Discovery and characterization of 4′-(2-furyl)-N-pyridin-3-yl-4, 5′-bipyrimidin-2′-amine (LAS38096), a potent, selective, and efficacious A2B adenosine receptor antagonist

Article abstract of DOI:10.1021/jm061333v

A novel series of N-heteroaryl 4′-(2-furyl)-4,5′-bipyrimidin- 2′-amines has been identified as potent and selective A_2B adenosine receptor antagonists. In particular, compound 5 showed high affinity for the A_2B receptor (K_i = 17 nM), good selectivity (IC₅₀: A₁ > 1000 nM, A_2A > 2500 nM, A₃ > 1000 nM), displayed a favorable pharmacokinetic profile in preclinical species, and showed efficacy in functional in vitro models.

Full text of DOI:10.1021/jm061333v

2
732
J. Med. Chem. 2007, 50, 2732-2736
Brief Articles
Discovery and Characterization of 4′-(2-Furyl)-N-pyridin-3-yl-4,5′-bipyrimidin-2′-amine
(LAS38096), a Potent, Selective, and Efficacious A2B Adenosine Receptor Antagonist
†
Bernat Vidal,* Arsenio Nueda, Cristina Esteve, Teresa Domenech, Sonia Benito, Raquel F. Reinoso, Merc e` Pont, Marta Calbet,
‡
‡
§
Rosa L o´ pez, Mar ´ı a Isabel Cadavid, Mar ´ı a Isabel Loza, AÄ lvaro C a´ rdenas, N u´ ria Godessart, Jorge Beleta,
|
Graham Warrellow, and Hamish Ryder
Almirall Research Center, Almirall, Ctra. Laure a` Mir o´ 408, E-08980 St. Feliu de Llobregat, Barcelona, Spain, and Departamento de
Farmacolog ´ı a, UniVersidade de Santiago de Compostela, E-15782 Santiago de Compostela, Spain
ReceiVed NoVember 17, 2006
A novel series of N-heteroaryl 4′-(2-furyl)-4,5′-bipyrimidin-2′-amines has been identified as potent and
selective A2B adenosine receptor antagonists. In particular, compound 5 showed high affinity for the A2B
receptor (K
i
) 17 nM), good selectivity (IC50: A
1
> 1000 nM, A2A > 2500 nM, A
3
> 1000 nM), displayed
a favorable pharmacokinetic profile in preclinical species, and showed efficacy in functional in vitro models.
Introduction
Chart 1. Structure of Some Selected A2B Adenosine Receptor
Antagonists
Adenosine is a mediator that functions as regulator of
cardiovascular homeostasis, tissue protection during ischemia
1,2
reperfusion, and as modulator of inflammatory processes. The
initial observation that adenosine induced bronchoconstriction
in asthmatics and that high levels of this mediator were detected
in their bronchoalveolar lavage led to its early implication in
the pathophysiology of human asthma.3
,4
Adenosine potentiates the IgE-dependent degranulation of
human mast cells through a mechanism believed to be mediated
4
,5
by the A2B receptor, one of the four adenosine receptors. A2B
is a low affinity receptor for adenosine that is mainly expressed
6
in the gastrointestinal tract, urinary bladder, and lung tissue.
Among immune cell lineages, A2B is expressed in mast cells,
neutrophils, monocytes, macrophages, dendritic cells, and T
cells.
have been reported to be potent A2B antagonists, but selectivity
7
,8
remained as a challenge. In particular, compound 3 has been
Characterization of mice deleted in the A2B gene has shown
no major deficiencies and suggests a potential anti-inflammatory
role of the A2B receptor.9 This is in contrast with a large body
of previous evidence demonstrating the overall pro-inflammatory
properties of this receptor, suggesting a potential tissue or cell
1
5
reported to show a good oral bioavailability.
We have recently discovered a number of N-heteroaryl 4′-
2-furyl)-4,5′-bipyrimidin-2′-amines as potent and selective A2B
adenosine receptor antagonists. Herein we report some of the
SAR we developed and the characterization of the lead
compound LAS38096.
,10
(
1
6
1
1
specific dual role in the context of inflammatory disease.
A2B receptors are responsible for the adenosine-mediated
release of several inflammatory cytokines from mast cells,
From an initial SAR optimization it was found that 2-furyl
and 3-pyrimidinyl formed a good substitution pattern at the
pyrimidine central core, not only to keep good potency in
antagonizing the A2B receptor, but more importantly, to improve
selectivity against the other adenosine receptor subtypes (A2A,
A1, and A3).
airway and bronchial epithelial cells, fibroblasts, smooth muscle
cells, intestinal epithelial cells, and monocytes.5
,11,12
Therefore,
A2B antagonists have the potential to become a new pharma-
cological drug class for the treatment of asthma.13
Chart 1 shows some A2B antagonists reported in the literature.
The recently disclosed xanthine-type structures 1 and 2, which
topologically have similar features, displayed an excellent in
Chemistry
1
4
Compounds 5-14 were prepared according to the synthetic
sequence outlined in Scheme 1. Thus, treatment of 4-methylpy-
rimidine 15 with LiHMDS followed by condensation with ethyl-
vitro profile but suffered from low oral absorption in rats.
Additionally, diarylheterocycles such as compounds 3 and 4
2
-furoate 16 provided ketone 17.
Further treatment with neat dimethylformamide dimethylac-
*
To whom correspondence should be addressed. Phone: 34 93 291
3
996. Fax: 34 93 312 86 35. E-mail: bernat.vidal@almirall.es.
†
Current address: Lacer, S.A. C/Sardenya 350, 08025 Barcelona.
Departamento de Farmacolog ´ı a, Universidade de Santiago de Com-
etal followed by condensation with guanidine in the presence
of potassium carbonate provided the key aminopyrimidine
derivative 18. Compound 5 was obtained by palladium-catalyzed
N-arylation of pyrimidine 18 with 3-bromopyridine in the
‡
postela, E-15782 Santiago de Compostela, Spain.
§
Current address: UCB, Belgium.
Current address: UCB Granta Park Cambridge CB1 6GS (U.K.).
|
1
0.1021/jm061333v CCC: $37.00 © 2007 American Chemical Society
Published on Web 05/01/2007

Brief Articles
Journal of Medicinal Chemistry, 2007, Vol. 50, No. 11 2733
Scheme 1a
Additional profiling revealed that compound 12 displayed
relatively low systemic exposures in rat oral and intravenous
pharmacokinetic studies. On the basis of the good binding
profile, compound 5 (LAS38096) was selected for further
characterization in functional cellular assays, pharmacokinetics,
as well as in vitro efficacy studies.
To further characterize the affinity of 5 against human and
mouse adenosine receptors, the compound was evaluated in
intracellular cAMP assays. Among other signaling pathways,
agonist stimulation of A2B receptors results in rapid increases
1
8a
of intracellular cAMP levels. Thus, we decided to test the
effect of 5 over the increase in cAMP levels induced by the
adenosine analog NECA in human HEK293 cells (expressing
A2B receptors) and CHO cells transfected with the mouse A2B
receptor.
Compound 5 was capable of inhibiting A2B mediated NECA
dependent increases in intracellular cAMP with IC50 of 321 nM
and 349 nM in cells expressing human and mouse receptors
respectively (Table 2). These results demonstrate that compound
5
is a functional A2B receptor antagonist which displays a similar
affinity for the human and mouse receptors.
a
Given that a role of the A3 receptor in mouse models of
Reagents and conditions: (a) LiHMDS, THF, rt, 2 h, 85%; (b) DMF-
1
9
DMA, 100 °C, 2 h, 75%; (c) guanidine‚HCl, K2CO3, DMF, 70 °C, 20 h,
allergy has been previously suggested we decided to evaluate
the affinity of 5 for this receptor to rule out any potential A3-
dependent effect in the context of murine efficacy models.
1
6
2
1%; (d) for 5, 6, and 9-11, Pd2(dba)3, R Br, Cs2CO3, xantphos, dioxane,
h, 100 °C, 40-75%; for 7, Pd(AcO)2, 2-chloropyrazine,
2-dicyclohexylphosphino-2′-(N,N-dimethylamino)biphenyl,
0
Nat-BuO,
In contrast to A2B, agonist stimulation of the A3 receptor
downregulates an adenylate cyclase-dependent increase in
toluene, 110 °C, 20 h, 33%; for 8, CuI, 5-bromo-2-methoxypyridine, N,N′-
dimethylethylenediamine, K2CO3, dioxane, 18 h, 110 °C, 69%; (e)
compound 8, HBr (aq), 110 °C, 5 h, 60%; (f) NaH, DMF, R Br, rt to
2
18b
intracellular cAMP. In agreement with radioligand binding
8
0 °C, 2 h, 40-57%.
studies performed with the human A3 receptor, 5 did not
significantly block the murine A3 receptor in a cellular assay
measuring intracellular cAMP levels in cells transfected
with this receptor (less than 5% inhibition at a concentration of
0 µM of compound 5).
Among other inflammatory cytokines, the A2B receptor
presence of Xantphos as ligand.17 Compounds 5, 6, and 9-11
were prepared in a similar manner. Compounds 7 and 8 were
prepared using a Pd- or Cu-catalyzed N-arylation, respectively,
using different ligands. Acid-catalyzed demethylation of com-
pound 8 provided pyridone 12 that was transformed into the
N-alkylated pyridones 13 and 14 by reaction with the corre-
sponding alkyl bromides in the presence of a base such as
sodium hydride.
1
mediates the NECA-induced release of IL-6 in airway epithelial
cells, bronchial smooth muscle cells, primary human fibroblasts,
intestinal epithelial cells, osteoblasts, pituitary folliculostellate
11
cells, and atroglioma/astrocytoma cells. Therefore, we decided
to evaluate the effect of 5 in an in vitro model of primary mouse
and human dermal fibroblasts.
Results and Discussion
As depicted in Table 1, a number of selected analogues were
prepared, showing good binding affinities for the A2B receptor
in the radioligand assay, as well as good selectivity versus A1,
A2A, and A3 adenosine receptors. Initially we introduced
Results depicted in Figure 1 show that incubation in the
presence of 10 µM NECA induced the synthesis of IL-6 both
in mouse and in human cells about 3-fold over nonstimulated
cells. Under those conditions, 5 was capable of inhibiting the
NECA-dependent production of IL-6 dose dependently with IC50
values of 340 nM and 640 nM in human and mouse fibroblasts,
respectively. This confirms the anti-inflammatory properties of
compound 5 in the context of a cellular in vitro model of IL-6
production.
1
unsubstituted nitrogen-containing heterocycles in R such as
pyridine, pyrimidine or pyrazine (compounds 5-7). Among
these, 3-pyridyl derivative 5 was found to show high potency
and selectivity. Substitution by a methoxy group (compounds
and 9) led to a drop in potency while keeping good selectivity.
We speculated that the nitrogen atoms of the 3-pyridyl or the
-pyrimidinyl rings were having a positive interaction with the
receptor, so we prepared compounds 10 and 11 to evaluate the
effect of substitution by a hydrogen bond acceptor. For cyano
derivative 10, even though affinity for the A2B receptor dropped,
we observed an excellent selectivity versus A3. N-Oxide 11 had
a 2-fold decrease in affinity compared to that of the correspond-
ing reduced analogue 5. Finally, we explored the introduction
of a pyridone moiety (compounds 12-14) and compound 12
was found to be one of the most potent (KiA2B: 16 nM) and
selective compounds within the series (IC50 A1 > 10 000 nM,
IC50 A2A > 2500 nM, IC50 A3 > 1000 nM). Alkylation at the
pyridine nitrogen had a slightly detrimental effect on A3
selectivity (compound 13) and on A2B potency for the more
lipophilic analogue 14.
8
The pharmacokinetic parameters of compound 5 in mouse,
rat, and dog are summarized in Table 3. Regardless of the
species, compound 5 was absorbed rapidly (tmax < 1 h), with
the longest tmax observed in the dog. The AUC in mouse (4
µM‚h) was four times lower than in the other two species
studied. Compound 5 exhibited good bioavailability (75 and
0% for the rat and dog, respectively). The half-life in rat and
dog was short (<1 h), resulting from a moderate-to-high plasma
clearance and a low-to-moderate volume of distribution.
3
8
The encouraging oral bioavailability exhibited by 5 has
subsequently allowed additional characterization of the efficacy
of the compound in vivo in an allergic mouse model. Therefore,
mice treated with compound 5 showed significantly less
bronchial hyperresponsiveness, mucus production, and OVA-

2
734 Journal of Medicinal Chemistry, 2007, Vol. 50, No. 11
Brief Articles
Table 1. Adenosine Receptor Affinity of N-Heteroaryl 4′-Furyl-4,5′-bipyrimidin-2′-amines
a
Ki (nM) or % inhibition of radioligand binding
at indicated concentration (nM) (SEMb
cmpd
R1
hA2B
hA2A
hA1
hA3
5
6
7
8
9
0
1
2
3-pyridyl
3-pyrimidinyl
2-pyrazinyl
6-methoxypyridin-3-yl
2-methoxypyrimidin-5-yl
5-cyanopyridin-3-yl
1-oxidopyridin-3-yl
6-oxo-1,6-
17 ( 4
24 ( 0
>2500 (40% ( 5)
>2500 (29% ( 32)
>2500 (21% ( 0.4)
>2500 (21% ( 3)
>2500 (25% ( 1)
>2500 (37% ( 0)
>2500 (24% ( 0.2)
>2500 (25% ( 1.5)
>1000 (14% ( 4)
>10 000 (45 ( 6)
>1000 (36% ( 4)
>1000 (42% ( 9)
>1000 (18% ( 6)
>1000 (29% ( 2)
>1000 (32% ( 4)
>1000 (24% ( 5)
>1000 (35% ( 4)
>1000 (15% ( 1)
116 ( 11
115 ( 25
39 ( 10
69 ( 10
34 ( 2
>10 000 (30% ( 3)
>10 000 (25% ( 9)
>10 000 (45% ( 5)
>10 000 (22% ( 8)
>10 000 (38% ( 5)
>10 000 (31% ( 5)
1
1
1
16 ( 1
dihydropyridin-3-yl
1-methyl-6-oxo-1,6-
dihydropyridin-3-yl
1-cyclopropylmethyl-
1
3
4
28 ( 9
>2500 (20% ( 2)
>10 000 (17% ( 4)
>10 000 (28% ( 2)
>1000 (28% ( 21)
>1000 (29% ( 7)
1
119 ( 39
>2500 (38.5% ( 1)
6-oxo-1,6-
dihydropyridin-3-yl
a
3
Values are reported as the mean of at least two independent determinations. Radioligand binding assay with H-DPCPX as ligand and membranes from
b
3
HEK293 cells transfected with human A2B receptor. Expressed as IC50. Radioligand binding assays: A2A, with H-ZM241385 in HeLa cells; A1, with
H-DPCPX in CHO cells; A3, with H-NECA in HeLa cells.
3
3
Table 2. Selectivity Profile of 5 in Intracellular cAMP Assays
Table 3. Pharmacokinetic Parameters of 5 in Mouse (only p.o.), Rat
and Dog after Intravenous (i.v.) and Oral (p.o.) Administration
human A2B
mouse A2B
349 ( 76
parameter
mousea
10
rata
dogb
IC50 cAMP (nM) ( SEMa
321 ( 41
-
1
p.o. dose (mg kg
)
10
10
1
a
IC50 values are reported as the mean of at least four experiments.
c
-1
i.v. dose (mg kg
)
1
Cmax (µM), p.o.
13 (9)
0.3
4
11 (4)
0.3 (0)
16 (8)
0.2 (0)
1.4 (0.2)
0.3 (0)
25 (3)
0.5 (0)
75 (37)
6
tmax (h), p.o.
1.3
15
0.8
1.8
0.7
28
1.1
81
d
AUC (µM.h), p.o.
t1/2 (h), i.v.
c
MRT (h), p.o.
MRT (h) i.v.
Cl (mL min kg-1), i.v.
e
-1
Vss (L kg-1), i.v.
f
g
F (%)
a
b
Results expressed as the mean ( SD in parenthesis (n ) 3). Results
c
d
expressed as the mean (n ) 2). MRT ) Mean residence time. AUC )
area under the curve. e Cl ) total plasma clearance. Vss ) volume of
distribution at steady state. g F ) bioavailability.
f
blockade of the A2B receptor may provide clinical benefits in
the treatment of chronic respiratory diseases.
In conclusion, we have identified a novel series of N-
heteroaryl 4′-furyl-4,5′-bipyrimidin-2′-amines as potent A2B
adenosine receptor antagonists and selective versus A2A, A1,
and A3 receptors. Optimization of the series SAR led to the
identification of 5 (LAS38096), which displayed a favorable
pharmacokinetic profile in preclinical species and showed
efficacy in functional in vitro and in vivo models of allergy
and inflammation.
Figure 1. Effect of compound 5 on NECA-induced IL-6 synthesis by
cultured dermal fibroblasts of human or mouse origin. Results are
representative of three independent experiments performed in duplicate.
B, basal (samples not treated with NECA); V, vehicle (samples treated
with NECA and DMSO). **p < 0.01 vs basal (B), #p < 0.05 vs vehicle
On the basis of its favorable in vitro pharmacology, efficacy,
and pharmacokinetic profile, compound 5 was advanced into
preclinical in vivo safety and toxicology studies.
(V), ##p < 0.01 vs vehicle (V).
Experimental Section
specific IgE levels and a slight decrease in eosinophil infiltration
and Th2 cytokine levels.20
Synthesis of Compound 5 (LAS38096). 1-(2-Furyl)-2-pyri-
midin-4-ylethanone (17). To a solution of 4-methylpyrimidine
0.93 g, 9.9 mmol) and ethyl 2-furoate (1.54 g, 11 mmol) in
anhydrous THF (8 mL) at 0 °C was added dropwise via syringe
pump (1 h) a solution of lithium bis(trimethylsilyl)amide (20 mL,
20 mmol, 1 M solution in hexanes). The resulting mixture was
stirred at room temperature for 2 h. The precipitate was collected
(
In agreement with these results, additional published studies
have also shown that selective A2B antagonists are active in the
context of functional murine in vivo models of allergy and
pulmonary inflammation.21 Overall, these results suggest that

Brief Articles
Journal of Medicinal Chemistry, 2007, Vol. 50, No. 11 2735
by filtration, washed with a saturated aqueous solution of am-
monium chloride and water, and dried under vacuum to yield the
title compound as a yellow solid (1.59 g, 85%).
(9) Yang, D.; Zhang, Y.; Nguyen, H. G.; Koupenova, M.; Chauhan, A.
K.; Makitalo, M.; Jones, M. R.; St Hilaire, C.; Seldin, D. C.; Toselli,
P.; Lamperti, E.; Schreiber, B. M.; Gavras, H.; Wagner, D. D.; Ravid,
K. The A2B adenosine receptor protects against inflammation and
excessive vascular adhesion. J. Clin. InVest. 2006, 116 (7), 1913-
3-(Dimethylamino)-1-(2-furyl)-2-pyrimidin-4-ylprop-2-en-1-
one. A suspension of 1-(2-furyl)-2-pyrimidin-4-ylethanone 17 (1.59
g, 8.45 mmol) in N,N-dimethylformamide dimethyl acetal (4.5 mL,
1923.
(
10) Hua, X.; Kovarova, M.; Chason K. D.; Nguyen, M.; Koller,
B. H.; Tilley, S. L. Enhanced mast cell activation in mice deficient
in the A2B adenosine receptor. J. Exp. Med. 2007, 204 (1), 117-
33.8 mmol) was heated to 100 °C for 2 h. The mixture was allowed
to cool to room temperature, the solvent was evaporated under
reduced pressure, and the residue was partitioned between ethyl
acetate and a saturated solution of ammonium chloride. The aqueous
phase was extracted with ethyl acetate, and the organic extracts
were washed with brine, dried (Na SO ), and evaporated under
2 4
reduced pressure to provide the title compound as a red oil
128.
(
11) Linden, J. New insights into the regulation of inflammation by
adenosine. J. Clin. InVest. 2006, 116 (7), 1835-1837.
(
12) (a) Feoktistov I.; Goldstein, A. E.; Ryzhov, S.; Zeng, D.; Belardinelli,
L.; Voyno-Yasenetskaya, T.; Biaggioni, I. Differential expression of
adenosine receptors in human endothelial cells: role of A2B receptors
in angiogenic factor regulation. Circ. Res. 2002, 90 (5), 531-538.
(b) Feoktistov, I.; Ryzhov, S.; Goldstein, A. E.; Biaggioni, I. Mast
cell-mediated stimulation of angiogenesis: Cooperative interaction
between A2B and A3 adenosine receptors. Circ. Res. 2003, 92 (5),
(
1.54 g, 75%).
′-(2-Furyl)-4,5′-bipyrimidin-2′-amine (18). A mixture of
-(dimethylamino)-1-(2-furyl)-2-pyrimidin-4-ylprop-2-en-1-one (1.54
CO (5.24 g, 38 mmol), and guanidine hydro-
4
3
g, 6.33 mmol), K
2
3
485-492. (c) Feoktistov, I.; Ryzhov, S.; Zhong, H.; Goldstein, A.
chloride (1.81 g, 19 mmol) in DMF (12 mL) was heated to 70 °C
for 20 h and then allowed to cool to room temperature. Water was
added, and the precipitate was collected by filtration and washed
copiously with water. The solid was dried under vacuum to yield
the title compound (920 mg, 61%).
E.; Matafonov, A.; Zeng, D.; Biaggioni, I. Hypoxia modulates
adenosine receptors in human endothelial and smooth muscle cells
toward an A2B angiogenic phenotype. Hypertension 2004, 44 (5),
649-654. (d) Rees, D. A.; Lewis, B. M.; Lewis, M. D.; Francis, K.;
Scanlon, M. F.; Ham, J. Adenosine-induced IL-6 expression in
pituitary folliculostellate cells is mediated via A2B adenosine receptors
coupled to PKC and p38 MAPK. Br. J. Pharmacol. 2003, 140 (4),
4
′-(2-Furyl)-N-pyridin-3-yl-4,5′-bipyrimidin-2′-amine (5). An
oven-dried resealable Schlenk tube was charged with 4,5-bis-
diphenylphosphino)-9,9-dimethylxanthene (Xantphos, 25.4 mg,
.044 mmol), 3-bromopyridine (96.3 mL, 1 mmol), Cs CO
456 mg, 1.4 mmol), 4′-(2-furyl)-4,5′-bipyrimidin-2′-amine (com-
7
64-772. (e) Zhong, H.; Wu, Y.; Belardinelli, L.; Zeng, D. A2B
(
adenosine receptors induce IL-19 from bronchial epithelial cells,
0
2
3
resulting in TNF-alpha increase. Am. J. Respir. Cell Mol. Biol. 2006,
(
35 (5), 587-592.
pound 19; 263 mg, 1.1 mmol) and dioxane (5 mL). The
Schlenk tube was subjected to three cycles of evacuation-
backfilling with argon, and tris(dibenzylideneacetone)dipalladium-
(
13) For recent reviews, see: (a) Beukers, M. W.; Meurs, I.; Ijzerman,
A. P. Structure-affinity relationships of adenosine A2B receptor
ligands. Med. Res. ReV. 2006, 26 (5), 667-698. (b) Zablocki, J.;
Elzein, E.; Kalla, R. A2B adenosine receptor antagonists and their
potential indications. Expert Opin. Ther. Pat. 2006, 16 (10), 1347-
2 3
(0) [Pd (dba) ; 18.3 mg, 0.02 mmol] was added. After three new
cycles of evacuation-backfilling with argon, the Schlenk tube was
capped and placed in a 100 °C oil bath. After 20 h, the mixture
was cooled, 10 mL of water was added, and the solid was collected
by filtration to give the title compound as a yellowish solid (211
mg, 67%).
1
357. (c) Cacciari, B.; Pastorin, G.; Bolcato, C.; Spalluto, G.;
Bacilieri, M.; Moro, S. A2B adenosine receptor antagonists: Recent
developments. Mini-ReV. Med. Chem. 2005, 5, 1053-1060. (d)
Jacobson, K. A.; Gao, Z.-G. Adenosine receptors as therapeutic
targets. Nat. ReV. Drug DiscoVery 2006, 247-264.
(
14) (a) Esteve, C.; Nueda, A.; D ´ı az, J. L.; Beleta, J.; C a´ rdenas, A.;
Lozoya, E.; Cadavid, M. I.; Loza, M. I.; Ryder, H.; Vidal, B. New
pyrrolopyrimidin-6-yl benzenesulfonamides: Potent A2B adenosine
receptor antagonists. Bioorg. Med. Chem. Lett. 2006, 16, 3642-3645.
Acknowledgment. We thank Jos e´ Luis D ´ı az for his support,
Montserrat Miralpeix for helpful comments to the manuscript,
Josep Maria Huerta and Sonia Espinosa for compound charac-
terization efforts, Rosario Cerrato, Israel Ramos and M o´ nica
Aparici for excellent technical assistance, and Galchimia for
the preparation of compounds 12-14.
(
b) Zablocki, J.; Kalla, R.; Perry, T.; Palle, V.; Varkhedkar, V.; Xiao,
D.; Piscopio, A.; Maa, T.; Gimbel, A.; Hao, J.; Chu, N.; Leung, K.;
Zeng, D. The discovery of a selective, high affinity A2B adenosine
receptor antagonist for the potential treatment of asthma. Bioorg. Med.
Chem. Lett. 2005, 15, 609-612.
(
15) (a) Press, N. J.; Taylor, R. J.; Fullerton, J. D.; Tranter, P.; McCarty,
C.; Keller, T. H.; Brown, L.; Cheung, R.; Christie, J.;
Haberthuer, S.; Hatto, J. D. I.; Keenan, M.; Mercer, M. K.; Press,
N. E.; Sahri, H.; Tuffnell, A. R.; Tweed, M.; Fozard, J. R. A new
orally bioavailable dual adenosine A2B/A3 receptor antagonist
with therapeutic potential. Bioorg. Med. Chem. Lett. 2005, 15,
3081-3085. (b) Harada, H.; Asano, O.; Ueda, M.; Miyazawa, S.;
Kotake, Y.; Kabasawa, Y.; Yasuda, M.; Yasuda, N.; Iida, D.;
Nagakawa, J.; Hirota, K.; Nakagawa, M. Pyrimidine compound and
medicinal composition thereof. PCT Int. Appl. WO2003035639,
Supporting Information Available: General experimental
details, experimental procedures, and characterization data for 5-14,
table of combustion analysis and HPLC data for key compounds,
and detailed description of pharmacokinetic and efficacy assays.
This material is available free of charge via the Internet at http://
pubs.acs.org.
References
(
(
(
(
1) Linden, J. Adenosine in tissue protection and tissue regeneration.
2003.
Mol. Pharmacol. 2005, 67 (5), 1385-1387.
2) Forsythe, P; Ennis, M. Adenosine, mast cells, and asthma. Inflam-
mation Res. 1999, 48 (6), 301-307.
3) Fozard, J. R. The case for a role for adenosine in asthma: almost
convincing? Curr. Opin. Pharmacol. 2003, 3, 264-269.
4) Holgate, S. T. The identification of the adenosine A2B receptor as a
novel therapeutic target in asthma. Br. J. Pharmacol. 2005, 145,
(
(
(
16) Vidal, B.; Esteve, C. Pyrimidin-2-amine derivatives and their use as
A2B adenosine receptor antagonists. PCT Int. Appl. WO2005040155,
2005.
17) Yin, J.; Zhao, M. M.; Huffman, M. A.; McNamara, J. M. Pd-
Catalyzed N-arylation of heteroarylamines. Org. Lett. 2002, 4 (20),
3481-3484.
18) (a) Gao, Z.; Chen, T.; Weber, M. J.; Linden, J. A2B adenosine and
P2Y2 receptors stimulate mitogen-activated protein kinase in human
embryonic kidney-293 cells. Cross-talk between cyclic AMP and
protein kinase c pathways. J. Biol. Chem. 1999, 274 (9), 5972-5980.
1
009-1015.
(
5) Feoktistov, I.; Biaggioni, I. Adenosine A2B receptors evoke inter-
leukin-8 secretion in human mast cells. An enprofylline-sensitive
mechanism with implications for asthma. J. Clin. InVest. 1995, 96
(
b) Zhou, Q. Y.; Li, C.; Olah, M. E.; Johnson, R. A.; Stiles, G. L.;
(4), 1979-1986.
Civelli, O. Molecular cloning and characterization of an adenosine
(
6) Feoktistov I.; Biaggioni I. Adenosine A2B receptors. Pharmacol. ReV.
receptor: The A3 adenosine receptor. Proc. Natl. Acad. Sci. U.S.A.
1997, 49 (4), 381-402.
1992, 89, 7432-7436.
(
7) Feoktistov, I.; Goldstein, A.; Sheller, J. R.; Schwartz, L. B.; Biaggioni,
I. Immunological characterization of A2B adenosine receptors in
human mast cells. Drug DeV. Res. 2003, 58, 461-471.
(19) (a) Tilley, S. L.; Tsai, M.; Williams, C. M.; Wang, Z. S.; Erikson,
C. J.; Galli, S. J.; Koller, B. H. Identification of A3 receptor-
and mast cell-dependent and -independent components of
adenosine-mediated airway responsiveness in mice. J. Immunol. 2003,
171 (1), 331-337. (b) Zhong, H.; Shlykov, S. G.; Molina, J. G.;
Sanborn, B. M.; Jacobson, M. A.; Tilley, S. L.; Blackburn, M. R.
(
8) Bours, M. J.; Swennen, E. L.; Di Virgilio, F.; Cronstein, B. N.;
Dagnelie, P. C. Adenosine 5′-triphosphate and adenosine as endog-
enous signaling molecules in immunity and inflammation. Pharmacol.
Ther. 2006, 112 (2), 358-404.

2
736 Journal of Medicinal Chemistry, 2007, Vol. 50, No. 11
Brief Articles
Activation of murine lung mast cells by the adenosine A3 receptor.
J. Immunol. 2003, 171 (1), 338-345. (c) Fan, M.; Qin, W.; Mustafa,
S. J. Characterization of adenosine receptor(s) involved in adenosine-
induced bronchoconstriction in an allergic mouse model. Am. J.
Physiol. 2003, 284 (6), 1012-1019.
(21) (a) Sun, C. X.; Zhong, H.; Mohsenin, A.; Morschl, E.; Chunn,
J. L.; Molina, J. G. Belardinelli. L.; Zeng, D. Blackburn
M. R. Role of A2B adenosine receptor signaling in adenosine-
dependent pulmonary inflammation and injury. J. Clin. InVest.
2
006, 116 (8), 2173-2182. (b) Fan, M.; Zeng, D.; Belardinelli,
L.; Mustafa, S. J. An adenosine receptor antagonist and
montelukast prevent AMP-induced bronchoconstriction in an
allergic mouse model. American Thoracic Society meeting, 2005;
Poster H75.
(
20) Aparici, M.; Nueda, A.; Beleta, J.; Prats, N.; Fernandez, R.; Miralpeix,
M. A potent adenosine A2B receptor antagonist attenuates metha-
choline-induced bronchial hyperresponsiveness, mucus production
and IgE levels in an allergic mouse model. CIA Symposium, 2006;
Poster 162.
JM061333V