Antagonists of the human A2A receptor. Part 6: Further optimization of pyrimidine-4-carboxamides

Article abstract of DOI:10.1016/j.bmc.2009.07.078

Antagonists of the human A_2A receptor have been reported to have potential therapeutic benefit in the alleviation of the symptoms associated with neurodegenerative movement disorders such as Parkinson's disease. As part of our efforts to discov

Full text of DOI:10.1016/j.bmc.2009.07.078

Bioorganic & Medicinal Chemistry 17 (2009) 6590–6605
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry
journal homepage: www.elsevier.com/locate/bmc
Antagonists of the human A2A receptor. Part 6: Further optimization
of pyrimidine-4-carboxamides
Roger J. Gillespie a, Samantha J. Bamford a, Alex Clay b, Suneel Gaur a, Tim Haymes a, Philip S. Jackson b,
a
a
a
a
a
Allan M. Jordan b, , Burkhard Klenke , Stefania Leonardi , Jeanette Liu , Howard L. Mansell , Sean Ng ,
Mona Saadi a, Heather Simmonite b, Gemma C. Stratton a, Richard S. Todd a, Douglas S. Williamson b,
Ian A. Yule a
*
a Department of Chemistry, Vernalis (R&D) Ltd, 613 Reading Road, Winnersh, Wokingham RG41 5UA, UK
b Department of Chemistry, Vernalis (R&D) Ltd, Granta Park, Cambridge CB21 6GB, UK
a r t i c l e i n f o
a b s t r a c t
Article history:
Antagonists of the human A2A receptor have been reported to have potential therapeutic benefit in the
alleviation of the symptoms associated with neurodegenerative movement disorders such as Parkinson’s
disease. As part of our efforts to discover potent and selective antagonists of this receptor, we herein
describe the detailed optimization and structure–activity relationships of a series of pyrimidine-4-car-
boxamides. These optimized derivatives display desirable physiochemical and pharmacokinetic profiles,
which have led to promising oral activity in clinically relevant models of Parkinson’s disease.
Ó 2009 Elsevier Ltd. All rights reserved.
Received 14 May 2009
Revised 28 July 2009
Accepted 31 July 2009
Available online 5 August 2009
Keywords:
Adenosine receptor
Parkinson’s disease
Pyrimidine carboxamide
1. Introduction
though 2 only met its primary end-point in one of three pivotal
trials.6
The human adenosine receptor is a G-protein coupled receptor
which is delineated into four distinct sub-types, designated A1, A2A
O
N
O
N
,
A2B and A3. The adenosine A2A receptor plays an important role in
regulating smooth and well co-ordinated movement, in part by
moderating the activity of dopamine sensitive neurons in the stri-
atum.1 Degradation of these dopaminergic neurons gives rise to
Parkinson’s disease, in which the imbalance of neurotransmission
results in the symptoms commonly associated with this condition,
such as muscle rigidity, resting tremor and postural instability.
There is strong, mounting evidence that adenosine A2A receptor
antagonists may provide a novel point of therapeutic intervention
for Parkinson’s disease by increasing the sensitivity of the dopami-
nergic neurons to the residual levels of striatal dopamine and
restoring balance to the systems controlling muscle movement.2
We recently reported the discovery that pyrimidine carboxamide
derivatives, typified by 1, are potent antagonists of the human aden-
osine A2A receptor subtype and possess good physiochemical and
pharmacokinetic profiles.3 With a Ki against the human A2A receptor
of 1.7 nM and a 25-fold selectivity against the A1 receptor, com-
pound 1 compares favourably with the clinically investigated KW-
6002 2, which has recently completed Phase III clinical trials for
the alleviation of symptoms associated with Parkinson’s disease,4,5
N
N
N
O
OMe
OMe
O
N
1
NH2
O
NH
N
2
Herein, we report the further evaluation and elaboration of this
interesting, highly ligand efficient lead.7
2. Results and discussion
The first modifications of 1 investigated were atom replacement
analogues of the pyrimidine scaffold itself. We had previously per-
formed detailed investigations into bicyclic scaffolds as adenosine
receptor antagonists,8–11 and we therefore wished to retain the
monocyclic nature of our scaffold at this time. Our initial targets
were the triazine class of compounds, exemplified by derivatives
6–14, below. These were prepared from the commercial 2-furoni-
trile 3 as described in Scheme 1. Treatment with guanidine gave
the intermediate 4, albeit in low overall yield, which readily cy-
clized with diethyl oxalate to yield the key ethyl 2-furyltriazine
carboxylate 5. The desired amides 6–14 were then prepared via di-
rect amidation.
* Corresponding author. Tel.: +44 01223 895555; fax: +44 01223 895556.
E-mail address: a.jordan@vernalis.com (A.M. Jordan).
0968-0896/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmc.2009.07.078

R. J. Gillespie et al. / Bioorg. Med. Chem. 17 (2009) 6590–6605
6591
NH
Preparation of this compound is detailed in Scheme 2. The
amide 17 was formed from dichloroisonicotinic acid 16 using car-
bonyldiimidazole to effect the coupling. After Suzuki coupling with
furan boronic acid to give the mono-arylated product 18, the 2-
chloro moiety was displaced with hydrazine and reduced with Ra-
ney Nickel to give the desired aminopyridine carboxamide 15.
As detailed in Table 2, the pyridyl derivative 15 bound to the A2A
receptor with a Ki of 126 nM, some sevenfold less potent than the
corresponding triazine 13 and 45-fold less potent than the associ-
ated aminopyrimidine 19. Selectivity was also rather poor, only
displaying a mediocre sevenfold difference in binding affinity over
the A1 receptor. Given these findings, no further work on these
alternate scaffolds was undertaken and our further efforts focused
upon optimization of the substituents around the aminopyrimi-
dine core itself.
NH
O
N
a
O
N
H
NH2
3
4
b
O
N
O
c
N
N
N
O
N
NH2
EtO2C
N
NH2
NHR
6-14
5
We were aware that, in some cases, the incorporation of a furan
moiety can hypothetically lead to a potential metabolic liability.12
However, we were also acutely aware that this heterocycle ap-
peared to be a privileged moiety for both potency and selectivity
in human A2A receptor antagonists.13 We therefore wished to
determine whether the 2-furyl functionality could be replaced
with alternate groups and still retain both potency and high levels
of selectivity against the other adenosine receptor subtypes (Table
3).
A series of around 20 aromatic and heteroaromatic derivatives
were investigated as potential furan replacements, employing a
limited subset of the two key 2-(aminomethyl)pyridine side chains
found to be efficacious in our previous investigations. The synthe-
sis of these compounds is detailed in Schemes 3–5 and data for a
representative selection of these derivatives are presented in Table
3. The original furan compounds and corresponding 5-methylfuran
derivatives were accessed from the commercial 2-amino-4,6-
dichloropyrimidine 20. Stille coupling selectively yielded the
mono-arylated product 2114 and displacement of the chlorine at
C-4 with sodium cyanide, followed by acidic hydrolysis, gave the
key acid intermediate 23 which could be elaborated with a variety
of amine substituents using solid-supported carbodiimide resin as
the coupling agent.
Scheme 1. Synthesis of 2-amino-6-furyl-triazine-4-carboxamides. Reagents and
conditions: (a) guanidine HCl, NaOMe, MeOH, 30 °C, 8 h, 20%; (b) diethyl oxalate,
NEt3, reflux, 3 h, 75%; (c) amine, EtOH, reflux o/n, 34–75%.
Our initial choice of targets was guided by our earlier work in
this series,3 allowing a direct comparison of the two scaffolds. Data
for these compounds are presented in Table 1.
The data in Table 1 demonstrated that ortho- and meta-substi-
tuted phenyl and pyridyl moieties gave potent A2A antagonists with
reasonable selectivity. A preference for 2- and 3-pyridyl over the 4-
pyridyl conjoiner was also apparent. These general trends mirrored
our earlier findings, though we noted that in almost all cases both po-
tency and selectivity were diminished compared to our original
pyrimidine carboxamide derivatives (e.g., 14 demonstrates a fivefold
reduction in potency compared to the corresponding pyrimidine 1).
The only exception to this was 13 which, though it was roughly two-
fold more selective against the adenosine A1 receptor than the corre-
sponding aminopyrimidine, was also almost sevenfold less potent.
Given that increasing the nitrogen count of the scaffold had
been detrimental to both potency and selectivity, we postulated
that perhaps the corresponding pyridine scaffold may display an
improved profile. To this end, we prepared 15, the direct analogue
of our most selective triazine, 13.
Thiazole-containing derivatives were prepared as described in
Scheme 4, from the appropriate commercial b-keto ester or by con-
densation of the appropriate 2-acetylthiazole with diethyl carbon-
ate. Cyclization of this b-keto ester with guanidine yielded the
O
N
O
N
NH2
NH
15
Cl
Cl
N
a
N
O
Table 1
N
Cl
HO
Binding affinity data for triazine-4-carboxamide derivatives against human adenosine
Cl
NH
b
A2A and A1 receptors22
17
16
O
O
N
N
O
N
NH2
O
O
N
Aryl
NH
Compound
Aryl
A2A Ki (nM)
A1 Ki (nM)
c
N
6
7
8
9
10
11
12
13
14
2-Cl-Phenyl
2-Me-Phenyl
3-Me-Phenyl
2-OMe-Phenyl
2-Pyridyl
4.9
12.3
7.5
6.5
25
41
105
103
202
223
409
586
1112
595
O
O
N
NH2
N
Cl
NH
NH
15
18
3-Pyridyl
88
Scheme 2. Synthesis of 2-amino-6-furyl-pyridine-4-carboxamides. Reagents and
conditions: (a) N,N0-carbonyldiimidazole, DMF, rt, 2 h then amine, rt, 3 h, 48%; (b) 2-
furanboronic acid, Na2CO3, Pd(PPh3)4, THF, reflux o/n, 31%; (c) hydrazine monohy-
drate, EtOH, 100 °C o/n then Raney Ni, H2; (d) EtOH, rt, 3 h, 28%.
4-Pyridyl
420
18.6
8.8
(30-Methyl)-2-pyridyl
(60-Methoxymethyl)-2-pyridyl

6592
R. J. Gillespie et al. / Bioorg. Med. Chem. 17 (2009) 6590–6605
Table 2
R
Comparison of the binding affinities of the three scaffolds against human adenosine
A2A and A1 receptors12
Cl
O
a
N
O
N
Cl
N
NH2
X
N
Cl
N
NH2
20
R = H 21
R = Me 22
O
N
Y
NH2
NH
b,c
R
R
Compound
X
Y
A2A Ki (nM)
A1 Ki (nM)
15
19
13
CH
CH
N
CH
N
N
126
2.8
18.6
921
97
1112
O
O
N
d
N
O
O
N
NH2
N
NH2
NR1R2
OH
corresponding 2-amino-4-hydroxypyrimidines 31 and 32, which
underwent chlorination with phosphorous oxychloride to give
the 6-chloro derivatives 33 and 34. This intermediate was con-
verted to the desired carboxylic acid 35 and 36 by treatment with
sodium cyanide and acidic hydrolysis, in a manner akin to that de-
scribed in Scheme 3.
R = H 23
R = Me 24
25-28
Scheme 3. Synthesis of 6-furylpyrimidines. Reagents and conditions: (a) Ar-SnBu3,
PdCl2(PPh3)2, DMF, 80 °C, 18 h, 57–63%; (b) NaCN, DABCO, DMSO, 6 days, rt, 10–
77%; (c) H2SO4, rt, 2 h, 90%; (d) R1R2NH, PS-CDI, HOBt, DMF, rt, 24 h, 26–85%.
Non-heteroaromatic derivatives were accessed as detailed in
Scheme 5, via a slightly shorter and more widely applicable route,
from the known methyl-2-amino-6-hydroxypyrimidine-4-carbox-
ylic acid ester 39.16 Cyclization of guanidine with sodium diet-
hyloxaloacetate and esterification with methanol under acid
catalysis gave the aminopyrimidine ester 39. Chlorination of this
intermediate proceeded smoothly to give the chloro ester 40, but
upon work-up generated a substantial quantity of the 2-amino-
6-chloro-pyrimidine-4-carboxylic acid as a by-product, which
could be converted back to the 4-hydroxy ester 39 and recycled.
Suzuki couplings with the desired boronic acids proceeded
smoothly and the crude products from the coupling protocol were
hydrolyzed to the corresponding carboxylic acids 41–56, which
could be isolated in acceptable purity simply by acidification of
the aqueous liquors and filtration. Amine formation was effected
in a parallel fashion by shaking overnight with hydroxybenzotria-
Table 3
Binding affinity data for furan replacement analogues against human adenosine A2A and A1 receptors12
Ar
N
H
N
NH2
N
R
O
Ar
R
N
N
Compound
A2A Ki (nM)
A1 Ki (nM)
Compound
A2A Ki (nM)
A1 Ki (nM)
2-Furyl
25
27
4.3
4
n/d
47
14
17
18
31
31
49
18
36
57
28
153
92
253
255
128
3290
122
222
26
28
37
2.8
3
586
n/d
6
14
9
24
23
28
9
97
90
74
5-Me-2 Furyl
2-Thiazolyl
4-Me-2-thiazolyl
Phenyl
38
57
59
61
63
65
67
69
71
73
75
77
79
81
83
85
87
463
66
48
38
408
40
1377
67
118
1242
252
478
>10,000
9171
1670
504
58
60
62
64
66
68
70
72
74
76
78
80
82
84
86
88
38
38
31
394
56
1208
94
83
720
199
276
>10,000
7902
1157
395
>10,000
2-F-phenyl
3-F-phenyl
2-Cl-phenyl
3-Cl-phenyl
2-Me-phenyl
3-Me-phenyl
4-Me-phenyl
2-MeO-phenyl
3 MeO-phenyl
4-MeO-phenyl
2-Et-phenyl
2-EtO-phenyl
2-CN-phenyl
3-CN-phenyl
MeO-
16
30
24
155
107
107
123
29
2450
>10,000

R. J. Gillespie et al. / Bioorg. Med. Chem. 17 (2009) 6590–6605
6593
Previous reports had suggested that a simple methoxy derivative
may be a potential mimic of the interactions afforded by the furan in
other A2A antagonists,15–17 but this was found not to be the case in
our particular series of derivatives (compounds 87 and 88). Hetero-
aromatic furan replacements afforded a better overall profile in
terms of potency and selectivity. Though the thiazole derivatives
37 and 38 showed some promise, the simple replacement of the fur-
an with the 5-methylfuran gave compounds with similar levels of
both potency and selectivity, whilst decreasing the potential risk
of oxidative metabolism and covalent adduct formation.
R
O
O
N
S
N
S
a
O
N
R
R = H 29
R = Me 30
N
NH2
HO
R = H 31
R = Me 32
b
The finding that the 2-ethylphenyl derivatives 79 and 80 and
the 2-ethoxyphenyl derivatives 81 and 82 showed increased selec-
tivity suggested to us that the steric encumbrance displayed by
these derivatives may induce torsion around the biaryl linkage.
We suggested that this conformational change may result in the
observed enhancement of selectivity. However, we reasoned that
steric encumbrance around the pendant aryl moiety may not be
tolerated by the receptor, resulting in the observed reduction in
potency. If this were the case, we suggested that similar torsions
may be invoked by substitution at the C-5 of the pyrimidine ring,
but that substitution of this area may be less affected by the spatial
restraints imposed by the receptor.
We therefore determined a limited series of compounds de-
signed to investigate this phenomenon. These derivatives were
prepared as described in Scheme 6. Formation of the desired alkyl
diethyl oxaloaceate was accomplished according to literature
methods,18 in rather disappointing yields. These were then cy-
clized with guanidine to give the functionalized aminopyrimidine
esters which were converted to the desired biaryl amides 91–94
in a similar manner to that outlined in Scheme 5.
It was immediately apparent from these results that this strat-
egy had not delivered the anticipated increases in selectivity, cer-
tainly not rivaling the >100-fold selectivity exhibited by 79
(Table 4). Indeed, these compounds even failed to deliver the 35-
fold and 70-fold selectivities displayed by the unsubstituted (and
more synthetically tractable) derivatives 81 and 82. Further studies
in this area were therefore terminated.
An area which had received little attention at this point was the
2-amino functionality. Earlier studies within our laboratories on
bicyclic adenosine A2A antagonists had revealed that, whilst the
amino functionality delivered good potency, it was by no means
the only tolerated functionality in this region.9 We therefore felt
it prudent to investigate tolerances around this region, which
had previously had an influence on the selectivities displayed by
our compounds.
R
R
N
R
N
S
N
S
N
N
S
N
e
c, d
HO
N
RHN
Cl
N
NH2
N
NH2
NH2
O
O
R = H 33
R = Me 34
R = H 35
R = Me 36
37-38
Scheme 4. Synthesis of 6-thiazolylpyrimidines. Reagents and conditions: (a)
guanidine carbonate, PhMe, EtOH, reflux, 40 h, 36%; (b) POCl3, 120 °C, 3 h, 60%;
(c) NaCN, DABCO, DMSO, 6 days, rt, 60–90%; (d) H2SO4, rt, 2 h, 90%; (e) R1R2NH, PS-
CDI, HOBt, DMF, rt, 24 h, 14–60%.
zole, polymer-bound carbodiimide, DMAP and an excess of the de-
sired amine. After filtration and concentration in vacuo, the desired
amides (compounds 57–86) were isolated by aqueous work-up,
trituration from water and freeze-drying. The corresponding meth-
oxy derivatives 87 and 88 were prepared in a similar manner, sim-
ply substituting the Suzuki coupling step for treatment with
refluxing methanol.
In general, acceptable functionality around this region was
limited. Though simple phenyl derivatives were tolerated with-
out a considerable decrease in potency, selectivity across the
majority of phenyl derivatives was greatly reduced. Only the
ortho-methyl and ortho-methoxy derivatives maintained a rea-
sonable degree of both potency and selectivity, though meta-sub-
stituents tended, in general, to be favoured in terms of absolute
potency. Whilst the ortho-ethyl and ortho-ethoxy derivatives
(compounds 79–82) displayed reasonable to good selectivity
against the A1 receptor, potency against the A2A receptor was
diminished considerably.
OH
O
O
NH
NH2
a, b
N
O
+
O
O
H2N
N
NH2
O
O
39
c, d
Cl
R
R
N
e
N
f
N
N
O
O
O
N
NH2
N
NH2
NH2
O
NR1R2
57-88
OH
40
41-56
Scheme 5. Synthesis of substituted 6-phenylpyrimidine analogues. Reagents and conditions: (a) NaOH, H2O, rt, 3.5 h, 78%; (b) MeOH, H2SO4, reflux, 18 h, 85%; (c) POCl3,
reflux, 3 h, 15%; (d) for 41–55: ArB(OH)2, Pd(PPh3)4, THF, NaHCO3, then LiOH, 90 °C, 2 h; for 56: MeOH, reflux, 18 h, 93%; (e) PS-DCC, HOBt, DMF, rt, 24 h, 2–74%.

6594
R. J. Gillespie et al. / Bioorg. Med. Chem. 17 (2009) 6590–6605
OH
R
Ar
N
NR1R2
91-94
O
O
R
N
a
N
O
O
O
O
N
NH2
NH2
R
O
O
R = Me 89
R = Et 90
R = Me, Et
Scheme 6. Synthesis of 5p-alkylpyrimidines. Reagents and conditions: (a) guanidine, NaOH, H2O, rt, 3.5 h, 65–74%.
Table 4
Binding affinity data for analogues substituted at C-5, against human adenosine A2A and A1 receptors12
O
R1
N
H
N
R2
NH2
N
O
R1
R2
N
N
Compound
A2A Ki (nM)
A1 Ki (nM)
Compound
A2A Ki (nM)
A1 Ki (nM)
H
Me
Et
27
91
93
4
12
25
222
314
435
28
92
94
3
155
183
90
576
504
C-2 alkylated derivatives were prepared from the corresponding
known dichloropyrimidines19 as detailed in Scheme 7. Coupling
with 5-methylfuran-2-boronic acid to give the biaryls 95–97 was
followed by displacement of the 4-chloro moiety with sodium cya-
nide and hydrolysis to yield the corresponding acids 98, 99 and 100.
Preparation of the desired amine was accomplished using hydroxy-
benzotriazole and polymer-bound carbodiimide (Scheme 8).
The corresponding 2-amino derivatives were prepared from
2,4,6-trichloropyrimidine 104 in a similar manner. Suzuki coupling
with 5-methylfuran boronic acid and displacement of the 2-chloro
moiety by refluxing with the requisite amine gave 105 and 106.
Conversion to the desired amide was then achieved in a manner
analogous to that employed for the alkylated derivatives to yield
109–110.
Cl
Cl
O
N
a
O
a, b
N
N
N
Cl
N
R
Cl
N
Cl
R = H, Me, iPr
Cl
N
R
Cl
N
NRR'
104
R = H 95
R = Me 96
R = iPr 97
R = NHMe 105
R = NMe2 106
c
b
O
N
O
N
O
N
O
N
d
H
HO
c
N
H
N
NRR'
HO
N
N
NRR'
N
N
R
N
N
R
O
O
O
O
R = NHMe 107
R = NMe2 108
R = NHMe 109
R = NMe2 110
R = H 98
R = Me 99
R = iPr 100
R = H 101
R = Me 102
R = iPr 103
Scheme 8. Preparation of 2-aminopyrimidine derivatives. Reagents and conditions:
(a) 5-Me-furan boronic acid, NaHCO3, Pd(PPh3)4, THF, reflux, 18 h, 74%; (b) amine,
MeOH, 80 °C, 30 min, 22–36%; (c) NaCN, DABCO, NMP, 80 °C, 1.5 h, then cH2SO4,
H2O, reflux, 4 h, 15–45%; (d) 2-pyridylmethylamine, PS-DCC, HOBt, DIPEA, DMF, rt,
16 h, 32–65%.
Scheme 7. Preparation of 2-alkylpyrimidine derivatives. Reagents and conditions:
(a) 5-Me-furan boronic acid, NaHCO3, Pd(PPh3)4, THF, reflux, 18 h, 39–48%; (b)
NaCN, DABCO, NMP, 80 °C, 1.5 h, then cH2SO4, H2O, reflux, 4 h, 70–98%; (c) 2-
pyridylmethylamine, PS-DCC, HOBt, DMAP, DMF, rt, 16 h, 32–65%.

R. J. Gillespie et al. / Bioorg. Med. Chem. 17 (2009) 6590–6605
6595
Table 6
Unlike our previous experiences, it was apparent that small al-
kyl groups (compounds 102 and 103) were not tolerated at this po-
sition, leading to a considerable decrease in activity. Furthermore,
the dimethylamino functionality displayed by 110 was also detri-
mental to activity. This was a moiety which we had previously
found to be efficacious,10 perhaps indicating considerable steric
restriction around this region or a requirement for a hydrogen
bond donor in this position.
This data also challenges our earlier assumption that these sys-
tems bind to the receptor in a directly analogous manner to our
earlier bicyclic derivatives,3 given this marked inconsistency in
the structure–activity relationships. Complete deletion of the ami-
no functionality gave compound 101, equally active with the
mono-methylamino derivative 109. This analogue was substan-
tially more active than the dimethylamino derivative 110, further
indicating that a hydrogen bond donor, rather than a lone pair or
other hydrogen bond acceptor was more important at this position.
It was evident, however, that the simple C-2 amino functionality
was optimal.
Binding affinity data for selected amide derivatives against human adenosine A2A and
A1 receptors12
O
N
H
N
R
N
NH2
O
Compound
R
A2A Ki (nM)
A1 Ki (nM)
27
28
Pyridin-2-yl
4
222
90
133
77.5
57
3-Methyl-pyridin-2-yl
6-Methyl-pyridin-2-yl
3.5
2.5
3
9.5
3
2.5
2
5
1
3.5
6
5.5
8.5
6.5
111
112
113
114
115
116
117
118
119
120
121
122
123
3,6-Dimethyl-pyridin-2-yl
4,6-Dimethyl-pyridin-2-yl
5,6-Dimethyl-pyridin-2-yl
1-Methyl-1H-pyrrol-2-yl
Pyrrol-2-yl
89
172
270
166
368
385
277
270
299
72.5
1,5-Dimethyl-1H-pyrrol-2-yl
Imidazol-2-yl
Our final point of investigation was the nature of the C-4 amide
functionality. We had found previously that pyridyl-containing
side-chains exhibited preferential properties in terms of solubility
and biological activity and these, therefore, formed the main focus
of our investigations.
1-Ethyl-1H-imidazol-2-yl
1-n-Propyl-1H-imidazol-2-yl
1-Isopropyl-1H-imidazol-2-yl
5-Methylisoxazol-3-yl
2-Methylthiazol-4-yl
A library of some 200 derivatives was prepared using the paral-
lel methodology described in Scheme 5. These studies further high-
lighted that non-heteroaromatic derivatives at this point were
detrimental, both in terms of potency and solubility.20 It soon be-
came clear that we had been extremely fortuitous with our initial
choice of amines, as these proved to be amongst the most active
investigated. Interestingly, the 6-(methoxymethyl)-pyridin-2-yl
methylamine side chain displayed in 1,3 which had proven highly
beneficial in our earlier studies on this template, proved to be con-
siderably less effective in this system and was not considered for
further evaluation, suggesting that the methylfuryl moiety forces
a somewhat different binding orientation within the receptor (Ta-
ble 5).
For those compounds showing 50-fold or greater selectivity
over the A1 receptor, selectivities against the other adenosine sub-
types were also determined. Selected data for all four subtypes are
detailed in Table 7. Though A1 selectivity was acceptable and gen-
erally consistent at roughly 50–100-fold (except for the highly A1-
selective derivative 118, which was found to be more than 350-
fold selective), selectivities against the A2B and A3 receptors were
found to be much higher. Indeed, values of 200-fold selectivity over
the A3 receptor and 1000-fold selectivity over the more closely re-
lated A2B receptor were not uncommon in this series.
In general terms, we found that a nitrogen directly adjacent to
the methylamine linker was highly favoured and that, alongside
our original pyridine-containing derivatives, pyrroles, pyrazoles
and imidazoles were also well tolerated. Selectivities of the deriv-
atives against the other adenosine receptors and physiochemical
properties could be influenced by substitution patterns around
the heteroaromatic ring but, in some cases, this was accompanied
by a moderate reduction of binding affinity at the A2A receptor. A
selection of the more active derivatives is described in Table 6.
Encouraged by the selectivities observed, the optimized com-
pounds described in Table 7 were investigated for their ability to
reduce Parkinson’s-like symptoms in the haloperidol-induced
hypolocomotion (HaloLMA) assay. In this model, the symptoms
of Parkinson’s disease can be induced by using agents such as hal-
operidol, a dopamine receptor antagonist which blocks dopami-
nergic neurotransmission and thus mimics the degradation of
striatal neurons observed in the disease.21 Animals treated with
this agent display an impairment of movement, mirroring that ob-
served in patients. We therefore assessed the in vivo efficacy of our
compounds by monitoring the reversal of the reduction in locomo-
tor activity induced by haloperidol administration. Data from this
assessment are detailed in Table 8.
Compound 27 and 116, our first derivatives to undergo assess-
ment, were found to be orally active and both derivatives reversed
hypolocomotion induced by haloperidol at 10 mg/kg. Interestingly,
though 116 was active in vivo, the closely related 118 was found to
have no discernable activity when dosed orally at 10 mg/kg.
We speculated that the observed activities for 27, 116 and 118
were being tempered by low brain penetration, potentially due to
their low lipophilicity limiting permeability across cell membranes
and we hoped that compounds 111 and 119, with their slightly
higher cLog P, would display improved CNS penetration. We antic-
ipated that this would manifest itself in lower efficacious doses in
the model, without hindering oral bioavailability. This was clearly
not the case for 119, which showed no improvement in activity,
again being active at 10 mg/kg. However, 111 clearly had an im-
proved profile, displaying activity in the model at just 1 mg/kg
after oral dosing.
Table 5
Binding affinity data for analogues substituted at C-2, against human adenosine A2A
and A1 receptors12
O
N
H
N
N
R
N
O
Compound
R
A2A Ki (nM)
A1 Ki (nM)
27
NH2
H
3.8
97
1117
1725
63
222
2545
4212
1086
151
101
102
103
109
110
Me
iPr
NHMe
NMe2
1789
1401

6596
R. J. Gillespie et al. / Bioorg. Med. Chem. 17 (2009) 6590–6605
Table 7
Binding affinities of selected derivatives against all human adenosine receptor subtypes12
O
N
H
R
N
NH2
N
O
Compound
R
A2A Ki (nM)
A1 Ki (nM)
A2B Ki (nM)
A3 Ki (nM)
27
Pyridin-2-yl
4
222
133
172
270
368
385
270
1089
3185
2466
>10,000
798
896
366
1150
9090
2104
741
111
115
116
118
119
121
6-Methyl-pyridin-2-yl
1-Methyl-1H-pyrrol-2-yl
Pyrrol-2-yl
Imidazo-2-yl
1-Ethyl-1H-imidazol-2-yl
1-Isopropyl-1H-imidazol-2-yl
2.5
2.5
2
1
3.5
5.5
1304
1844
1627
or IST Flash II, 54 Å from Argonaut, Hengoed UK). Thin layer chro-
matography was conducted with 5 ꢀ 10 cm plates coated with
Merck Type 60 F254 silica gel to a thickness of 0.25 mm.
Table 8
Minimum oral dose required for reversal of haloperidol-induced hypolocomotion in
mice
Microanalyses and high resolution mass spectrometry were
performed by Medac Ltd, Egham, UK (http://www.medacltd.com).
All reagents obtained from commercial sources were used without
further purification. Anhydrous solvents were obtained from the
Sigma–Aldrich Chemical Company Ltd, and used without further
drying. All compounds were >95% purity as determined by LC–
MS (wavelength 220 nm) and by 1H NMR, unless otherwise indi-
cated. Where Cl or Br were present, expected isotopic distribution
patterns were observed. Reactions that are specified as being car-
ried out in a microwave oven were conducted in a Biotage Synthe-
sizer, Biotage Initiator or CEM Explorer microwave.
Compound
HaloLMA activity (mg/kg)
27
10
1
10
10
>10
10
111
115
116
118
119
In vitro DMPK screening of 111 indicated low microsomal turn-
over across several species, with metabolism primarily attributable
to the CYP450 1A2 isoform. The compound was screened for inhi-
bition of common CYP isoforms and was found not to be an inhib-
3.1. Analytical chemistry procedures
itor of these enzymes at concentrations up to 10 lM. Plasma
protein binding was also investigated and the compound found
to be 84% bound. Pharmacokinetic analysis indicated the com-
pound to have a reasonable terminal half-life of around 3 h and a
plasma Tmax of 15 min in rats. Clearance was found to be moderate
at 1.95 L/h/kg, however given the promising in vivo efficacy after
oral dosing, we were surprised to find a relatively low volume of
distribution 0.7 L/kg and an oral bioavailability of just 3%. At this
time, we have no data to suggest why the bioavailability of this
derivative is so low, especially as other derivatives from this com-
pound class, which display similar calculated and measured phar-
macokinetic parameters, have shown bio-availabilities in the order
of 90%.3 Despite this, our compound clearly exhibits a beneficial
profile once absorbed, given its observed potency in the HaloLMA
model. Indeed, we speculate that this efficacy may be further en-
hanced through appropriate formulation strategies, which may al-
low improvements in the observed oral bio-availability.
In summary, we have described a series of soluble, low molec-
ular weight antagonists of the human adenosine A2A receptor.
These derivatives show good to excellent selectivity against the
other adenosine receptor subtypes. Iterative optimization of the
scaffold has resulted in a number of highly potent compounds
which display excellent in vitro activity. More importantly, these
derivatives also show promising activity in a clinically validated
model of Parkinson’s disease and may, therefore, be of clinical rel-
evance and utility.
3.1.1. LC–MS methods
The methods referred to in Section 2 are described in detail in
the Supplementary data, which can be found in the online version
of this article.
3.1.2. 1H NMR
Proton NMR spectra were recorded on a 400 MHz Bruker spec-
trometer. Solutions were typically prepared in either deuterochlo-
roform (CDCl3) or deuterated dimethylsulfoxide (DMSO-d6) with
chemical shifts referenced to tetramethylsilane (TMS) as an inter-
nal standard. 1H NMR data is reported indicating the chemical shift
(d), the integration (e.g., 1H), the multiplicity (s, singlet; d, doublet;
t, triplet; q, quartet; m, multiplet; br, broad; dd, doublet of dou-
blets etc.) and the coupling constant (J) in Hz (app implies apparent
coupling on broadened signals). Deuterated solvents were ob-
tained from the Sigma–Aldrich Chemical Company or Fluorochem.
Mass spectra were acquired via loop injection on a Waters ZQ
Mass Detector equipped with an Electrospray source operated in
Positive/Negative Ion switching mode and a cone voltage of 25 V.
3.2. Biological assay protocols
3.2.1. Radioligand binding assay
Four cell lines, stably transfected to express human recombi-
nant adenosine receptors (hA1, A2A, A2B or A3), were grown in Dul-
becco’s Modified Eagles Medium (DMEM) supplemented with 10%
(v/v) foetal bovine serum, 1% (v/v) penicillin–streptomycin, 1% (v/
3. Experimental
v)
and 10
bator at 37 °C in 5% CO2:95% air mixture, they were harvested
L
-glutamine, 1% (v/v) MEM non-essential amino acid solution
Flash chromatography was performed using pre-packed silica
gel cartridges (Strata Si-1, 61 Å from Phenomenex, Cheshire UK,
l
M sodium pyruvate. Cells were kept in a humidified incu-

R. J. Gillespie et al. / Bioorg. Med. Chem. 17 (2009) 6590–6605
6597
using a cell scraper and centrifuged at 1000g for 20 min. The resul-
tant pellet was resuspended in Dulbecco’s phosphate buffered sal-
ine and centrifuged at 1000g for 20 min. The pellet was then stored
at ꢁ80 °C until use.
mined by placing the cages within a frame containing a 3 ꢀ 6 array
of photocells linked to a computer, which tabulates beam breaks.
Animals were left undisturbed to explore for 1 h, and the period
of time spent active (assessed by beam breaks) served as a record
of locomotor activity.
Frozen cells were reconstituted in 50 mM Tris HCl buffer (pH
7.5–8.0) containing 10 mM MgCl2, 1 mM EDTA (A2B, A3 assays only)
and 0.1 IU/mL adenosine deaminase using a Ultra-Turrax homoge-
niser. The resultant homogenate was kept for immediate use in the
binding.
3.3. Synthetic procedures
3.3.1. Ethyl-2-amino-4-(2-furyl)-triazine-6-carboxylate 5
A solution of guanidine [prepared by treating NaOMe (0.58 g,
10.7 mmol) in MeOH (10 mL) with guanidine hydrochloride
(0.51 g, 5.34 mmol)] was treated with 2-furonitrile (0.5 g,
5.37 mmol) over 30 min. The suspension was stirred at 30 °C for
8 h, filtered, and the filtrate was acidified with hydrochloric acid.
The solid was filtered off to give N-aminoiminomethylfuran-2-
carboximidamide hydrochloride 4 (0.20 g, 20%) as a cream solid
which was used directly in the next step.
Binding assays were performed in a total volume of 250 lL, con-
taining radioligand, membranes and additional drugs. Following 60
(A2B, A3) or 90 (A1, A2A) min incubation at 21 °C, assays were termi-
nated by rapid filtration with GF/B filters (presoaked in 0.1% (w/v)
polyethylenimine) using a Canberra Packard filtermate 196. The
radioactivity was assessed using a Canberra Packard TopCount
microplate scintillation counter.
3.2.2. Functional assay
A solution of N-aminoiminomethylfuran-2-carboximidamide
hydrochloride 4 (0.20 g, 1.06 mmol) and Et3N (0.16 g, 1.60 mmol)
in diethyl oxalate (2.15 g, 14.7 mmol) was heated under reflux
for 3 h, allowed to cool, poured into water (50 mL) and extracted
with EtOAc (3 ꢀ 50 mL). The extracts were dried (MgSO4), concen-
trated in vacuo, and purified by chromatography [SiO2; EtOAc–iso-
hexane (1:1)] to give 5 (186 mg, 75%) as a white solid; NMR dH
(400 MHz, DMSO) 1.25 (3H, t, J 7.2 Hz), 4.20 (2H, q, J 6.7 Hz),
6.73 (1H, dd, J 2.0, 3.2 Hz), 7.38 (1H, d, J 3.6 Hz), 8.19–7.90 (3H,
m, J 1.2 Hz); m/z 235 (M+1)+, 257 (M+Na)+.
Cells were plated out into black walled, clear bottom 96-well
tissue culture plates at a density of 30,000 cells per well. This seed-
ing density was sufficient to ensure that the cells formed a conflu-
ent monolayer after an overnight incubation. On the day of assay,
cells were dye loaded by incubating for approximately 1 h with
4 lM Fluo-3-AM in ULTRA-CHO media supplemented with
20 mM HEPES and 2.5 mM probenecid, an inhibitor of anion ex-
change which prevents dye extrusion from the cells. Unincorpo-
rated dye was removed by four media changes using a Denley
cell washer, which was programmed to leave 100 lL of a balanced
salt solution (BSS: GIBCO 14065-049) containing 20 mM HEPES
3.3.2. General amide synthesis for compounds 6–14
and 2.5 mM probenecid in each well.
A suspension of ethyl 4-amino-6-(2-furyl)triazine-2-carboxyl-
ate 5 (0.150 g, 0.64 mmol) in EtOH (2.5 mL) was treated with the
appropriate amine (0.83 mmol), refluxed overnight, cooled to room
temperature and the resulting precipitate was filtered and washed
with cold EtOH (2 ꢀ 2 mL) to give the desired amide derivative.
The test compound was dissolved in 100% DMSO to a stock con-
centration of 3 mM, and diluted manually in BSS to produce the
working stock solutions for use in the assay.
Background fluorescence readings were set to approximately
10,000 fluorescence units by altering the laser strength, with a typ-
ical laser setting being in the range of 0.4–0.8 W. Agonists were
3.3.2.1. N-(2-Chlorobenzyl)-2-amino-4-(2-furyl)-1,3,5-triazine-
6-carboxamide 6. Yield = 75%; IR mmax (DR)/cmꢁ1 3477, 3377,
3308, 1741, 1686, 1624, 1558, 1415 and 1370; NMR dH
(400 MHz, DMSO) 4.55 (2H, d, J 6.0 Hz), 6.74 (1H, dd, J 3.5 Hz,
2.0 Hz), 7.40–7.27 (3H, m), 7.47 (1H, dd, J 1.5 Hz, 7.0 Hz), 7.56
(1H, d, J 3.5 Hz), 7.96 (2H, br s), 7.98 (1H, d, J 1.0 Hz), 9.22 (1H, t,
J 6.0 Hz). Anal. Calcd for C15H12N5O2Cl: C, 54.61; H, 3.67, N,
21.23. Found: C, 54.10; H, 3.39; N, 21.54; m/z 330.1 (M+H)+,
352.1 (M+Na)+; LC retention time 2.3 min. Method A.
added at a rate of 70
agonist studies 50 L of agonist was added to each well for a final
volume of 150 L. For antagonist studies, 50 L of a fixed concen-
lL/s following a 10 s baseline reading. For
l
l
l
tration of antagonist was added manually to the cells ‘off line’ and
incubated at 37 °C for 15 min. The final well volume following ago-
nist application in this case was 200 lL. Agonist concentration–re-
sponse curves were constructed in the absence and presence of
varying concentrations of antagonist and the pA2 value estimated
by Schild analysis.
3.3.2.2. N-(ortho-Tolyl)-2-amino-4-(2-furyl)-1,3,5-triazine-6-
3.2.3. Haloperidol-induced hypolocomotion assay
carboxamide 7. Yield = 75%; IR m
max (DR)/cmꢁ1 3504, 3462, 3326,
All work reported in this manuscript was performed in accor-
dance with Home Office regulations as detailed in the Animals (Sci-
entific Procedures) Act 1986.
Female TO mice (25–30 g) and Sprague-Dawley rats (300–
400 g) were used for all experiments. Animals were allowed free
access to food and water, and were allowed at least 7 days to accli-
matize after delivery before experimental use.
1676, 1517, 1224, 1143, and 1078; NMR dH (400 MHz, DMSO) 2.33
(3H, s), 4.46 (2H, d, J 6.1 Hz), 6.73 (1H, dd, J 1.8 Hz, 3.4 Hz), 7.20-
7.14 (3H, m), 7.25 (1H, t, J 3.9 Hz), 7.53 (1H, d, J 0.7 Hz, 3.4 Hz),
7.94 (2H, br s), 7.97 (1H, d, J 0.75 Hz), 9.02 (1H, t, J 6.1 Hz); m/z
310.2 (M+H)+, 332.2 (M+Na)+; LC retention time 1.9 min. Method
A.
Liquid injectable haloperidol (1 mL Serenance ampoules from
Baker Norton, Harlow, Essex, each containing haloperidol BP
5 mg) were diluted to a final concentration of 0.02 mg/mL for mice
and 0.05 mg/mL for rats using saline. Mice were dosed at 10 mL/kg
(final dose 0.2 mg/kg sc) and rats at 2 mL/kg (final dose 0.1 mg/kg
sc). The test compound was prepared as an aqueous suspension in
1% methylcellulose.
1.5 h before testing, animals were administered haloperidol.
The test compound was administered 15 min (mice) or 120 min
(rat) prior to testing. The animals were then placed individually
into clean, clear polycarbonate cages [20 (width) ꢀ 40
(length) ꢀ 20 (height) cm]. Horizontal locomotor activity is deter-
3.3.2.3. N-(meta-Tolyl)-2-amino-4-(2-furyl)-1,3,5-triazine-6-
carboxamide 8. Yield = 74%; IR m
max (DR)/cmꢁ1 3462, 3308, 1670,
1636, 1542,1412, 1363, 1233, 1190, 1148, 1096 and 1065; NMR dH
(400 MHz, DMSO) 2.29 (3H, s), 4.44 (2H, d, J 6.5 Hz), 6.74 (1H, dd, J
2.0 Hz, 3.5 Hz), 7.14–7.04 (3H, m), 7.22 (1H, d, J 7.5 Hz), 7.55 (1H,
dd, J 1.0 Hz, 3.5 Hz), 7.93 (2H, br s), 7.97 (1H, d, J 1.0 Hz), 9.15
(1H, t, J 6.0 Hz); m/z 310.2 (M+H)+, 332.2 (M+Na)+; LC retention
time 2.0 min. Method A.
3.3.2.4. N-(2-Methoxyphenyl)-2-amino-4-(2-furyl)-1,3,5-tri-
azine-6-carboxamide 9. Yield = 65%; IR mmax (DR)/cmꢁ1 3370,
3188, 2953, 2834, 1686, 1648, 1542, and 1247; NMR dH

6598
R. J. Gillespie et al. / Bioorg. Med. Chem. 17 (2009) 6590–6605
(400 MHz, DMSO) 3.85 (3H, s), 4.45 (2H, d, J 6.0 Hz), 6.79 (1H, dd, J
1.5 Hz, 3.5 Hz), 6.92 (1H, dt, J 7.5 Hz, 1.0 Hz), 7.01(1H, d, J 7.5 Hz),
7.20 (1H, dd, J 1.5 Hz, 7.5 Hz), 7.26 (1H, t, J 8.0 Hz, 1.5 Hz), 7.53 (1H,
d, J 3.5 Hz), 7.95 (2H, br s), 7.97 (1H, d, J 1.0 Hz), 8.98 (1H, t, J
6.0 Hz); m/z 326.2 (M+H)+, 348.2 (M+Na)+; LC retention time
1.7 min. Method A.
were dried (MgSO4), filtered, concentrated in vacuo and the result-
ing solid was triturated with EtOAC–isohexane (1:5) and filtered to
give 17 (4.30 g, 48%) as a cream solid; NMR dH (400 MHz, CDCl3)
2.36 (3H, s), 4.67 (2H, d, J 4.0 Hz), 7.23 (1H, dd, J 8.0, 5.0 Hz),
7.56 (1H, d, J 8.0 Hz), 7.74 (2H, s), 8.45 (1H, d, J 5.0 Hz), 8.50 (1H,
br s); m/z 296 (M+H)+, 298 (M+H)+.
3.3.2.5. N-((Pyridin-2-yl)methyl)-2-amino-4-(2-furyl)-1,3,5-tri-
azine-6-carboxamide 10. Yield = 74%; IR mmax (DR)/cmꢁ1, 3301,
1697, 1633, 1518, 1224, 1189 and 1151; NMR dH (400 MHz,
DMSO): 4.59 (2H, d, J 6.0 Hz), 6.75 (1H, dd, J 2.0, 3.5 Hz) 7.28
(1H, dd, J .1.0 Hz, 5.0), 7.35 (1H, d, J 7.5 Hz), 7.56 (1H, dd, J
1.0 Hz, 3.5 Hz), 7.77 (1H, dt, J 1.5 Hz, 7.5 Hz), 7.94 (2H, br s), 7.98
(1H, d, J 1.5 Hz), 8.53 (1H, d, J 4.0 Hz), 9.29 (1H, t, J 6.0 Hz). Anal.
Calcd for C14H12N6O2: C, 56.75; H, 4.08, N, 28.35. Found: C,
55.37; H, 4.06; N, 28.10; m/z 297 (M+H)+; LC retention time
2.3 min. Method B.
3.3.2.11. N-((6-Methoxymethyl-pyridin-2-yl)methyl)-2-chloro-
6-furyl-isonicotinamide 18. A solution of 2,6-dichloro-N-[(3-
methyl)pyridyl]methyl pyridine-4-carboxamide 17 (1.20 g, 4.05
mmol) in THF (30 mL) was treated with 2 M aqueous Na2CO3
(7 mL), 2-furanboronic acid (544 mg, 4.86 mmol) and Pd(PPh3)4
(468 mg, 0.405 mmol) and refluxed with vigorous stirring under
argon overnight. The mixture was cooled to room temperature, di-
luted with water (100 mL) and extracted with EtOAc (3 ꢀ 100 mL).
The combined organic phases were dried (MgSO4), concentrated in
vacuo and purified by chromatography [SiO2; isohexane–EtOAc
(2:1)] to give 18 (413 mg, 31%) as a cream solid; NMR dH
(400 MHz, CDCl3) 2.35 (3H, s), 4.68 (2H, d, J 4.0 Hz), 6.58–6.56
(1H, m), 7.22–7.19 (2H, m), 7.54 (1H, d, J 8.0 Hz), 7.58 (1H, d, J
2.5 Hz), 7.62 (1H, d, J 1.5 Hz), 8.03 (1H, d, J 2.5 Hz), 8.47–8.44
(2H, m); m/z 328 (M+H)+, 330 (M+H)+.
3.3.2.6. N-((Pyridin-3-yl)methyl)-2-amino-4-(2-furyl)-1,3,5-tri-
azine-6-carboxamide 11. Yield = 72%; mp 216.2.–219.3 °C; IR
mmax (DR)/cmꢁ1 3453, 3308, 1633, 1537, 1227 and 1140; NMR dH
(400 MHz, DMSO) 4.5 (2H, d, J 6.0 Hz), 6.75–6.73 (1H, m), 7.38–
7.33 (1H, m), 7.55 (1H, dd, J 1.0 Hz, 3.5 Hz), 7.73 (1H, d, J 8.0 Hz),
7.94 (2H, br s), 7.97 (1H, d, J 1.0 Hz), 8.56 (1H, d, J 1.5 Hz),
8.47(1H, dd, J 2.0 Hz, 5.0 Hz), 9.3 (1H, t, J 6.0 Hz). Anal. Calcd for
C14H12N6O2: C, 56.75; H, 4.08, N, 28.35. Found: C, 56.12; H, 4.06;
N, 28.40; m/z 297.19 (M+H)+; LC retention time 0.5 min. Method A.
3.3.2.12. N-((6-Methoxymethyl-pyridin-2-yl)methyl)-2-amino-
6-furyl-isonicotinamide 15. A solution of 2-chloro-6-(2-furyl)-
N-[(3-methyl)pyridyl] methylpyridine-4-carboxamide 18 (413 mg,
1.26 mmol) in EtOH (5 mL) and hydrazine monohydrate (5 mL)
was stirred at 100 °C overnight, cooled to room temperature,
poured onto water (50 mL) and extracted with EtOAc (3 ꢀ
50 mL). The combined organic phases were dried (MgSO4) and con-
centrated in vacuo to give 2-(2-furyl)-6-hydrazino-N-[(3-methyl)-
pyridyl]methylpyridine-4-carboxamide (400 mg) as a yellow oil.
This was dissolved in EtOH (30 mL) and treated with Raney-Ni
(approximately 200 mg), stirred under an hydrogen atmosphere
for 3 h, filtered through Celite, concentrated in vacuo and purified
by chromatography [SiO2; EtOAc–isohexane–Et3N (80:18:2)] to
give 15 (110 mg, 28%) as a cream solid; mp 53.2–56.8 °C; NMR
dH (400 MHz, DMSO) 2.33 (3H, s), 4.57 (2H, d, J 5.0 Hz), 6.28 (2H,
br s), 6.61 (1H, dd, J 3.5, 2.0 Hz), 6.79 (1H, d, J 1.0 Hz), 6.93–6.92
(1H, m), 7.22 (1H, dd, J 7.5, 4.5 Hz), 7.30 (1H, d, J 1.5 Hz), 7.59
(1H, dd, J 7.5, 1.0 Hz), 7.78–7.77 (1H, m), 8.36 (1H, d, J 4.5 Hz),
8.92 (1H, t, J 5.0 Hz); m/z 309 (M+H)+; LC retention time 1.0 min.
Method A.
3.3.2.7. N-((Pyridin-4-yl)methyl)-2-amino-4-(2-furyl)-1,3,5-tri-
azine-6-carboxamide 12. Yield = 71%; IR mmax (DR)/cmꢁ1 3390,
1664, 1517, 1230, 993 and 799; NMR dH (400 MHz, DMSO) 4.50
(2H, d, J 6.0 Hz), 6.76–6.73 (1H, m), 7.57 (1H, d, J 1.0 Hz, J
3.5 Hz), 7.96 (2H, br s), 7.98 (1H, d, J 1.0 Hz), 8.51 (2H, d, J
6.0 Hz), 9.35 (1H, t, J 6.0 Hz), 7.31 (2H, d, J 6.0 Hz); m/z 297.2
(M+H)+, 319.2 (M+Na)+; LC retention time 1.8 min. Method B.
3.3.2.8. N-((3-Methyl-pyridin-2-yl)methyl)-2-amino-4-(2-
furyl)-1,3,5-triazine-6-carboxamide 13. Yield = 34%; IR mmax
(DR)/cmꢁ1 3999, 3318, 1693, 1504, 1223, 1142, 1083 and 1008;
NMR dH (400 MHz, DMSO) 2.33 (3H, s), 4.63 (2H, d, J 5.0 Hz),
6.75 (1H, dd, J 1.5 Hz, 3.5 Hz), 7.26 (1H, dd, J 5.0 Hz, 7.5 Hz), 7.48
(1H, dd, J 1.0 Hz, 3.5 Hz), 7.63 (1H, d, J 7.0 Hz), 7.98–7.93 (2H, broad
signal), 7.99(1H, d, J 1.0 Hz), 8.41 (1H, d, J 3.5 Hz), 9.24 (1H, t, J
5.0 Hz); m/z 311.1 (M+H)+, 333.1(M+Na)+; LC retention time
0.9 min. Method A.
3.3.2.13. 2-Amino-4-chloro-6-furyl-pyrimidine 21. A solution
of 2-(tributylstannyl)furan (35.7 g, 100 mmol) in DMF (100 mL)
was treated with 2-amino-4,6-dichloropyrimidine 20 (16.4 g,
100 mmol) and dichlorobis(triphenylphosphine)palladium(II)
(3.51 g, 5.0 mmol). The suspension was stirred at 80 °C for 18 h, al-
lowed to cool to room temperature and poured onto ice (400 g).
The solid precipitate was filtered off, washed with water, dried in
air, and the filtrate was extracted with EtOAc (300 mL), washed
with water (100 mL), mixed with the solid precipitate and concen-
trated. The crude product was purified by chromatography [SiO2;
EtOAc–toluene (0:1–1:9–2:3)] and the material with Rf 0.23 (iso-
propyl ether) was triturated with isohexane to give 21 (11.1 g,
57%) as a yellow solid; mp 133–140 °C; NMR dH (400 MHz, DMSO)
6.70 (1H, q, J 2.0 Hz), 6.95 (1H, s), 7.16 (2H, br s), 7.27 (1H, d, J
3.6 Hz), 7.92 (1H, t, J 1.0 Hz).
3.3.2.9. N-((6-Methoxymethyl-pyridin-2-yl)methyl)-2-amino-4-
(2-furyl)-1,3,5-triazine-6-carboxamide 14. Yield = 74%; mp 215.9–
217.1 °C; IR mmax (DR)/cmꢁ1 3300, 3122, 2917, 2827, 1690, 1633,
1593, 1511, 1409, 1331 and 1188; NMR dH (400 MHz, DMSO)
3.38 (3H, s), 4.50 (2H, s), 4.57 (2H, d, J 6.0 Hz), 6.75 (1H, dd, J
1.5 Hz, 3.5 Hz), 7.25 (1H, d, J 8.0 Hz), 7.31 (1H, d, J 7.5 Hz), 7.56
(1H, dd, J 1.0 Hz, 3.5 Hz), 7.79 (1H, t, J 7.5 Hz), 7.97(2H, br s),
7.99 (1H, d, J 1.0 Hz), 9.35 (1H, t, J 6.0 Hz). Anal. Calcd for
C16H16N6O3: C, 56.47; H, 4.74, N, 24.68. Found: C, 55.60; H, 4.62;
N, 24.72; m/z 341.2 (M+H)+, 363.2 (M+Na)+; LC retention time
3.5 min. Method B.
3.3.2.10. N-((6-Methoxymethyl-pyridin-2-yl)methyl)-2,6-
dichloroisonicotinamide 17. A solution of 2,6-dichloroisonicoti-
nic acid 16 (5.80 g, 30.2 mmol) in DMF (30 mL) was treated with
N,N0-carbonyldiimidazole (5.39 g, 33.2 mmol), stirred at room tem-
perature for 2 h, then treated with 2-aminomethyl-3-methylpyri-
dine (4.42 g, 36.3 mmol). The reaction mixture was stirred at
room temperature for 3 h, poured onto water (150 mL) and ex-
tracted with EtOAc (3 ꢀ 100 mL). The combined organic phases
3.3.2.14. 2-Amino-6-(2-furyl)pyrimidine-4-carboxylic acid 23.
A
solution of 2-amino-4-chloro-6-(2-furyl)pyrimidine 21
(9.78 g, 50.0 mmol) in DMSO (200 mL) was treated with sodium
cyanide (14.7 g, 300 mmol) and 1,4-diazabicyclo[2.2.2]octane
(DABCO) (0.56 g, 5.0 mmol). The suspension was stirred for 4 days,
and more DABCO (5.04 g, 45 mmol) and DMSO (100 mL) were

R. J. Gillespie et al. / Bioorg. Med. Chem. 17 (2009) 6590–6605
6599
added. The suspension was stirred for a further 2 days, poured onto
a mixture of ice (750 g) and water (750 mL), the crude product was
filtered off, washed with water and MeCN, and dried in air to give
3.3.3.5. 4-Hydroxy-6-(2-thiazolyl)pyrimidine-2-amine
31. Guanidine carbonate (3.48 g, 19.32 mmol) was suspended in
EtOH (100 mL) and toluene (20 mL) and 50 mL of the solvent was
distilled off using a Dean and Stark apparatus. The suspension
was cooled to 40 °C, treated with a solution of ethyl b-oxo-2-thia-
zolepropionate (7.7 g, 38.65 mmol) in EtOH (20 mL), refluxed for
40 h, cooled, treated with water (50 mL) and refluxed for 30 min.
The suspension was cooled to 0 °C, treated with a solution of concd
HCl (4 mL) in water (40 mL), stirred at 0 °C for 30 min and the
resulting precipitate filtered, washed with water (2 ꢀ 25 mL) and
MeCN (2 ꢀ 25 mL) and air dried to give 31 (2.7 g, 36%) as a yellow
2-amino-6-(2-furyl)pyrimidine-4-carbonitrile (7.1 g, 77%) as
a
brown solid; mp 193–194 °C; NMR dH (400 MHz, DMSO) 6.74
(1H, q, J 1.6 Hz), 7.32 (2H, br s), 7.39 (1H, d, J 3.6 Hz), 7.43 (1H,
s), 7.98 (1H, d, J 1.2 Hz); m/z 187 (M+H)+.
A suspension of 2-amino-6-(2-furyl)pyrimidine-4-carbonitrile
(7.06 g, 37.9 mmol) in water (30 mL) was treated carefully with
concentrated sulfuric acid (30 mL), stirred at 100 °C for 2 h, al-
lowed to cool to room temperature and poured onto a mixture of
ice (150 g) and water (150 mL). After standing for 1 h the crude
product was filtered off, washed with water and MeCN, and dried
solid; IR m
max (DR)/cmꢁ1 3188 br, 1664, 1609, 1460, 1437, 1376 and
1245; NMR dH (400 MHz, DMSO) 6.27 (1H, s), 6.79 (2H, br s), 7.90
in air to give 15 (7.02 g, 90%) as
a brown solid; NMR dH
(1H, d, J 3.2 Hz) and 7.98 (1H, d, J 3.2 Hz).
(400 MHz, DMSO) 6.71 (1H, dd, J 1.6, 3.6 Hz), 7.04 (2H, br s), 7.30
(1H, d, J 3.6 Hz), 7.36 (1H, s), 7.94 (1H, d, J 1.2 Hz).
The following compound was also prepared using the above
methodology.
3.3.3.6. 4-Chloro-6-(2-thiazolyl)pyrimidine-2-amine 33. A sus-
pension of the 4-hydroxy-6-(2-thiazolyl)pyrimidine-2-amine 31
(2.64 g, 13.6 mmol) in POCl3 (30 mL) was heated at 120 °C for
3 h, cooled and concentrated in vacuo. The resulting brown solid
was added to ice/water (200 g), basified with NH4OH (8 mL), fil-
tered and purified by chromatography [SiO2; EtOAc–isohexane
(2:3–1:0)] to give 33 (1.73 g, 60%) as a pale yellow solid; NMR dH
(400 MHz, DMSO) 7.22 (1H, s), 7.40 (2H, br s), 8.01 (1H, d, J
3.2 Hz) and 8.07 (1H, d, J 3.2 Hz); m/z 213, 215 (M+H)+.
3.3.2.15. 2-Amino-6-(5-methyl-2-furyl)-pyrimidine-4-carbox-
ylic acid 24. Yield = 91%, dH (400 MHz, DMSO); 2.38 (3H, s), 6.34
(1H, br d), 6.97 (2H, br s), 7.21 (1H, d, J 3.0 Hz), 7.30 (1H, s); m/z
241 (M+H)+.
This derivative was treated in a similar manner to the prepara-
tion of 21 and 22 above to give:
3.3.3. General method for amide couplings
A mixture of the appropriate acid (1.0 mmol), the desired amine
(1.0 mmol), polymer supported carbodiimide (Argonaut Technolo-
gies, loading 1.38 mmol/g, 1.10 g, 1.5 mmol) and 1-hydroxybenzo-
triazole hydrate (203 mg, 1.5 mmol) in DMF (5 mL) was stirred at
room temperature for 24 h. The mixture was filtered through a
pad of Celite, washing through with EtOAc. The filtrate was washed
successively with H2O (10 mL), 2 M Na2CO3 (2 ꢀ 10 mL) and H2O
(10 mL), dried (MgSO4) and concentrated in vacuo. The resulting
oil was dissolved in MeOH (1.0 mL), added dropwise with stirring
to H2O (2 mL) and the resulting precipitate filtered to give the
amide.
3.3.3.7. 2-Amino-6-(2-thiazolyl)-pyrimidine-4-carboxylic acid
35. Yield = 90%; m/z 223 (M+H)+, retention time 0.50 min (Meth-
od B).
The following compound was also prepared using the above
methodology:
3.3.3.8. 2-Amino-6-(4-methyl-2-thiazolyl)-pyrimidine-4-car-
boxylic acid 36. m/z 237 (M+H)+, retention time 0.73 min (Meth-
od B).
The following two derivatives were prepared from 35 and 36,
respectively, using the general amide coupling method outlined
above.
Prepared using this methodology were:
3.3.3.1. N-((Pyridin-2-yl)methyl)-2-amino-6-(20-furyl)-pyrimi-
dine-4-carboxamide 25. Yield = 44%; NMR dH (400 MHz, DMSO)
4.62 (2H, d, J 6.0 Hz), 6.68–6.75 (1H, m), 6.94 (2H, s), 7.26–7.33
(2H, m), 7.35 (1H, d, J 7.5 Hz), 7.43 (1H, s), 7.78 (1H, dt, J 7.5,
1.5 Hz), 7.94 (1H, s), 8.54 (1H, d, J 4.5 Hz), 8.96 (1H, t, J 6.0 Hz).
3.3.3.9. N-((3-Methyl-pyridin-2-yl)methyl)-2-amino-6-(2-thiaz-
olyl)-pyrimidine-4-carboxamide 37. Yield = 60%; NMR dH
(400 MHz, DMSO) 2.39 (3H, s), 4.48 (2H, d, J 6.5 Hz), 6.33–6.34
(1H, m), 6.82 (2H, s), 7.20 (1H, d, J 3.5 Hz), 7.28–7.33 (2H, m),
7.35 (1H, s), 7.37–7.39 (2H, m) and 8.93 (1H, t, J 6.5 Hz); m/z 344
(M+H)+, retention time 1.27 min (Method A).
3.3.3.2. N-((3-Methyl-pyridin-2-yl)methyl)-2-amino-6-(2-
furyl)-pyrimidine-4-carboxamide 26. Yield = 35%; NMR dH
(400 MHz, DMSO) 2.33 (3H, s), 4.63 (2H, d, J 5.0 Hz), 6.70–6.73
(1H, m), 7.01 (2H, s), 7.27 (1H, dd, J 7.5, 4.5 Hz), 7.31 (1H, d, J
3.5 Hz), 7.46 (1H, s), 7.64 (1H, dt, J 7.5, 1.0 Hz), 7.94–7.96 (1H,
m), 8.41 (1H, dd, J 4.5, 1.0 Hz); retention time 1.50 min (Method B).
3.3.3.10. N-((Pyridin-2-yl)methyl)-2-amino-6-(4-methyl-2-
thiazolyl)-pyrimidine-4-carboxamide 38. Yield = 14%; IR mmax
(DR)/cmꢁ1 3569, 3470, 3348, 2924, 1671, 1622, 1451, 1346,
1226, 1138, 854 and 737; NMR dH (400 MHz, DMSO) 2.34 (3H, d,
J 1.0 Hz), 2.47 (3H, d, J 1.0 Hz), 4.73 (2H, d, J 6.0 Hz), 7.16–7.17
(3H, m), 7.58 (1H, s), 7.71 (1H, s) and 9.22 (1H, t, J 6.0 Hz); m/z
347 (M+H)+.
3.3.3.3. N-((Pyridin-2-yl)methyl)-2-amino-6-(5-methyl-2-
furyl)-pyrimidine-4-carboxamide 27. Yield = 60%; NMR dH (400
MHz, DMSO) 2.39 (3H, s), 3.74 (3H, s), 4.46 (2H, d, J 6.0 Hz),
6.33–6.34 (1H, m), 6.82–6.90 (5H, m), 7.20 (1H, d, J 3.0 Hz), 7.25
(1H, t, J 8.0 Hz), 7.36 (1H, s) and 8.76 (1H, t, J 6.5 Hz); m/z 309
(M)+ retention time 1.19 min (Method A); HRMS found 308.1152.
C16H14N5O2 ([MꢁH]ꢁ) requires 308.1147.
3.3.3.11. 2-Amino-6-phenylpyrimidine-4-carboxylic acid 41.
Ethyl-2-amino-6-chloropyrimidine-4-carboxylate (0.2 g, 1.07
mmol) (prepared according to the literature method17) and phenyl
boronic acid (0.16 g, 1.3 mmol) were dissolved in THF (10 mL) and
saturated aqueous sodium bicarbonate (1.6 mL) added. Nitrogen
was bubbled through the resultant solution for 5 min then tetra-
kis(triphenylphosphine) palladium(0) added (0.04 g) and the mix-
ture refluxed under nitrogen overnight. The crude mixture was
then treated with aqueous lithium hydroxide (1 M, 1 mL) and
heated at 90 °C for 2 h. The mixture was concentrated to dryness
in vacuo and partitioned between ethyl acetate and water. The
3.3.3.4. N-((3-Methyl-pyridin-2-yl)methyl)-2-amino-6-(50-methyl-
20-furyl)-pyrimidine-4-carboxamide 28. Yield = 24%; NMR dH (400
MHz, DMSO) 2.32 (3H, s), 2.39 (3H, s), 4.62 (2H, d, J 5.0 Hz), 6.34 (1H,
dd, J 1.0 Hz, 3.3 Hz), 6.99 (2H, br s), 7.22 (1H, d, J 3.3 Hz), 7.26 (1H, dd,
J 4.8 Hz, 7.6 Hz), 7.39 (1H, s), 7.63 (1H, dd, J 0.6 Hz, 7.6 Hz), 9.06 (1H, t,
J 5.0 Hz); m/z 324 (M+H)+, retention time 1.88 min (Method C).

6600
R. J. Gillespie et al. / Bioorg. Med. Chem. 17 (2009) 6590–6605
aqueous layer was then acidified to pH 1 with 2 N hydrochloric
acid. The resultant solids were obtained by centrifugation and
decantation of the liquors and drying overnight in vacuo to give
the acid as a white powder (0.17 g, 72%) which was used in the
next step without additional purification; m/z 216 (M+H)+; reten-
tion time 1.60 min (Method C).
This white solid was suspended in water (10 mL) and 2 N aque-
ous lithium hydroxide solution (5 mL). After 10 min, the starting
material had dissolved completely and 2 N hydrochloric acid
(5 mL) was added. A white precipitate formed which was filtered
off, rinsed with water and dried to give 56. Yield = 98%; m/z 170
(M+H)+; retention time 0.37 min (Method C).
The following intermediates were also synthesized by this
method.
The following derivatives were prepared from 56, using the pre-
viously described coupling general amide coupling method.
3.3.3.12. 2-Amino-6-(2-fluorophenyl)pyrimidine-4-carboxylic acid
3.3.3.27. N-((Pyridin-2-yl)methyl)-2-amino-6-phenyl-pyrimidine-
4-carboxamide 57. Yield = 27%; NMR dH (400 MHz, CDCl3) 4.63
(2H, d, J 6.0 Hz), 6.99 (2H, br s), 7.30 (1H, m), 7.36 (1H, d, J 7.8 Hz),
7.53 (1H, d, J 2.2 Hz), 7.54 (2H, d, J 1.7 Hz), 7.62 (1H, s), 7.79 (1H,
dt, J 1.7 Hz, 4.2 Hz), 8.13 (2H, m), 8.54 (1H, m), 9.03 (1H, t, J
6.0 Hz); m/z 306 (M+H)+, retention time 2.03 min (Method C).
42. m/z 234 (M+H)+.
3.3.3.13. 2-Amino-6-(3-fluorophenyl)pyrimidine-4-carboxylic acid
43. NMR dH (400 MHz, DMSO) 7.13 (2H, br s), 7.39 (1H, m), 7.56 (1H,
m), 7.60 (1H, s), 7.93 (1H, d, J 10.0 Hz), 7.98 (1H, d, J 8.0 Hz), 13.52 (1H,
br s).
3.3.3.28. N-((3-Methyl-pyridin-2-yl)methyl)-2-amino-6-phenyl-
pyrimidine-4-carboxamide 58. Yield = 16%; NMR dH (400 MHz,
CDCl3) 2.33 (3H, s), 4.63 (2H, d, J 5.9 Hz), 7.07 (2H, br s), 7.27
(2H, dd, J 4.8 Hz, 7.5 Hz), 7.52 (1H, d, J 1.8 Hz), 7.54 (2H, d, J
1.8 Hz), 7.65 (1H, s), 8.13 (2H, m), 8.42 (1H, d, J 3.9 Hz), 9.12 (1H,
t, J 5.9); m/z 320 (M+H)+, retention time 1.98 min (Method C).
3.3.3.14. 2-Amino-6-(2-chloropheny)pyrimidine-4-carboxylic acid
44. m/z 250 (M+H)+; retention time 1.71 min (Method C).
3.3.3.15. 2-Amino-6-(3-chlorophenyl)pyrimidine-4-carboxylic acid
45. m/z 250 (M)+; retention time 1.83 min (Method C).
3.3.3.16. 2-Amino-6-(2-methylphenyl)pyrimidine-4-carboxylic
3.3.3.29. N-((Pyridin-2-yl)methyl)-2-amino-6-(2-fluorophenyl)-
pyrimidine-4-carboxamide 59. Yield = 74%; NMR dH (400 MHz,
DMSO) 4.63 (2H, d, J 6.0 Hz), 7.03 (2H, br s), 7.30 (1H, m), 7.37 (3H,
m), 7.53 (1H, d, J 3.0 Hz), 7.58 (1H, m), 7.78 (1H, td, J 1.8 Hz, 7.7
Hz), 8.02 (1H, td, J 1.8 Hz, 7.7 Hz), 8.55 (1H, d, J 5.0 Hz), 9.01 (1H, t,
J 6.0 Hz); m/z 324 (M+H)+, retention time 1.20 min (Method A).
acid 46. m/z 230 (M+H)+; retention time 1.69 min (Method C).
3.3.3.17. 2-Amino-6-(3-methylphenyl)pyrimidine-4-carboxylic
acid 47. m/z 230 (M+H)+; retention time 1.77 min (Method C).
3.3.3.18. 2-Amino-6-(4-methylphenyl)pyrimidine-4-carboxylic
acid 48. m/z 230 (M+H)+; retention time 1.75 min (Method C).
3.3.3.30. N-((3-Methyl-pyridin-2-yl)methyl)-2-amino-6-(2-fluo-
rophenyl)pyrimidine-4-carboxamide 60. Yield = 55%; NMR dH
(400 MHz, DMSO) 9.09 (1H, t, J 5.0 Hz), 8.42 (1H, dm, J 5.0 Hz),
8.03 (1H, td, J 7.7, 1.8 Hz), 7.64 (1H, d, J 7.5 Hz), 7.59 (1H, m),
7.56 (1H, d, J 2.5 Hz), 7.37 (2H, tm, J 8.8 Hz), 7.28 (1H, dd, J 4.5,
3.0 Hz), 7.10 (2H, br s), 4.63 (2H, d, J 5.0 Hz), 2.33 (3H, s); m/z
338 (M+H)+, retention time 2.16 min (Method A).
3.3.3.19. 2-Amino-6-(2-methoxyphenyl)pyrimidine-4-carboxylic
acid 49. m/z 246 (M+H)+, retention time 1.01 min (Method A).
3.3.3.20. 2-Amino-6-(3-methoxyphenyl)pyrimidine-4-carbox-
ylic acid 50. m/z 246 (M+H)+; retention time 1.69 min (Method C).
3.3.3.21. 2-Amino-6-(4-methoxyphenyl)pyrimidine-4-carboxylic
acid 51. NMR dH (400 MHz, DMSO) 3.84 (3H, s), 6.93 (2H, br s),
7.07 (2H, d, J 9.0 Hz), 7.51 (1H, s), 8.10 (2H, d, J 8.5 Hz); m/z 246
(M+H)+.
3.3.3.31. N-((Pyridin-2-yl)methyl)-2-amino-6-(3-fluorophenyl)-
pyrimidine-4-carboxamide 61. Yield = 25%; NMR dH (400 MHz,
DMSO) 4.64 (2H, d, J 6.0 Hz), 7.02 (2H, br s), 7.30 (1H, dd, J
5.0 Hz, 7.5 Hz), 7.38 (2H, m), 7.58 (1H, td, J 6.0 Hz, 8.0 Hz), 7.65
(1H, s), 7.78 (1H, td, J 1.8 Hz, 7.6 Hz), 7.93 (1H, dm, J 10.5 Hz),
7.98 (1H, dm, J 7.5 Hz), 8.54 (1H, dm, J 5.5 Hz), 9.01 (1H, t, J
6.0 Hz); m/z 324 (M+H)+, retention time 2.25 min (Method A).
3.3.3.22. 2-Amino-6-(2-ethyl)pyrimidine-4-carboxylic acid 52. m/
z 244 (M)+; retention time 1.80 min (Method C).
3.3.3.23. 2-Amino-6-(2-ethoxyphenyl)pyrimidine-4-carboxylic
3.3.3.32. N-((3-Methyl-pyridin-2-yl)methyl)-2-amino-6-(3-fluo-
rophenyl)pyrimidine-4-carboxamide 62. Yield = 16%; NMR dH
(400 MHz, DMSO) 2.34 (3H, s), 4.64 (2H, d, J 5.0 Hz), 7.09 (2H, br
s), 7.27 (1H, dd, J 7.5, 4.5 Hz), 7.39 (1H, td, J 2.8 Hz, 8.5 Hz), 7.58
(1H, td, J 6.0 Hz, 8.0 Hz), 7.64 (1H, dm, J 7.5 Hz), 7.68 (1H, s), 7.94
(1H, dm, J 10.3 Hz), 7.99 (1H, dm, J 8.0 Hz), 8.42 (1H, dm, J
5.0 Hz), 9.09 (1H, t, J 4.8 Hz); m/z 338 (M+H)+, retention time
3.78 min (Method A).
acid 53. m/z 260 (M)+; retention time 1.72 min (Method C).
3.3.3.24. 2-Amino-6-(2-cyanophenyl)-pyrimidine-4-carboxylic
acid 54. m/z 241 (M+H)+; retention time 0.79 min (Method C).
3.3.3.25. 2-Amino-6-(3-cyanophenyl)-pyrimidine-4-carboxylic
acid 55. m/z 241 (M+H)+; retention time 1.64 min (Method C).
3.3.3.26. 2-Amino-6-methoxy-pyrimidine-4-carboxylic acid 56. 2-
Amino-6-chloro-pyrimidine-4-carboxylic acid methyl ester 40
(500 mg, 2.67 mmol) was dissolved in methanol (25 mL) under the
addition of 4 N hydrochloric acid in 1,4-dioxan (0.5 mL) and heated
to reflux for 18 h. The solvents were evaporated under reduced pres-
sure and the white residue was taken up in water. Saturated aqueous
sodium hydrogen carbonate solution was added until pH 8 was
reached and a white precipitate formed. This was filtered off, rinsed
with diethyl ether and dried. Yield = 93%; NMR dH (400 MHz, DMSO)
3.81 (3H, s), 3.85 (3H, s), 6.49 (1H, s), 7.01 (2H, br s); m/z 184 (M+H)+;
retention time 1.60 min (Method C).
3.3.3.33. N-((Pyridin-2-yl)methyl)-2-amino-6-(2-chlorophenyl)-
pyrimidine-4-carboxamide 63. Yield = 5%; NMR dH (400 MHz,
DMSO) 4.62 (2H, d, J 6.0 Hz), 7.07 (2H, br s), 7.30 (1H, qd, J
1.1 Hz, 6.0 Hz), 7.33 (1H, s), 7.36 (1H, d, J 7.8 Hz), 7.48 (2H, m),
7.62 (2H, m), 7.77 (1H, dt, J 1.8 Hz, 7.5 Hz), 8.53 (1H, ddd, J
0.8 Hz, 1.6 Hz, 5.6 Hz), 9.02 (1H, t, J 6.0 Hz); m/z 340 (M+H)+, reten-
tion time 2.03 min (Method C).
3.3.3.34. N-((3-Methyl-pyridin-2-yl)methyl)-2-amino-6-(2-chlo-
rophenyl)pyrimidine-4-carboxamide 64. Yield = 17%; NMR dH
(400 MHz, DMSO) 2.31 (3H, s), 4.64 (2H, d, J 4.9 Hz), 7.15 (2H, br

R. J. Gillespie et al. / Bioorg. Med. Chem. 17 (2009) 6590–6605
6601
s), 7.27 (1H, dd, J 4.8 Hz, 7.7 Hz), 7.35 (1H, s), 7.49 (2H, m), 7.63
(3H, m), 8.41 (1H, dd, J 1.0 Hz, 5.0 Hz), 9.10 (1H, t, J 4.9 Hz); m/z
354 (M+H)+, retention time 2.11 min (Method C).
3.3.3.43. N-((Pyridin-2-yl)methyl)-2-amino-6-(2-methoxyphenyl)-
pyrimidine-4-carboxamide 73. Yield = 68%; dH (400 MHz, DMSO);
3.86 (3H, s), 4.62 (2H, d, J 6.0 Hz), 6.84 (2H, br s), 7.07 (1H, td, J 7.5,
1.0 Hz), 7.18 (1H, d, J 8.0 Hz), 7.30 (1H, m), 7.36 (1H, d, J 8.0 Hz),
7.48 (1H, tdm, J 2.0 Hz, 7.5 Hz), 7.64 (1H, s), 7.78 (1H, td, J 2.0 Hz,
7.5 Hz), 7.83 (1H, dd, J 2.0 Hz, 7.5 Hz), 8.98 (1H, t, J 5.7 Hz),
8.54 (1H, dm, J 5.0 Hz); m/z 336 (M+H)+, retention time 1.01 min
(Method A).
3.3.3.35. N-((Pyridin-2-yl)methyl)-2-amino-6-(3-chlorophenyl)-
pyrimidine-4-carboxamide 65. Yield = 5%; NMR dH (400 MHz,
DMSO) 4.62 (2H, d, J 6.0 Hz), 7.07 (2H, br s), 7.30 (1H, qd, J
1.1 Hz, 6.0 Hz), 7.33 (1H, s), 7.36 (1H, d, J 7.8 Hz), 7.48 (2H, m),
7.62 (2H, m), 7.77 (1H, dt, J 1.8 Hz, 7.5 Hz), 8.53 (1H, ddd, J
0.8 Hz, 1.6 Hz, 5.6 Hz), 9.02 (1H, t, J 6.0 Hz); m/z 340 (M+H)+, reten-
tion time 2.03 min (Method C).
3.3.3.44. N-((3-Methyl-pyridin-2-yl)methyl)-2-amino-6-(2-
methoxyphenyl)pyrimidine-4-carboxamide 74. Yield = 72%; NMR
dH (400 MHz, DMSO) 2.33 (3H, s), 3.87 (3H, s), 4.62 (2H, d, J 5.0 Hz),
6.91 (2H, br s), 7.08 (1H, td, J 1.0 Hz, 7.5 Hz), 7.18 (1H, d, J 7.5 Hz),
7.27 (1H, dd, J 5.0 Hz, 7.5 Hz), 7.48 (1H, m), 7.64 (1H, dd, J 1.0 Hz,
7.5 Hz), 7.67 (1H, s), 7.83 (1H, dd, J 1.8 Hz, 7.8 Hz), 8.42 (1H, dd, J
1.0 Hz, 5.0 Hz), 9.06 (1H, t, J 5.0 Hz); m/z 350 (M+H)+, retention time
1.81 min (Method A).
3.3.3.36. N-((3-Methyl-pyridin-2-yl)methyl)-2-amino-6-(3-chlo-
rophenyl)pyrimidine-4-carboxamide 66. Yield = 8%; NMR dH
(400 MHz, DMSO) 2.35 (3H, s), 4.63 (2H, d, J 4.9 Hz), 7.13 (2H, br
s), 7.27 (1H, dd, J 4.9 Hz, 7.5 Hz), 7.62 (3H, m), 7.68 (1H, s), 8.09
(1H, dt, J 1.4 Hz, 7.7 Hz), 8.19 (1H, t, J 1.7 Hz), 8.41 (1H, d, J
3.7 Hz), 9.10 (1H, t, J 4.9 Hz); m/z 354 (M+H)+, retention time
2.36 min (Method C).
3.3.3.45. N-((Pyridin-2-yl)methyl)-2-amino-6-(3-methoxy-
phenyl)pyrimidine-4-carboxamide 75. Yield = 5%; NMR (400
MHz, DMSO) dH 3.84 (3H, s), 4.62 (2H, d, J 5.9 Hz), 7.00 (2H, br s),
7.12 (1H, dd, J 1.7 Hz, 7.6 Hz), 7.29 (1H, dd, J 0.6 Hz, 4.8 Hz), 7.36
(1H, d, J 7.9 Hz), 7.44 (1H, t, J 7.9 Hz), 7.61 (1H, s), 7.66 (2H, m),
7.77 (1H, dt, J 1.7 Hz, 7.6 Hz), 8.53 (1H, dd, J 0.6 Hz, 4.8 Hz),
9.03 (1H, t, 5.9 Hz); m/z 336 (M+H)+, retention time 2.07 min
(Method C).
3.3.3.37. N-((Pyridin-2-yl)methyl)-2-amino-6-(ortho-tolyl)pyri-
midine-4-carboxamide 67. Yield = 36%; NMR dH (400 MHz,
CDCl3) 2.37 (3H, s), 4.62 (2H, d, J 5.9 Hz), 6.97 (2H, br s), 7.18
(1H, s), 7.33 (5H, m), 7.42 (1H, m), 7.78 (1H, dt, J 1.8 Hz, 7.7 Hz),
8.54 (1H, m), 9.03 (1H, t, 5.9 Hz); m/z 320 (M+H)+, retention time
2.06 min (Method C).
3.3.3.38. N-((3-Methyl-pyridin-2-yl)methyl)-2-amino-6-(ortho-
tolyl)pyrimidine-4-carboxamide 68. Yield = 45%; NMR dH (400
MHz, CDCl3) 2.32 (3H, s), 2.37 (3H, s), 4.63 (2H, d, J 5.9 Hz), 7.05
(2H, br s), 7.21 (1H, s), 7.28 (2H, m), 7.32 (1H, d, J 0.7 Hz), 7.35
(1H, m), 7.43 (1H, m), 7.64 (1H, m), 8.41 (1H, dd, J 1.0 Hz,
4.8 Hz), 9.10 (1H, t, J 5.9 Hz); m/z 334 (M+H)+, retention time
2.12 min (Method C).
3.3.3.46. N-((3-Methyl-pyridin-2-yl)methyl)-2-amino-6-(3-
methoxyphenyl)pyrimidine-4-carboxamide 76. Yield = 5%; NMR
dH (400 MHz, CDCl3) 2.33 (3H, s), 3.84 (3H, s), 4.62 (2H, d, J
5.9 Hz), 7.07 (2H, br s), 7.11 (1H, dd, J 1.5 Hz, 8.1 Hz), 7.27 (1H,
dd, J 4.6 Hz, 7.5 Hz), 7.44 (1H, t, J 8.0 Hz), 7.63 (1H, s), 7.66 (2H,
m), 7.68 (1H, dt, J 1.3 Hz, 7.5 Hz), 8.41 (1H, dd, J 1.0 Hz, 4.6 Hz),
9.11 (1H, t, J 5.9 Hz); m/z 350 (M+H)+, retention time 2.03 min
(Method C).
3.3.3.39. N-((Pyridin-2-yl)methyl)-2-amino-6-(meta-tolyl)pyrimi-
dine-4-carboxamide 69. Yield = 11%; dH (400 MHz, CDCl3) 2.39
(3H, s), 4.63 (2H, d, J 5.9), 6.96 (2H, br s), 7.35 (4H, m), 7.61 (1H,
s), 7.77 (1H, dt, J 1.8 Hz, 7.7 Hz), 7.91 (1H, d, J 7.7 Hz), 7.96 (1H,
br s), 8.54 (1H, d, J 4.3 Hz), 9.02 (1H, t, J 5.9 Hz); m/z 320 (M+H)+,
retention time 2.18 min (Method C).
3.3.3.47. N-((Pyridin-2-yl)methyl)-2-amino-6-(4-methoxy-
phenyl)pyrimidine-4-carboxamide 77. Yield = 47%, NMR dH
(400 MHz, DMSO); 3.84 (3H, s), 4.63 (2H, d, J 5.5 Hz), 6.86 (2H, br
s), 7.07 (2H, d, J 9.0 Hz), 7.30 (1H, m), 7.36 (1H, d, J 7.5 Hz), 7.58
(1H, s), 7.78 (1H, m), 8.11 (2H, d, J 8.5 Hz) 8.55 (1H, br d), 8.98
(1H, br t); m/z 336 (M+H)+, LC retention time 1.40 min (Method A).
3.3.3.40. N-((3-Methyl-pyridin-2-yl)methyl)-2-amino-6-(meta-
tolyl)pyrimidine-4-carboxamide 70. Yield = 42%; NMR dH (400
MHz, CDCl3) 2.33 (3H, s), 2.40 (3H, s), 4.64 (2H, d, J 5.9 Hz), 7.05
(2H, br s), 7.27 (2H, dd, J 4.7 Hz, 7.6 Hz), 7.36 (2H, m), 7.64 (1H,
s), 7.91 (1H, d, J 7.6 Hz), 7.96 (1H, br s), 8.42 (1H, dd, J 0.9 Hz,
4.7 Hz), 9.11 (1H, t, J 5.9 Hz); m/z 334 (M+H)+, retention time
2.26 min (Method C).
3.3.3.48. N-((3-Methyl-pyridin-2-yl)methyl)-2-amino-6-(4-
methoxyphenyl)pyrimidine-4-carboxamide 78. Yield = 23%,
NMR dH (400 MHz, DMSO) 2.34 (3H, s), 3.84 (3H, s), 4.63 (2H,
d, J 5.0 Hz), 6.93 (2H, br s), 7.06 (2H, d, J 9.0 Hz), 7.27 (1H, m),
7.60 (1H, s), 7.63 (1H, br d), 8.11 (2H, d, J 9.0 Hz), 8.41 (1H, br
d), 9.07 (1H, br t); m/z 350 (M+H)+, retention time 2.57 min
(Method A).
3.3.3.41. N-((Pyridin-2-yl)methyl)-2-amino-6-(para-tolyl)pyrimi-
dine-4-carboxamide 71. Yield = 25%; NMR dH (400 MHz, CDCl3)
2.34 (3H, s), 4.63 (2H, d, J 6.0 Hz), 6.94 (2H, br s), 7.30 (4H, m),
7.59 (1H, s), 7.80 (1H, dt, J 1.9 Hz, 3.4 Hz), 8.03 (2H, d, J 7.8 Hz),
8.53 (1H, m), 9.01 (1H, t, J 6.0 Hz); m/z 320 (M+H)+, retention time
2.17 min (Method C).
3.3.3.49. N-((Pyridin-2-yl)methyl)-2-amino-6-(2-ethylphenyl)-
pyrimidine-4-carboxamide 79. Yield = 21%; NMR dH (400 MHz,
DMSO) 1.08 (3H, t, J 7.5 Hz), 2.73 (2H, q, J 7.5 Hz), 4.62 (2H, d, J
5.8 Hz), 6.96 (2H, br s), 7.15 (1H, s), 7.36 (5H, m), 7.59 (1H, m),
7.78 (1H, td, J 1.8 Hz, 7.7 Hz), 8.54 (1H, d, J 4.2 Hz), 9.01 (1H, t, J
5.8 Hz); m/z 334 (M+H)+, retention time 2.14 min (Method C).
3.3.3.42. N-((3-Methyl-pyridin-2-yl)methyl)-2-amino-6-(para-
tolyl)pyrimidine-4-carboxamide 72. Yield = 18%; NMR dH (400
MHz, CDCl3) 2.33 (3H, s), 2.38 (3H, s), 4.62 (2H, d, J 6.0 Hz), 7.02
(2H, br s), 7.27 (1H, dd, J 4.8 Hz, 7.4 Hz), 7.32 (2H, d, J 8.2 Hz),
7.62 (1H, s), 7.64 (1H br s), 8.04 (2H, d, J 8.2 Hz), 8.41 (1H, d, J
3.8 Hz), 9.11 (1H, t, J 6.0 Hz); m/z 334 (M+H)+, retention time
2.25 min (Method C).
3.3.3.50. N-((3-Methyl-pyridin-2-yl)methyl)-2-amino-6-(2-eth-
ylphenyl)pyrimidine-4-carboxamide 80. Yield = 27%; NMR dH
(400 MHz, DMSO) 1.07 (3H, t, J 7.4 Hz), 2.33 (3H, s), 2.72 (2H, q, J
7.4 Hz), 4.62 (2H, d, J 5.0 Hz), 7.03 (2H, br s), 7.17 (1H, s), 7.35
(4H, m), 7.64 (1H, dd, J 0.8 Hz, 7.5 Hz), 8.41 (1H, dd, J 0.8 Hz,
3.7 Hz), 9.09 (1H, t, J 5.0 Hz); m/z 348 (M+H)+, retention time
2.25 min (Method C).

6602
R. J. Gillespie et al. / Bioorg. Med. Chem. 17 (2009) 6590–6605
3.3.3.51. N-((Pyridin-2-yl)methyl)-2-amino-6-(2-ethoxy-
phenyl)pyrimidine-4-carboxamide 81. Yield = 22%; NMR dH
(400 MHz, DMSO) 1.35 (3H, t, J 7.0 Hz), 3.32 (2H, s), 4.14 ((2H, q,
J = 7.0 Hz), 4.62 (2H, d, J = 5.9 Hz), 6.84 (2H, br s), 7.06 (1H, t, J
7.4 Hz), 7.15 (1H, d, J 8.3 Hz), 7.29 (1H, dd, J 5.2 Hz, 7.4 Hz), 7.35
(1H, d, J 7.8 Hz), 7.45 (1H, td, J 1.7 Hz, 7.8 Hz), 7.78 (1H, td, J
1.7 Hz, 7.8 Hz), 7.81 (1H, s), 7.88 (1H, dd, J 1.7 Hz, 7.8 Hz), 8.54
(1H, d, J 4.7 Hz), 8.97 (1H, t, J 5.9 Hz); m/z 350 (M+H)+, retention
time 2.10 min (Method C).
dissolved in 2.5 M aqueous sodium hydroxide solution (20 mL).
Guanidine carbonate (4.26 g, 23.64 mmol) was added to the solu-
tion which was then heated to 100 °C for 18 h. The reaction mix-
ture was cooled to room temperature and acidified to pH 2 with
2 M hydrochloric acid. The white precipitate was then filtered off
and dried, then suspended in methanol (100 mL). Concentrated
sulfuric acid (98%, 15 mL) was slowly added, upon which the re-
agent dissolved completely. The solution was heated to reflux for
24 h, then cooled to room temperature and carefully neutralized
with aqueous ammonia (Sp. Gr. 1.18, 40 mL). Methanol was re-
moved under reduced pressure and the residue filtered off and
dried.
3.3.3.52. N-((3-Methyl-pyridin-2-yl)methyl)-2-amino-6-(2-eth-
oxyphenyl)pyrimidine-4-carboxamide 82. Yield = 25%; NMR dH
(400 MHz, DMSO) 1.36 (3H, t, J 6.8 Hz), 2.32 (3H, s), 4.15 (2H, q, J
6.8 Hz), 4.63 (2H, d, J 4.9 Hz), 6.91 (2H, br s), 7.06 (1H, td, J
0.9 Hz, 7.8 Hz), 7.15 (1H, d, J 8.3 Hz), 7.26 (1H, dd, J 4.9 Hz,
7.5 Hz), 7.45 (2H, m), 7.26 (2H, m), 7.84 (1H, s), 7.90 (1H, dd, J
1.8 Hz, 6.7 Hz), 9.01 (1H, t, J 4.9 Hz); m/z 364 (M+H)+, retention
time 2.18 min (Method C).
Yield = 65%; dH (400 MHz, DMSO) 1.83 (s, 3H), 3.77 (s, 3H), 6.52
(br s, 2H), 11.13 (br s, 1H); m/z 184 (M+H)+, retention time
0.74 min (Method C).
This crude solid was suspended in phosphorous oxychloride
(20 mL) and heated to reflux for 2 h. The reaction was cooled to
room temperature, evaporated in vacuo and the residue was
poured onto saturated aqueous solution of sodium hydrogen car-
bonate (90 mL). The product was extracted into 2-butanone
(2 ꢀ 50 mL) and adsorbed onto sorbent granules. Purification was
carried out by flash chromatography on 20 g silica gel, eluting with
hexane–ethyl acetate (1:1) to give 89 as a white solid.
Yield = 49%; dH (400 MHz, CDCl3) 2.13 (3H, s), 3.86 (3H, s), 7.19
(2H, br s); m/z 202 (M+H)+, retention time 1.56 min (Method C).
The following intermediate was also synthesized by this
method.
3.3.3.53. N-((Pyridin-2-yl)methyl)-2-amino-6-(2-cyanophenyl)-
pyrimidine-4-carboxamide 83. Yield = 2%; NMR dH (400 MHz,
MeOD) 4.72 (2H, d, J 0.7 Hz), 7.33 (1H, dd, J 0.5 Hz, 3.9 Hz), 7.43
(1H, d, J 7.8 Hz), 7.63 (1H, s), 7.67 (1H, td, J 1.2 Hz, 6.7 Hz), 7.80
(2H, m), 7.91 (2H, m), 8.51 (1H, dd, J 0.7 Hz, 4.0 Hz); m/z 331
(M+H)+, retention time 1.87 min (Method C).
3.3.3.54. N-((3-Methyl-pyridin-2-yl)methyl)-2-amino-6-(2-cya-
nophenyl)-pyrimidine-4-carboxamide 84. Yield = 4%; NMR dH
(400 MHz, MeOD) 3.29 (3H, t, J 1.6 Hz), 4.71 (2H, s), 7.24 (1H, dd,
J 4.8 Hz, 6.6 Hz), 7.63 (1H, s), 7.65 (2H, m), 7.78 (1H, td, J 1.6 Hz,
7.8 Hz), 7.90 (2H, m), 8.37 (1H, d, J 4.8 Hz); m/z 344 (M+H)+, reten-
tion time 1.91 min (Method C).
3.3.3.60. Methyl-2-Amino-5-ethyl-6-hydroxy-pyrimidine-4-car-
boxylate 90. Yield = 74%; dH (400 MHz, CDCl3) 0.94 (3H, t, J
7.4 Hz), 2.23 (2H, q, J 7.3 Hz), 3.77 (3H, s), 6.55 (2H, br s), 11.10
(1H, br s); m/z 216 (M+H)+, retention time 2.01 min (Method C).
Using the methods described above, these intermediates were
converted to:
3.3.3.55. N-((Pyridin-2-yl)methyl)-2-amino-6-(30-cyanophenyl)-
pyrimidine-4-carboxamide 85. Yield = 16%; NMR dH (400 MHz,
CDCl3) 4.63 (2H, d, J 5.9 Hz), 7.22 (2H, br s), 7.29 (1H, dd, J
1.1 Hz, 7.5 Hz), 7.34 (1H, d, J 8.2 Hz), 7.74 (1H, s), 7.77 (2H, m),
8.18 (1H, dt, J 1.4 Hz, 6.5 Hz), 8.45 (1H, m), 8.54 (1H, m), 8.58
(1H, m), 9.05 (1H, t, 5.9 Hz); m/z 331 (M+H)+, retention time
2.01 min (Method C).
3.3.3.61. N-((Pyridin-2-yl)methyl)-2-amino-5-methyl-6-(5-
methyl-2-furyl)-pyrimidine-4-carboxamide 91. Yield = 30%; dH
(400 MHz, DMSO) 2.30 (3H, s), 2.37 (3H, s), 4.51 (2H, d, J 6.1 Hz),
6.33 (1H, dd, J 0.9 Hz, 2.4 Hz), 6.62 (2H, br s), 7.04 (1H, d, J
3.3 Hz), 7.27 (1H, m), 7.37 (1H, d, J 7.8 Hz), 7.77 (1H, m), 8.51
(1H, m), 9.06 (1H, br t, 1H, J 6.1 Hz); m/z 324 (M+H)+, retention
time 1.76 min (Method C).
3.3.3.56. N-((3-Methyl-pyridin-2-yl)methyl)-2-amino-6-(30-cya-
nophenyl)-pyrimidine-4-carboxamide 86. Yield = 24%; NMR dH
(400 MHz, CDCl3) 2.33 (3H, s), 4.64 (2H, d, J 5.9 Hz), 7.19 (2H, br
s), 7.27 (1H, dd, J 4.9 Hz, 7.5 Hz), 7.64 (1H, d, J 7.5 Hz), 7.74 (1H,
t, J 7.8 Hz), 7.76 (1H, s), 8.01 (1H, d, J 7.8 Hz), 8.41 (1H, d, J
3.9 Hz), 8.47 (1H, d, J 8.1 Hz), 8.59 (1H, br s), 9.13 (1H, t, J
5.9 Hz); m/z 345 (M+H)+, retention time 2.07 min (Method C).
3.3.3.62. N-((3-Methyl-pyridin-2-yl)methyl)-2-amino-5-
methyl-6-(50-methyl-20-furyl)-pyrimidine-4-carboxamide
92. Yield = 36%; dH (400 MHz, DMSO) 2.34 (3H, s), 2.35 (3H, s),
2.37 (3H, s), 4.54 (2H, d, J 5.2 Hz), 6.32 (1H, dd, J 1.0 Hz, 2.4 Hz),
6.61 (2H, br s), 7.04 (1H, d, J 3.4 Hz), 7.22 (1H, dd, J 2.7 Hz,
4.8 Hz), 7.60 (1H, m), 8.36 (1H, dd, J 1.0 Hz, 3.7 Hz), 8.85 (1H, br
t, J 5.2 Hz); m/z 338 (M+H)+, retention time 1.78 min (Method C).
3.3.3.57. N-((Pyridin-2-yl)methyl)-2-amino-6-methoxy-pyrimi-
dine-4-carboxamide 87. Yield = 55%; NMR dH (400 MHz, DMSO)
3.86 (3H, s), 4.57 (2H, d, J 5.9 Hz), 6.52 (1H, s), 6.84 (2H, br s),
7.28 (2H, m), 7.34 (1H, br s), 7.75 (1H, dt, J 7.7 Hz), 8.52 (1H, m),
8.84 (1H, t, J 5.9 Hz); m/z 260 (M+H)+, retention time 1.53 min
(Method C).
3.3.3.63. N-((Pyridin-2-yl)methyl)-2-amino-5-ethyl-6-(5-
methyl-2-furyl)-pyrimidine-4-carboxamide 93. Yield = 16%; dH
(400 MHz, DMSO) 1.09 (3H, t, J 7.5 Hz), 2.4 (3H, s), 2.76 (2H, q, J
7.3 Hz), 4.51 (2H, d, J 6.1 Hz), 6.32 (1H, dd, J 1.0 Hz, 2.4 Hz), 6.62
(2H, br s), 7.03 (1H, d, J 3.3 Hz), 7.27 (1H, m), 7.37 (1H, d, J
7.8 Hz), 7.77 (1H, m), 8.51 (1H, m), 9.06 (1H, br t, J 6.1 Hz); m/z
338 (M+H)+, retention time 1.91 min (Method C).
3.3.3.58. N-((3-Methyl-pyridin-2-yl)methyl)-2-amino-6-meth-
oxy-pyrimidine-4-carboxamide 88. Yield = 16%; NMR dH (400
MHz, CDCl3) 1.09 (3H, t, J 7.5, 7.2 Hz), 2.4 (3H, s), 2.76 (2H, q, J
7.3 Hz), 4.51 (2H, d, J 6.1 Hz), 6.32 (1H, dd, J 1.0, 2.4 Hz), 6.62
(2H, br s), 7.03 (1H, d, J 3.3 Hz), 7.27 (1H, m), 7.37 (1H, d, J
7.8 Hz), 7.77 (1H, m), 8.51 (1H, m), 9.06 (1H, br t, J 6.1 Hz); m/z
338 (M+H)+, retention time 1.91 min (Method C).
3.3.3.64. N-((3-Methyl-pyridin-2-yl)methyl)-2-amino-5-ethyl-6-
(5-methyl-2-furyl)-pyrimidine-4-carboxamide 94. Yield = 23%;
dH (400 MHz, DMSO) 1.10 (3H, t, J 7.3 Hz), 2.35 (3H, s), 2.37 (3H,
s), 2.83 (2H, q, J 7.0 Hz), 4.54 (2H, d, J 5.3 Hz), 6.31 (1H, dd, J
0.9 Hz, 2.4 Hz), 6.61 (2H, br s), 7.02 (1H, d, J 3.3 Hz), 7.22 (1H, dd,
J 2.7 Hz, 4.8 Hz), 7.60 (1H, d, J 7.0 Hz), 8.35 (1H, m), 8.83 (1H, br
t, J 5.3 Hz); m/z 352 (M+H)+, retention time 1.96 min (Method C).
3.3.3.59. Methyl-2-amino-6-hydroxy-5-methyl-pyrimidine-4-
carboxylate 89. Diethyl oxalopropionate (9.56 g, 47.3 mmol) was

R. J. Gillespie et al. / Bioorg. Med. Chem. 17 (2009) 6590–6605
6603
3.3.3.65. 6-(5-Methyl-2-furyl)pyrimidine-4-carboxylic
acid
ane and water. The organic phase was separated and the aqueous
phase extracted with dichloromethane (2 ꢀ 50 mL). The combined
organic extracts were dried (MgSO4) and evaporated. The residue
was subjected to silica-gel column chromatography [hexane then
hexane–EtOAc (9:1) as eluent]. The eluted material, obtained as a
pale-yellow solid (5.08 g, 74%), was identified as 2,4-dichloro-6-
(5-methylfuran-2-yl)-pyrimidine; NMR dH (400 MHz, CDCl3) 2.42
(3H, s), 6.22–6.23 (1H, m), 7.30–7.31 (1H, m) and 7.47 (1H, s).
To a solution of 2,4-dichloro-6-(5-methylfuran-2-yl)-pyrimi-
dine (2) (0.70 g, 3.07 mmol) in methanol (5 mL) was added a 2 N
solution of methylamine in ethanol (2 mL, 4 mmol). The reaction
mixture was heated at 80 °C for 30 min, cooled and then evapo-
rated. The residual material was subjected to silica-gel column
chromatography [hexane then hexane–EtOAc (0–10%) as eluent]
to give 105 as a white solid (0.17 g, 22%); NMR dH (400 MHz,
CD3OD) 2.38 (3H, s), 2.93 (3H, s), 6.22–6.23 (1H, m), 6.83 (1H, s)
and 7.12–7.13 (1H, m); MS (ES+) m/z (M+H)+ 224 (100).
98. A solution of 4,6-dichloropyrimidine (9.78 g, 50.0 mmol) in
DMSO (200 mL) was treated with sodium cyanide (14.7 g,
300 mmol) and 1,4-diazabicyclo[2.2.2]octane (DABCO) (0.56 g,
5.0 mmol). The suspension was stirred for 4 days, and more DABCO
(5.04 g, 45 mmol) and DMSO (100 mL) were added. The suspension
was stirred for a further 2 days, poured onto a mixture of ice
(750 g) and water (750 mL), the crude product was filtered off,
washed with water and MeCN, and dried in air to give the carboni-
trile, which was suspended in water (30 mL) was treated carefully
with concentrated sulfuric acid (30 mL), stirred at 100 °C for 2 h, al-
lowed to cool to room temperature and poured onto a mixture of
ice (150 g) and water (150 mL). After standing for 1 h the crude
product was filtered off, washed with water and MeCN, and dried
in air to give the pyrimidine acid (7.02 g, 90%) as a brown solid.
Yield = 98%; NMR dH (400 MHz, DMSO) 2.43 (3H, s), 6.37 (1H, d, J
2.5 Hz), 7.40 (1H, d, J 2.5 Hz), 8.04 (1H, s), 9.16 (1H, s); m/z 205
(M+H)+, retention time 1.55 min (Method C).
The following derivatives were also made using the method de-
tailed above.
3.3.3.72. 2-Methylamino-6-(5-methylfuran-2-yl)-pyrimidine-4-
carboxylic acid 107. A solution of [4-chloro-6-(5-methylfuran-2-
yl)-pyrimidin-2-yl]-methylamine 105 (0.17 g, 0.76 mmol), sodium
cyanide (0.22 g, 4.56 mmol) and 1,4-diazabicyclo[2.2.2]octane
(0.09 g, 0.76 mmol) in 1-methyl-2-pyrrolidinone (6 mL) was
heated at 80 °C for 1.5 h. The reaction mixture was cooled, poured
onto an ice-water mixture and the resulting precipitate was fil-
tered. The residue was washed with dichloromethane–methanol,
and the resulting solution was evaporated to a brown solid. The
material was subjected to silica-gel column chromatography [hex-
ane–EtOAc (0–10%) as eluent] to give the nitrile as a white solid
(0.073 g, 45%), which was contaminated with 1-methyl-2-pyrrolid-
inone; NMR dH (400 MHz, CD3OD) (inter alia) 2.40 (3H, s), 2.93 (3H,
s), 6.26–6.27 (1H, m), 7.16 (1H, s) and 7.21–7.22 (1H, m); m/z
(M+H)+ 215.
A solution of 2-methylamino-6-(5-methylfuran-2-yl)-pyrimi-
dine-4-carbonitrile (0.073 g, 0.34 mmol) in water and (4 mL) and
concentrated sulfuric acid (4 mL) was heated at reflux for 4 h.
The reaction mixture was then cooled and poured onto ice but
did not solidify. The material could not be extracted into ethyl ace-
tate, owing to its zwitterionic nature. The solution was introduced
onto an acidic ion-exchange column (IsoluteÒ Flash SCX-2). The
column was eluted with dichloromethane–methanol, followed by
3.3.3.66. 2-Methyl-6-(5-methyl-2-furyl)pyrimidine-4-carbox-
ylic acid 99. Yield = 70%; NMR dH (400 MHz, DMSO) 2.68 (3H, s),
3.18 (3H, s), 6.42 (1H, d, J 3.3 Hz), 7.44 (1H, d, J 3.3 Hz) and 7.94
(1H, s).
3.3.3.67. 2-Isopropyl-6-(5-methyl-2-furyl)pyrimidine-4-carbox-
ylic acid 100. Yield = 93%; NMR dH (400 MHz, CDCl3) 1.39 (6H, d, J
6.9 Hz), 2.45 (3H, s), 3.28 (1H, sept, J 6.9 Hz), 6.23 (1H, d, J 3.3 Hz),
7.33 (1H, d, J 3.4 Hz) and 8.14 (1H, s); m/z 247 (M+H)+, retention
time 2.14 min (Method C).
The desired amines were synthesized from the above deriva-
tives and the appropriate amine, using the general amide coupling
method, to give:
3.3.3.68. 6-(5-Methyl-2-furyl)-N-(2-pyridylmethyl)pyrimidine-
4-carboxamide 101. Yield = 65%; NMR dH (400 MHz, CDCl3) 2.38
(3H, s), 4.75 (2H, d, J 5.5 Hz), 6.16 (1H, d, J 3.4 Hz), 7.20 - 7.16
(2H, m), 7.28 (1H, d, J 7.8 Hz), 7.64 (1H, td, J 7.7, 1.8 Hz), 8.26
(1H, s), 8.57 - 8.55 (1H, m), 8.95 (1H, br s) and 9.07 (1H, s); m/z
295 (M+H)+, retention time 2.04 min (Method C).
1 N ammonia–methanol, yielding XX as
a pale brown solid
3.3.3.69. N-(2-Pyridylmethyl)-2-Methyl-6-(5-methyl-2-furyl)-
pyrimidine-4-carboxamide 102. Yield = 35%; NMR dH (400 MHz,
CDCl3) 2.37 (3H, s), 2.70 (3H, s), 4.75 (2H, d, J 5.8 Hz), 6.14 (1H, d, J
3.4 Hz), 7.18–7.16 (2H, m), 7.31 (1H, d, J 7.8 Hz), 7.64 (1H, td, J 7.7,
1.8 Hz), 8.08 (1H, s), 8.57 - 8.55 (1H, m) and 8.88 (1H, br s); m/z 309
(M+H)+, retention time 2.15 min (Method C).
(0.08 g, quant.); NMR dH (400 MHz, CD3OD) 2.39 (3H, s), 2.99 (3H,
s), 6.21–6.22 (1H, m), 7.11–7.12 (1H, m) and 7.33 (1H, s); m/z
(M+H)+ 234.
3.3.3.73. N-(Pyridin-2-ylmethyl)-2-Methylamino-6-(5-methyl-
furan-2-yl)-pyrimidine-4-carboxamide 109. A mixture of 2-meth-
ylamino-6-(5-methylfuran-2-yl)-pyrimidine-4-carboxylic acid 107
(0.080 g, 0.34 mmol), 2-(aminomethyl)pyridine (0.074 g, 0.68
mmol), polymer supported carbodiimide (0.86 g, 1.04 mmol), 1-
hydroxybenzotriazole (0.07 g, 0.52 mmol) and N,N0-diisopropyl-
ethylamine (0.09 mL, 0.52 mmol) in dimethyl formamide (5 mL)
was stirred at ambient temperature. After 16 h, the reaction mix-
ture was filtered through Celite, and the filtrate was partitioned be-
tween water and ethyl acetate. The organic phase was separated,
and the aqueous phase was twice re-extracted with ethyl acetate.
The combined organic extracts were dried (MgSO4) and evapo-
rated. The resulting syrup was subjected to silica-gel column chro-
matography [hexane–EtOAc (0–100%) gradient] to give a yellow
gum, which was subjected to preparative LC–MS, giving XX as an
off-white solid (0.01 g, 9%); NMR dH (400 MHz, CD3OD) 2.40 (3H,
s), 3.02 (3H, s), 4.71 (2H, s), 6.23–6.24 (1H, m), 7.16 (1H, d, J
3.5 Hz), 7.32 (1H, dd, J 7.5 and 5.5 Hz), 7.42 (1H, d, J 7.5 Hz), 7.46
(1H, s), 7.78–7.83 (1H, m) and 8.50 (1H, d, J 4.5 Hz); MS (ES+) m/
z (M+H)+ 324.
3.3.3.70. N-(2-Pyridylmethyl)-2-Isopropyl-6-(5-methyl-2-furyl)-
pyrimidine-4-carboxamide 103. Yield = 32%; NMR dH (400 MHz,
CDCl3) 1.40 (6H, d, J 6.9 Hz), 2.44 (3H, s), 3.27 (1H, sept, J 6.9 Hz),
4.84 (2H, d, J 5.8 Hz), 6.21 (1H, d, J 3.3 Hz), 7.26–7.24 (2H, m),
7.40 (1H, d, J 7.8 Hz), 7.72 (1H, td, J 7.7, 1.6 Hz), 8.16 (1H, s), 8.63
(1H, d, J 4.3 Hz) and 9.05 (1H,br s); m/z 337 (M+H)+, retention time
2.63 min (Method C).
3.3.3.71. [4-Chloro-6-(5-methylfuran-2-yl)-pyrimidin-2-yl]-
methylamine 105. A mixture of 2,4,6-trichloropyrimide (104)
(5.50 g, 30 mmol), 5-methylfuran-2-boronic acid, methyl ester
(4.91 g, 30 mmol), saturated aqueous sodium hydrogencarbonate
(30 mL) and tetrahydrofuran (30 mL) was degassed with a stream
of nitrogen for 10 min. Palladium(0) tetrakis(triphenylphosphine)
(1.73 g, 1.5 mmol) was then added, and the reaction mixture was
heated at reflux under a nitrogen atmosphere for 18 h. The reaction
mixture was then cooled and partitioned between dichlorometh-

6604
R. J. Gillespie et al. / Bioorg. Med. Chem. 17 (2009) 6590–6605
3.3.3.74. [4-Chloro-6-(5-methylfuran-2-yl)pyrimidin-2-yl]-
dimethylamine 106. mixture of (4,6-dichloropyrimidin-2-
Derivatives 111–123 were prepared from the 2-amino-(5-
methyl-2-furyl)pyrimidine-4-carboxylic acid 24 using the general
amide synthesis method outlined above.
A
yl)dimethylamine (3.32 g, 17.3 mmol), 5-methylfuran-2-boronic
acid methyl ester (2.66 g, 17.3 mmol), saturated aqueous sodium
hydrogencarbonate (15 mL) and tetrahydrofuran (15 mL) was de-
gassed with a stream of nitrogen for 10 min. Palladium(0) tetra-
kis(triphenylphosphine) (1.00 g, 0.87 mmol) was then added, and
the reaction mixture was heated at reflux under a nitrogen atmo-
sphere for 18 h. The reaction mixture was then cooled and parti-
tioned between dichloromethane and water. The organic phase
was separated and the aqueous phase twice extracted with dichlo-
romethane. The combined organic extracts were dried (Na2SO4)
and evaporated. The residue was subjected to silica-gel column
chromatography [hexane then hexane–EtOAc (9:1) as eluent], giv-
ing 106 as a pale-yellow solid (1.46 g, 36%); NMR dH (400 MHz,
CD3OD) 2.38 (3H, s), 3.17 (6H, s), 6.20–6.22 (1H, m), 6.76 (1H, s)
and 7.10–7.11 (1H, m); m/z (M+H)+ 238 (100%).
3.3.3.77. N-(6-Methyl-pyridin-2-ylmethyl)-2-amino-(5-methyl-
2-furyl)pyrimidine-4-carboxamide 111. Yield = 44%; NMR dH
(400 MHz, CDCl3) 2.39 (3H, s), 2.48 (3H, s), 4.55 (2H, d, J 6.0 Hz),
6.34–6.35 (1H, m), 6.88 (2H, s), 7.14 (2H, t, J 8.0 Hz), 7.21 (1H, d,
J 23.0 Hz), 7.37 (1H, s), 7.65 (1H, t, J 7.5 Hz), 8.92 (1H, t, J 6.0 Hz);
m/z 324 (M+H)+; LC retention time 1.86 min. (Method C); HRMS
found 346.1283. C17H17N5O4Na ([M+Na]+) requires 346.1279.
3.3.3.78. N-(3,6-Dimethyl-pyridin-2-ylmethyl)-2-amino-(5-methyl-
2-furyl)pyrimidine-4-carboxamide 112. Yield = 11%; NMR dH
(400 MHz, DMSO) 2.26 (3H, s), 2.39 (3H, s), 2.50 (3H, s), 4.54
(2H, d, J 4.8 Hz), 6.98 (2H, br s), 7.11 (1H, d, J 7.7 Hz), 7.21 (1H, d,
J 3.3 Hz), 7.39 (1H, s), 7.51 (1H, d, J 7.7 Hz), 9.11 (1H, t, J 4.8 Hz);
m/z 338 (M+H)+, retention time 1.77 min (Method C).
3.3.3.75. 2-Dimethylamino-6(5-methylfuran-2-yl)-pyrimidine-
4-carboxylic acid, lithium salt 108. A solution of [4-chloro-6-(5-
methylfuran-2-yl)pyrimidin-2-yl]dimethylamine 106 (1.44 g,
6.06 mmol), sodium cyanide (1.78 g, 36.35 mmol) and 1,4-diazabi-
cyclo[2.2.2]octane (0.68 g, 6.06 mmol) in dimethyl sulfoxide
(50 mL) was stirred at ambient temperature for 3 days. The reac-
tion mixture was poured onto an ice-water mixture and the result-
ing precipitate was filtered; the residue was obtained a brown
solid (1.40 g). The material was subjected to silica-gel column
chromatography [hexane–EtOAc (10:1) as eluent], yielding 2-
dimethylamino-6-(5-methylfuran-2-yl)-pyrimidine-4-carbonitrile
as a yellow solid (0.68 g, 49%); NMR dH (400 MHz, CD3OD) 2.40
(3H, s), 3.20 (6H, s), 6.25–6.26 (1H, m), 7.11 (1H, s) and 7.21–
7.22 (1H, m); m/z (M+H)+ 229.
2-Dimethylamino-6-(5-methylfuran-2-yl)-pyrimidine-4-carbo-
nitrile (0.68 g, 2.98 mmol) in 6 M hydrochloric acid (40 mL) and
tetrahydrofuran (10 mL) were heated at reflux for 6 h. The reaction
mixture was evaporated and the residue subjected to ion-exchange
column chromatography (IsoluteÒ Flash SCX-2). The column was
eluted with dichloromethane–methanol, followed by 1 N ammo-
nia–methanol. The eluted material (0.42 g) was identified as a mix-
ture of the desired product (108) and its methyl ester. This material
was diluted with methanol (15 mL) and water (15 mL) and treated
with lithium hydroxide (0.072 g, 1.81 mmol). The reaction mixture
was stirred at ambient temperature for 1 h. The resulting precipi-
tate was filtered, and the residue dried in vacuo to afford 108 as
a white solid (0.15 g, 30%); NMR dH (400 MHz, CD3OD) 2.38 (3H,
s), 3.23 (6H, s), 6.19–6.20 (1H, m), 7.08–7.09 (1H, m) and 7.31
(1H, s); m/z (M+H)+ 248.
3.3.3.79. N-(4,6-Dimethyl-pyridin-2-ylmethyl)-2-amino-(5-meth-
yl-2-furyl)pyrimidine-4-carboxamide 113. Yield = 22%; NMR dH
(400 MHz, DMSO) 2.25 (3H, s), 2.39 (3H, s), 2.43 (3H, s), 4.51
(2H, d, J 6 Hz), 6.35 (1H, dd, J 3 and 1 Hz), 6.93 (2H, br s), 6.95
(1H, s), 6.35 (1H, s), 7.22 (1H, d, J 3 Hz), 7.37 (1H, s) and 8.91
(1H, t, J 6 Hz); LC retention time 1.64 min (Method C); m/z
(M+H)+ 338.
3.3.3.80. N-(5,6-Dimethyl-pyridin-2-ylmethyl)-2-amino-(5-meth-
yl-2-furyl)pyrimidine-4-carboxamide 114. Yield = 44%, NMR dH
(400 MHz, DMSO); 2.22 (3H, s), 2.39 (3H, s), 2.43 (3H, s), 4.52
(2H, d, J 6.0 Hz), 6.34 (1H, br d), 6.88 (2H, br s), 7.06 (1H, d, J
8.0 Hz), 7.21 (1H, br d), 7.36 (1H, s), 7.48 (1H, d, J 7.5 Hz), 8.87
(1H, br t); m/z 338 (M+H)+, LC retention time 4.57 min (Method E).
3.3.3.81. N-(1-Methyl-1H-pyrrol-2-ylmethyl)-2-amino-(5-methyl-
2-furyl)pyrimidine-4-carboxamide 115. Yield = 52%; NMR dH
(400 MHz, DMSO) 2.39 (3H, s), 4.50 (2H, d, J 6.0 Hz), 6.33–6.34
(1H, m), 6.82 (2H, s), 7.06–7.17 (3H, m), 7.21 (1H, d, J 3.5 Hz),
7.35 (1H, s), 7.35–7.41 (1H, m) and 8.91 (1H, t, J 6.5 Hz); m/z 312
(M+H)+; HRMS found 310.1294. C16H16N5O2 ([MꢁH]ꢁ) requires
310.1304.
3.3.3.82. N-(Pyrrol-2-ylmethyl)-2-amino-(5-methyl-2-furyl)-pyri-
midine-4-carboxamide 116. Yield = 59%; NMR dH (400 MHz,
DMSO); 2.39 (3H, s), 4.43 (2H, d, J 6.0 Hz), 5.94 (1H, m), 5.96 (1H,
br m), 6.34 (1H, d, J 2.5 Hz), 6.67 (1H, m), 6.88 (2H, br s), 7.20
(1H, d, J 3.5 Hz), 7.36 (1H, s), 8.31 (1H, br t), 10.73 (1H, br, s); m/
z 298 (M+H)+, retention time 4.97 min (Method D); HRMS found
296.1156. C15H14N5O2 ([MꢁH]ꢁ) requires 296.1147.
The filtrate was evaporated to afford an off-white solid (0.334 g,
68%), which was also identified as largely the desired product 108.
3.3.3.76. N-(Pyridin-2-ylmethyl)-2-Dimethylamino-6-(5-
methyl-furan-2-yl)-pyrimidine-4-carboxamide 110. A mixture
of 2-dimethylamino-6(5-methylfuran-2-yl)-pyrimidine-4-carbox-
ylic acid, lithium salt 108 (0.100 g, 0.41 mmol), 2-(aminomethyl)-
pyridine (0.088 g, 0.82 mmol), polymer supported carbodiimide
(1.51 g, 1.81 mmol), 1-hydroxybenzotriazole (0.24 g, 1.81 mmol)
and N,N0-diisopropylethylamine (0.07 mL, 0.41 mmol) in dimethyl
formamide (5 mL) was stirred at ambient temperature. After 16 h,
the reaction mixture was evaporated. The residue was subjected to
silica-gel column chromatography [hexane–EtOAc (0–100%) as elu-
ent]. The eluted material was subjected to preparative LC–MS to give
a white solid (0.028 g, 26%); NMR dH (400 MHz, CD3OD) 2.39 (3H, s),
3.26 (6H, s), 4.71 (2H, s), 6.22–6.23 (1H, m), 7.14 (1H, d, J 3.5 Hz),
7.29–7.32 (1H, m), 7.42 (1H, s), 7.80 (1H, dt, J 7.5, 7.5 and 2.0 Hz)
and 8.49–8.51 (1H, m); m/z (M+H)+ 338.
3.3.3.83. N-(1,5-Dimethyl-1H-pyrrol-2-ylmethyl)-2-amino-(5-
methyl-2-furyl)pyrimidine-4-carboxamide 117. Yield = 5%; IR
mmax (DR)/cmꢁ1 3329, 3219, 2939, 1628, 1521, 1217, 1129, 1023,
860 and 777; NMR dH (400 MHz, DMSO) 2.39 (3H, s), 3.80 (3H,
s), 4.43 (2H, d, J 6.0 Hz), 6.15 (1H, d, J 2.0 Hz), 6.33–6.34 (1H, m),
6.87 (2H, s), 7.20 (1H, d, J 3.5 Hz), 7.36 (1H, s), 7.60 (1H, d, J
2.0 Hz) and 8.48 (1H, t, J 6.0 Hz); m/z 313 (M+H)+.
3.3.3.84. N-(Imidazo-2-ylmethyl)-2-amino-(5-methyl-2-furyl)-
pyrimidine-4-carboxamide 118. Yield = 24%, NMR dH (400 MHz,
DMSO); 2.39 (3H, s), 4.52 (2H, d, J 2.5 Hz), 6.34 (1H, d, J 2.5 Hz),
6.91 (2H, br s), 6.94 (2H, s), 7.21 (1H, d, J 3.0 Hz), 7.37 (1H, s),
8.62 (1H, br t); m/z 299 (M+H)+, LC retention time 2.19 min (Meth-
od D); HRMS found 297.1113. C14H13N9O2 ([MꢁH]ꢁ) requires
297.1100.

R. J. Gillespie et al. / Bioorg. Med. Chem. 17 (2009) 6590–6605
6605
3.3.3.85. N-(1-Ethyl-1H-imidazol-2-ylmethyl)-2-amino-(5-meth-
Supplementary data
yl-2-furyl)pyrimidine-4-carboxamide 119. Yield = 46%; NMR dH
(400 MHz, DMSO); 1.28 (3H, t, J 7.3 Hz), 2.39 (3H, s), 4.00 (2H, q, J
7.3 Hz), 4.57 (2H, d, J 5.5 Hz), 6.34 (1H, dd, J 1.0 Hz, 3.5 Hz), 6.85
(1H, d, J 1.0 Hz), 6.93 (2H, br s), 7.18 (1H, d, J 1.0 Hz), 7.21 (1H, d,
J 3.5 Hz), 7.37 (1H, s), 8.61 (1H, t, J 5.5 Hz); m/z 327 (M+H)+, reten-
tion time 0.72 min (Method F) and 3.59 min (Method G); HRMS
found 325.1425. C16H17N6O2 ([MꢁH]ꢁ) requires 325.1413.
Supplementary data (purity information, analytical methods and
NMR spectra of key derivatives) associated with this article can be
found, in the online version, at doi:10.1016/j.bmc.2009.07.078.
References and notes
1. Xu, K.; Bastia, E.; Schwarzschild, M. Pharmacol. Ther. 2005, 105, 267.
2. Bara-Jimenez, W.; Sherzai, A.; Dimitrova, T.; Favit, A.; Bibbiani, F.; Gillespie, M.;
Morris, M. J.; Mouradian, M. M.; Chase, T. N. Neurology 2003, 61, 293.
3. Gillespie, R. J.; Bamford, S. J.; Guar, S.; Jordan, A. M.; Lepiniere, J.; Mansell, H. L.;
Stratton, G. C. Bioorg. Med. Chem. Lett. 2009, 19, 2664.
4. Rabasseda, X.; Sorbera, L. A.; Martin, L.; Leeson, P. A.; Castaner, J. Drugs Future
2001, 26, 20.
5. LeWitt, P. A.; Guttman, M.; Tetrud, J. W.; Tuire, P. J.; Mori, A.; Chaikin, P.;
Sussman, N. M. Ann. Neurol. 2008, 63, 295.
6. http://www.kyowa-kirin.co.jp/english/news/kyowa/er080228_01.html; http://
www.kyowa-kirin.co.jp/english/news/2009/e20090115_01.htm.
7. Gillespie, R. J.; Todd, R. S.; Stratton, G. C.; Jordan, A. M. PCT Int. Appl.
WO2005079801, 2005; Gillespie, R. J.; Williamson, D. S. PCT Int. Appl.
WO2005079800, 2005.
8. Gillespie, R. J.; Adams, D. R.; Benwell, K.; Bebbington, D.; Cliffe, I. A.; Dawson, C.
E.; Dourish, C. T.; Fletcher, A.; Giles, P. R.; Gaur, S.; Jordan, A. M.; Knight, A. R.;
Knutsen, L. J. S.; Lawrence, A.; Lerpiniere, J.; Misra, A.; Porter, R. H. P.; Pratt, R.
M.; Shepherd, R.; Upton, R.; Ward, S. E.; Weiss, S. M.; Williamson, D. S. Bioorg.
Med. Chem. Lett. 2008, 18, 2916.
3.3.3.86. N-(1-n-Propyl-1H-imidazol-2-ylmethyl)-2-amino-(5-
methyl-2-furyl)pyrimidine-4-carboxamide 120. Yield = 30%, NMR
dH (400 MHz, DMSO); 0.83 (3H, t, J 7.3 Hz), 4.68 (2H, m), 2.39 (3H, s),
3.92 (2H, t, J 7.3 Hz), 4.57 (2H, d, J 5.5 Hz), 6.34 (1H, d, J 2.5 Hz), 6.85
(1H, d, J 1.0 Hz), 6.93 (2H, br s), 7.16 (1H, d, J 1.0 Hz), 7.21 (1H, d, J
3.0 Hz), 7.37 (1H, s), 8.61 (1H, br t); m/z 341 (M+H)+, LC retention
time 1.63 min (Method E).
3.3.3.87. N-(1-Isopropyl-1H-imidazol-2-ylmethyl)-2-amino-(5-
methyl-2-furyl)pyrimidine-4-carboxamide 121. Yield = 8%, NMR
dH (400 MHz, DMSO); 1.34 (6H, d, J 6.5 Hz), 2.39 (3H, s), 4.52 (1H,
m), 4.59 (2H, d, J 5.5 Hz), 6.34 (1H, br d), 6.87 (1H, br d), 6.94
(2H, br s), 7.21 (1H, d, J 3.0 Hz), 7.28 (1H, br d), 7.37 (1H, s),
8.61 (1H, br t); m/z 341 (M+H)+, LC retention time 1.51
min (Method E); HRMS found 341.1719. C17H21N6O2 ([MꢁH]ꢁ) re-
quires 341.1726.
9. Gillespie, R. J.; Cliffe, I. A.; Dawson, C. E.; Dourish, C. T.; Gaur, S.; Giles, P. R.;
Jordan, A. M.; Knight, A. R.; Lawrence, A.; Lerpiniere, J.; Misra, A.; Pratt, R. M.;
Todd, R. S.; Upton, R.; Weiss, S. M.; Williamson, D. S. Bioorg. Med. Chem. Lett.
2008, 18, 2920.
10. Gillespie, R. J.; Cliffe, I. A.; Dawson, C. E.; Dourish, C. T.; Gaur, S.; Jordan, A. M.;
Knight, A. R.; Lerpiniere, J.; Misra, A.; Pratt, R. M.; Roffey, J.; Stratton, G. C.;
Upton, R.; Weiss, S. M.; Williamson, D. S. Bioorg. Med. Chem. Lett. 2008, 18,
2924.
11. Gillespie, R. J.; Bamford, S. J.; Botting, R.; Comer, M.; Denny, S.; Gaur, S.; Griffin,
M.; Jordan, A. M.; Knight, A. R.; Lerpiniere, J.; Leonardi, S.; Lightowler, S.;
McAteer, S.; Merrett, A.; Misra, A.; Padfield, A.; Reece, M.; Saadi, M.; Selwood,
D. L.; Stratton, G. C.; Surry, D.; Todd, R.; Tong, X.; Ruston, V.; Upton, R.; Weiss, S.
M. J. Med. Chem. 2009, 52, 33.
12. For additional details of Ki determination, see: Weiss, S. M.; Benwell, K.; Cliffe,
I. A.; Gillespie, R. J.; Knight, A. R.; Lerpiniere, J.; Misra, A.; Pratt, R. M.; Revell, D.;
Upton, R.; Dourish, C. T. Neurology 2003, 61, S101. All values are the mean of at
least two separate values.
13. Broughton, H. B.; Watson, I. A. J. Mol Graphics Modell. 2004, 23, 51.
14. Dixon, J. A.; Nagarathnam, D.; Zhang, L.; Wang, C.; Yi, L.; Chen, Y.; Chen, J.; Bear,
B. R.; Brands, M.; Hillisch, A.; PCT Int. Appl. WO2006099231, 2006;
Nagarathnam, D.; Dumas, J.; Hatoum-Mokdad, H.; Boyer, S.; Pluempe, H. PCT
Int. Appl. WO2003062227, 2003.
3.3.3.88. N-(5-Methylisoxazol-3-ylmethyl)-2-amino-(5-methyl-
2-furyl)pyrimidine-4-carboxamide 122. Yield = 84%; IR mmax (DR)/
cmꢁ1 3324, 3183, 1686, 1540, 1359, 1220, 1136 and 1021; NMR dH
(400 MHz, DMSO) 2.40 (3H, s), 6.35–6.36 (1H, m), 6.96 (2H, br s),
7.15 (1H, t, J 7.4 Hz), 7.25 (1H, d, J 3.6 Hz), 7.37–7.42 (3H, m),
7.79 (2H, d, J 7.2 Hz) and 10.22 (1H, s); m/z 295 (M+H)+; LC reten-
tion time 2.02 min (Method C).
3.3.3.89. N-(2-Methylaminothiazol-4-ylmethyl)-2-amino-(5-
methyl-2-furyl)pyrimidine-4-carboxamide 123. Yield = 31%, NMR
dH (400 MHz, DMSO); 2.39 (3H, s), 2.64 (3H, s), 4.54 (2H, d, J 6.0 Hz),
6.34 (1H, br d), 6.88 (2H, br s), 7.20 (1H, d, J 3.0 Hz), 7.26 (1H, s), 7.36
(1H, s), 8.66 (1H, br t); m/z 330 (M+H)+, LC retention time 2.20 min
(Method E).vv
15. Richardson, C. M.; Gillespie, R. J.; Williamson, D. S.; Jordan, A. M.; Fink, A.;
Knight, A. R.; Sellwood, D. M.; Misra, A. Bioorg. Med. Chem Lett. 2006, 16, 5993.
16. Kiselgof, E.; Tulshian, D. B.; Arik, L.; Zhang, H.; Fawzi, A. Bioorg. Med. Chem. Lett.
2005, 15, 2119.
Acknowledgements
17. Davies, G. D.; Baiocchi, F.; Robins, R. K.; Cheng, C. C. J. Org. Chem. 1961, 2755.
18. Flohr, A.; Norcross, R. D. U.S. Pat. Appl. 2004204584, 2004.
19. Emerson, D. W.; Titus, R. L.; Gonzalez, R. M. J. Org. Chem. 1991, 56, 5301;
Emerson, D. W.; Titus, R. L.; Gonzalez, R. M. J. Org. Chem. 1990, 55, 3572.
20. Gershon, H.; Braun, R.; Scala, A.; Rodin, R. J. Med. Chem. 1964, 7, 808.
21. Data not shown.
We wish to thank Lynne Barratt, Sarah Denny, Sean Lightowler,
Angela Merritt, Anil Mirsa, Anthony Padfield and Daniel Selwood
for undertaking the biological assessment of the derivatives de-
scribed in these studies.
22. Bezard, E.; Imbert, C.; Gross, C. E. Rev. Neurosci. 1998, 9, 71.