Preparation of 5-amino-6-oxo-1,6-dihydro[1,2,4]triazine-3-carboxylic acid derivatives and synthesis of compound libraries thereof

Article abstract of DOI:10.1016/j.tetlet.2004.02.025

Treatment of [1,3,5]triazine-2,4,6-tricarboxylic acid triethyl ester (4) with arylhydrazines provided 5-amino-6-oxo-1,6-dihydro[1,2,4]triazine-3- carboxylic acid ethyl esters 5a-g in moderate to good yields. Hydrolysis under basic conditions gave the corresponding free carboxylic acids 6a-d. Despite the relatively high number of heteroatoms present the amido as-triazine compounds 6a-d showed good solubility in phosphate buffer as determined by a lyophilization solubility assay. Building block 5a served as starting point for the syntheses of two discrete exocyclic 5-amido and 3-amido compound libraries 7 and 8, respectively.

Full text of DOI:10.1016/j.tetlet.2004.02.025

Tetrahedron
Letters
Tetrahedron Letters 45 (2004) 2791–2795
Preparation of 5-amino-6-oxo-1,6-dihydro[1,2,4]triazine-3-
carboxylic acid derivatives and synthesis of compound
libraries thereof
Romain Gambert, Christoph Kuratli and Rainer E. Martin*
F. Hoffmann-La Roche Ltd, Pharmaceuticals Division, CH-4070 Basel, Switzerland
Received 20 January 2004;accepted 6 February 2004
Abstract—Treatment of [1,3,5]triazine-2,4,6-tricarboxylic acid triethyl ester (4) with arylhydrazines provided 5-amino-6-oxo-1,6-
dihydro[1,2,4]triazine-3-carboxylic acid ethyl esters 5a–g in moderate to good yields. Hydrolysis under basic conditions gave the
corresponding free carboxylic acids 6a–d. Despite the relatively high number of heteroatoms present the amido as-triazine com-
pounds 6a–d showed good solubility in phosphate buffer as determined by a lyophilization solubility assay. Building block 5a served
as starting point for the syntheses of two discrete exocyclic 5-amido and 3-amido compound libraries 7 and 8, respectively.
ꢀ 2004 Elsevier Ltd. All rights reserved.
As part of our continuing efforts to construct novel
compound libraries with interesting structural motifs for
high-throughput biological profiling of various medic-
inal targets, our attention was recently drawn to the
structural class of as-triazines 1 and 2 as depicted in
Figure 1. Surprisingly, upon checking the literature,
only two publications have appeared dealing with the
synthesis of parent molecules 5a and 6a (Table 1).1;2
However, no further derivatization of these interesting
heterocyclic template molecules has been described,
which allow three different side chains to be attached
easily in a nearly triangular fashion. Therefore, we
decided to investigate this potentially interesting class of
compounds.
The synthesis of building blocks 5a–g and 6a–d, which
may serve as starting points for library syntheses are
outlined in Scheme 1. The preparation of the key
intermediates commenced with commercially available
ethyl cyano-formate (3), which under dry HCl gas
catalysis undergoes in a single step reaction at rt within
2 d trimerization to 2,4,6-tris(ethoxycarbonyl)[1,3,5]tri-
azine (4) in 71% yield.3–5 Addition of arylhydrazines to a
solution of the sym-triazine 4 in EtOH at rt afforded the
corresponding as-triazines 5a–g after intramolecular
rearrangement in moderate to good yields (Table 1,
entries 1–7).1;2 Alternatively, the reaction can also be
conducted under reflux conditions, which reduces reac-
tion times typically down to 2–3 h. In all cases investi-
gated the reaction products precipitated out of solution
and could be easily isolated by filtration. Further puri-
fication by recrystallization from EtOH provided
compounds 5a–g in analytically pure quality.6 All aryl-
hydrazines applied in this study are commercially
available, except 2,3-dichlorophenylhydrazine, which
was prepared from 2,3-dichloroaniline by reduction of
the corresponding diazonium salt employing SnCl2/
HCl.7;8 Interestingly, conducting the condensation
reaction using methyl- or benzylhydrazine did not pro-
vide the anticipated products. Saponification of the ethyl
ester groups in 5a–d was achieved with 1 M NaOH using
either EtOH and H2O or a mixture of EtOH/THF (3:1)
O
N
R3
1 R1 = aryl, R2 = RCO, R3 = OCH2CH3
2 R1 = aryl, R2 = H, R3 = NHR
N
R2
N
N
H
R1
O
Figure 1. Target structures as-triazine ethyl esters 1 and corresponding
amides 2.
Keywords: Triazine;Synthesis;Combinatorial chemistry;Medicinal
chemistry.
* Corresponding author. Tel.: +41-61-6887350;fax: +41-61-6888714;
e-mail: rainer_e.martin@roche.com
0040-4039/$ - see front matter ꢀ 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetlet.2004.02.025

2792
R. Gambert et al. / Tetrahedron Letters 45 (2004) 2791–2795
Table 1. Synthesis of as-triazine ethyl esters 5a–g and free acids
6a–d
O
N
O
N
O
a
Entry
R
Product
Reaction
time (h)
Yield
(%)c
O
N
O
O
N
O
O
24a
24a
66
59
3
4
1
5a
CH3
R'
R'
R'
NHNHR
HN
N
N
N
N
NH
2
3
5b
5c
N
b
CH3
R
R'
N
H
O
O
O
CH3
CH3
R' = COOCH2CH3
48a
53
92
O
N
OH
O
O
Cl
Cl
N
N
c
N
N
N
4
5d
48a
H
H
R
N
N
H
R
O
H
O
Cl
6
5
Cl
5
6
7
8
5e
5f
48a
48a
24a
24b
61
82
30
70
Scheme 1. Reagents and conditions: (a) dry HCl gas, rt, 2 d, 71%;
(b) RNHNH2, EtOH, rt;(c) 1 M NaOH, EtOH/THF (3:1), H 2O, rt;
isolated yields (see Table 1). Yields were not optimized.
CF3
N
formation of a gel-like, high viscosity solution, which
significantly hampered efficient stirring of the reaction
mixture.
5g
6a
The analytical data recorded for 5a and 6a are in
accordance with those published for these two com-
pounds.1 The spectroscopic data of all new compounds
CH3
1
5b–g and 6b–d, which were fully characterized by H
9
6b
6c
24b
24b
49
58
NMR, 13C NMR, FTIR and high-resolution mass
spectrometry (HRMS) were consistent with the pro-
posed structures. Solubilities in phosphate buffer of both
the ethyl esters and the free acids were assessed using a
lyophilization assay.11 For instance, depending on the
aryl substitution pattern solubilities varied for the ethyl
ester compounds from 12 lg/mL for 5e to >348 lg/mL
for 5g. Similarly, lipophilicity changed from log D ¼ 2.6
for 5e to log D ¼ )0.3 for 5g, respectively.12 In the case
of the free acids solubilities were typically high as
exemplified by >309 lg/mL for 5a or >347 lg/mL in the
case of both 6b and 6c whereas log D values were mea-
sured to be lower than )1. The free acids 6a–d showed
two ionization constants typically at pH < 2 and around
2.8, respectively.13
CH3
CH3
CH3
10
Cl
Cl
11
6d
24b
36
a Conditions: EtOH, rt.
b Conditions: 1 M NaOH, EtOH/THF (3:1), H2O, rt.
c Isolated yields. Yields were not optimized.
and H2O depending on the solubility of starting mate-
rials (Scheme 1). After stirring for 24 h at rt the solutions
were neutralized with 1 M HCl and compounds 6a–d
precipitated out of solution after concentration of the
reaction mixture by evaporation of the solvents under
reduced pressure (Table 1, entries 8–11). Further puri-
fication was accomplished by recrystallization from
mixtures of ethanol/H2O.9 However, in the case of 6d
preparative HPLC was used to obtain an analytically
pure sample.10 Running the hydrolysis under less dilute
conditions resulted after addition of the base in the
With the 5-amino-as-triazine 5a as a central building
block the synthesis of exocylic 5-amido 7 and 3-amido 8
compound libraries was examined (Scheme 2). Library 7
containing an exocylic 5-amido group was generated by
treatment of 5-amino[1,2,4]triazine-3-carboxylic acid
ethyl ester 5a (reaction scale 0.1 mmol) dissolved in 1 mL
DMF with 1.5 equiv of the corresponding acid chlorides
in the presence of diisopropylethylamine (DIEA) as a
base and shaking at 60 ꢁC for 24 h. Evaporation of
DMF and DIEA under reduced pressure and purifica-
tion of the crude reaction mixture dissolved in DMSO

R. Gambert et al. / Tetrahedron Letters 45 (2004) 2791–2795
2793
Table 2. Parallel synthesis of 5-amido-as-triazine ethyl esters 7
O
N
O
O
N
O
Entry
1
Starting
material
Acid chloride
Product
Yield
(%)a
a
N
N
N
N
O
H
O
R
N
H
N
H
5a
5a
7a
51
O
O
Cl
5a
7
O
Cl
2
7b
13
b
O
3
4
5a
5a
7c
7d
41
60
Cl
O
O
N
OH
O
NHR
c
N
N
N
N
N
Cl
H
H
N
H
N
O
O
O
H
5
6
7
5a
5a
5a
7e
7f
55
13
50
Cl
6a
8
O
Scheme 2. Reagents and conditions: (a) RCOCl, DIEA, DMF, 60 ꢁC,
24 h;(b) 1 M NaOH, EtOH/THF (3:1), H 2O, rt, 24 h;then (c) RNH
CDI or HATU, DIEA, DMF, 70 ꢁC, 24 h.
Cl
,
2
F
O
O
7g
Cl
Cl
by preparative HPLC gave compounds 7 in moderate to
good yields and typically >95% purity (Table 2).10 All 12
discrete members of the library were characterized by
O
1
LC/MS and flow injection H NMR analysis. Solubili-
8
5a
7h
78
ties of individual members of library 7 varied from
values as low as 3 lg/mL for phenoxypyridine 7i to
361 lg/mL for dimethyloxazole 7l. Similarly, lipophili-
cities were strongly affected by the nature of the side
chains attached. For instance, the lipophilicities of
2-fluorophenyl 7g or 2-phenoxypyridine 7i were too
high to be measured due to precipitation, whereas for
compounds 7e and 7h, medium lipophilicities with
log D ¼ 2.4 and 2.0, respectively, were measured and for
the oxazole derivative 7k a very low lipophilicity of only
)1.0 was obtained.
O
O
O
O
9
5a
5a
7i
7j
50
71
Cl
Cl
N
10
The preparation of as-triazine library 8 is outlined in
Scheme 2. The free carboxylic acid 6a (reaction scale
0.1 mmol) dissolved in 1 mL DMF was preactivated with
1,10-carbonyldiimidazole (CDI) for 1 h. Subsequently,
DIEA and the corresponding amines (1.5 equiv) were
added and the reaction mixture heated to 70 ꢁC for 24 h.
Evaporation of solvent and purification by preparative
HPLC provided compounds 8 in moderate to good
yields (Table 3). Similar results for the amide bond
formation were obtained when 7-aza-3-[(dimethylimin-
ium)(dimethylamino)methyl]-1,2,3-benzotriazol-1-ium-
1-olate hexafluorophosphate (HATU) was employed as
a coupling reagent. The chemical integrity of all com-
pounds of library 8 was examined by LC/MS and flow
injection 1H NMR analysis. Again, solubilities and
lipophilicities were strongly influenced by the nature of
the side chains attached. For instance, compounds 8i
and 8l displayed a solubility of only 5 lg/mL, whereas
for most other compounds in this series such as 8a,b,f or
8g solubilities between 30 and 40 lg/mL were obtained.
The highest value was observed for compound 8c with
>434 lg/mL. Unfortunately, log D values could only be
assessed for few compounds in this series as most of
O
O
O
11
12
5a
5a
7k
7l
29
24
Cl
Cl
N
N
O
a Isolated yields after purification by preparative HPLC.10
them precipitated out from phosphate buffer solution
during measurement. The bis(trifluoromethyl) derivative
8i showed a high lipophilicity with log D ¼ 3.2, whereas
medium values of 1.9 and 1.3 were obtained for 8b and
8a, respectively. The lowest value in this series was
measured for compound 8c with log D ¼ 0.4.
In conclusion, we have described a convenient approach
for the solution phase synthesis of 5-amino[1,2,4]tri-
azine-3-carboxylic acid ethyl esters 5 and the corre-
sponding free carboxylic acids 6. The rapid assembly of
exocylic 5-amido 7 and 3-amido 8 compound libraries

2794
R. Gambert et al. / Tetrahedron Letters 45 (2004) 2791–2795
Table 3. Parallel synthesis of 3-amido-5-amino-as-triazines 8
evaporated under reduced pressure yielding 6d in 36%
yield (0.24 g) and >90% purity, which is sufficiently high
for library synthesis. Analytically pure samples were
obtained by purification with preparative HPLC.
Entry
Starting Primary amine
material
Product Yield (%)a
H2N
1
2
5a
8a
8b
24
25
Compound library 7a–l: To a stirred solution of build-
ing block 5a (0.026 g, 0.1 mmol) in 1 mL DMF was
added DIEA (0.3 mmol, 3 equiv) and the corresponding
acid chloride (0.2 mmol, 2 equiv). After shaking at 60 ꢁC
for 24 h the solvent was removed under reduced pres-
sure, the residues dissolved in DMSO, filtered and
purified by preparative HPLC.
H2N
5a
3
4
5a
8c
8d
18
18
H2N
H2N
H2N
O
5a
5a
5
8e
31
Compound library 8a–l: To a stirred solution of build-
ing block 6a (0.026 g, 0.1 mmol) in 1 mL DMF was
added DIEA (0.3 mmol, 3 equiv), HATU (0.12 mmol,
1.2 equiv) and the corresponding primary amine
(0.18 mmol, 1.8 equiv). After shaking the vials at 70 ꢁC
for 24 h the solvent was removed under reduced pres-
sure, the residues dissolved in DMSO, filtered and
purified by preparative HPLC.
F
H2N
H2N
6
7
5a
5a
8f
23
16
F
F
8g
F
CF3
H2N
H2N
8
9
5a
5a
8h
8i
41
63
CF3
Acknowledgements
We would like to thank Dr. K. Bleicher, Dr. L. Green,
€
continuous interest in this work and helpful comments
during the preparation of this manuscript. We are also
grateful to the analytical services at Roche Basel for
providing spectroscopic data.
CF3
Dr. M. Rogers-Evans and Prof. Klaus Muller for their
H2N
H2N
10
11
5a
5a
8j
61
7
CF3
O
O
8k
O
12
5a
8l
56
H2N
References and notes
a Isolated yields after purification by preparative HPLC.10
1. Alekseeva, N. V.;Turchin, K. F.;Anisimova, O. S.;
Sheinker, Y. N.;Yakhontov, L. N. Khim. Geterotsik.
Soedine 1989, 11, 1529–1538.
2. Alekseeva, N. V.;Turchin, K. F.;Anisimova, O. S.;
Sheinker, Y. N.;Yakhontov, L. N. Khim. Geterotsik.
Soedine 1990, 12, 1655–1664.
was exemplified with building block 5a. The 5-amino-
[1,2,4]triazine-3-carboxylic acid core resembles an
interesting and promising template structure that allows
numerous further modifications, which might open an
avenue to the generation of biologically active mole-
cules.
3. Ott, E. Chem. Ber. 1919, 52, 656–665.
4. Boger, D. L.;Dang, Q. Tetrahedron 1988, 44, 3379–3390.
5. Sugiyama, Y.;Sasaki, T.;Nagato, N. J. Org. Chem. 1978,
43, 4485–4487.
1
6. Spectroscopic data: Compound 5a: H NMR (400 MHz,
DMSO): d 1.27 (t, J ¼ 7.2 Hz, 3H), 4.27 (q, J ¼ 7.2 Hz,
General procedure: Compound 5d: To a stirred suspen-
sion of sym-triazine 4 (3.0 g, 10.0 mmol) in dry EtOH
(50 mL) at rt was added 3,4-dichlorophenylhydrazine
(5.32 g, 30.0 mmol, 3 equiv). After 48 h the slightly
orange precipitate was filtered off and recrystallized
from EtOH to give compound 5d in 92% yield (3.0 g).
2H), 7.36–7.64 (m, 5H), 8.22 (br s, 1H), 8.66 (br s, 1H). 13
C
NMR (100 MHz, DMSO): d 14.06, 61.32, 125.31, 128.30,
128.73, 140.31, 141.96, 149.70, 157.68, 162.04. FTIR
(ATR, cmÀ1): 3456 (s), 3088 (br m), 1724 (s), 1668 (s),
1631 (s), 1595 (s), 1560 (m), 1493 (s), 1377 (s), 1246 (s),
1197 (s). HRMS (ESI) m=z calculated for C12H13N4O3
(M+H)þ: 261.0988, found: 261.0990. These data are in
accordance with those published in Ref. 1. Compound 5b:
1H NMR (400 MHz, DMSO): d 1.25 (t, J ¼ 7.0 Hz, 3H),
2.05 (s, 3H), 2.34 (s, 3H), 4.25 (q, J ¼ 7.0 Hz, 2H), 7.13–
7.25 (m, 3H), 8.20 (br s, 1H), 8.65 (br s, 1H). 13C NMR
(100 MHz, DMSO): d 14.04, 16.94, 20.64, 61.31, 127.00,
127.17, 131.06, 133.86, 136.98, 138.69, 141.90, 149.59,
157.46, 161.97. FTIR (ATR, cmÀ1): 3460 (s), 3110 (br m),
1736 (s), 1673 (s), 1635 (s), 1504 (m), 1372 (m), 1242 (s),
1194 (s), 1168 (s). HRMS (ESI) m=z calculated for
Compound 6d: To a stirred solution of 5d (0.73 g,
2.2 mmol) in EtOH/THF (300 mL, 3:1) was added H2O
(3 mL) and 1 M NaOH (2.2 mL, 2.2 mmol, 1.0 equiv).
After stirring at rt for 24 h, 1 M HCl (6.6 mL, 6.6 mmol,
3.0 equiv) was added and the solution volume reduced to
ca. 100 mL by evaporation under reduced pressure. Satd
NaCl solution (10 mL) was added and the reaction
mixture extracted with ethyl acetate. The collected
organic phases were dried over MgSO4 and the solvent

R. Gambert et al. / Tetrahedron Letters 45 (2004) 2791–2795
2795
C14H17N4O3 (M+H)þ: 289.1301, found: 289.1300. Com-
pound 5c: 1H NMR (400 MHz, DMSO): d 1.25 (t,
J ¼ 7.2 Hz, 3H), 2.03 (s, 3H), 2.32 (s, 3H), 4.25 (q,
J ¼ 7.2 Hz, 2H), 7.18–7.27 (m, 3H), 8.21 (br s, 1H), 8.67
(br s, 1H). 13C NMR (100 MHz, DMSO): d 14.05, 16.55,
20.25, 61.33, 127.49, 129.82, 130.42, 131.00, 136.11,
139.22, 141.94, 149.47, 157.46, 161.95. FTIR (ATR,
cmÀ1): 3459 (s), 3122 (br m), 1738 (s), 1669 (s), 1634 (s),
1510 (m), 1369 (m), 1241 (s), 1219 (s), 1176 (s). HRMS
(ESI) m=z calculated for C14H17N4O3 (M+H)þ: 289.1301,
found: 289.1300. Compound 5d: 1H NMR (400 MHz,
DMSO): d 1.27 (t, J ¼ 7.2 Hz, 3H), 4.28 (q, J ¼ 7.2 Hz,
2H), 7.71 (dd, J ¼ 8.2, 2.4 Hz, 1H), 7.81 (d, J ¼8.2 Hz,
1H), 8.00 (d, J ¼ 2.4 Hz, 1H), 8.31 (br s, 1H), 8.74 (br s,
1H). 13C NMR (100 MHz, DMSO): d 14.05, 61.42, 125.44,
127.07, 130.71, 130.76, 130.93, 139.89, 142.23, 149.74,
157.67, 161.93. FTIR (ATR, cmÀ1): 3447 (s), 3107 (br m),
1745 (s), 1671 (s), 1645 (s), 1519 (w), 1471 (m), 1376 (m),
1349 (m), 1242 (s), 1196 (s), 1151 (s). HRMS (ESI) m=z
calculated for C12H11N4O3Cl2 (M+H)þ: 329.0208, found:
8. Cox, R. J.;Williams, R. M. Tetrahedron Lett. 2002, 43,
2149–2152.
9. Spectroscopic data: Compound 6a: H NMR (400 MHz,
1
DMSO): d 7.42–7.66 (m, 4H), 8.16 (br s, 1H), 8.56 (br s,
1H), 13.10 (br s, 1H). 13C NMR (100 MHz, DMSO): d
125.21, 128.21, 128.64, 140.34, 142.66, 149.64, 157.66,
163.42. FTIR (ATR, cmÀ1): 3342 (s), 3155 (br m), 1749 (s),
1718 (s), 1632 (s), 1594 (s), 1494 (s), 1416 (s), 1287 (s), 1242
(s), 1198 (s), 1173 (s), 1135 (s). HRMS (ESI) m=z calculated
for C10H9N4O3 (M+H)þ: 233.0675, found: 233.0677. These
data are in accordance with those published in Ref. 1.
Compound 6b: 1H NMR (400 MHz, DMSO): d 2.01 (s,
1H), 2.32 (s, 1H), 7.12 (br s, 1H), 7.18 (br d, J ¼ 8.0 Hz,
1H), 7.24 (d, J ¼ 8.0 Hz, 1H), 7.78 (br s, 1H), 8.40 (br s,
1H), 13.08 (br s, 1H). 13C NMR (100 MHz, DMSO): d
16.66, 20.27, 127.46, 129.33, 130.20, 130.83, 135.90, 139.82,
148.74, 149.34, 157.06, 164.57. FTIR (ATR, cmÀ1): 3433
(w), 3148 (br w), 2922 (s), 2853 (m), 1680 (m), 1613 (br s),
1505 (s), 1452 (m), 1400 (s), 1281 (s), 1233 (m), 1183 (m),
1150 (w). HRMS (ESI) m=z calculated for C12H13N4O3
(M+H)þ: 261.0988, found: 261.0988. Compound 6c: 1H
NMR (400 MHz, DMSO): d 2.04 (s, 1H), 2.32 (s, 1H), 7.18
(br s, 1H), 7.21 (br d, J ¼ 7.8 Hz, 1H), 7.26 (d, J ¼ 7.8 Hz,
1H), 8.14 (br s, 1H), 8.56 (br s, 1H), 13.10 (br s, 1H). 13C
NMR (100 MHz, DMSO): d 17.03, 20.65, 126.92, 127.05,
130.90, 133.74, 137.58, 138.12, 148.78, 149.50, 157.09,
164.64. FTIR (ATR, cmÀ1): 3431 (m), 3171 (br s), 2921 (br
s), 1680 (s), 1622 (br s), 1519 (s), 1456 (s), 1420 (s), 1377 (s),
1287 (s), 1241 (w), 1208 (s), 1166 (m). HRMS (ESI) m=z
calculated for C12H13N4O3 (M+H)þ: 261.0988, found:
1
329.0209. Compound 5e: H NMR (400 MHz, DMSO): d
1.25 (t, J ¼ 7.2 Hz, 3H), 4.26 (q, J ¼ 7.2 Hz, 2H), 7.58 (t,
J ¼ 8.0 Hz, 1H), 7.68 (d, 6.8 Hz, 1H), 7.84 (d, 8.0 Hz, 1H),
8.42 (br s, 1H), 8.82 (br s, 1H). 13C NMR (100 MHz,
DMSO): d 14.03, 61.50, 128.43, 129.06, 129.23, 131.58,
132.37, 139.37, 142.36, 149.32, 157.34, 161.73. FTIR
(ATR, cmÀ1): 3432 (s), 3133 (br m), 1734 (s), 1681 (s),
1638 (s), 1571 (m), 1456 (m), 1424 (m), 1377 (m), 1359 (w),
1237 (s), 1208 (s), 1190 (s), 1150 (s). HRMS (ESI) m=z
calculated for C12H11N4O3Cl (M+H)þ: 329.0208, found:
1
1
329.0206. Compound 5f: H NMR (400 MHz, DMSO): d
261.0990. Compound 6d: H NMR (400 MHz, DMSO): d
1.27 (t, J ¼ 7.0 Hz, 3H), 4.28 (q, J ¼ 7.0 Hz, 2H), 7.76–8.07
(m, 4H), 8.30 (br s, 1H), 8.73 (br s, 1H). 13C NMR
(100 MHz, DMSO): d 14.47, 61.83, 122.50, 124.18 (q,
J ¼ 271 Hz), 125.36, 129.70, 129.80 (q, J ¼ 32 Hz), 130.57,
141.27, 142.69, 150.32, 158.16, 162.41. 19F NMR
(282 MHz, DMSO): d 61.63. FTIR (ATR, cmÀ1): 3450
(s), 3102 (br m), 1726 (s), 1670 (s), 1651 (s), 1596 (w), 1458
(m), 1379 (m), 1348 (m), 1324 (s), 1313 (s), 1293 (s), 1244
(s), 1176 (s), 1167 (s). HRMS (ESI) m=z calculated for
C13H12N4O3F3 (M+H)þ: 329.0861, found: 329.0861. Com-
pound 5g: 1H NMR (400 MHz, DMSO): d 1.26 (t,
J ¼ 7.2 Hz, 3H), 4.27 (q, J ¼ 7.2 Hz, 2H), 7.54–8.63 (m,
4H), 8.29 (br s, 1H), 8.72 (br s, 1H). 13C NMR (100 MHz,
DMSO): d 14.05, 61.37, 121.56, 124.66, 138.84, 141.83,
141.83, 149.10, 149.67, 151.96, 157.68, 161.95. FTIR
(ATR, cmÀ1): 3461 (s), 3110 (br m), 1729 (s), 1633 (s),
1589 (s), 1571 (s), 1466 (s), 1436 (s), 1376 (s), 1252 (s), 1241
(s), 1201 (s), 1244 (s), 1157 (w). HRMS (ESI) m=z
calculated for C11H12N5O3 (M+H)þ: 262.0940, found:
262.0944.
7.74–8.04 (m, 3H), 8.25 (br s, 1H), 8.65 (br s, 1H), 13.20 (br
s, 1H). 13C NMR (100 MHz, DMSO): d 126.53, 128.15,
131.83, 131.86, 132.16, 141.20, 144.21, 150.95, 158.93,
164.54. FTIR (ATR, cmÀ1): 3365 (m), 3167 (br m), 1746
(s), 1727 (w), 1663 (s), 1638 (s), 1590 (w), 1473 (s), 1410 (s),
1299 (w), 1234 (s), 1189 (s), 1148 (s), 1037 (s). HRMS (ESI)
m=z calculated for C10H7N4O3Cl2 (M+H)þ: 300.9895,
found: 300.9900.
10. Compounds were purified by preparative HPLC on a
Phenomenex Aqua 5 lm C18 125A 60 · 21.20 mm column
equipped with a Gilson Liquid Handler 215 autosampler,
two Varian Prep Star Model SD-1 pumps, a Sedex ELSD
75 lightscatter and a Dionex UVD 340S UV detector.
11. Solubility was measured from lyophilized DMSO stock
solutions spectrophotometrically at pH ¼ 6.5 in a 0.05 M
phosphate buffer.
12. log D values were measured spectrophotometrically at
pH ¼ 7.4 in a 1-octanol/50 mM TAPSO buffer system
containing 5% (v/v) DMSO.
13. pKa values were determined spectrophotometrically on a
ProfilerSGA instrument in a SGA buffer system contain-
ing 10% (v/v) methanol at an ionic strength of 150 mM.
7. Boido, A.;Novelli, F.;Savelli, F.;Sparatore, F.;Russo, S.
Il Farmaco 1989, 44, 279–302.