr id in -3-
yl)-7-(1,2-d im et h ylp r op yla m in o)p yr a zolo[1,5-a ]p yr im i-
d in e Ditr iflu or oa ceta te (26a ). A solution of 24b (32 mg, 0.1
mmol) and 1,2-dimethylpropylamine (4 equiv) in acetonitrile
(0.5 mL) was heated to reflux for 3 h. The product was purified
by LC-MS to give the product as a colorless oil, 42 mg: 1H
NMR 1.07 (d, J ) 6.3 Hz, 3H), 1.09 (d, J ) 6.6 Hz, 3H), 1.40
(d, J ) 6.9 Hz, 3H), 2.02 (m, 1H), 2.24 (s, 3H), 2.33 (s, 3H),
2.62 (s, 3H), 3.32 (s, 6H), 3.69 (m, 1H), 5.94 (s, 1H), 6.73 (s,
1H), 6.99 (d, J ) 9.3 Hz, 1H), 8.17 (s, 1H); MS (EI) 367 (MH+).
Anal. (C21H30N6‚2TFA‚2/3H2O) C, H, N.
1H), 6.12 (s, 1H), 6.81 (s, 1H), 7.56 (d, J ) 9.6 Hz, 1H), 7.90
(s, 1H); MS (EI) 383 (MH+). Anal. (C21H30N6O‚3TFA‚3H2O) C,
H, N.
2,5-Dim et h yl-3-(6-d im et h yla m in o-4-m et h ylp yr id in -3-
yl)-7-[{(1S)-m et h oxym et h yl}p h en et h yla m in o]p yr a zolo-
[1,5-a ]p yr im id in e Ditr iflu or oa ceta te (26f). This was pre-
pared in a manner similar to the procedure described for 26a
using (S)-benzyl(methoxymethyl)methylamine: colorless oil,
1
48 mg; H NMR 2.21 (s, 3H), 2.33 (s, 3H), 2.49 (s, 3H), 3.08
(dd, J ) 7.5, 10.5 Hz, 1H), 3.13 (dd, J ) 6.6, 10.5 Hz, 1H),
3.32 (s, 6H), 3.47 (s, 3H), 3.61 (dd, J ) 4.8, 10.6 Hz, 1H), 3.64
(dd, J ) 3.3, 10.6 Hz, 1H), 4.06 (m, 1H), 5.64 (brs, 1H), 6.73
(s, 1H), 7.30 (m, 5H), 7.45 (d, J ) 8.7 Hz, 1H), 8.12 (s, 1H);
MS (EI) 445 (MH+). Anal. (C26H32N6O ‚2.5TFA) C, H, N.
2,5-Dim et h yl-3-(6-d im et h yla m in o-4-m et h ylp yr id in -3-
yl)-7-(N-bu tyl-N-eth yla m in o)p yr a zolo[1,5-a ]p yr im id in e
Tr iflu or oa ceta te Ditr iflu or oa ceta te (26g). This was pre-
pared in a manner similar to the procedure described for 26a
using N-ethyl-N-butylamine: colorless oil, 43 mg; 1H NMR
1.04 (t, J ) 6.9 Hz, 3H), 1.47 (t, J ) 7.8 Hz, 3H), 1.49 (m, 2H),
1.86 (m, 2H), 2.21 (s, 3H), 2.27 (s, 3H), 2.48 (s, 3H), 3.30 (s,
6H), 4.02 (brs, 4H), 5.81 (s, 3H), 6.83 (s, 1H), 7.89 (s, 1H); MS
(EI) 381 (MH+). Anal. (C22H32N6 ‚3TFA) C, H, N.
2,5-Dim et h yl-3-(6-d im et h yla m in o-4-m et h ylp yr id in -3-
yl)-7-(N-cyclop r op a n em eth yl-N-p r op yla m in o)p yr a zolo-
[1,5-a ]p yr im id in e Ditr iflu or oa ceta te (26i). This was pre-
pared in a manner similar to the procedure described for 26a
using N-cyclopropanemethyl-N-propylamine: colorless oil, 32
1
mg; H NMR 0.45 (m, 2H), 0.74 (m, 2H), 1.04 (t, J ) 6.9 Hz,
3H), 1.23 (m, 1H), 1.89 (m, 2H), 2.20 (s, 3H), 2.27 (s, 3H), 2.49
(s, 3H), 3.29 (s, 6H), 4.02 (brs, 4H), 5.94 (s, 1H), 6.85 (s, 1H),
7.85 (s, 1H); MS (EI) 393 (MH+). Anal. (C23H32N6 ‚3TFA) C,
H, N.
2,5-Dim et h yl-3-(6-d im et h yla m in o-4-m et h ylp yr id in -3-
yl)-7-d ibu tyla m in op yr a zolo[1,5-a ]p yr im id in e Ditr iflu o-
r oa ceta te (26j). This was prepared in a manner similar to
the procedure described for 26a using dibutylamine: colorless
oil, 43 mg; 1H NMR 1.03 (t, J ) 6.9 Hz, 6H), 1.47 (m, 4H),
1.84 (m, 4H), 2.20 (s, 3H), 2.26 (s, 3H), 2.47 (s, 3H), 3.29 (s,
6H), 4.02 (brs, 4H), 5.80 (s, 1H), 6.84 (s, 1H), 7.85 (s, 1H); MS
(EI) 409 (MH+). Anal. (C24H36N6‚3TFA‚0.5H2O) C, H, N.
2,5-Dim et h yl-3-(6-d im et h yla m in o-4-m et h ylp yr id in -3-
yl)-7-[N-(2-m eth ylben zyl)-N-eth yla m in o]p yr a zolo[1,5-a ]-
p yr im id in e Ditr iflu or oa ceta te (26k ). This was prepared in
a manner similar to the procedure described for 26a using
N-ethyl-N-(2-methylbenzyl)amine: colorless oil, 48 mg; 1H
NMR 1.50 (t, J ) 6.9 Hz, 3H), 2.24 (s, 3H), 2.27 (s, 3H), 2.38
(s, 3H), 2.50 (s, 3H), 3.32 (s, 6H), 4.15 (m, 2H), 5.12 (brs, 1H),
5.14 (brs, 1H), 5.73 (s, 1H), 6.73 (s, 1H), 7.07 (d, J ) 6.9 Hz,
1H), 7.29 (m, 3H), 8.17 (s, 1H); MS (EI) 429 (MH+). Anal.
(C26H32N6‚2.7TFA) C, H, N.
2,5-Dim et h yl-3-(6-d im et h yla m in o-4-m et h ylp yr id in -3-
yl)-7-[N-(3-m eth ylben zyl)-N-eth yla m in o]p yr a zolo[1,5-a ]-
p yr im id in e Ditr iflu or oa ceta te (26l). This was prepared in
a manner similar to the procedure described for 26a using
N-ethyl-N-(2-methylbenzyl)amine: colorless oil, 47 mg; 1H
NMR 1.47 (t, J ) 6.9 Hz, 3H), 2.25 (s, 3H), 2.29 (s, 3H), 2.39
(s, 3H), 2.52 (s, 3H), 3.32 (s, 6H), 4.07 (m, 2H), 5.20 (m, 2H),
5.73 (s, 1H), 6.74 (s, 1H), 7.08 (d, J ) 7.5 Hz, 1H), 7.10 (s,
1H), 7.19 (d, J ) 7.8 Hz, 1H), 7.32 (t, J ) 7.5 Hz, 1H), 8.18 (s,
1H); MS (EI) 429 (MH+). Anal. (C26H32N6 ‚2.3TFA‚0.7H2O) C,
H, N.
2,5-Dim et h yl-3-(6-d im et h yla m in o-4-m et h ylp yr id in -3-
yl)-7-(5-m e t h yl-2-h e xyla m in o)p yr a zolo[1,5-a ]p yr im i-
d in e Ditr iflu or oa ceta te (26b). This was prepared in a
manner similar to the procedure described for 26a using
1
2-amino-5-methylhexane: colorless oil, 44 mg; H NMR 0.94
(d, J ) 6.3 Hz, 6H), 1.32 (m, 2H), 1.44 (d, J ) 6.6 Hz, 3H),
1.61 (m, 1H), 1.75 (m, 1H), 2.24 (s, 3H), 2.33 (s, 3H), 2.62 (s,
3H), 3.32 (s, 6H), 3.83 (m, 1H), 5.93 (s, 1H), 6.98 (brs, 1H),
8.16 (s, 1H); MS (EI) 395 (MH+). Anal. (C23H34N6‚2.3TFA) C,
H, N.
2,5-Dim et h yl-3-(6-d im et h yla m in o-4-m et h ylp yr id in -3-
yl)-7-(3-p en t yla m in o)p yr a zolo[1,5-a ]p yr im id in e Dit r i-
flu or oa ceta te (26c). This was prepared in a manner similar
to the procedure described for 26a using 3-aminopentane:
colorless oil, 38 mg; 1H NMR 1.05 (t, J ) 7.2 Hz, 3H), 1.06 (t,
J ) 7.5 Hz, 3H), 1.76 (m, 2H), 1.86 (m, 2H), 2.20 (s, 3H), 2.32
(s, 3H), 2.60 (s, 3H), 3.31 (s, 6H), 3.63 (m, 1H), 6.01 (s, 1H),
6.81 (s, 1H), 7.19 (d, J ) 9.6 Hz, 1H), 7.96 (s, 1H); MS (EI)
367 (MH+). Anal. (C21H30N6‚3TFA‚1/4H2O) C, H, N.
2,5-Dim et h yl-3-(6-d im et h yla m in o-4-m et h ylp yr id in -3-
yl)-7-(4-h ep t yla m in o)p yr a zolo[1,5-a ]p yr im id in e Dit r i-
flu or oa ceta te (26d ). This was prepared in a manner similar
to the procedure described for 26a using 4-heptylamine:
colorless oil, 27 mg; 1H NMR 0.98 (t, J ) 6.9 Hz, 3H), 0.99 (t,
J ) 7.5 Hz, 3H), 1.46 (m, 4H), 1.74 (m, 4H), 2.22 (s, 3H), 2.32
(s, 3H), 2.59 (s, 3H), 3.31 (s, 6H), 3.80 (m, 1H), 6.00 (s, 1H),
6.83 (s, 1H), 7.24 (d, J ) 9.6 Hz, 1H), 7.91 (s, 1H); MS (EI)
395 (MH+). Anal. (C23H34N6‚3TFA) C, H, N.
2,5-Dim et h yl-3-(6-d im et h yla m in o-4-m et h ylp yr id in -3-
yl)-7-[N-(4-m eth ylben zyl)-N-eth yla m in o]p yr a zolo[1,5-a ]-
p yr im id in e Ditr iflu or oa ceta te (26m ). This was prepared
in a manner similar to the procedure described for 26a using
N-ethyl-N-(4-methylbenzyl)amine: colorless oil, 50 mg;
1H
NMR 1.46 (t, J ) 6.9 Hz, 3H), 2.24 (s, 3H), 2.29 (s, 3H), 2.38
(s, 3H), 2.51 (s, 3H), 3.32 (s, 6H), 4.05 (m, 2H), 5.18 (brs, 1H),
5.36 (brs, 1H), 5.82 (s, 1H), 6.74 (s, 1H), 7.18 (d, J ) 8.1 Hz,
2H), 7.23 (d, J ) 8.1 Hz, 2H), 8.17 (s, 1H); MS (EI) 429 (MH+).
Anal. (C26H32N6 ‚2.3TFA‚0.7H2O) C, H, N.
2,5-Dim et h yl-3-(6-d im et h yla m in o-4-m et h ylp yr id in -3-
yl)-7-[1-(m et h oxym et h yl)p r op yla m in o]p yr a zolo[1,5-a ]-
p yr im id in e Ditr iflu or oa ceta te (26e). This was prepared in
a manner similar to the procedure described for 26a using
2-amino-1-methoxybutane: colorless oil, 34 mg; 1H NMR 0.94
(t, J ) 7.2 Hz, 3H), 1.85 (m, 2H), 2.20 (s, 3H), 2.31 (s, 3H),
2.56 (s, 3H), 3.30 (s, 6H), 3.35 (s, 3H), 3.54 (m, 2H), 3.88 (m,
2,5-Dim et h yl-3-(6-d im et h yla m in o-4-m et h ylp yr id in -3-
yl)-7-[N-(2-flu or oben zyl)-N-eth yla m in o]p yr a zolo[1,5-a ]-

Design of NBI 30775/ R121919
J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 19 4795
p yr im id in e Ditr iflu or oa ceta te (26n ). This was prepared
in a manner similar to the procedure described for 26a using
N-ethyl-N-(2-fluorobenzyl)amine: colorless oil, 45 mg; 1H NMR
1.46 (t, J ) 6.9 Hz, 3H), 2.25 (s, 3H), 2.29 (s, 3H), 2.53 (s, 3H),
3.32 (s, 6H), 3.97 (q, J ) 6.3 Hz, 2H), 5.32 (brs, 1H), 5.52 (brs,
1H), 5.85 (s, 1H), 6.73 (s, 1H), 7.18 (m,2H), 7.33 (m, 2H), 8.18
(s, 1H); MS (EI) 433 (MH+). Anal. (C25H29FN6‚2TFA‚2H2O) C,
H, N.
2,5-Dim et h yl-3-(6-d im et h yla m in o-4-m et h ylp yr id in -3-
yl)-7-[N-(4-ch lor oben zyl)-N-eth yla m in o]p yr a zolo[1,5-a ]-
p yr im id in e Ditr iflu or oa ceta te (26o). This was prepared in
a manner similar to the procedure described for 26a using
N-ethyl-N-(4-chlorobenzyl)amine: colorless oil, 51 mg; 1H NMR
1.43 (t, J ) 6.9 Hz, 3H), 2.24 (s, 3H), 2.27 (s, 3H), 2.53 (s, 3H),
3.32 (s, 6H), 3.92 (m, 2H), 5.27 (brs, 1H), 5.42 (brs, 1H), 5.84
(s, 1H), 6.73 (s, 1H), 7.27 (d, J ) 9.0 Hz, 2H), 7.39 (d, J ) 9.0
Hz, 2H), 8.17 (s, 1H); MS (EI) 449 (MH+). Anal. (C25H29ClN6
‚2TFA‚2H2O) C, H, N.
2,5-Dim et h yl-3-(6-d im et h yla m in o-4-m et h ylp yr id in -3-
yl)-7-[N-(3,4-d ich lor oben zyl)-N-eth yla m in o]p yr a zolo[1,5-
a ]p yr im id in e Ditr iflu or oa ceta te (26p ). This was prepared
in a manner similar to the procedure described for 26a using
N-ethyl-N-(3,4-dichlorobenzyl)amine: colorless oil, 48 mg; 1H
NMR 1.43 (t, J ) 6.9 Hz, 3H), 2.25 (s, 3H), 2.27 (s, 3H), 2.53
(s, 3H), 3.32 (s, 6H), 3.85 (m, 2H), 5.35 (brs, 1H), 5.40 (brs,
1H), 5.88 (s, 1H), 6.74 (s, 1H), 7.19 (dd, J ) 2.4, 8.4 Hz, 1H),
7.46 (d, J ) 2.4 Hz, 1H), 7.49 (d, J ) 8.4 Hz, 1H), 8.14 (s, 1H);
MS (EI) 483 (MH+). Anal. (C25H28Cl2N6‚2TFA‚2H2O) C, H, N.
2,5-Dim et h yl-3-(6-d im et h yla m in o-4-m et h ylp yr id in -3-
yl)-7-(N-b en zyl-N-isop r op yla m in o)p yr a zolo[1,5-a ]p yr i-
m id in e (26q). This was prepared in a manner similar to the
procedure described for 26h using N-isopropyl-N-benzyl-
amine: colorless oil, 18 mg; 1H NMR 1.38 (d, J ) 6.6 Hz, 6H),
2.14 (s, 3H), 2.31 (s, 3H), 2.36 (s, 3H), 3.10 (s, 6H), 4.66 (s,
2H), 5.41 (hept, J ) 7.2 Hz, 1H), 5.82 (s, 1H), 6.48 (s, 1H),
7.27 (m, 5H), 8.02 (s, 1H); MS (EI) m/e 429 (MH+). Anal.
(C26H32N6‚2/3H2O) C, H, N.
(s, 1H), 7.31 (m, 5H), 8.05 (s, 1H); MS (EI) 443 (MH+). Anal.
(C27H34N6‚0.5H2O) C, H, N.
2,5-Dim et h yl-3-(6-d im et h yla m in o-4-m et h ylp yr id in -3-
yl)-7-(N-p h en yl-N-p r op yla m in o)p yr a zolo[1,5-a ]p yr im i-
d in e Ditr iflu or oa ceta te (26v). This was prepared in a
manner similar to the procedure described for 26a using
1
N-propyl-N-phenylamine: colorless oil, 45 mg; H NMR 1.00
(t, J ) 6.9 Hz, 3H), 1.89 (m, 2H), 2.26 (s, 3H), 2.32 (s, 3H),
2.38 (s, 3H), 3.32 (s, 6H), 4.47 (brs, 1H), 4.64 (brs, 1H), 5.37
(s, 1H), 6.73 (s, 1H), 7.32 (dm, J ) 7.8 Hz, 2H), 7.51 (t, J ) 7.8
Hz, 1H), 7.60 (t, J ) 7.2 Hz, 2H); MS (EI) 415 (MH+). Anal.
(C25H30N6‚2TFA‚0.75H2O) C, H, N.
3-(6-Dim eth yla m in op yr id in -3-yl)-2,5-d im eth yl-7-d ip r o-
p yla m in op yr a zolo[1,5-a ]p yr im id in e (25). 3-(6-Dimethyl-
aminopyridin-3-yl)-2,5-dimethyl-7-hydroxypyrazolo[1,5-a]pyrimidine
(23a ) was prepared, in a manner similar to the procedure
described for 23b using 2-aminopyridine, as a tan solid: 1H
NMR 2.18 (s, 3H), 2.38 (s, 3H), 3.02 (s, 6H), 5.39 (s, 1H), 6.70
(d, J ) 8.8 Hz, 1H), 7.88 (dd, J ) 2.1, 8.8 Hz, 1H), 8.40 (s,
1H); MS (EI) 284 (MH+). Anal. (C15H17N5O) C, H, N.
A suspension of 23a (2 g) and POCl3 (2 equiv) in acetonitrile
(20 mL) was heated to reflux for 1 h. The reaction was
quenched with ice and basified with Na2CO3. The product was
extracted with ethyl acetate (2 × 100 mL). The extract was
dried over MgSO4, filtered through a silica gel pad, and
concentrated in vacuo to give 2,5-dimethyl-3-(6-dimethylami-
nopyridin-3-yl)-7-chloropyrazolo[1,5-a]pyrimidine 24a as a yel-
lowish solid: 1H NMR 2.54 (s, 3H), 2.61 (s, 3H), 3.11 (s, 6H),
6.63 (d, J ) 8.8 Hz, 1H), 6.75 (s, 1H), 7.80 (d, J ) 8.8 Hz, 1H),
8.46 (s, 1H); MS (EI) 302 (MH+).
A solution of 24a obtained above and dipropylamine (3 mL)
in acetonitrile (20 mL) was heated to reflux for 2 h. The
mixture was concentrated in vacuo, and the residue was
dissolved in ethyl acetate and filtered through a short silica
gel column with ethyl acetate. The filtrate was concentrated
in vacuo to give 2,5-dimethyl-3-(6-dimethylaminopyridin-3-yl)-
7-dipropylaminopyrazolo[1,5-a]pyrimidine 25 as a yellowish
solid, which was crystallized from ether-hexanes (1.6 g): 1H
NMR 0.94 (t, J ) 7.3 Hz, 6H), 1.72 (m, 4H), 2.45 (s, 3H), 2.54
(s, 3H), 3.12 (s, 6H), 3.70 (m, 4H), 5.79 (s, 1H), 6.64 (d, J ) 8.8
Hz, 1H), 7.90 (dd, J ) 2.4, 8.8 Hz, 1H), 8.48 (d, J ) 2.4 Hz,
1H); MS (EI) 367 (MH+). Anal. (C21H30N6), C, H, N.
2,5-Dim et h yl-3-(6-d im et h yla m in o-4-m et h ylp yr id in -3-
yl)-7-(N-b en zyl-N-p r op yla m in o)p yr a zolo[1,5-a ]p yr im i-
d in e Ditr iflu or oa ceta te (26r ). This was prepared in a
manner similar to the procedure described for 26a using
1
N-propyl-N-benzylamine: colorless oil, 29 mg; H NMR 1.03
(t, J ) 7.5 Hz, 3H), 1.92 (m, 2H), 2.22 (s, 3H), 2.27 (s, 3H),
2.45 (s, 3H), 3.30 (s, 6H), 4.00 (brs, 2H), 5.26 (m, 2H), 5.85 (s,
1H), 6.84 (s, 1H), 7.28 (m, 2H), 7.41 (m, 3H), 7.90 (s, 1H); MS
(EI) 429 (MH+). Anal. (C26H32N6‚3TFA‚0.5H2O) C, H, N.
2,5-Dim et h yl-3-(6-d im et h yla m in o-4-m et h ylp yr id in -3-
yl)-7-[N-(2-n a p h t h ylm et h yl)-N-p r op yla m in o]p yr a zolo-
[1,5-a ]p yr im id in e Ditr iflu or oa ceta te (26s). This was pre-
pared in a manner similar to the procedure described for 26a
using N-propyl-N-(naphthylmethyl)amine: colorless oil, 22 mg;
1H NMR 1.01 (t, J ) 7.5 Hz, 3H), 1.93 (m, 2H), 2.26 (s, 3H),
2.30 (s, 3H), 2.50 (s, 3H), 3.33 (s, 6H), 3.95 (brs, 2H), 5.41 (brs,
1H), 5.52 (brs, 1H), 5.85 (s, 1H), 6.73 (s, 1H), 7.40 (dd, J )
1.8, 8.1 Hz, 1H), 7.53 (m, 1H), 7.54 (d, J ) 9.3 Hz, 1H), 7.71
(s, 1H), 7.86 (m, 2H), 7.91 (d, J ) 8.7 Hz, 1H), 8.21 (s, 1H);
MS (EI) 479 (MH+). Anal. (C30H34N6‚2TFA‚0.5H2O) C, H, N.
2,5-Dim et h yl-3-(6-d im et h yla m in o-4-m et h ylp yr id in -3-
yl)-7-[N-(3-m eth oxyben zyl)-N-p r op yla m in o]p yr a zolo[1,5-
a ]p yr im id in e Ditr iflu or oa ceta te (26t). This was prepared
in a manner similar to the procedure described for 26a using
N-propyl-N-(3-methoxybenzyl)amine: colorless oil, 19 mg; 1H
NMR 1.00 (t, J ) 6.9 Hz, 3H), 1.90 (m, 2H), 2.26 (s, 3H), 2.30
(s, 3H), 2.49 (s, 3H), 3.32 (s, 6H), 3.82 (s, 3H), 3.92 (brs, 2H),
5.19 (brs, 1H), 5.26 (brs, 1H), 5.80 (s, 1H), 6.73 (s, 1H), 6.83
(s, 1H), 6.89 (m, 2H), 7.33 (t, J ) 8.1 Hz, 1H), 8.18 (s, 1H); MS
(EI) 459 (MH+). Anal. (C27H34N6O‚2TFA‚0.5H2O) C, H, N.
2,5-Dim et h yl-3-(6-d im et h yla m in o-4-m et h ylp yr id in -3-
yl)-7-(N -b e n zyl-N -b u t yla m in o)p yr a zolo[1,5-a ]p yr im i-
d in e (26u ). This was prepared in a manner similar to the
procedure described for 26h using N-butyl-N-benzylamine:
colorless oil, 18 mg; 1H NMR 0.92 (t, J ) 7.5 Hz, 3H), 1.33 (m,
2H), 1.74 (m, 2H), 2.18 (s, 3H), 2.34 (s, 3H), 2.40 (s, 3H), 3.11
(s, 6H), 3.62 (t, J ) 6.9 Hz, 2H), 5.13 (s, 2H), 5.82 (s, 1H), 6.50
3-(2-Meth yl-6-d im eth yla m in op yr id in -3-yl)-2,5-m eth yl-
7-d ip r op yla m in op yr a zolo[1,5-a ]p yr im id in e (27). 3-(2-
Methyl-6-dimethylaminopyridin-3-yl)-2,5-methyl-7-hydroxy-
pyrazolo[1,5-a]pyrimidine (23c), prepared in a manner similar
to the procedure described for 23b using 2-amino-5-bromo-6-
methyl-pyridine, was converted to 3-(2-methyl-6-dimethylami-
nopyridin-3-yl)-2,5-methyl-7-chloropyrazolo[1,5-a]pyrimidine
24c as a yellowish solid: 1H NMR 2.30 (s, 3H), 2.40 (s, 3H),
2.52 (s, 3H), 3.14 (s, 6H), 6.47 (d, J ) 8.0 Hz, 1H), 6.78 (s,
1H), 7.34 (d, J ) 8.0 Hz, 1H); MS (EI) 316 (MH+).
A solution of 24c (32 mg, 0.1 mmol) and dipropylamine (4
equiv) in acetonitrile (0.5 mL) was heated to reflux for 3 h.
The mixture was concentrated in vacuo, the residue was
dissolved in ethyl acetate and filtered through a short silica
gel column with ethyl acetate, and the filtrate was concen-
trated in vacuo to give the title compound as a yellowish solid,
which was crystallized from ether-hexanes: 1H NMR 0.92 (t,
J ) 7.0 Hz, 6H), 1.70 (m, 4H), 2.28 (s, 6H), 2.41 (s, 3H), 3.09
(s, 6H), 3.68 (m, 4H), 5.77 (s, 1H), 6.40 (d, J ) 8.0 Hz, 1H),
7.32 (d, J ) 8.0 Hz, 1H); MS (EI) 381 (MH+). Anal. (C22H32N6)
C, H, N.
3-(2,4-Dim et h yl-6-d im et h yla m in op yr id in -3-yl)-2,5-d i-
m eth yl-7-d ip r op yla m in op yr a zolo[1,5-a ]p yr im id in e (28).
3-(2,4-Dimethyl-6-dimethylaminopyridin-3-yl)-2,5-dimethyl-7-
chloropyrazolo[1,5-a]pyrimidine (24d ) was prepared, in
a
manner similar to the procedure described for 24b using
2-amino-5-bromo-4,6-dimethylpyridine, as a yellow solid: 1H
NMR 2.00 (s, 3H), 2.28 (s, 3H), 2.33 (s, 3H), 2.49 (s, 3H), 3.24
(s, 6H), 6.52 (s, 1H), 6.80 (s, 1H); MS (EI) 330 (MH+).
A solution of 24d (33 mg, 0.1 mmol) in dipropylamine
(excess) was heated to reflux for 3 h. The mixture was
concentrated in vacuo and the residue dissolved in ethyl

4796 J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 19
Chen et al.
acetate. This solution was filtered through a short silica gel
column with ethyl acetate, and the filtrate was concentrated
in vacuo to give the title compound as a colorless oil: 1H NMR
0.96 (t, J ) 7.6 Hz, 6H), 1.74 (m, 4H), 1.92 (s, 3H), 2.19 (s,
3H), 2.23 (s, 3H), 2.40 (s, 3H), 3.12 (s, 6H), 3.70 (m, 4H), 5.70
(s, 1H), 6.38 (s, 1H); MS (EI) 395 (MH+). Anal. (C23H34N6) C,
H, N.
3-(4,6-Dim eth ylpyr idin -3-yl)-2,5-m eth yl-7-d ip r op yla m i-
n op yr a zolo[1,5-a ]p yr im id in e (30). 3-(4,6-Dimethylpyridin-
3-yl)-2,5-methyl-7-chloropyrazolo[1,5-a]pyrimidine (24f) was
prepared in a manner similar to the procedure described for
24e using methyl 2,4-dimethylnicotinate:24 1H NMR 2.14 (s,
3H), 2.37 (s, 3H), 2.47 (s, 3H), 2.53 (s, 3H), 6.78 (s, 1H), 7.11
(s, 1H), 8.28 (s, 1H); MS (EI) m/e 287 (MH+);
A solution of 24f (50 mg) and dipropylamine (1.5 mL) was
heated at 100 °C in a sealed reacti-vial for 3 h. Chromatog-
raphy on silica gel with 1:3 ethyl acetate-hexanes gave the
desired product as a colorless oil, 43 mg: 1H NMR 0.96 (t, J )
7.2 Hz, 6H), 1.75 (m, 4H), 2.22 (s, 3H), 2.32 (s, 3H), 2.40 (s,
3H), 2.55 (s, 3H), 3.72 (m, 4H), 5.80 (s, 1H), 7.12 (s, 1H), 8.35
(s, 1H); MS (EI) 352 (MH+). Anal. (C23H29N5) C, H, N.
3-(6-Meth ylpyr idin -3-yl)-2,5-m eth yl-7-dipr opylam in opy-
r a zolo[1,5-a ]p yr im id in e (29). 3-(6-Meth ylp yr id in -3-yl)-
2,5-m eth yl-7-ch lor op yr a zolo[1,5-a ]p yr im id in e (24e). A
solution of methyl 6-methylnicotinate (30.2 g, 0.2 mol) in dry
THF (40 mL) was added dropwise into a suspension of LiAlH4
(10.5 g) in THF (100 mL) at room temperature. The addition
caused a gentle reflux. The gray suspension was then stirred
at room temperature for 1 h. The reaction was quenched
carefully with a limited amount of water, and the mixture was
diluted with ethyl acetate (300 mL). More water was added
carefully to generate a white suspension, and the yellow
solution was decanted and washed several time with ethyl
acetate. The combined solution was concentrated in vacuo to
give 5-(hydroxylmethyl)-2-methylpyridine as a yellow oil (22.5
g): MS (EI) 124 (MH+).
3-(2,4-Dim eth yl-6-d im eth yla m in op yr id in -3-yl)-5-m eth -
yl-7-dipr opylam in opyr azolo[1,5-a ]pyr im idin e (34). 3-(2,4-
Dim et h yl-6-d im et h yla m in op yr id in -3-yl)-5-m et h yl-7-h y-
d r oxp yr a zolo[1,5-a ]p yr im id in e (32). A solution of 2,4-
dimethyl-3-cyanomethyl-6-dimethylaminopyridine (10 g, 50
mmol) in THF (10 mL) was added slowly into a suspension of
NaH (5 g, 125 mmol) in THF (15 mL) with vigorous stirring.
Ethyl formate (3.8 g, 54 mmol) was added dropwise, and the
resulting mixture was stirred at room temperature for 1 h,
before being quenched with water. The product was extracted
with ethyl acetate, dried over MgSO4, filtered, and concen-
trated to give the crude 1-cyano-1-(6-dimethylamino-2,4-dim-
ethylpyridin-3-yl)acetaldehyde 31: MS (EI) 218 (MH+).
To a stirred solution of 3-(hydroxymethyl)-2-methylpyridine
(5.0 g) in dichloromethane (200 mL) was added thionyl chloride
(50 mL). The mixture was stirred at room temperature for 4
h and then concentrated in vacuo. The residue was partitioned
between saturated NaHCO3 (150 mL) and CH2Cl2 (150 mL).
The organic layer was removed, and the aqueous layer was
extracted with CH2Cl2 (2 × 100 mL). The combined organic
extracts were dried over Na2SO4, filtered, and concentrated
in vacuo to give 5-(chloromethyl)-2-methylpyridine46 as a
yellowish oil, which was used for the next step without further
purification: MS (EI) 142 (MH+).
The above compound was dissolved in an ethanol/water (9:
1) mixture and treated with hydrazine hydrobromide (10 g).
The mixture was heated at reflux for 1 h and then concen-
trated in vacuo. The residue was partitioned in ethyl acetate/
aqueous NaHCO3, and the organic layer was separated, dried,
and concentrated in vacuo to give the crude 3-amino-4-(6-
dimethylamino-2,4-dimethylpyridin-3-yl)pyrazole, which was
used without further purification: MS (EI) 230 (MH+).
A mixture of 5-(chloromethyl)-2-methylpyridine (from above)
and NaCN (50 mmol) in DMSO (30 mL) was heated at 100 °C
for 1 h, cooled, and partitioned between ethyl acetate (100 mL)
and water (50 mL). The aqueous layer was extracted twice
with ethyl acetate (50 mL), and the combined extracts were
dried over MgSO4, filtered, and concentrated in vacuo. The
product was purified by chromatography on silica gel with 1:1
ethyl acetate-hexanes to give 5-(cyanomethyl)-2-methylpyri-
dine as a colorless oil (1.8 g): MS (EI) 133 (MH+).
The above compound was dissolved in dioxane (100 mL) and
treated with ethyl acetoacetate (2 equiv). This mixture was
heated at reflux overnight, cooled, and diluted with ether. The
white precipitate was collected by filtration to give 3-(2,4-
dimethyl-6-dimethylaminopyridin-3-yl)-5-methyl-7-hydroxy-
pyrazolo[1,5-a]pyrimidine 32 as a white solid: 1H NMR
(DMSO-d6): 1.98 (s, 3H), 2.11 (s, 3H), 2.25 (s, 3H), 3.25 (s,
6H), 5.60 (s, 1H), 6.50 (brs, 1H), 7.76 (s, 1H); MS (EI) 298
(MH+). Anal. (C16H20N5O) C, H, N.
To a suspension of 5-(cyanomethyl)-2-methylpyridine (1.8
g) and sodium hydride (1.4 g, 60% in mineral oil) in dry THF
(10 mL) was added ethyl acetate (5 mL). This mixture was
stirred at room temperature; after about 5 min an exothermic
reaction started, and a brown suspension formed after 1 h.
The mixture was concentrated in vacuo and coevaporated with
THF twice. The residue was dissolved in ethanol-water-
acetic acid (10:1:5 mL), mixed with hydrazine hydrobromide
(3.1 g, 2 equiv), and refluxed for 1 h. Another portion of
hydrazine hydrobromide (1.6 g) was added, and the reflux was
continued for one more hour. Ethyl acetoacetate (7.1 g, 4 equiv)
was added, and the mixture was refluxed overnight. The
reaction mixture was cooled, and the resultant solid was
collected by vacuum filtration to give 3-(6-methylpyridin-3-
yl)-2,5-dimethyl-7-hydroxypyrazolo[1,5-a]pyrimidine (8 g, mixed
with NaBr).
3-(2,4-Dim eth yl-6-d im eth yla m in op yr id in -3-yl)-5-m eth -
yl-7-dipr opylam in opyr azolo[1,5-a ]pyr im idin e (34). A mix-
ture of 32 (0.5 g) and POCl3 (5 mL) in acetonitrile (5 mL) was
heated at reflux for 1 h, cooled, and poured into ice-water/
EtOAc. This mixture was basified with solid sodium bicarbon-
ate to pH ∼ 10. The organic layer was separated, and the
aqueous layer was extracted with ethyl acetate twice. The
combined extracts were dried over MgSO4 and concentrated
in vacuo to give 3-(2,4-dimethyl-6-dimethylaminopyridin-3-yl)-
5-methyl-7-chloropyrazolo[1,5-a]pyrimidine 33 (520 mg) as a
yellow solid: 1H NMR 2.01 (s, 3H), 2.20 (s, 3H), 2.51 (s, 3H),
3.05 (s, 6H), 6.29 (s, 1H), 6.82 (s, 1H), 8.03 (s, 1H); MS (EI)
316 (MH+).
A solution of 33 (30 mg, 0.1 mmol) in dipropylamine (excess)
was heated to reflux for 3 h. The mixture was concentrated in
vacuo, and the residue was dissolved in ethyl acetate. The
mixture was filtered through a short silica gel column with
ethyl acetate, and the filtrate was concentrated in vacuo to
give the title compound as a colorless oil: 1H NMR 0.96 (t, J
) 7.6 Hz, 6H), 1.76 (m, 4H), 2.00 (s, 3H), 2.30 (s, 3H), 2.40 (s,
3H), 3.12 (s, 6H), 3.72 (m, 4H), 5.78 (s, 1H), 6.35 (s, 1H), 7.93
(brs, 1H); MS (EI) 381 (MH+).
A mixture of 3-(6-methylpyridin-3-yl)-2,5-dimethyl-7-hy-
droxypyrazolo[1,5-a]pyrimidine (from above) and POCl3 (16
mL) was refluxed for 1 h. The reaction mixture was poured
into ice-water and neutralized with Na2CO3. The product was
extracted with ethyl acetate, dried over MgSO4 and concen-
trated in vacuo to give the title compound 24e as a yellow
solid: MS (EI) 273 (MH+).
3-(6-Meth ylpyr idin -3-yl)-2,5-m eth yl-7-dipr opylam in opy-
r a zolo[1,5-a ]p yr im id in e (29). A solution of 24e (50 mg) and
dipropylamine (1.5 mL) was heated at 100°C in a sealed reacti-
vial for 3 h. Chromatography on silica gel with 1:3 ethyl
acetate-hexanes gave the desired product as a colorless oil,
35 mg: 1H NMR 0.96 (t, J ) 7.2 Hz, 6H), 1.75 (m, 4H), 2.22
(s, 3H), 2.32 (s, 3H), 2.40 (s, 3H), 2.55 (s, 3H), 3.72 (m, 4H),
5.80 (s, 1H), 7.12 (s, 1H), 8.35 (s, 1H); MS (EI) 338 (MH+).
3-(4-Meth yl-6-d im eth yla m in op yr id in -3-yl)-2,5-d im eth -
yl-6-flu or o-7-d ip r op yla m in op yr a zolo[1,5-a ]p yr im id in e
(35a ). A solution of 26h (40 mg) and (PhSO2)2NF (1.2 equiv)
in chloroform (2 mL) was stirred at room temperature for 2
days. Chromatography on silica gel with 1:5 ethyl acetate/
hexanes gave the product as a white solid: 1H NMR 0.87 (t, J
) 7.1 Hz, 6H), 1.56 (m, 4H), 2.16 (s, 3H), 2.35 (s, 3H), 2.76 (s,

Design of NBI 30775/ R121919
J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 19 4797
(9) For recent reviews on small molecule CRF receptor antagonists,
see: Grigoriadis, D. E.; Haddach, M.; Ling, N.; Saunders: J . The
CRF receptor: structure, function and potential for therapeutic
intervention. Curr. Med. Chem. 2001, 1, 63-97.
3H), 3.11 (s, 6H), 3.57 (m, 4H), 6.49 (s, 1H), 8.02 (s, 1H); MS
(EI) 399 (MH+). Anal. (C22H31FN6) C, H, N.
3-(4-Meth yl-6-d im eth yla m in op yr id in -3-yl)-2,5-d im eth -
yl-6-ch lor o-7-d ip r op yla m in op yr a zolo[1,5-a ]p yr im id in e
(35b). A solution of 26h (40 mg) and NCS (1.2 equiv) in
chloroform (2 mL) was stirred at room temperature for 2 h.
Chromatography on silica gel with 1:5 ethyl acetate/hexanes
gave the product as a white solid: 1H NMR 0.88 (t, J ) 7.1
Hz, 6H), 1.56 (m, 4H), 2.15 (s, 3H), 2.35 (s, 3H), 2.72 (s, 3H),
3.11 (s, 6H), 3.57 (m, 4H), 6.49 (s, 1H), 8.02 (s, 1H); MS (EI)
415 (MH+).
3-(4-Meth yl-6-d im eth yla m in op yr id in -3-yl)-2,5-d im eth -
yl-6-b r om o-7-d ip r op yla m in op yr a zolo[1,5-a ]p yr im id in e
(35c). A solution of 26h (40 mg) and NBS (1.2 equiv) in
chloroform (2 mL) was stirred at room temperature overnight.
Chromatography on silica gel with 1:5 ethyl acetate/hexanes
gave the product as a white solid: 1H NMR 0.90 (t, J ) 7.1
Hz, 6H), 1.56 (m, 4H), 2.13 (s, 3H), 2.35 (s, 3H), 2.62 (s, 3H),
3.11 (s, 6H), 3.57 (m, 4H), 6.49 (s, 1H), 8.02 (s, 1H); MS (EI)
460 (MH+).
Biologica l Eva lu a tion . Ki values reported are the average
of several independent measurements depending on compound
potency, typically at least three measurements for compounds
with Ki values less than 50 nM. Experimental details for the
CRF1 receptor binding assay, inhibition of CRF stimulated
cAMP inhibitory assay, and inhibition of CRF stimulated
ACTH release assay in rat anterior pituitary cells have been
previously reported.42
Ra t P h a r m a cok in etics. Compound was dosed as hydro-
chloride salts in aqueous solution. The pharmacokinetic profile
of 26h was determined in male Sprague-Dawley rats (N )
3/time points at a dose of 10 mg/kg). The dosing solution was
prepared in purified water and filtered through a 0.2 µm Nylon
filter before administration (2 mL/kg) via the tail vain (iv) or
oral gavage (po).
(10) Webster, E. L.; Lewis, D. B.; Torpy, D. J .; Zachman, E. K.; Rice,
K. C.; Chrousos, G. P. In vivo and in vitro characterization of
antalarmin, a nonpeptide corticotropin-releasing hormone (CRH)
receptor antagonist: suppression of pituitary ACTH release and
peripheral inflammation. Endocrinology 1996, 137, 5747-5750.
(11) Chen, C.; Dagnino, R., J r.; De Souza, E. B.; Grigoriadis, D. E.;
Huang, C. Q.; Kim, K. I.; Liu, Z.; Moran, T.; Webb, T. R.;
Whitten, J . P.; Xie, Y. F.; McCarthy, J . R. Design and synthesis
of a series of non-peptide high-affinity human corticotropin-
releasing factor1 receptor antagonists. J . Med. Chem. 1996, 39,
4358-4360.
(12) Gilligan, P. J .; Baldauf, C.; Cocuzza, A.; Chidester, D.; Zaczek,
R.; Fitzgerald, L. W.; McElroy, J .; Smith, M. A.; Shen, H. L.;
Saye, J . A. Christ, D.; Trainor, G.; Robertson, D. W.; Hartig, P.
The discovery of 4-(3-pentylamino)-2,7-dimethyl-8-(2-methyl-4-
methoxyphenyl)-pyrazolo-[1,5-a]-pyrimidine: A corticotropin-
releasing factor (hCRF1) antagonist. Bioorg. Med. Chem. 2000,
8, 181-189.
(13) Arai, K.; Ohata, H.; Shibasaki, T. Non-peptidic corticotropin-
releasing hormone receptor type 1 antagonist reverses restraint
stress-induced shortening of sodium pentobarbital-induced sleep-
ing time of rats: evidence that an increase in arousal induced
by stress is mediated through CRH receptor type 1. Neurosci.
Lett. 1998, 255, 103-106.
(14) Griebel, G.; Simiand, J .; Steinberg, R.; J ung, M.; Gully, D.; Roger,
P.; Geslin, M.; Scatton, B.; Maffrand, J .-P.; Soubrie, P. 4-(2-
Chloro-4-methoxy-5-methylphenyl)-N-[(1S)-2-cyclopropyl-1-(3-
fluoro-4-methylphenyl)ethyl]5-methyl-N-(2-propynyl)-1,3-thiazol-
2-amine hydrochloride (SSR125543A), a potent and selective
corticotrophin-releasing factor1 receptor antagonist. II. Charac-
terization in rodent models of stress-related disorders. J . Phar-
macol. Exp. Ther. 2002, 301, 333-345.
(15) Hsin, L.-W.; Tian, X.; Webster, E. L.; Coop, A.; Caldwell, T. M.;
J acobson, A. E.; Chrousos, G. P.; Gold, P. W.; Habib, K. E.; Ayala,
A.; Eckelman, W. C.; Contoreggi, C.; Rice, K. C. CRHR1 receptor
binding and lipophilicity of pyrrolopyrimidines, potential non-
peptide corticotropin-releasing hormone type 1 receptor antago-
nists. Bioorg. Med. Chem. 2002, 10, 175-183.
(16) Keller, C.; Bruelisauer, A.; Lemaire, M.; Enz, A. Brain pharma-
cokinetics of a nonpeptidic corticotropin-releasing factor receptor
antagonist. Drug Metab. Dispos. 2002, 30, 173-176.
Su p p or tin g In for m a tion Ava ila ble: Elemental analyses
for compounds 11, 15, 20b, 23a ,b, 25, 26a -v, 27-28, 30, 32,
and 35a . This material is available free of charge via the
Internet at http://pubs.acs.org.
(17) (a) Wilcoxen, K.; Chen, C.; Huang, C.; Haddach, M.; Xie, Y.;
Wing, L.; Grigoriadis, D. E.; De Souza E. B.; McCarthy, J . R.
Design and synthesis of NBI 30545 and analogs as potent CRF
receptor antagonists. Abstracts of Papers, 217th National Meet-
ing of the American Chemical Society, Anaheim, CA; American
Chemical Society: Washington, DC, 1999; MEDI 002. (b) Li, Y.;
Hill, G.; Wong, H.; Kelly, N.; Ward, K.; Pierdomenico, M.; Ren,
S.; Gilligan, P.; Grossman, S.; Trainor, G.; Taub, R.; McElroy,
J .; Zazcek, R. Receptor occupancy of nonpeptide corticotropin-
releasing factor 1 antagonist DMP696: correlation with drug
exposure and anxiolytic efficacy. J . Pharmacol. Exp. Ther. 2003,
305, 86-96. (c) Chaki, S.; Nakazato, A.; Kennis, L.; Nakamura,
M.; Mackie, C.; Sugiura, M.; Vinken, P.; Ashton, D.; Langlois,
X.; Steckler, T. Anxiolytic- and antidepressant-like profile of a
new CRF1 receptor antagonist, R278995/CRA0450. Eur. J .
Pharmacol. 2004, 485, 145-158.
(18) Wustrow, D. J .; Capiris, T.; Rubin, R.; Knobelsdorf, J . A.;
Akunne, H.; Davis, M. D.; MacKenzie, R.; Pugsley, T. A.; Zoski,
K. T.; Heffner, T. G.; Wise, L. D. Pyrazolo[1,5-a]pyrimidine
CRF-1 receptor antagonists. Bioorg. Med. Chem. Lett. 1998, 8,
2067-2070.
(19) Advanced Chemistry Development, Inc., 90 Adelaide Street
West, Toronto, Ontario, M5H 3V9, Canada.
(20) Waterhouse, R. N. Determination of lipophilicity and its use as
Refer en ces
(1) Vale, W.; Speiss, J .; Rivier, C.; Rivier, J . Characterization of a
41-residue ovine hypothalamic peptide that stimulates secretion
of corticotropin and beta-endorphin. Science 1981, 213, 1394-
1397.
(2) (a) Owens, M. J .; Nemeroff, C. B. Physiology and pharmacology
of corticotropin-releasing factor. Pharmacol. Rev. 1991, 43, 425-
473. (b) De Souza, E. B.; Grigoriadis, D. E. In Psychopharma-
cology: The fourth generation of progress; Bloom, F. E., Kupfer,
D. J ., Eds.; Raven: New York, 1995; pp 505-517.
(3) (a) Vale, W.; Rivier, C.; Brown, M. R.; Spiess, J .; Koob, G.;
Swanson, L.; Bilezikjian, L.; Bloom, F.; Rivier, J . Chemical and
biological characterization of corticotropin-releasing factor. Re-
cent Prog. Horm. Res. 1983, 39, 245-270. (b) Koob, G. F.; Bloom,
F. E. Corticotropin-releasing factor and behavior. Fed. Proc.
1985, 44, 259-263.
(4) (a) Rivier, C.; Brownstein, M.; Spiess, J .; Rivier, J .; Vale, W. In
vivo corticotropin-releasing factor-induced secretion of adreno-
corticotropin, beta-endorphin, and corticosterone. Endocrinology
1982, 110, 272-278. (b) Antoni, F. A.; Fink, G.; Sheward, W. J .
Corticotrophin-releasing peptides in rat hypophysial portal blood
after paraventricular lesions: a marked reduction in the con-
centration of corticotrophin-releasing factor-41, but no change
in vasopressin. J . Endocrinol. 1990, 125, 175-183.
(5) Steckler, T.; Holsboer, F. Corticotropin-releasing hormone recep-
tor subtypes and emotion. Biol. Psych. 1999, 46, 1480-1508.
(6) Hernandez, J .-F.; Kornreich, W.; Rivier, C.; Miranda, A.; Yama-
moto, G.; Andrews, J .; Tache, Y.; Vale, W.; Rivier, J . Synthesis
and relative potencies of new constrained CRF antagonists. J .
Med. Chem. 1993, 36, 2860-2867.
(7) O’Bien, D.; Skelton, K. H.; Owen, M. J .; Nemeroff, C. B. Are CRF
receptor antagonists potential antidepressants? Hum. Psychop-
harmacol. Clin. Exp. 2001, 16, 81-87.
(8) Schulz, D. W.; Mansbach, R. S.; Sprouse, J ., Braselton, J . P.;
Collins, J .; Corman, M.; Dunaiskis, A.; Faraci, S.; Schmidt, A.
W.; Seeger, T.; Seymour, P.; Tingley, F. D., III; Winston, E. N.;
Chen, Y.; Heym, J . CP-154,526: a potent and selective nonpep-
tide antagonist of corticotropin releasing factor receptors. Proc.
Natl. Acad. Sci. U.S.A. 1996, 93, 10477-10482.
a
predictor of blood-brain barrier penetration of molecular
imaging agents. Mol. Imaging Biol. 2003, 5, 376-389.
(21) Part of this work was reported at the 221st National Meeting of
the American Chemical Society, San Diego, April 1-5, 2001.
Chen, C.; Wilcoxen, K.; Bozigian, H.; Chen, T. K.; Cha, M.;
McCarthy, J . R.; Huang, C. Q.; Haddach, H.; Zhu, Y. F.; Murphy,
B.; De Souza, E. B.; Grigoriadis, D. E. Orally active 3-(3-pyridyl)-
pyrazolo[1,5-a]pyrimidines as nonpeptide CRF1 receptor antago-
nists. Abstracts of Papers, 221st National Meeting of the
American Chemical Society, San Diego, CA; American Chemical
Society: Washington, DC, 2001; MEDI 214.
(22) (a) Keck, M. E.; Welt, T.; Wigger, A.; Renner, U.; Engelmann,
M.; Holsboer, F.; Landgraf, R. The anxiolytic effect of the CRH1
receptor antagonist R121919 depends on innate emotionality in
rats. Eur. J . Neurosci. 2001, 13, 373-380. (b) Keck, M. E.; Welt,
T.; Mueller, M. B.; Landgraf, R.; Holsboer, F. The high-affinity
non-peptide CRH1 receptor antagonist R121919 attenuates
stress-induced alterations in plasma oxytocin, prolactin, and
testosterone secretion in rats. Pharmacopsychiatry 2003, 36, 27-

4798 J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 19
Chen et al.
31. (c) Risbrough, V. B.; Hauger, R. L.; Pelleymounter, M. A.;
Geyer, M. A. Role of corticotrophin releasing factor (CRF)
receptor 1 and 2 in CRF-potentiated acoustic startle in mice.
Psychopharmacology 2003, 170, 178-187. (d) Oshima, A.; Fl-
achskamm, C.; Reul, J . M. H. M.; Holsboer, F.; Linthorst, A. C.
E. Altered serotonegic neurotransmission but normal hypotha-
lamic-pituitary-adrenocortical axis activity in mice chronically
treated with the corticotrophin-releasing hormone receptor type
I antagonist NBI 30775. Neuropsychopharmacology 2003, 28,
2148-2159. (e) Rivier, C. L.; Grigoriadis, D. E.; Rivier, J . E. Role
of corticotrophin-releasing factor receptors type 1 and 2 in
modulating the rat adrenocorticotropin response to stressors.
Endocrinology 2003, 144, 2396-2403.
radioligand for the pharmacological and biochemical study of
human corticotropin-releasing factor2R receptors. Mol. Pharma-
col. 1996, 50, 679-586.
(38) When 25 (10 mg/kg) was given as an iv bolus injection, the peak
brain concentration (2.26 µg/mL) appeared at about 5 min, and
this was 2 times greater than that of plasma; see: Machay, K.
B.; Bozigian, H.; Grigoriadis, G. E.; Loddick, S. A.; Verge, G.;
Foster, A. C. Neuroprotective effects of the CRF1 antagonist
R121919 after permanent focal ischemia in the rat. J . Cereb.
Blood Flow Metab. 2001, 21, 1208-1214.
(39) Plosky, P. M.; Cunningham, E. T., J r.; Widmaier, E. P. Cat-
echolaminergic modulation of corticotropin-releasing factor and
adrenocorticotropin secretion. Endocr. Rev. 1989, 10, 437-458.
(40) (a) Berridge, C. W.; Dunn, A. J . Corticotropin-releasing factor
elicited naloxone sensitive stress-like alternations in exploratory
behavior in mice. Regul. Pept. 1986, 16, 83-93. (b) Berridge, C.
W.; Dunn, A. J . A corticotropin-releasing factor antagonist
reverses the stress-induced changes of exploratory behavior in
mice. Horm. Behav. 1987, 21, 393-401. (c) Berridge, C. W.;
Dunn, A. J . Restraint stress-induced changes in exploratory
behavior appear to be mediated by norepinephrine-stimulated
release of CRF. J . Neurosci. 1989, 9, 3513-3521. (d) Berridge,
C. W.; Dunn, A. J . CRF and restraint-stress decrease exploratory
behavior in hypophysectomized mice. Pharmacol. Biochem.
Behav. 1989, 34, 517-519.
(41) Heinrichs, S. C.; De Souza, E. B.; Schulteis, G.; Lapsansky, J .
L.; Grigoriadis, D. E. Brain penetrance, receptor occupancy and
antistress in vivo efficacy of a small molecule corticotropin
releasing factor type I receptor selective antagonist. Neuropsy-
chopharmacology 2002, 27, 194-202.
(42) Gutman, D. A.; Owens, M. J .; Skelton, K. H.; Thrivikraman, K.
V.; Nemeroff, C. B. The corticotropin-releasing factor1 receptor
antagonist R121919 attenuates the behavioral and endocrine
responses to stress. J . Pharmacol. Exp. Ther. 2003, 304, 874-
880.
(43) To a solution of sodium ethoxide (27.2 g, 0.4 mol) in ethanol (300
mL) was added 5-methylisoxazole (36.6 g, 0.44 mol) with stirring
under a nitrogen atmosphere at room temperature. A yellow
solid formed, and the exothermic reaction mixture was stirred
at room temperature for 3 h. The solid was collected by filtration,
washed with ethanol, and dried to give the cyanoacetone sodium
salt (30.6 g, 73%).
(44) (a) Hawkins, G. F.; Arthur, R. The preparation of 5-fluoronico-
tinic acid and 5-fluoronicotinamide. J . Org. Chem. 1949, 14,
328-332. (b) Nemec, J .; Meeker, F. S.; Schreiber, E. C. Synthesis
of 2-[3′-(Trifluoromethyl)anilino]-5-hydroxynicotinic Acid. J . Het-
erocycl. Chem. 1974, 11, 569-573.
(45) (a) Hatton, P. M.; Sternhell, S. An N. M. R. Investigation of
polarization of pyridine by +R substituents and a proposed new
method for determination of the substituent resonance param-
eter (σR). Aust. J . Chem. 1993, 1, 149-152. (b) Whittle, T. Alkyl
migrations and nitrene/formimine eliminations in alkylamino
heteroaromatic compounds. Tetrahedron Lett. 1968, 9, 3689-
3692.
(46) Bell, I. M.; Erb, J . M.; Freidinger, R. M.; Gallicchio, S. N.; Guare,
J . P.; Guidotti, M. T.; Halpin, R. A.; Hobbs, D. W.; Homnick, C.
F.; Kuo, M. S.; Lis, E. V.; Mathre, D. J .; Michelson, S. R.;
Pawluczyk, J . M.; Pettibone, D. J .; Reiss, D. R.; Vichers, S.;
Williams, P. D.; Woyden, C. J . Development of orally active
oxytocin antagonists: studies on 1-(1-{4-[1-(2-methyl-1-oxidopy-
ridin-3-ylmethyl)piperidin-4-yloxy]-2-methoxybenzoyl}piperidin-
4-yl)-1,4-dihydrobenz[d][1,3]oxazin-2-one (L-372,662) and related
pyridines. J . Med. Chem. 1998, 41, 2146-2163.
(23) (a) Zobel, A. W.; Nickel, T.; Kunzel, H. E.; Ackl, N.; Sonntag, A.;
Ising, M.; Holsboer, F. Effects of the high-affinity corticotropin-
releasing hormone receptor 1 antagonist R121919 in major
depression: the first 20 patients treated. J . Psychiatr. Res. 2000,
34, 171-181. (b) Kunzel, H. E.; Zobel, A. W.; Nickel, T.; Ackl,
N.; Uhr, M.; Sonntag, A.; Ising, M.; Holsboer, F. Treatment of
depression with the CRH-1-receptor antagonist R121919: en-
docrine changes and side effects. J . Psychiatr. Res. 2003, 37,
525-533. (c) Held, K.; Kunzel, H.; Ising, M.; Schmid, D. A.; Zobel,
A.; Murck, H.; Holsboer, F.; Steiger, A. Treatment with the
CRH1-receptor-antagonist R121919 improves sleep-EEG in
patients with depression. J . Psychiatr. Res. 2004, 38, 129-136.
(24) Ciller, J . A.; Seoane, C.; Soto, J . L. On the ring cleavage of
isoxazoles: a note. Heterocycles 1984, 22, 1989-1993.
(25) Katz, R. B.; Voyle, M. Synthesis of some nitropyridylacetonitriles.
Synthesis 1989, 314-316.
(26) Liang, F.; Navarro, H. A.; Abraham, P.; Kotian, P.; Ding, Y.-S.
Synthesis and nicotinic acetylcholine receptor binding properties
of exo-2-(2′-fluoro-5′-pyridinyl)-7-azabicyclo[2.2.1]heptane: a new
positron emission tomography ligand for nicotinic receptors. J .
Med. Chem. 1997, 40, 2293-2295.
(27) Paudler, W. W.; J ovanovic, M. V. Bromination of some pyridine
and diazine N-oxides. J . Org. Chem. 1983, 48, 1064-1069.
(28) Comins, D. L.; Killpack, M. O. Lithiation of methoxypyridines
directed by R-amino alkoxides. J . Org. Chem. 1990, 55, 69-73.
(29) van Leusen, A. M.; Oomkes, P. G. One-step conversion of
aldehydes to nitriles. introduction of a one-carbon unit. Synth.
Commun. 1980, 10, 399-403.
(30) Matsumoto, I.; Nakagawa, K.; Kubo, K. 5-(Carboxymethyl)-2-
pyridinemethanol carbamates. J P 48099178, 1973.
(31) The cyclization of 21 with free hydrazine or hydrazine hydrate
gave low yield of the desired products in our hand, and the
deacetyl compounds 20 were the major byproducts.
(32) De Souza, E. B. Corticotropin-releasing factor receptors in the
rat central nervous system: characterization and regional
distribution. J . Neurosci. 1987, 7, 88-100.
(33) Battaglia, G.; Webster, E. L.; De Souza, E. B. Characterization
of corticotropin-releasing factor receptor-mediated adenylate
cyclase activity in the rat central nervous system. Synapse 1987,
1, 572-581.
(34) Chen, C.; Webb, T. R.; McCarthy, J . R.; Moran, T. J .; Wilcoxen,
K. M. Pyrazolopyrimidines as CRF receptor antagonists. WO
9729109, 1997.
(35) Aminopyridine has a pKa value of 6.8, and the calculated pKa
value for 2-dimethylaminopyridine was 7.0 using ACD/pKa DB.
(36) Hodge, C. N.; Aldrich, P. E.; Wasserman, Z. R.; Fernandez, C.
H.; Nometh, G. A.; Arvanitis, Cheeseman, R. S.; Chorvat, R. J .;
Ciganek, E.; Christos, T. E.; Gilligan, P. J .; Krenitsky, Scholfield,
E.; Strucely, P. Corticotropin-Releasing Hormone Receptor
Antagonists: Framework Design and Synthesis Guided by
Ligand Conformational Studies. J . Med. Chem. 1999, 42, 819-
832.
(37) For a CRF2 binding assay, see: Grigoriadis, D. E.; Liu, X. J .;
Vaughn, J .; Palmer, S. F.; True, C. D.; Vale, W. W.; Ling, N.;
De Souza, E. B. 125I-Tyro-sauvagine:
a
novel high affinity
J M040058E