N-[6-Amino-2-(heteroaryl)pyrimidin-4-yl]acetamides as A2A receptor antagonists with improved drug like properties and in vivo efficacy

Article abstract of DOI:10.1021/jm800908d

In the present article, we report on a strategy to improve the physical properties of a series of small molecule human adenosine 2A (hA_2A) antagonists. One of the aromatic rings typical of this series of antagonists is replaced with a series of

Full text of DOI:10.1021/jm800908d

J. Med. Chem. 2009, 52, 709–717
709
N-[6-Amino-2-(heteroaryl)pyrimidin-4-yl]acetamides as A2A Receptor Antagonists with
Improved Drug Like Properties and in Vivo Efficacy
Marion C. Lanier,# Manisha Moorjani,# Zhiyong Luo,# Yongsheng Chen,# Emily Lin,# John E. Tellew,# Xiaohu Zhang,#
John P. Williams,# Raymond S. Gross,† Sandra M. Lechner,‡ Stacy Markison,‡ Tanya Joswig,‡ William Kargo,‡ Jaime Piercey,‡
Mark Santos,§ Siobhan Malany,§ Marilyn Zhao,† Robert Petroski,‡ Mar´ıa I. Crespo, Jose´-Luis D´ıaz, John Saunders,#
Jenny Wen,| Zhihong O’Brien,| Kayvon Jalali,| Ajay Madan,| and Deborah H. Slee*,#
Departments of Medicinal Chemistry, Pharmacology, Neuroscience, Chemical DeVelopment, and Preclinical DeVelopment, Neurocrine
Biosciences, 12780 El Camino Real, San Diego, California 92130, and Almirall Research Center, Almirall, Ctra. Laurea` Miro´, 408-410,
E-08980 St. Feliu de Llobregat, Barcelona, Spain
ReceiVed July 21, 2008
In the present article, we report on a strategy to improve the physical properties of a series of small molecule
human adenosine 2A (hA2A) antagonists. One of the aromatic rings typical of this series of antagonists is
replaced with a series of aliphatic groups, with the aim of disrupting crystal packing of the molecule to
lower the melting point and in turn to improve the solubility. Herein, we describe the SAR of a new series
of water-soluble 2,4,6-trisubstituted pyrimidines where R1 is an aromatic heterocycle, R2 is a short-chain
alkyl amide, and the typical R3 aromatic heterocyclic substituent is replaced with an aliphatic amino
substituent. This approach significantly enhanced aqueous solubility and lowered the log P of the system to
provide molecules without significant hERG or CYP liabilities and robust in vivo efficacy.
Introduction
On the basis of its distribution in the brain and interaction
with dopamine receptors, the human A2A (hA2Aa) receptor has
emerged as a novel nondopaminergic target to treat Parkinson’s
disease (PD).1 There is accumulating evidence to suggest that
antagonists of this receptor will improve the motor dysfunction
associated with PD while reducing the severe side effects that
Figure 1. Examples of A2A antagonists in clinical development.
result from long-term dopaminergic therapies. Many companies
are interested in this therapeutic approach, and currently several
A2A antagonists are in clinical development.2 The xanthine
derivative Istradefylline3 (1, also known as KW-6002, Figure
1) was discovered by Kyowa Hakko Kogyo Corporation. This
molecule represents the adenosine A2A receptor antagonist that
has advanced the furthest in terms of clinical development.
Schering-Plough has developed a series of purine analogues,
and SCH-4208144 (2, Figure 1) is in phase II clinical trials.
Figure 2. Novel approach proposed to improve the solubility of the
pyrimidine series.
Biogen Idec initiated a phase II clinical trial for PD with the
Compound 3 showed good in vitro and in vivo profiles (hA2A Ki
non-xanthine A2A antagonist BIIB014 (also known as V-2006)
in May 2007 (structure not disclosed).5 Similarly Synosia is
also in phase II clinical trials with SYN115 (structure not
disclosed).6
) 2.3 nM, hcAMP IC50 ) 85 nM, 82-fold selectivity over the
human A1 (hA1) receptor; efficacious in the rat haloperidol-induced
catalepsy (HIC) model at 1 mg/kg), but its poor solubility (<0.01
mg/mL at pH g 2) hindered further development. We attributed
this poor solubility to the observed high melting point (283 °C)
indicating a high crystal lattice energy. In our earlier work8 we
described adding polar or basic substituents to improve drug like
properties and in particular to increase aqueous solubility. In
parallel, we also pursued a strategy of replacing one of the aromatic
rings with an aliphatic group, which we expected would disrupt
crystal packing, lower the melting point, and in turn improve the
solubility. Herein, we report a new series of water-soluble 2,4,6-
trisubstituted pyrimidines where R1 is an aromatic heterocycle, R2
is a short-chain alkyl amide, and the typical R3 aromatic hetero-
cyclic substituent is replaced with an aliphatic amino substituent
(compound 4, Figure 2).
Our research efforts have focused on the development of
trisubstituted pyrimidines as human A2A (hA2A) antagonists. Previ-
ously we reported on compound 37 (Figure 2), where a pyrimidine
core is substituted at the 2 and 4 positions by an aromatic or
heteroaromatic ring and at the 6 position by a simple amide.
* To whom correspondence should be addressed. Phone: 858 617-7849.
Fax: 858 617-7925. E-mail: dslee@neurocrine.com.
#
Department of Medicinal Chemistry, Neurocrine Biosciences.
Department of Chemical Development, Neurocrine Biosciences.
Department of Neuroscience, Neurocrine Biosciences.
Department of Pharmacology, Neurocrine Biosciences.
†
‡
§
Almirall Research Center.
|
Department of Preclinical Development, Neurocrine Biosciences.
a Abbreviations: hA2A, human adenosine 2A; hA1, human adenosine 1;
HIC, haloperidol induced catalepsy; hERG, human ether-a-go-go related
gene; CYP, cytochrome P450; PBS, phosphate buffered saline; SAR,
structure activity relationship; po, oral dosing; 6-OHDA, 6-hydroxydopa-
mine.
Chemistry
Preparation of intermediates 6a and 6b (Scheme 1) was
carried out through the reaction of either 3,5-dimethylpyrazole
10.1021/jm800908d CCC: $40.75
2009 American Chemical Society
Published on Web 01/13/2009

710 Journal of Medicinal Chemistry, 2009, Vol. 52, No. 3
Lanier et al.
Table 1c
Scheme 1a
a Reagents and conditions: 3,5-dimethylpyrazole (for 6a) or pyrazole (for
6b), cesium carbonate, dioxane, reflux, 39% yield.
Figure 3. Common key intermediates used for final compound
synthesis.
Scheme 2a
a Reagents and conditions. (a) R2 ) Me: Ac2O, AcOH, 90 °C, 18 h,
t
83% yield. (b) R2 ) Et or Bu: propionyl chloride or isovaleryl chloride,
pyridine, DMF, room temp, 12 h. (c) R3 ) amine: amine, dioxane, 80 °C,
2 h. (d) R3 ) pyrrolidin-1-yl-2-one: 2-pyrrolidinone, palladium acetate,
xanthpos, cesium carbonate, toluene, 100 °C, 18 h.
or pyrazole with 2,4-dichloro-6-aminopyrimidine 5 in the
presence of cesium carbonate in dioxane at reflux. Preparation
of intermediates 6c-f (Figure 3) was carried according to the
procedures described previously.9
Amines 6a-f were then acetylated using acetic anhydride in
acetic acid to give 7a-f, respectively. Compound 6a was also
reacted with propionyl or isovaleryl chloride in the presence of
pyridine to give 8a and 9a, respectively (Scheme 2). The
displacement of the chlorine atom of the pyrimidine intermedi-
ates (7a-f, 8a, and 9a) was carried out either in the presence
of the desired amine in refluxing dioxane or in the presence of
a lactam using palladium-mediated coupling conditions, as
outlined in Scheme 2, to give the final products 10-41 (Tables
1-5).
a Displacement of specific [3H]46 ([3H]-ZM 241385, Figure 7)12 binding
at human A2A receptors expressed in HEK293 cells. b Displacement of
specific [3H]47 ([3H]-DPCPX, Figure 7)13 binding at human A1 receptors
expressed in HEK293 cells. c Data are expressed as geometric mean values
of at least two runs ( the standard error measurement (SEM). ND: not
determined.
explore the structure activity relationship (SAR) around the R3
group with the goal of replacing the typical aromatic R3 moiety
with an aliphatic group (Table 1). By use of the versatile chloro
intermediates 7a-f, 8a, and 9a as starting points, a diverse set
of amine-linked side chains which included cyclic and open
chain amines and lactams was incorporated into the structure
at the R3 position. The initial results were encouraging, and it
was found that compounds with a simple diethylamine 10,
unsubstituted pyrrolidine 11, or piperidine 12 moiety at R3 were
quite potent lead like molecules with hA2A receptor affinity of
approximately 100 nM and selectivity on the order of 45-fold
over the human A1 receptor (hA1) (Table 1). While the
ethylamine analogue 10 had similar activity and selectivity to
the cyclic systems, subsequent attempts to improve upon this
with additional open chain analogues proved unfruitful (data
not shown), and the ethylamine remained the most potent in
this subseries. Interestingly the lactam analogue 13 had signifi-
cantly better affinity for the hA2A receptor (hA2A Ki ) 12 nM)
and was found to be slightly more selective (74-fold) for the
hA2A receptor over the hA1 receptor than the corresponding
pyrrolidine 11. We hypothesized that the carbonyl of the lactam
might be picking up a key hydrogen bonding interaction with
the receptor which accounted for this increase in potency.
Unfortunately, it was observed that in general lactam analogues
Synthesis of compound 43 where R2 is an amine or 44 where
R2 is an alkoxy group was accomplished via first displacing
the chlorine atom of the aminopyrimidine intermediate 6a with
(R)-2-methoxymethylpyrrolidine to give intermediate 42, fol-
lowed by reaction with triphosgene and addition of either
isopropylamine (for 43) or methanol (for 44) (Scheme 3). All
final compounds were purified by HPLC.
Results and Discussion
From previous experience with the pyrimidine system,9 it was
apparent that a wide range of substitution was tolerated at the
R3 position of the molecule (Figure 2, general structure 4). While
we were unable to get a crystal structure of the lead compound
3, we were able to get a crystal structure of a closely related
compound 4510 (hA2A Ki ) 1.9 nM) (Figure 4), which showed
that the pyrimidine system was planar, helping to explain the
high melting points and low solubility observed for the initial
leads.
With the aim of reducing the planarity of the system, and
the hope of improving physical properties, we set out to further

Acetamides as A2A Receptor Antagonists
Journal of Medicinal Chemistry, 2009, Vol. 52, No. 3 711
Table 2c
Figure 4. Crystal structure of a pyrimidine dimethylpyrazole containing
lead molecule 45 showing the planarity of the system.
Table 3c
Ki (nM) ( SEM
Selectivity
hA1/hA2A
a
b
Compound
R4
hA2A
hA1
30
31
trans-OMe
cis-OMe
7.5 ( 3.7
23 ( 3
352 ( 117
620 ( 180
47
27
a Displacement of specific [3H]46 binding at human A2A receptors
b
expressed in HEK293 cells. Displacement of specific [3H]47 binding at
human A1 receptors expressed in HEK293 cells. c Data are expressed as
geometric mean values of at least two runs ( the standard error measurement
(SEM).
inhibition of hcAMP release for 13). The idea that there might
be alternative stable analogues that could take advantage of this
potential interaction was pursued further, and the focus shifted
to incorporation of heteroatoms either into the aliphatic system
or as substituents off the ring system. Incorporation of heteroa-
toms into the ring system as exemplified by the morpholine
analogue 14 (hA2A Ki ) 313 nM) and the N-methylpiperazine
analogue 15 (hA2A Ki ) 1867 nM) proved unsuccessful, as was
the case with other polar substituents such as amino, amide (data
not shown), and ester moieties (e.g., compounds 19 and 20,
Table 2). In contrast, adding lipophilic groups such as the fused
phenyl ring in compound 16 boosted both binding for the human
A2A receptor (4.2 nM) and selectivity over the hA1 receptor (77-
fold). However, as expected, the strategy of adding lipophilicity
to gain potency severely compromised physical properties,
leading again to poorly soluble compounds (the solubility of
compound 16 in phosphate buffer at pH 7.2 was 0.01 mg/mL).
Additional focus on pyrrolidines substituted with simple alkyl
and alkoxy side chains in an attempt to balance activity,
selectivity, and solubility (Table 2) led to some exciting results.
A small alkyl chain such as a methyl (17) or an n-propyl (18)
at the 2 position of the pyrrolidine gave a 4-fold boost in activity
compared to the unsubstituted pyrrolidine 11. Further, the
methoxymethyl (MOM, 21) was even better with a Ki value
for the human A2A receptor equal to 9.0 nM for the racemic
mixture. After synthesis of the single enantiomers it was found
that the R enantiomer 22 was significantly more active and
selective for the human A1 receptor than the S enantionmer 23
(hA2A Ki of 4.7 and 324 nM, and 34- and 14-fold selective vs
hA1, respectively). These results again suggested that addition
of an appropriately placed hydrogen bond accepting group was
a Displacement of specific [3H]46 binding at human A2A receptors
b
expressed in HEK293 cells. Displacement of specific [3H]47 binding at
human A1 receptors expressed in HEK293 cells. c Data are expressed as
geometric mean values of at least two runs ( the standard error measurement
(SEM). ND: not determined.
Scheme 3a
a Reagents and conditions: (a) (R)-2-methoxymethylpyrrolidine, dioxane,
80 °C, 2 h; (b) triphosgene, pyridine, DCM, 0 °C, 0.5 h, then isopropylamine
(for 43) or methanol (for 44).
were prone to chemical instability over time, and lactam ring
opening readily occurred under basic conditions. When tested
further in secondary assays, it was found that the lactams also
suffered from poor functional activity11 (IC50 ) 1000 nM for

712 Journal of Medicinal Chemistry, 2009, Vol. 52, No. 3
Lanier et al.
Table 4c
Table 5c
a Displacement of specific [3H]46 binding at human A2A receptors
b
expressed in HEK293 cells. Displacement of specific [3H]47 binding at
human A1 receptors expressed in HEK293 cells. c Data are expressed as
geometric mean values of at least two runs ( the standard error measurement
(SEM).
a Displacement of specific [3H]46 binding at human A2A receptors
b
expressed in HEK293 cells. Displacement of specific [3H]47 binding at
human A1 receptors expressed in HEK293 cells. c Data are expressed as
geometric mean values of at least two runs ( the standard error measurement
(SEM).
sensitive to the configuration of the MOM group, and in general
the 3,5-dimethylpyrazole analogues displayed an increase in
selectivity for the human A2A receptor over the human A1
receptor. In the case of the 2-thiophene, 2-thiazole, and
2-pyridine analogues (compounds 34-39), the stereochemistry
of the MOM group had little or no influence on the binding at
the human A2A receptor and the selectivity over the human A1
receptor was greatly decreased.
beneficial and that the chirality was important for both potency
and selectivity. Extension of the methyl to ethyl (24) or addition
of heterocyclic substituents (28) was not well tolerated. Extend-
ing the carbon chain between the piperidine ring and the oxygen
by one carbon to give 26 (hA2A Ki ) 275 nM, 17-fold selectivity
vs hA1) resulted in a sharp loss of both activity and selectivity.
Removal of the methyl group to reveal a hydroxyl moiety (25)
resulted in a 4-fold loss in potency, and additional substitution
on the pyrrolidine ring (27) did not improve the profile.
Additional SAR around the pyrrolidine ring concentrated on
combining the MOM group at the 2 position of the pyrrolidine
ring with a second simple substitution around the ring, with
the aim of further refining the activity and selectivity of the
molecule (examples shown in Table 3). Combining the R-2-
MOM of 22 (hA2A Ki ) 4.7 nM) with a 4-OMe group
maintained potency against the human A2A receptor in the case
of the trans diastereoisomer 30 (hA2A Ki ) 7.5 nM, 47-fold
selective over hA1). The cis diasteroisomer 31 was not as active
(hA2A Ki ) 23 nM) and was also slightly less selective over
the hA1 receptor (27-fold selective). The same pattern was
observed for the 4-Me analogues (data not shown). In summary,
from a limited exploration of substitution at the 4-position of
the pyrrolidine ring no improvement was seen, and compound
22 remained the most attractive lead molecule.
Finally, the R2 region was explored (Table 5). Compound
42 (the deacetylated amine analogue of 22) showed a Ki value
for the human A2A receptor of 261 nM and was 9.5-fold selective
over the human A1 receptor, indicating that the carbonyl of the
acetate group of compound 22 was essential for activity.
Extension of the alkyl group to give compounds 40 and 41
reduced selectivity and also potency in the case of 41. A urea
(43) or a carbamate (44) was tolerated but again had an inferior
profile compared to compound 22. After extensive synthetic
efforts to further optimize the series, it was concluded that the
simple 2-methylmethoxypyrrolidine analogue 22 had the most
attractive profile in terms of activity and selectivity. In terms
of physical properties compound 22 had a low molecular weight
(344 g/mol), a measured log D of 2.2, and good solubility (1
mg/mL at pH 7.4 as the free base and >6.7 mg/mL as the HCl
salt). The melting point for compound 22 was significantly lower
than that of the lead molecule 3 (186 °C vs 283 °C), which we
believe is largely responsible for the improvement in physical
properties. Overall, compound 22 has the profile of an efficient
molecule14 with excellent physical properties for development
and hence was further investigated in preclinical and efficacy
assays.
The R1 region of the molecule was also revisited. The 3,5-
dimethylpyrazole was replaced by various heterocycles such as
5-methylfuran, thiophene, thiazole, and pyridine in combination
with the 2-MOM pyrrolidine (Table 4). The 3,5-dimethylpyra-
zole 22, 23, and the 5-methylfuran 32, 33 were the most
Additional characterization of compound 22 for human A2A
functional activity, rat A2A receptor binding affinity, metabolic
stability, membrane permeability, cytochrome P450 (CYP450)

Acetamides as A2A Receptor Antagonists
Journal of Medicinal Chemistry, 2009, Vol. 52, No. 3 713
Table 6. In Vitro Data for Compound 22
parameter
value
4.7 ( 0
85 ( 16
48 ( 10
>50
hA2A Ki (nM) ( SEMa d
,
hcAMP IC50 (nM) ( SEMb d
,
rA2A Ki (nM) ( SEMc d
,
CYP 3A4/2D6/2C9/2C19 inhibition (µM)
CYP 1A2 inhibition (µM)
11
17
scaled intrinsic clearance
(human liver microsomes) ((mL/min)/kg)
scaled intrinsic clearance
74
(rat liver microsomes) ((mL/min)/kg)
Caco-2 rate × 10-6 cm/s
70 [0.7]
[B > A/A > B ratio]
hERG patchclamp block at 10 µM (%)
solubility in PBS (mg/mL)
19
>6.7 (HCl salt)
Figure 5. Effect of compound 22 (2 h after dose) on the mean decent-
latency ((standard error) in seconds on haloperidol-induced catalepsy
in the bar test at 3, 10, and 30 mg/kg, po: (/) vehicle versus treated
rats, p < 0.05.
a Displacement of specific [3H]46 binding at human A2A receptors
expressed in HEK293 cells. b hA2A receptor antagonism of 3-[4-[2-[[6-
amino-9-[(2R,3R,4S,5S)-5-(ethylcarbamoyl)-3,4-dihydroxyoxolan-2-yl]purin-
2-yl]amino]ethyl]phenyl]propanoic acid (CGS-21680)15 stimulated cAMP
c
Table 8. Plasma and Brain Exposure for Compound 22, at 2 h After
Oral Dosing, in Rats used in the HIC Model
production. Displacement of specific [3H]46 binding at rat A2A receptors
expressed in CHO cells. d Data are expressed as geometric mean values of
at least two runs ( the standard error measurement (SEM).
dose (mg/kg)
plasma (ng/mL)
brain (ng/g)
B/P ratio
3
10
30
98
1062
4638
34
488
2024
0.37
0.46
0.45
Table 7. Plasma and Brain Exposure of 22 after Oral Administration at
a Dose of 10 mg/kg in Ratsa
time
point (h)
brain levels
(ng/g)
plasma levels
(ng/mL)
B/P ratio
1
4
24
863 ( 530
116 ( 71
BQL
1604 ( 716
333 ( 148
BQL
0.51 ( 0.13
0.33 ( 0.08
NA
a BQL: below the limits of quantitation. NA: not available.
inhibition, human ether-a-go-go related gene (hERG) inhibition,
and solubility (as the HCl salt) is summarized in Table 6.
Compound 22 showed no significant inhibition of the major
CYP450 enzymes, CYP3A4, 2D6, 2C9, 2C19, but was found
to be a weak inhibitor of CYP1A2 (11 µM). Metabolic stability
was good when incubated with human and rat liver microsomes,
and no significant hERG channel block was observed at the
concentrations tested. Importantly, compound 22 had very good
solubility in phosphate buffered saline (PBS) as the HCl salt.
Although binding at the rat A2A receptor was 10 times weaker
than at the human receptor, the potency of the compound was
still sufficient to show efficacy in rat in vivo models.
Figure 6. Potentiation of L-dopa induced rotations in unilaterally
6-OHDA-lesioned rats by 22 dosed orally at 30 mg/kg alone and 0, 3,
10, and 30 mg/kg plus L-dopa. The “×” notes that a 1 mg/kg dose of
L-dopa causes a significant increase in rotations when compared to
vehicle alone.
Compound 22 was then characterized in a discrete rat
pharmacokinetic study with 10 mg/kg oral dosing (po) and
showed good exposure in both plasma and brain (Table 7).
The Tmax was found to be around 1 h (0.9 h) and the
compound was rapidly eliminated. After 4 h, the brain levels
were significantly decreased (863 ng/g at 1 h and 116 ng/g
at 4 h) and were below the limits of quantitation at 24 h.
Compound 22 was subsequently tested for efficacy in two
in vivo rat models. First, the ability of 22 to reverse
haloperidol induced catalepsy (HIC) in rodent was evaluated.
In this assay, compound 22 (3, 10, 30 mg/kg, po) was
administered 2 h prior to the assay and significantly reduced
descent latency at the 10 and 30 mg/kg doses (Figure 5).
Exposure at all doses was acceptable (Table 8).
Compound 22 was also evaluated for its ability to
potentiate L-dopa induced rotational behavior in the 6-hy-
droxydopamine (6-OHDA) unilateral lesioned rat. Lesioned,
L-dopa sensitized rats (three treatments with 10 mg/kg L-dopa)
were tested in a repeated measure, randomized design for
responsiveness to vehicle, L-dopa (1 mg/kg), and 22 (3, 10,
30 mg/kg, po) in combination with L-dopa. As shown in
Figure 6, compound 22 dose-dependently increased rotational
behavior compared to L-dopa alone, with significant effects
at both the 10 and 30 mg/kg doses.
Figure 7. Structures of antagonists 46 and 47 used in binding assays.
The behavioral study in the HIC model was carried out
2 h after oral dosing of 22, and the total contralateral rotation
count with 6-OHDA was taken 5 h after oral dosing of 22.
Although the peak concentration was reached well before
the time of measurement in both animal models, the in vivo
concentration was still sufficient to account for the observed
efficacy. Given that binding affinity of 22 to the human A2A
receptor is at least 10 times better than in the rat, it is
expected that efficacy in humans should be observed at lower
doses. Compound 22 was further assayed for off-target
activity at Cerep16 in 25 binding assays and 17 enzyme assays

714 Journal of Medicinal Chemistry, 2009, Vol. 52, No. 3
Lanier et al.
× 75 mL). The solid was dried in a vacuum oven at 50 °C
overnight. The acetic acid solvate of 7a was obtained as an off-
white crystalline solid (48.2 g, 0.15 mol, 83%). 1H NMR (CDCl3):
δ 9.07 (s, 1H), 8.03 (s, 1H), 6.03 (s, 1H), 2.65 (s, 3H), 2.30 (s,
3H), 2.22 (s, 3H), 2.12 (s, 3H).
and was found only to have activity on the closely related
A2B and A3 receptors (hA2B Ki ) 145 nM; hA3 Ki ) 19 nM).
Conclusion
We have developed an atypical novel series of potent A2A
receptor antagonists with a reduced number of aromatic
heterocycles. This decreases the planarity of the system and
results in compounds with good pharmaceutical properties for
drug development. Compound 22 demonstrates that it is possible
to make hA2A receptor antagonists with very good physical
properties, good functional activity at the human A2A receptor,
and with no CYP or hERG liabilities. Despite a rat A2A binding
Ki of approximately 50 nM, compound 22 showed oral efficacy
in two animal models at a dose of 10 mg/kg, and exhibited
good exposure without the need of formulation. This work
illustrates how less hydrophobic compounds can be developed
as small molecule antagonists for the human A2A receptor.
Compound 22 was selected to advance into safety screening
studies and for further detailed preclinical evaluation. These
results will be reported in due course.
Intermediates 7b-f were prepared according to the same
procedure using the corresponding intermediates 6b-f as starting
materials.
N-(6-Chloro-2-pyrazol-1-ylpyrimidin-4-yl)acetamide (7b). 1H
NMR (CDCl3): δ 8.54 (d, J ) 2.4, 1H), 8.41 (s, 1H), 8.09 (s, 1H),
7.79 (bs, 1H), 6.49 (dd, J ) 2.7, 0.9, 1H), 2.24 (s, 3H).
N-(6-Chloro-2-(5-methyl-2-furan-2-ylpyrimidin-4-yl))aceta-
1
mide (7c). H NMR (CDCl3): δ 8.21 (bs, 1H), 7.97 (s, 1H), 7.24
(d, J ) 3.6, 1H), 6.18 (dd, J ) 3.6, 0.9, 1H), 2.43 (d, J ) 0.9, 3H),
2.22 (s, 3H).
N-[(6-Chloro-2-thiophen-2-yl)pyrimidin-4-yl]acetamide (7d). 1H
NMR (CDCl3): δ 8.00 (s, 1H), 7.98 (dd, J ) 3.6, 1.2, 1H), 7.50
(dd, J ) 5.1, 1.2, 1H), 7.13 (dd, J ) 4.8, 0.9, 1H), 2.27 (s, 3H).
N-(6-Chloro-2-thiazol-2-ylpyrimidin-4-yl)acetamide (7e). 1H NMR
(CDCl3): δ 8.42 (bs, 1H), 8.20 (s, 1H), 8.02 (d, J ) 3.0, 1H), 7.58
(d, J ) 3.0, 1H), 2.25 (s, 3H).
N-(6-Chloro-2-pyridin-2-ylpyrimidin-4-yl)acetamide (7f). 1H NMR
(CDCl3): δ 8.80 (d, J ) 4.5, 1H), 8.51 (d, J ) 7.3, 1H), 8.42 (bs,
1H), 8.23 (s, 1H), 7.87 (dt, J ) 7.3, 1.8, 1H), 7.43 (dd, J ) 4.5,
1.2, 1H), 2.24 (s, 3H).
Experimental Section
Human and rat A2A and A1 binding assays,7 metabolism studies,8
hERG assays,17 pharmacokinetic assays,6 cytochrome P450 inhibi-
tion,6 Caco-2 permeability assays,6 HIC and 6-OHDA efficacy
studies,7 and solubility studies8 were performed as described
previously.
N-[6-Chloro-2-(3,5-dimethylpyrazol-1-yl)pyrimidin-4-yl]propi-
onamide (8a). Propionyl chloride (1.4 mL, 16.3 mmol, 1.2 equiv)
was added slowly to cold dimethylformamide (30 mL, ice bath)
followed by addition of anhydrous pyridine (1.3 mL, 16.3 mmol,
1.2 equiv) and intermediate 6a (3.0 g, 13.6 mmol, 1 equiv). The
mixture was allowed to warm to room temperature and stirred
overnight. After completion of the reaction, the reaction mixture
was neutralized with a saturated aqueous solution of sodium
bicarbonate and the product extracted with dichloromethane (3 ×
50 mL). The organic layers were combined, dried over magnesium
sulfate, and concentrated. Purification by column chromatography
eluting with dichloromethane with 2% methanol yielded the desired
product 8a as a light-brown solid (3.4 g, 75%). 1H NMR (CDCl3):
δ 8.26 (bs, 1H), 8.06 (s, 1H), 6.04 (s, 1H), 2.66 (s, 3H), 2.43 (q, J
) 7.5, 2H), 2.33 (s, 3H), 1.64 (bs, 1H), 1.24 (t, J ) 7.5, 3H).
Chemistry. Reagents, starting materials, and solvents were
purchased from commercial suppliers and used as received.
Concentration refers to evaporation under vacuum using a Bu¨chi
rotatory evaporator. Reaction products were purified, when neces-
sary, by flash chromatography on silica gel (40-63 µm) with the
solvent system indicated. All NMR spectroscopic data were
recorded on a Varian Mercury 300 MHz spectrometer. Coupling
constants J are reported in Hz. The elemental analysis was done
by Robertson Microlit Laboratory, Madison, NJ. Descriptions of
analytical HPLC-MS methods 1-5 are given in Supporting
Information. Preparative HPLC-MS platform: Dionex, equipped
with a Gilson 215 autosampler/fraction collector, UV detector, and
a Dionex MSQ mass detector. HPLC column: Phenomenex Synergy
Max-RP, 21.2 mm × 50 mm. HPLC gradient: 35 mL/min, 5%
acetonitrile in water to 95% acetonitrile in water in 17.7 min. Both
acetonitrile and water have 0.05% TFA.
N-[6-Chloro-2-(3,5-dimethylpyrazol-1-yl)pyrimidin-4-yl]-3-me-
thylbutyramide (9a). Intermediate 9a was prepared by reacting
intermediate 6a with isovaleryl chloride in a similar way as for
intermediate 8a. The residue was purified by liquid chromatography
using a mixture of 1:1 ethyl acetate/hexanes to afford 9a as a white
1
6-Chloro-2-(pyrazol-1-yl)pyrimidin-4-amine (6b). 6-Amino-
2,4-dichloropyrimidine (25.0 g, 164 mmol, 1 equiv), pyrazole (15.5
g, 228 mmol, 1.5 equiv), and cesium carbonate (16.4 g, 228 mmol,
1.5 equiv) were heated at reflux in dioxane (150 mL) for 3 days.
The reaction was allowed to cool to room temperature and filtered
over Celite. The Celite was washed with dioxane (300 mL), and
the filtrate was concentrated under vacuum. The residue was slurried
with dichloromethane for 16 h and then filtered to give the desired-
product as an off-white solid (8.1 g). The operation was repeated
with the mother liquor to get a second crop (3.6 g) (39% overall
solid in similar yield. H NMR (CDCl3): δ 8.09 (s, 1H), 6.05 (s,
1H), 2.66 (s, 3H), 2.31 (s, 3H), 2.30-2.16 (m, 3H), 1.01 (d, J )
6, 6H). LCMS-1: tR ) 5.51 (97%). MS: m/z 308.3 [M + H]+,
expected 308.3 [M + H]+.
General Method for Compounds 10-31. Intermediate 7a (50
mg, 0.19 mmol, 1 equiv) was dissolved in dry dioxane (2 mL)
followed by addition of the appropriate amine (1.2 equiv, 0.23
mmol). The mixture was heated at 80 °C for 2 h, cooled to room
temperature, filtered, and purified by HPLC.
N-[2-(3,5-Dimethylpyrazol-1-yl)-6-diethylamino-1-yl-pyrimidin-
1
yield). H NMR (CDCl3): δ 8.52 (d, J ) 2.1, 1H), 7.78 (d, J )
1
4-yl]acetamide (10). H NMR (DMSO-d6): δ 8.09 (bs, 1H), 7.17
0.6, 1H), 7.65 (d, J ) 1.8, 1H), 6.45 (dd, J ) 2.1 and 1.8, 1 H),
5.8 (bs, NH2). LCMS-1: tR ) 3.03 (98%). MS: m/z 196.0 [M +
H]+, expected 196.0 [M + H]+.
(s, 1H), 5.97 (s, 1H), 3.55-3.40 (m, 4H), 2.64 (s, 3H), 2.30 (s,
3H), 2.14 (s, 3H), 1.20 (t, J ) 6.9, 6H). LCMS-2: tR ) 5.08 (100%).
MS: m/z 303.1 [M + H]+, expected 303.1 [M + H]+.
Intermediate 6a was prepared according to the same procedure
using 3,5-dimethylpyrazole in place of pyrazole.
N-[2-(3,5-Dimethylpyrazol-1-yl)-6-pyrrolidin-1-ylpyrimidin-4-
yl]acetamide (11). 1H NMR (DMSO-d6): δ 10.65 (s, 1H), 7.01 (s,
1H), 6.06 (s, 1H), 3.50 (brm, 2H), 3.35 (brm, 2H), 2.57 (s, 3H),
2.15 (s, 3H), 2.09 (s, 3H), 1.96 (brm, 4H). LCMS-3: tR ) 5.21
(100%). MS: m/z 301.0 [M + H]+, expected 301.0 [M + H]+.
N-[2-(3,5-Dimethylpyrazol-1-yl)-6-piperidin-1-ylpyrimidin-4-
yl]acetamide (12). 1H NMR (CDCl3): δ 7.11 (s, 1H), 6.13 (s, 1H),
3.80-3.70 (m, 4H), 2.67 (s, 3H), 2.34 (s, 6H), 1.82-1.64 (m, 6H).
LCMS-2: tR ) 5.38 (100%). MS: m/z 314.9 [M + H]+, expected
315.4 [M + H]+.
N-[6-Chloro-2-(3,5-dimethylpyrazol-1-yl)pyrimidin-4-yl]aceta-
mide (7a).9 6-Chloro-2-(3,5-dimethylpyrazol-1-yl)pyrimidin-4-
ylamine 6a (40.0 g, 0.18 mol, 1 equiv) was dissolved in acetic
acid (200 mL, 0.9 mol, 5 equiv) and stirred at ambient temperature.
Acetic anhydride (80 mL, 0.8 mol, 4.7 equiv) was added, and the
mixture was heated at 90 °C overnight. Once the reaction was
complete, the mixture was cooled to room temperature and water
(16 mL) was added over 30 min. The mixture was then filtered
through filter paper, and the filter cake was washed with water (4

Acetamides as A2A Receptor Antagonists
Journal of Medicinal Chemistry, 2009, Vol. 52, No. 3 715
N-[2-(3,5-Dimethylpyrazol-1-yl)-6-(2-oxopyrrolidin-1-yl)pyrimi-
din-4-yl]acetamide (13). A mixture of intermediate 6a (50 mg, 0.19
mmol, 1 equiv), pyrrolidinone (81 mg, 0.95 mmol, 5 equiv),
palladium acetate (5 mg, 0.02 mmol, 0.1 equiv), 4,5-bis(diphe-
nylphosphino)-9,9-dimethylxanthene (17 mg, 0.03 mmol, 0.15
equiv), and cesium carbonate (68 mg, 0.21 mmol, 1.1 equiv) was
heated in dry toluene (2 mL) at 100 °C overnight. After return to
room temperature and filtration, the mixture was purified by HPLC.
1H NMR (CDCl3): δ 8.92 (s, NH), 8.60 (s, 1H), 7.26 (s, 1H), 4.06
(t, J ) 6.9, 2H), 2.68 (t, J ) 6.9, 2H), 2.64 (s, 3H), 2.31 (s, 3H),
2.19 (s, 3H), 2.15 (t, J ) 6.9, 2H). LCMS-2: tR ) 4.60 (96%).
MS: m/z 315.2 [M + H]+, expected 315.3 [M + H]+.
N-[2-(3,5-Dimethylpyrazol-1-yl)-6-morpholin-4-ylpyrimidin-4-
yl]acetamide (14). 1H NMR (CDCl3): δ 7.20 (s, 1H), 6.16 (s, 1H),
3.85-3.70 (brm, 8H), 2.69 (s, 3H), 2.28 (s, 3H), 2.33 (s, 3H).
LCMS-1: tR ) 6.19 (100%). MS: m/z 317.3 [M + H]+, expected
317.4 [M + H]+.
N-[2-(3,5-Dimethylpyrazol-1-yl)-6-(2-ethoxymethylpyrrolidin-1-
yl)pyrimidin-4-yl]acetamide (24). H NMR (CDCl3): δ 7.02 and
1
6.89 (2s, 1H), 6.12 (s, 1H), 4.46 and 4.22 (2brs, 1H), 3.66-3.32
(brm, 4H), 3.46 (q, J ) 6.9, 2H), 2.69 (s, 3H), 2.34 (s, 3H), 2.33
(s, 3H), 2.22-1.96 (m, 4H), 1.18 (t, J ) 6.9, 3H). LCMS-1: tR )
8.02 (100%). MS: m/z 359.7 [M + H]+, expected 359.4 [M + H]+.
N-[2-(3,5-Dimethylpyrazol-1-yl)-6-((R)-2-hydroxymethylpyrro-
lidin-1-yl)pyrimidin-4-yl]acetamide (25). 1H NMR (CDCl3): δ 7.52
(s, 1H), 6.14 (s, 1H), 4.14 (brs, 1H), 3.78-3.45 (brm, 4H), 2.68 (s,
3H), 2.37 (s, 3H), 2.33 (s, 3H), 2.27-2.05 (m, 4H). LCMS-3: tR )
4.57 (100%). MS: m/z 331.2 [M + H]+, expected 331.4 [M + H]+.
N-[2-(3,5-Dimethylpyrazol-1-yl)-6-[(R)-2-(2-methoxyethyl)piperi-
din-1-yl]pyrimidin-4-yl]acetamide (26). LCMS-3: tR ) 5.83 (96%).
MS: m/z 373.0 [M + H]+, expected 373.5 [M + H]+.
N-[2-(3,5-Dimethylpyrazol-1-yl)-6-((R)-2-methoxymethyl-5-me-
thylpyrrolidin-1-yl)pyrimidin-4-yl]acetamide (27). 1H NMR
(CDCl3): δ 6.81 (brs, 1H), 6.14 (s, 1H), 4.46 (brs, 1H), 4.13 (brd,
J ) 36.9, 1H), 3.65-3.39 (m, 2H), 3.36 (s, 3H), 2.69 (s, 3H), 2.35
(s, 3H), 2.34 (s, 3H), 2.19-1.78 (m, 4H), 1.37 and 1.35 (2s, 3H).
LCMS-3: tR ) 5.50 (95%). MS: m/z 359.2 [M + H]+, expected
359.4 [M + H]+. LCMS-1: tR ) 3.61 (100%). MS: m/z 359.3 [M
+ H]+, expected 359.4 [M + H]+.
N-[2-(3,5-Dimethylpyrazol-1-yl)-6-(4-methylpiperazin-1-yl)pyri-
midin-4-yl]acetamide (15). 1H NMR (CDCl3): δ 8.10 (bs, 1H), 7.26
(s, 1H), 5.98 (s, 1H), 3.70 (t, J ) 5.1, 4H), 2.62 (s, 2H), 2.49 (t, J
) 5.1, 4H), 2.35 (s, 3H), 2.31 (s, 3H), 2.15 (s, 3H). LCMS-2: tR )
2.53 (100%). MS: m/z 330.1 [M + H]+, expected 330.4 [M + H]+.
N-[2-(3,5-Dimethylpyrazol-1-yl)-6-[(R)-2-(pyridin-2-yloxymeth-
yl)pyrrolidin-1-yl]pyrimidin-4-yl]acetamide (28). 1H NMR (CDCl3):
δ 8.09 (d, J ) 5.1, 1H), 7.70-7.57 (m, 1H), 6.99-6.80 (m, 2H),
6.74 (s, 1H), 6.11 (s, 1H), 4.72 (brs, 1H), 4.55-4.47 (m, 1H),
4.42-4.34 (m, 1H), 3.82-3.48 (m, 1H), 2.63 (s, 3H), 2.36 (s, 3H),
2.34 (s, 3H), 2.34-2.08 (m, 4H). LCMS-2: tR ) 5.63 (100%). MS:
N-[6-(3,4-Dihydro-1H-isoquinolin-2-yl)-2-(3,5-dimethylpyrazol-
1-yl)pyrimidin-4-yl]acetamide (16). 1H NMR (DMSO-d6): δ 10.68
(s, 1H), 7.35 (s, 1H), 7.30-7.22 (m, 1H), 7.22-7.15 (m, 4H), 4.71
(brs, 2H), 3.79 (brm, 2H), 2.92 (t, J ) 5.7, 2H), 2.59 (s, 3H), 2.15
(s, 3H), 2.10 (s, 3H). LCMS-2: tR ) 6.57 (100%). MS: m/z 363.0
[M + H]+, expected 363.4 [M + H]+.
m/z 407.9 [M + H]+, expected 408.5 [M + H]+. LCMS-1: tR
)
N-[2-(3,5-Dimethylpyrazol-1-yl)-6-(2-methylpyrrolidin-1-yl)py-
3.80 (100%). MS: m/z 408.3 [M + H]+, expected 408.5 [M + H]+.
N-[2-(3,5-Dimethylpyrazol-1-yl)-6-[(S)-2-(pyridin-2-yloxymeth-
1
rimidin-4-yl]acetamide (17). H NMR (CDCl3): δ 6.68 and 6.61
(2s, 1H), 6.14 (s, 1H), 4.47 and 4.16 (2m, 1H), 3.83-3.90 (m, 2H),
2.69 (brs, 3H), 2.34 (s, 3H), 2.32 (s, 3H), 2.20-1.78 (m, 4H), 1.28
and 1.26 (2s, 3H). LCMS-1: tR ) 7.91 (100%). MS: m/z 315.6 [M
+ H]+, expected 315.4 [M + H]+.
yl)pyrrolidin-1-yl]pyrimidin-4-yl]acetamide (29). LCMS-2: tR
)
5.66 (100%). MS: m/z 408.0 [M + H]+, expected 408.5 [M + H]+.
LCMS-5: tR ) 2.23 (100%). MS: m/z 408.8 [M + H]+, expected
408.5 [M + H]+.
N-[2-(3,5-Dimethylpyrazol-1-yl)-6-(2-propylpyrrolidin-1-yl)py-
rimidin-4-yl]acetamide (18). 1H NMR (CDCl3): δ 6.89 (s, 1H), 6.12
(s, 1H), 4.27 (brs, 1H), 3.85 (brd, J ) 36, 2H), 3.56 (brd, J )
49.2, 2H), 2.69 (s, 3H), 2.34 (s, 6H), 2.20-1.60 (m, 4H), 1.45-1.20
(m, 2H), 1.06-0.90 (m, 3H). LCMS-1: tR ) 9.27 (97%). MS: m/z
343.6 [M + H]+, expected 343.5 [M + H]+.
(R)-1-[6-Acetylamino-2-(3,5-dimethylpyrazol-1-yl)pyrimidin-4-
yl]pyrrolidine-2-carboxylic Acid Methyl Ester (19). 1H NMR
(CDCl3): δ 8.15 (bs, 1H), 7.13 (s, 1H), 5.95 (s, 1H), 4.73 (d, J )
9, 1H), 3.81-3.65 (m, 1H), 3.66 (s, 3H), 3.58-3.44 (m, 1H), 2.52
(s, 3H), 2.29 (s, 3H), 2.14 (s, 3H), 2.18-2.05 (m, 2H), 1.88-1.78
(m, 2H). LCMS-2: tR ) 4.87 (100%). MS: m/z 359.2 [M + H]+,
expected 359.4 [M + H]+.
(S)-1-[6-Acetylamino-2-(3,5-dimethylpyrazol-1-yl)pyrimidin-4-
yl]pyrrolidine-2-carboxylic Acid Methyl Ester (20). 1H NMR
(CDCl3): δ 8.18 (bs, 1H), 7.14 (s, 1H), 5.95 (s, 1H), 4.73 (d, J )
9, 1H), 3.81-3.65 (m, 1H), 3.66 (s, 3H), 3.58-3.44 (m, 1H), 2.52
(s, 3H), 2.29 (s, 3H), 2.15 (s, 3H), 2.20-2.00 (m, 2H), 2.00-1.80
(m, 2H). LCMS-3: tR ) 4.20 (98%). MS: m/z 359.1 [M + H]+,
expected 359.4 [M + H]+.
N-[2-(3,5-Dimethylpyrazol-1-yl)-6-(2-methoxymethylpyrrolidin-
1-yl)pyrimidin-4-yl]acetamide (21). LCMS-2: tR ) 5.04 (99%). MS:
m/z 344.9 [M + H]+, expected 345.4 [M + H]+.
N-[2-(3,5-Dimethylpyrazol-1-yl)-6-((S)-4-methoxy-(R)-2-meth-
oxymethylpyrrolidin-1-yl)pyrimidin-4-yl]acetamide (30). 1H NMR
(CDCl3): δ 6.81 (d, J ) 30.6, 1H), 6.13 (s, 1H), 4.44 (d, J ) 30.6,
1H), 4.20 (brs, 1H), 3.72 (dd, J ) 12.3 and 5.1, 2H), 3.66-3.35
(brm, 2H), 3.33 (s, 3H), 3.30 (s, 3H), 2.67 (d, J ) 10.2, 3H), 2.34
(s, 6H), 2.30-2.10 (m, 2H). LCMS-2: tR ) 4.85 (100%). MS: m/z
375.4 [M + H]+, expected 375.4 [M + H]+.
N-[2-(3,5-Dimethylpyrazol-1-yl)-6-((R)-4-methoxy-(R)-2-meth-
oxymethylpyrrolidin-1-yl)pyrimidin-4-yl]acetamide (31). 1H NMR
(CDCl3): δ 6.75 (s, 1H), 6.15 (s, 1H), 4.54-3.42 (m, 4H), 3.36 (s,
6H), 2.70 (s, 3H), 2.36 (s, 3H), 2.34 (s, 3H), 2.45-2.05 (m, 2H).
LCMS-2: tR ) 4.82 (99%). MS: m/z 375.3 [M + H]+, expected
375.4 [M + H]+. LCMS-1: tR ) 3.15 (100%). MS: m/z 375.2 [M
+ H]+, expected 375.4 [M + H]+.
Compounds 32-39 were prepared according to the same
procedure used to prepare compound 10, using 7c-f to the yield
the desired product in similar yields.
N-[6-((R)-2-Methoxymethylpyrrolidin-1-yl)-2-(5-methylfuran-2-
1
yl)pyrimidin-4-yl]acetamide (32). H NMR (DMSO-d6): δ 10.55
(s, 1H), 7.01 (d, J ) 3, 1H), 6.26 (dd, J ) 0.9, 2.1, 1H), 3.37-3.34
(m, 5H), 3.31 (s, 3H), 2.34 (s, 3H), 2.09 (s, 3H), 1.95 (brm, 4H).
LCMS-3: tR ) 5.29 (100%). MS: m/z 331.1 [M + H]+, expected
331.4 [M + H]+.
N-[2-(3,5-Dimethylpyrazol-1-yl)-6-(2-(R)-methoxymethylpyrro-
lidin-1-yl)pyrimidin-4-yl]acetamide (22). 1H NMR (DMSO-d6): δ
6.82 (s, 1H), 6.14 (s, 1H), 4.38 (brs, 1H), 3.60-3.20 (brm, 4H),
3.25 (s, 3H), 2.57 (s, 3H), 2.17 (s, 3H), 2.12 (s, 3H), 2.05-1.90
(m, 4H). LCMS-4: tR ) 18.17 (100%). MS: m/z 345.2 [M + H]+,
expected 345.4 [M + H]+.
N-[6-((S)-2-Methoxymethylpyrrolidin-1-yl)-2-(5-methylfuran-2-
yl)pyrimidin-4-yl]acetamide (33). H NMR (DMSO-d6): δ 10.52
(s, 1H), 6.99 (d, J ) 3, 1H), 6.26 (d, J ) 3, 1H), 3.37-3.34 (m,
5H), 3.31 (s, 3H), 2.34 (s, 3H), 2.08 (s, 3H), 1.95 (brm, 4H). LCMS-
2: tR ) 4.16 (98%). MS: m/z 331.1 [M + H]+, expected 331.4 [M
+ H]+.
1
N-[2-(3,5-Dimethylpyrazol-1-yl)-6-(2-(S)-methoxymethyl)pyrro-
lidin-1-ylpyrimidin-4-yl]acetamide (23). 1H NMR (CDCl3): δ 7.04
and 6.92 (s, 1H), 6.11 and 6.05 (s, 1H), 3.74-3.37 (m, 2H), 3.37
(s, 3H), 2.68 (s, 3H), 2.34 (s, 3H), 2.32 (s, 3H), 2.24-1.94 (m,
4H). LCMS-1: tR ) 6.33 (98%). MS: m/z 345.2 [M + H]+, expected
345.4 [M + H]+.
N-[6-((R)-2-Methoxymethylpyrrolidin-1-yl)-2-thiophen-2-ylpy-
rimidin-4-yl]acetamide (34). 1H NMR (CDCl3): δ 8.39 (d, J ) 3.6,
1H), 7.60 (d, J ) 5.1, 1H), 7.27 (d, J ) 5.1, 1H), 7.21 (t, J ) 5.1,
1H), 3.71-3.40 (m, 5H), 3.86 (s, 3H), 2.31 (s, 1H), 2.30-1.95
(m, 4H). LCMS-1: tR ) 5.36 (97%). MS: m/z 332.9 [M + H]+,
expected 333.4 [M + H]+.

716 Journal of Medicinal Chemistry, 2009, Vol. 52, No. 3
Lanier et al.
N-[6-((S)-2-Methoxymethylpyrrolidin-1-yl)-2-thiophen-2-yl-py-
rimidin-4-yl]acetamide (35). 1H NMR (CDCl3): δ 8.43 (d, J ) 3.9,
1H), 7.65 (d, J ) 3.9, 1H), 7.27-7.19 (m, 2H), 4.64 (brs, 1H),
3.89 (brs, 1H), 3.69-3.40 (brm, 3H), 3.39 (s, 3H), 2.34 (s, 3H),
2.28-2.05 (m, 4H). LCMS-1: tR ) 8.79 (97%). MS: m/z 333.3 [M
+ H]+, expected 333.4 [M + H]+.
N-[6-((R)-2-Methoxymethylpyrrolidin-1-yl)-2-thiazol-2-ylpyrimi-
din-4-yl]acetamide (36). 1H NMR (CDCl3): δ 8.05 (d, J ) 2.7, 1H),
7.63 (d, J ) 2.7, 1H), 7.14 (s, 1H), 4.60 (m, 1H), 4.20 (m, NH),
3.81 and 3.63 (AB syst, 2H), 3.62 and 3.50 (AB syst, 2H), 3.39 (s,
3H), 2.31 (s, 3H), 2.26-2.00 (m, 4H). LCMS-2: tR ) 4.60 (97%).
MS: m/z 334.0 [M + H]+, expected 334.4 [M + H]+.
N-[6-((S)-2-Methoxymethylpyrrolidin-1-yl)-2-thiazol-2-ylpyrimi-
din-4-yl]acetamide (37). 1H NMR (CDCl3): δ 8.12 (d, J ) 3.0, 1H),
7.73 (d, J ) 3.0, 1H), 6.97 (s, 1H), 4.65 (brs, 1H), 3.87 (brs, 1H),
3.69-3.35 (m, 3H), 3.39 (s, 3H), 2.37 (s, 3H), 2.29-1.95 (m, 4H).
LCMS-2: tR ) 4.60 (99%). MS: m/z 334.2 [M + H]+, expected
334.4 [M + H]+. LCMS-1: tR ) 3.15 (100%).
N-[6-((R)-2-Methoxymethylpyrrolidin-1-yl)-2-pyridin-2-ylpyri-
midin-4-yl]acetamide (38). 1H NMR (CDCl3): δ 8.82 (d, J ) 4.2,
1H), 8.40 (m, 1H), 7.99 (t, J ) 6.3, 1H), 7.60 (t, J ) 6.3, 1H),
7.10 (s, 1H), 4.70 (m, 1H), 4.25 (m, NH), 3.90 and 3.68 (AB syst,
2H), 3.62 and 3.50 (AB syst, 2H), 3.67 (s, 3H), 2.39 (s, 3H),
2.30-2.00 (m, 4H). LCMS-3: tR ) 4.84 (100%). MS: m/z 328.2
[M + H]+, expected 328.4 [M + H]+.
[M + H]+, expected 388.5 [M + H]+. LCMS-5: tR ) 2.29 (100%).
MS: m/z 387.8 [M + H]+, expected 388.5 [M + H]+.
[2-(3,5-Dimethylpyrazol-1-yl)-6-((R)-2-methoxymethylpyrrolidin-
1-yl)pyrimidin-4-yl]carbamic Acid Methyl Ester (44). To 42 (75
mg) in dichloromethane (1 mL) at 0 °C was added dry pyridine
(20 µL, 1 equiv) followed by triphosgene (75 mg, 1 equiv). After
30 min, methanol (1 equiv) was added. The mixture was allowed
to warm up to room temperature and stirred overnight. Dichlo-
romethane was removed by evaporation, the residue dissolved in
methanol (1 mL), and the product compound 44 purified by HPLC.
1H NMR (CDCl3): δ 6.72 (s, 1H), 6.14 (s, 1H), 4.45 (m, 1H),
4.40-3.90 (m, 2H), 3.87 (s, 3H), 3.70-3.40 (m, 2H), 3.33 (s, 3H),
2.68 (s, 3H), 235 (s, 3H), 2.25-1.95 (m, 4H). LCMS-3: tR ) 5.62
(100%). MS: m/z 361.1 [M + H]+, expected 361.4 [M + H]+.
Acknowledgment. We thank Shawn Ayube, Chris Devore,
Paddi Ekhlassi, and John Harman for analytical support.
Supporting Information Available: Compound purities, de-
tailed descriptions of HPLC conditions used for purity assessment,
and NMR and LCMS data for final compounds. This material is
available free of charge via the Internet at http://pubs.acs.org.
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N-[6-((S)-2-Methoxymethylpyrrolidin-1-yl)-2-pyridin-2-ylpyri-
midin-4-yl]acetamide (39). 1H NMR (CDCl3): δ 8.78-8.84 (m, 1H),
8.41 (dd, J ) 16.8 and 8.1, 1H), 8.05-7.95 (m, 1H), 7.68-7.57
(m, 1H), 6.78 (s, 1H), 4.71 (brs, 1H), 3.90 (brs, 1H), 3.70-3.42
(brm, 3H), 3.37 (s, 3H), 2.37 (s, 3H), 2.26-1.96 (m, 4H). LCMS-
3: tR ) 4.83 (100%). MS: m/z 328.5 [M + H]+, expected 328.4
[M + H]+.
N-[2-(3,5-Dimethylpyrazol-1-yl)-6-((R)-2-methoxymethylpyrro-
lidin-1-yl)pyrimidin-4-yl]propionamide (40). Compound 40 was
prepared by reacting intermediate 8a with (R)-2-methoxymeth-
1
ylpyrrolidine using the method described for compound 10. H
NMR (DMSO-d6): δ 10.62 (s, 1H), 7.09 (s, 1H), 6.06 (s, 1H), 4.36
(brs, 1H), 3.80-3.40 (brm, 4H), 3.27 (brs, 3H), 2.56 (s, 3H), 2.41
(q, J ) 7.5, 2H), 2.15 (s, 3H), 2.10-1.80 (m, 4H), 1.04 (t, J ) 7.5,
3H). LCMS-3: tR ) 5.56 (100%). MS: m/z 359.1 [M + H]+,
expected 359.4 [M + H]+.
N-[2-(3,5-Dimethylpyrazol-1-yl)-6-((R)-2-methoxymethylpyrro-
lidin-1-yl)pyrimidin-4-yl]-3-methylbutyramide (41). Compound 41
was prepared by reacting intermediate 9a with (R)-2-methoxym-
ethylpyrrolidine using the method described for compound 10. 1H
NMR (DMSO-d6): δ 10.62 (s, 1H), 6.07 (s, 1H), 3.37-3.34 (m,
5H), 3.27 (s, 3H), 2.57 (s, 3H), 2.30-2.28 (m, 3H), 2.16 (s, 3H),
1.96 (brm, 4H), 0.91 (d, J ) 6.6, 6H). LCMS-3: tR ) 6.11 (100%).
MS: m/z 387.1 [M + H]+, expected 387.5 [M + H]+.
(5) Lightowler, S. Presented at the International Research Conference,
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CNS Disorders, Boston, MA, May 2006.
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S.; Malany, S.; Santos, M.; Gross, R. S.; Jalali, K.; Sai, Y.; Zuo,
Z.; Yang, C.; Castro-Palomino, J. C.; Crespo, M. I.; Prat, M.; Gual,
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as A2A receptor antagonists: 1. Structure-activity relationships
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2-(3,5-Dimethylpyrazol-1-yl)-6-((R)-2-methoxymethylpyrrolidin-
1-yl)pyrimidin-4-ylamine (42). To ethanol (2 mL) was added
6-chloro-2-(3,5-dimethylpyrazol-1-yl)pyrimidin-4-ylamine 6a (250
mg, 1.1 mmol), diisopropylamine (3 equiv), and (R)-2-methoxym-
ethylpyrrolidine (3 equiv). The mixture was heated overnight at
80 °C to give compound 42. The product was purified by HPLC.
1H NMR (CDCl3): δ 8.18 (m, 2H), 6.04 (s, 1H), 5.50 (bs, 1H),
4.25-4.15 (m, 1H), 4.10-3.80 (m, 2H), 3.60-3.40 and 3.40-3.20
(AB syst, 2H), 3.33 (s, 3H), 2.60 (s, 3H), 2.27 (s, 3H), 2.20-1.80
(m, 4H). LCMS-3: tR ) 4.93 (100%). MS: m/z 303.1 [M + H]+,
expected 303.4 [M + H]+.
1-[2-(3,5-Dimethylpyrazol-1-yl)-6-((R)-2-methoxymethylpyrro-
lidin-1-yl)pyrimidin-4-yl]-3-isopropylurea (43). To 42 (75 mg) in
dichloromethane (1 mL) at 0 °C was added dry pyridine (20 µL, 1
equiv) followed by triphosgene (75 mg, 1 equiv). After 30 min,
isopropylamine (1 equiv) was added. The mixture was allowed to
warm to room temperature and stirred overnight. Dichloromethane
was removed by evaporation, the residue dissolved in methanol (1
1
mL), and the product compound 43 purified by HPLC. H NMR
(DMSO-d6): δ 9.38 (s, 1H), 8.90 (s, 1H), 6.10 (s, 1H), 3.75-3.45
(m, 5H), 3.26 (s, 3H), 2.59 (s, 3H), 2.17 (s, 3H), 1.95 (brm, 4H),
1.16 (d, J ) 6.3, 6H). LCMS-3: tR ) 6.09 (100%). MS: m/z 388.1
(10) Crystal structures were generated at the UCSD Small-Molecule
Crystallography Facility. The crystal system and space group
assignments were unambiguous. All non-hydrogen atoms were

Acetamides as A2A Receptor Antagonists
Journal of Medicinal Chemistry, 2009, Vol. 52, No. 3 717
refined anisotropically by full-matrix least-squares (SHELXL-97).
All hydrogen atoms, with the exception of the hydroxyl hydrogen
H2a, were placed using a riding model. Their positions were
constrained relative to their parent atom using the appropriate HFIX
command in SHELXL-97. The hydroxyl hydrogen H2a was located
from the difference map, and its location was refined isotropically.
The target molecule cocrystallized with a half of molecule of 1,4-
dioxane, which lies on the inversion center, to form the asymmetric
unit. All software was contained in the APEX, SAINT, and SHELX
software distributed by Bruker-AXS, Madison, WI. Crystal data
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j
for 45: CCDC 710881, C19H21N5O3, triclinic, space group P1, a )
8.0030 (9) Å, b ) 9.9780 (12) Å, c ) 11.6910 (14) Å, ꢀ )
77.992(2)°, V ) 893.07 (18) Å3, Z ) 2, T ) 100 K, Rint ) 0.0409.
R1 is 6.3% based on 3142 independent reflections.
(16) http://www.cerep.fr.
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Y.; Rueter, J. K.; Lechner, S. M.; Markison, S.; Malany, S.; Joswig,
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JM800908D