A New, One-Pot, Multicomponent Synthesis of Bioactive N -Pyrazolylformamidines under Microwave Irradiation

Article abstract of DOI:10.1055/s-0035-1561616

A one-pot, three-component, microwave-assisted reaction of polysubstituted 5-aminopyrazoles, triethyl orthoformate, and a series of cyclic secondary amines was developed and successfully employed for the synthesis of novel N-pyrazolylformamidines. Under c

Full text of DOI:10.1055/s-0035-1561616

SYNTHESIS
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© Georg Thieme Verlag Stuttgart · New York
2015, 47, A–F
paper
A
F. P. Lim et al.
Paper
Synthesis
A New, One-Pot, Multicomponent Synthesis of Bioactive N-Pyra-
zolylformamidines under Microwave Irradiation
Felicia Phei Lin Lima
Giuseppe Lunab
Anton V. Dolzhenko*a,b,c
a School of Pharmacy, Monash University Malaysia, Jalan
Lagoon Selatan, Bandar Sunway, Selangor Darul Ehsan
47500, Malaysia
anton.dolzhenko@monash.edu
dolzhenkoav@gmail.com
b School of Pharmacy, Curtin Health Innovation Research
Institute, Faculty of Health Sciences, Curtin University,
GPO Box U1987 Perth, Western Australia 6845, Australia
c Faculty of Pharmacy, South Ural State Medical University,
64 Vorovskogo Street, Chelyabinsk, 454092, Russian
Federation
Dedicated to Professor Viktor E. Kolla on the occasion of his 90th birthday
Received: 26.01.2015
Accepted after revision: 16.03.2016
Published online: 20.04.2016
N-Pyrazolylformamidines have been reported to pos-
sess anticancer activity.9 In this group of compounds, par-
ticular attention was devoted to binucleine 2, a nitrile-sub-
stituted N-pyrazolylformamidine, which was found to be a
potent and selective inhibitor of Aurora B kinase.10 Con-
struction of more complex heterocyclic systems using N-
pyrazolylformamidines as synthons has also proved to be
an efficient methodology, substantiating the special place
of these compounds in the chemistry of fused pyrazoles.11
It was demonstrated that N-pyrazolylformamidines
could be synthesised by reaction of aminopyrazoles, N,N-
disubstituted formamides, and trifluoroacetic anhydride in
the presence of sodium hydride.8 N-Pyrazolylformamidines
were also prepared when the corresponding aminopyra-
zoles were treated with N,N-disubstituted formamides and
phosphorous oxychloride under microwave irradiation.9,12
However, applications of these reagents are limited due to
possible formylation of the pyrazole ring and lability of oth-
er functional groups.13
Herein, we report a new, selective, one-pot, multicom-
ponent synthesis of bioactive formamidines constructed on
the 5-amino-3-anilinopyrazole-4-carbonitrile scaffold. The
synthesis of simple symmetric formamidines by using a
multicomponent reaction of anilines and triethyl orthofor-
mate has been well documented in the literature since the
report of a general methodology by Taylor et al.14 This reac-
tion has been well explored and was found to proceed effec-
tively under catalysis by cerium(IV) ammonium nitrate,15 β-
cyclodextrin,16 sulphated zirconia,17 and γ-Fe2O3@SiO2-HA.18
Good results were also obtained when hexafluoroisopropa-
nol19 or deep eutectic mixtures [tin(II) chloride–choline
chloride]20 were used as solvents. Ultrasound irradiation
was also reported to expedite a multicomponent synthesis
of symmetric formamidines.21 However, synthesis of com-
plex unsymmetric formamidines by using a multicompo-
DOI: 10.1055/s-0035-1561616; Art ID: ss-2016-z0063-op
Abstract A one-pot, three-component, microwave-assisted reaction
of polysubstituted 5-aminopyrazoles, triethyl orthoformate, and a se-
ries of cyclic secondary amines was developed and successfully em-
ployed for the synthesis of novel N-pyrazolylformamidines. Under cata-
lyst-free conditions, the reaction proceeded in
a chemo- and
regioselective manner, resulting in the formation of unsymmetric form-
amidines, which were isolated in high yields and purity. Some of the
prepared compounds were found to inhibit interleukin-17 secretion in
phenotypic in vitro assays.
Key words formamidines, pyrazoles, orthoesters, multicomponent
reaction, microwave-assisted synthesis
Formamidines are well known as useful building blocks
in organic synthesis.1 They are also a common feature in a
variety of biologically active compounds. It has been
demonstrated that transformation of primary amino
groups of some anticancer2 and antiviral3 drugs by linking
them to cyclic amines via a formamidine moiety resulted in
enhancement of their therapeutic properties. Construction
of these and other non-symmetric formamidines typically
involves functionalisation of the primary amino group to an
imidate, followed by its reaction with other amines.4 An-
other approach exploits initial formation of N,N-dimethyl-
formamidines in the reaction of primary amines with N,N-
dimethylformamide dimethylacetal, followed by trans-ami-
dination using an excess of other amines.5 Several one-pot
strategies have been developed based on reactions of pri-
mary amines with N,N-disubstituted formamides in the
presence of coupling reagents such as sulfonyl chlorides,6
phenyl chloroformate,7 or trifluoroacetic anhydride and so-
dium hydride.8
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2015, 47, A–F

B
F. P. Lim et al.
Paper
Synthesis
N
NH
NR1R2
N
NH
MW, 150 °C, 20 min
MeOH
PhHN
N
NHR1R2
HC(OEt)3
PhHN
NH2
N
N
1a
2a–d
N
NH
N
NH
N
NH
N
NH
N
N
N
N
PhHN
N
PhHN
N
PhHN
N
PhHN
N
N
O
Me
N
N
2c 73%
N
N
2b 64%
2d 78%
2a 77%
Scheme 1 Transformation of 5-amino-3-(phenylamino)pyrazole-4-carbonitrile (1a) into N-pyrazolylformamidines 2a–d
nent approach has remained unexplored. Selectivity of the
reaction appears to be the main problem for this approach
due to competition with the formation of symmetric N,N′-
bis(pyrazolyl)formamidines.22 We anticipated that this
problem could be solved by using focused microwave irra-
diation and careful selection of the reagent ratio, particular-
ly by applying an excess of orthoformate and cyclic amine.23
5-Amino-3-(arylamino)pyrazole-4-carbonitriles 1 were
prepared by using previously reported methods, viz. reac-
tion of 3,3,-bis(methylsulfanyl)-2-cyanoacrylonitrile24 with
anilines and subsequent treatment of the resulting 3-anili-
no-3-methylsulfanyl-2-cyanoacrilonitrile with hydrazine.25
The three-component reaction of 5-amino-3-(phenylami-
no)pyrazole-4-carbonitrile (1a) with triethyl orthoformate
and morpholine was conducted first under reflux in metha-
nol for 24 hours. Only traces of product (2a) were detected
in the reaction mixture. However, the three-component re-
action under microwave irradiation (150 °C, 20 min) in
methanol by using the same reagents was found to afford
selective formation of 5-[(morpholinomethylene)amino]-3-
(phenylamino)-1H-pyrazole-4-carbonitrile (2a) in good
yield (Scheme 1).
Improvement in some properties of several anticancer
drugs has been achieved through the conversion of amino
groups to morpholine-based formamidines.2 Therefore, we
further applied our method to the preparation of an ex-
tended library of substituted pyrazoles with this moiety for
biological testing. Under microwave irradiation, this reac-
tion was effectively employed for the synthesis of a series of
2 containing various arylamino substituents (Table 1). It
should be noted that the developed process was catalyst-
free and involved very simple isolation of the highly pure
products by simple filtration.
In the NMR spectra of all compounds of the prepared se-
ries, we observed magnetic non-equivalence of the mor-
pholine signals of atoms located on the opposite sides of the
ring. The delocalisation of the electron pair on the morpho-
line nitrogen atom to the formamidine moiety was further
extended over the pyrazole ring and cyano group. This high
level of delocalisation resulted in restricted rotation around
the C–N formamidine bond, which was translated into two
signals in the 13C NMR spectra at δ = 42.5 and 48.8 ppm
from carbon atoms adjacent to the morpholine nitrogen
and two groups of signals from the corresponding methy-
1
The structure of product 2a was confirmed by spectro-
scopic data indicating the presence of the formamidine
moiety (signal of methine proton at δ = 8.18 ppm in the 1H
NMR spectrum and signal of corresponding carbon atom at
δ = 155 ppm in the 13C NMR spectrum). A band at 2201 cm–1
lene protons in the H NMR spectra at δ = 3.46–3.55 and
3.60–3.68 ppm. Moreover, the observed anisotropic effect
was further extended to carbon atoms adjacent to the mor-
pholine oxygen, splitting their signals in the 13C NMR spec-
tra to δ = 65.4 and 66.5 ppm.
in the IR spectrum and a signal at δ = 115.6 ppm in the 13
C
The prepared compounds were subjected to pharmaco-
logical screening in a series of in vitro assays under the
Open Innovation Drug Discovery (OIDD) platform support-
ed by Eli Lilly.26 Some of compounds 2 were found to signifi-
cantly affect secretion of interleukin-17 (IL-17), which
plays an important role in many autoimmune diseases.27
Stimulated memory T-cells by anti-CD3, anti-CD28 and IL-
23 in human peripheral blood mononuclear cells (hPBMC)
were used to identify inhibitors of IL-17 secretion by using
ELISA assays. The most active compounds identified in the
series were 2h and 2k, which inhibited secretion of IL-17 in
hPBMC with IC50 values of 0.34 and 0.63 μM, respectively.
NMR spectrum confirmed that the cyano group remained
intact in the product. A singlet of the secondary amino
group at δ = 8.46 ppm and a broad signal of the tautomeris-
able endocyclic proton on the pyrazole at δ = 12.07 ppm in-
dicated that these groups did not participate in the reac-
tion.
In similar reactions, by replacing morpholine with other
cyclic amines, such as pyrrolidine, piperidine, and 4-meth-
ylpiperazine, the corresponding N-pyrazolylformamidines
2b, 2c, and 2d were successfully obtained (Scheme 1).
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2015, 47, A–F

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F. P. Lim et al.
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Synthesis
Table 1 Synthesis of 3-(Arylamino)-5-[(morpholinomethylene)amino]-1H-pyrazole-4-carbonitriles 2e–p
N
NH
N
NH
N
MW, 150 °C, 20 min
MeOH
ArHN
NH2
ArHN
N
O
HC(OEt)3
O
NH
N
N
1
2
Entry
Ar
4-FC6H4
Product
Yield (%)
Mp (°C)
Entry
Ar
4-EtC6H4
Product
Yield (%)
Mp (°C)
1
2
3
4
5
6
2e
2f
91
91
92
90
87
87
267–269a
266–268a
285–287b
268–270a
253–255b
256–258c
7
8
2k
2l
86
82
88
93
85
78
268–270c
264–266b
224–226b
219–220b
231–233b
235–237b
4-ClC6H4
3-BrC6H4
4-BrC6H4
3-MeC6H4
4-MeC6H4
2-MeOC6H4
4-MeOC6H4
2-EtOC6H4
4-EtOC6H4
3-F3CC6H4
2g
2h
2i
9
2m
2n
2o
2p
10
11
12
2j
a Recrystallised from MeOH.
b Recrystallised from MeCN.
c Recrystallised from i-PrOH.
These compounds also demonstrated good selectivity over
inhibition of IL-5 secretion and were found to possess a fa-
vourable cytotoxicity profile (EC50 > 30 μM) against hPBMC.
In conclusion, we have successfully developed a micro-
wave-assisted, multicomponent, catalyst-free method for
the synthesis of new bioactive N-pyrazolylformamidines 2
by using easily attainable reagents. The attractive practical
aspects of this method also include short reaction times
and simple isolation of the products obtained in good
yields.
IR (ATR): 3329 (N-H), 3164 (N-H), 2907 (C-H), 2201 (C≡N), 1612,
1532, 1436, 1269, 1114 cm–1
1H NMR (400 MHz, DMSO-d6): δ = 3.46–3.49 (m, 2 H, CH2), 3.63–3.67
(m, 6 H, (CH2)3), 6.77 (t, 3J = 7.9 Hz, 2 H, H-3′ and H-5′), 7.18 (t, 3J = 7.3
Hz, 1 H, H-4′), 7.43 (br s, 2 H, H-2′ and H-6′), 8.18 (s, 1 H, CH), 8.46 (br
s, 1 H, NH), 12.07 ( br s, 1 H, NH).
13C NMR (75 MHz, DMSO-d6): δ = 42.5 (CH2), 48.8 (CH2), 65.4 (CH2),
66.5 (CH2), 68.6 (C-4), 115.7 (C≡N), 116.1 (C-2′ and C-6′), 119.2 (C-4′),
128.5 (C-3′ and C-5′), 142.6 (C-1′), 151.6 (C-3), 155.0 (CH=N), 155.2
(C-5).
.
Anal. Calcd for C15H16N6O: C, 60.80; H, 5.44; N, 28.36. Found: C, 60.77;
H, 5.52; N, 28.27.
Melting points (uncorrected) were determined on a Gallenkamp melt-
ing point apparatus. 1H NMR spectra were recorded on a Bruker
Avance III spectrometer (400 MHz). 13C NMR spectra and HMBC ex-
periments used for the signal assignments were performed using a
Bruker Fourier 300 spectrometer (300 MHz) and by using DMSO-d6 as
a solvent. TMS was used as an internal reference. IR spectra were re-
corded using ATR sample base plate diamond on a Spectrum Two
(PerkinElmer) FT-IR spectrometer. Microwave-assisted reactions
were carried out in the closed vessel focused single mode by using a
CEM Discover microwave synthesizer. The reaction temperature was
monitored by an equipped IR sensor.
3(5)-(Phenylamino)-5(3)-[(pyrrolidinomethylene)amino]-1H-pyr-
azole-4-carbonitrile (2b)
Yellow solid; yield: 179 mg (64%); mp 297–299 °C (MeCN).
IR (ATR): 3305 (N-H), 3136 (N-H), 2955 (C-H), 2212 (C≡N), 1621,
1537, 1465, 1250, 1174 cm–1
.
1H NMR (400 MHz, DMSO-d6): δ = 1.86–1.94 (m, 4 H, (CH2)2), 3.38–
3.42 (m, 2 H, CH2), 3.54–3.58 (m, 2 H, CH2), 6.77 (t, 3J = 7.3 Hz, 1 H, H-
4′), 7.18 (t, 3J = 7.9 Hz, 2 H, H-3′ and H-5′), 7.45 (d, 3J = 7.2 Hz, 2 H, H-2′
and H-6′), 8.34 (s, 1 H, CH), 8.42 (br s, 1 H, NH), 12.00 (br s, 1 H, NH).
13C NMR (75 MHz, DMSO-d6): δ = 24.0 (CH2), 24.6 (CH2), 45.3 (CH2),
48.7 (CH2), 67.9 (C-4), 116.0 (C≡N), 116.0 (C-2′ and C-6′), 119.1 (C-4′),
128.5 (C-3′ and C-5′), 142.7 (C-1′), 151.6 (C-3), 153.0 (CH=N), 155.6
(C-5).
N-Pyrazolylformamidines 2; General Procedure
A mixture of 1 (1 mmol), the appropriate amine (2.5 mmol), and
HC(OEt)3 (0.42 mL, 2.5 mmol) in MeOH (2 mL) was irradiated in a 10
mL seamless pressure vial by using the microwave system operating
at maximal microwave power up to 150 W at 150 °C for 20 min. After
cooling of the mixture, the precipitated product 2 was filtered,
washed with cold MeOH, and recrystallised from a suitable solvent.
Anal. Calcd for C15H16N6: C, 64.27; H, 5.75; N, 29.98. Found: C, 64.08;
H, 5.86; N, 29.79.
3(5)-(Phenylamino)-5(3)-[(1-piperidylmethylene)amino]-1H-pyr-
azole-4-carbonitrile (2c)
Yellow solid; yield: 215 mg (73%); mp 275–277 °C (MeCN).
5(3)-[(Morpholinomethylene)amino]-3(5)-(phenylamino)-1H-
pyrazole-4-carbonitrile (2a)
IR (ATR): 3323 (N-H), 3054 (N-H), 2941 (C-H), 2201 (C≡N), 1614,
1532, 1440, 1250 cm–1
.
Yellow solid; yield: 227 mg (77%); mp 266–268 °C (MeOH).
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2015, 47, A–F

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F. P. Lim et al.
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Synthesis
1H NMR (400 MHz, DMSO-d6): δ = 1.56–1.60 (m, 4 H, (CH2)2), 1.62–
1.66 (m, 2 H, CH2), 3.39–3.42 (m, 2 H, CH2), 3.57–3.60 (m, 2 H, CH2),
6.77 (t, 3J = 7.3 Hz, 1 H, H-4′), 7.18 (t, 3J = 7.9 Hz, 2 H, H-3′ and H-5′),
7.45 (d, 3J = 6.9 Hz, 2 H, H-2′ and H-6′), 8.13 (s, 1 H, CH), 8.43 (br s, 1 H,
NH), 11.98 (br s, 1 H, NH).
13C NMR (75 MHz, DMSO-d6): δ = 23.8 (CH2), 24.6 (CH2), 26.2 (CH2),
42.4 (CH2), 50.0 (CH2), 68.2 (C-4), 115.8 (C≡N), 116.0 (C-2′ and C-6′),
119.1 (C-4′), 128.5 (C-3′ and C-5′), 142.7 (C-1′), 151.5 (C-3), 154.7
(CH=N), 155.7 (C-5).
13C NMR (75 MHz, DMSO-d6): δ = 42.4 (CH2), 48.8 (CH2), 65.3 (CH2),
66.4 (CH2), 68.3 (C-4), 115.4 (C≡N), 117.5 (C-2′ and C-6′), 122.4 (C-4′),
128.2 (C-3′ and C-5′), 141.4 (C-1′), 151.2 (C-3), 155.0 (CH=N), 155.2
(C-5).
Anal. Calcd for C15H15ClN6O: C, 54.47; H, 4.57; N, 25.41. Found: C,
54.40; H, 4.62; N, 25.36.
3(5)-(3-Bromophenylamino)-5(3)-[(morpholinomethylene)ami-
no]-1H-pyrazole-4-carbonitrile (2g)
Anal. Calcd for C16H18N6: C, 65.29; H, 6.16; N, 28.55. Found: C, 65.20;
H, 6.22; N, 28.47.
Yellow solid; yield: 343 mg (92%); mp 285–287 °C (MeCN).
IR (ATR): 3324 (N-H), 3196 (N-H), 2914 (C-H), 2203 (C≡N), 1614,
1531, 1434, 1265, 1115 cm–1
.
5(3)-[(4-Methylpiperazinylmethylene)amino]-3(5)-(phenylami-
no)-1H-pyrazole-4-carbonitrile (2d)
1H NMR (400 MHz, DMSO-d6): δ = 3.47–3.53 (m, 2 H, CH2), 3.61–3.68
4
4
3
(m, 6 H, (CH2)3), 6.94 (ddd, J = 0.8, J = 1.86, J = 7.86 Hz, 1 H, H-4′),
7.14 (t, 3J = 8.1 Hz, 1 H, H-5′), 7.39 (d, 3J = 8.0 Hz, 1 H H-6′), 7.82 (s, 1 H,
H-2′), 8.19 (s, 1 H, CH), 8.79 (br s, 1 H, NH), 12.18 (br s, 1 H, NH).
Yellow solid; yield: 241 mg (78%); mp 256–258 °C (MeCN).
IR (ATR): 3340 (N-H), 3057 (N-H), 2932 (C-H), 2202 (C≡N), 1617,
1540, 1438, 1250, 1140 cm–1
.
13C NMR (75 MHz, DMSO-d6): δ = 42.5 (CH2), 48.9 (CH2), 65.3 (CH2),
66.5 (CH2), 68.6 (C-4), 115.0 (C-6′), 115.4 (C≡N), 118.2 (C-2′), 121.6 (C-
4′), 121.7 (C-3′), 130.4 (C-5′), 144.1 (C-1′), 151.0 (C-3), 155.1 (CH=N),
155.3 (C-5).
1H NMR (400 MHz, DMSO-d6): δ = 2.22 (s, 3 H, CH3), 2.34–2.39 (m, 4
H, (CH2)2), 3.43–3.46 (m, 2 H, CH2), 3.59–3.62 (m, 2 H, CH2), 6.77 (t,
3J = 7.3 Hz, 1 H, H-4′), 7.18 (t, 3J = 7.9 Hz, 2 H, H-3′ and H-5′), 7.44 (d,
3J = 6.3 Hz, 2 H, H-2′ and H-6′), 8.14 (s, 1 H, CH), 8.45 (br s, 1 H, NH),
12.03 (br s, 1 H, NH).
Anal. Calcd for C15H15BrN6O: C, 48.01; H, 4.03; N, 22.40. Found: C,
47.87; H, 4.11; N, 22.32.
13C NMR (75 MHz, DMSO-d6): δ = 41.7 (CH3), 45.6 (CH2), 48.6 (CH2),
53.5 (CH2), 54.8 (CH2), 68.5 (C-4), 115.7 (C≡N), 116.0 (C-2′ and C-6′),
119.2 (C-4′), 128.5 (C-3′ and C-5′), 142.6 (C-1′), 151.5 (C-3), 154.8
(CH=N), 155.5 (C-5).
3(5)-(4-Bromophenylamino)-5(3)[(morpholinomethylene)ami-
no]-1H-pyrazole-4-carbonitrile (2h)
Yellow solid; yield: 339 mg (90%); mp 268–270 °C (MeOH).
Anal. Calcd for C16H19N7: C, 62.12; H, 6.19; N, 31.69. Found: C, 62.02;
H, 6.33; N, 31.55.
IR (ATR): 3298 (N-H), 3129 (N-H), 2910 (C-H), 2219 (C≡N), 1614,
1540, 1416, 1235, 1112 cm–1
.
1H NMR (400 MHz, DMSO-d6): δ = 3.47–3.52 (m, 2 H, CH2), 3.63–3.67
(m, 6 H, (CH2)3), 7.34 (d, 3J = 8.9 Hz, 2 H, H-3′ and H-5′), 7.44 (d, 2 H,
3J = 8.4 Hz H-2′ and H-6′), 8.18 (s, 1 H, CH), 8.70 (br s, 1 H, NH), 12.13
(br s, 1 H, NH).
3(5)-(4-Fluorophenylamino)-5(3)-[(morpholinomethylene)ami-
no]-1H-pyrazole-4-carbonitrile (2e)
Yellow solid; yield: 287 mg (91%); mp 267–269 °C (MeOH).
IR (ATR): 3330 (N-H), 3155 (N-H), 2902 (C-H), 2202 (C≡N), 1617,
13C NMR (75 MHz, DMSO-d6): δ = 42.5 (CH2), 48.9 (CH2), 65.4 (CH2),
66.5 (CH2), 68.5 (C-4), 110.3 (C-4′), 115.5 (C≡N), 118.1 (C-2′ and C-6′),
131.2 (C-3′ and C-5′), 141.9 (C-1′), 151.2 (C-3), 155.1 (CH=N), 155.4
(C-5).
1537, 1450, 1272, 1110 cm–1
.
1H NMR (400 MHz, DMSO-d6): δ = 3.46–3.50 (m, 2 H, CH2), 3.62–3.67
3
(m, 6 H, (CH2)3), 7.02 (dd, 3J = 8.9, JH-F = 8.9 Hz, 2 H, H-3′ and H-5′),
7.49 (br s, 2 H, H-2′ and H-6′), 8.18 (s, 1 H, CH), 8.51 (br s, 1 H, NH),
12.04 (br s, 1 H, NH).
Anal. Calcd for C15H15BrN6O: C, 48.01; H, 4.03; N, 22.40. Found: C,
47.90; H, 4.14; N, 22.28.
13C NMR (75 MHz, DMSO-d6): δ = 42.4 (CH2), 48.8 (CH2), 65.3 (CH2),
2
66.4 (CH2), 67.9 (C-4), 114.8 (d, JC-F = 22.0 Hz, C-3′ and C-5′), 115.6
3(5)-(3-Methylphenylamino)-5(3)-[(morpholinomethylene)ami-
no]-1H-pyrazole-4-carbonitrile (2i)
(C≡N), 117.4 (d, 3JC-F = 7.2 Hz, C-2′ and C-6′), 138.9 (d, 4JC-F = 1.4 Hz, C-
1
1′), 153.4 (d, JC-F = 261.2 Hz, C-4′), 154.2 (C-3), 155.0 (CH=N), 157.3
Yellow solid; yield: 267 mg (87%); mp 253–255 °C (MeCN).
(C-5).
IR (ATR): 3332 (N-H), 3163 (N-H), 2912 (C-H), 2202 (C≡N), 1614,
Anal. Calcd for C15H15FN6O: C, 57.32; H, 4.81; N, 26.74. Found: C,
57.26; H, 4.88; N, 26.69.
1533, 1435, 1269, 1115 cm–1
.
1H NMR (400 MHz, DMSO-d6): δ = 2.23 (s, 3 H, CH3), 3.46–3.49 (m, 2
H, CH2), 3.62–3.67 (m, 6 H, (CH2)3), 6.60 (d, 3J = 7.3 Hz, 1 H, H-4′), 7.06
(t, 3J = 7.8 Hz, 1 H, H-5′), 7.20–7.29 (m, 2 H, H-2′ and H-6′), 8.17 (s, 1 H,
CH), 8.37 (br s, 1 H, NH), 12.05 (br s, 1 H, NH).
13C NMR (75 MHz, DMSO-d6): δ = 21.4 (CH3), 42.5 (CH2), 48.9 (CH2),
65.4 (CH2), 66.5 (CH2), 68.6 (C-4), 113.4 (C-6′), 115.7 (C≡N), 116.6 (C-
2′), 120.0 (C-4′), 128.4 (C-5′), 137.5 (C-3′), 142.6 (C-1′), 151.7 (C-3),
155.0 (CH=N), 155.2 (C-5).
3(5)-(4-Chlorophenylamino)-5(3)-[(morpholinomethylene)ami-
no]-1H-pyrazole-4-carbonitrile (2f)
Yellow solid; yield: 301 mg (91%); mp 266–268 °C (MeOH).
IR (ATR): 3333 (N-H), 3144 (N-H) 2902 (C-H), 2199 (C≡N), 1615, 1532,
1450, 1272, 1115 cm–1
.
1H NMR (400 MHz, DMSO-d6): δ = 3.47–3.52 (m, 2 H, CH2), 3.63–3.67
3
(m, 6 H, (CH2)3), 7.22 (d, J = 9.0 Hz, 2 H, H-3′ and H-5′), 7.49 (d, 2 H,
Anal. Calcd for C16H18N6O: C, 61.92; H, 5.85; N, 27.08. Found: C, 61.85;
H, 5.91; N, 26.99.
3J = 8.2 Hz H-2′ and H-6′), 8.18 (s, 1 H, CH), 8.68 (br s, 1 H, NH), 12.12
(br s, 1 H, NH).
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F. P. Lim et al.
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Synthesis
3(5)-(4-Methylphenylamino)-5(3)-[(morpholinomethylene)ami-
no]-1H-pyrazole-4-carbonitrile (2j)
1H NMR (400 MHz, DMSO-d6): δ = 3.46–3.50 (m, 2 H, CH2), 3.62–3.66
(m, 6 H, (CH2)3), 3.67 (s, 3 H, CH3), 6.79 (d, 3J = 9.0 Hz, 2 H, H-3′ and H-
5′), 7.40 (br s, 2 H, H-2′ and H-6′), 8.16 (s, 1 H, CH), 8.23 (br s, 1 H, NH),
11.93 (br s, 1 H, NH).
13C NMR (75 MHz, DMSO-d6): δ = 42.4 (CH2), 48.8 (CH2), 55.1 (OCH3),
65.3 (CH2), 66.5 (CH2), 67.7 (C-4), 113.8 (C-3′ and C-5′), 115.8 (C≡N),
117.7 (C-2′ and C-6′), 136.1 (C-1′), 152.3 (C-3), 152.7 (C-4′), 154.9
(CH=N), 155.1 (C-5).
Yellow solid; yield: 271 mg (87%); mp 256–258 °C (i-PrOH).
IR (ATR): 3302 (N-H), 3140 (N-H), 2917 (C-H), 2220 (C≡N), 1621,
1538, 1417, 1265, 1112 cm–1
.
1H NMR (400 MHz, DMSO-d6): δ = 2.20 (s, 3 H, CH3), 3.46–3.48 (m, 2
3
H, CH2), 3.60–3.67 (m, 6 H, (CH2)3), 6.99 (d, J = 8.3 Hz, 2 H, H-3′ and
H-5′), 7.34 (br s, 2 H, H-2′ and H-6′), 8.17 (s, 1 H, CH), 8.33 (br s, 1 H,
NH), 12.01 (br s, 1 H, NH).
13C NMR (75 MHz, DMSO-d6): δ = 20.3 (CH3), 42.5 (CH2), 48.9 (CH2),
65.4 (CH2), 66.5 (CH2), 68.2 (C-4), 115.8 (C≡N), 116.2 (C-2′ and C-6′),
127.7 (C-4′), 128.9 (C-3′ and C-5′), 140.2 (C-1′), 151.9 (C-3), 155.0
(CH=N), 155.2 (C-5).
Anal. Calcd for C16H18N6O2: C, 58.88; H, 5.56; N, 25.75. Found: C,
58.80; H, 5.62; N, 25.69.
3(5)-(2-Ethoxyphenylamino)-5(3)-[(morpholinomethylene)ami-
no]-1H-pyrazole-4-carbonitrile (2n)
Yellow solid; yield: 316 mg (93%); mp 219–220 °C (MeCN).
Anal. Calcd for C16H18N6O: C, 61.92; H, 5.85; N, 27.08. Found: C, 61.80;
H, 5.98; N, 26.95.
IR (ATR): 3427 (N-H), 3181 (N-H), 2974 (C-H), 2193 (C≡N), 1625,
1556, 1445, 1246, 1114 cm–1
.
3(5)-(4-Ethylphenylamino)-5(3)-[(morpholinomethylene)amino]-
1H-pyrazole-4-carbonitrile (2k)
1H NMR (400 MHz, DMSO-d6): δ = 1.38 (t, 3J = 6.9 Hz, 3 H, CH3), 3.47–
3.49 (m, 2 H, CH2), 3.63–3.68 (m, 6 H, (CH2)3), 4.12 (q, 3J = 7.0 Hz, 2 H,
CH2), 6.81 (td, 4J = 1.8, 3J = 7.7 Hz, 1 H, H-3′), 6.86 (td, 4J = 1.5, 3J = 7.6
Hz, 1 H, H-5′), 6.93 (br s, 1 H, H-4′), 6.97 (dd, 4J = 1.6, 3J = 7.8 Hz, 1 H,
H-6′), 7.83 (br s, 1 H, NH), 8.18 (s, 1 H, CH), 12.15 (br s, 1 H, NH).
13C NMR (75 MHz, DMSO-d6): δ = 14.7 (CH3), 42.5 (CH2), 48.9 (CH2),
64.0 (OCH2), 65.3 (CH2), 66.4 (CH2), 68.4 (C-4), 111.4 (C-3′), 115.2
(C≡N), 115.2 (C-6′), 119.8 (C-4′), 120.7 (C-5′), 131.0 (C-1′), 145.6 (C-
2′), 151.5 (C-3), 154.7 (C-5), 155.1 (CH=N).
Yellow solid; yield: 278 mg (86%); mp 268–270 °C (i-PrOH).
IR (ATR): 3329 (N-H), 3132 (N-H), 2925 (C-H), 2202 (C≡N), 1618,
1534, 1420, 1269, 1115 cm–1
.
1H NMR (400 MHz, DMSO-d6): δ = 1.14 (t, 3J = 7.6 Hz, 3 H, CH3), 2.50
3
(q, J = 7.6 Hz, 2 H, CH2), 3.46–3.48 (m, 2 H, CH2), 3.60–3.67 (m, 6 H,
(CH2)3), 7.02 (d, 3J = 8.4 Hz, 2 H, H-3′ and H-5′), 7.36 (br s, 2 H, H-2′
and H-6′), 8.17 (s, 1 H, CH), 8.34 (br s, 1 H, NH), 12.01 (br s, 1 H, NH).
Anal. Calcd for C17H20N6O2: C, 59.99; H, 5.92; N, 24.69. Found: C, 59.93
H, 6.03; N, 24.62.
13C NMR (75 MHz, DMSO-d6): δ = 15.9 (CH3), 27.4 (CH2), 42.4 (CH2),
48.8 (CH2), 65.3 (CH2), 66.5 (CH2), 68.2 (C-4), 115.7 (C≡N), 116.3 (C-2′
and C-6′), 127.7 (C-3′ and C-5′), 134.4 (C-4′), 140.4 (C-1′), 151.9 (C-3),
155.0 (CH=N), 155.1 (C-5).
3(5)-(4-Ethoxyphenylamino)-5(3)-[(morpholinomethylene)ami-
no]-1H-pyrazole-4-carbonitrile (2o)
Anal. Calcd for C17H20N6O: C, 62.95; H, 6.21; N, 25.91. Found: C, 62.90;
H, 6.24; N, 25.86.
Greenish-yellow solid; yield: 290 mg (85%); mp 231–233 °C (MeCN).
IR (ATR): 3298 (N-H), 3098 (N-H), 2963 (C-H), 2218 (C≡N), 1622,
1538, 1422, 1233, 1112 cm–1
.
3(5)-(2-Methoxyphenylamino)-5(3)-[(morpholinomethylene)ami-
no]-1H-pyrazole-4-carbonitrile (2l)
1H NMR (400 MHz, DMSO-d6): δ = 1.29 (t, 3J = 7.0 Hz, 3 H, CH3), 3.46–
3.48 (m, 2 H, CH2), 3.62–3.67 (m, 6 H, (CH2)3), 3.94 (q, 3J = 7.0 Hz, 2 H,
CH2), 6.78 (d, 3J = 9.0 Hz, 2 H, H-3′ and H-5′), 7.38 (br s, 2 H, H-2′ and
H-6′), 8.16 (s, 1 H, CH), 8.21 (br s, 1 H, NH), 11.92 (br s, 1 H, NH).
13C NMR (75 MHz, DMSO-d6): δ = 14.7 (CH3), 42.4 (CH2), 48.7 (CH2),
63.0 (OCH2), 65.3 (CH2), 66.4 (CH2), 67.6 (C-4), 114.4 (C-3′ and C-5′),
115.7 (C≡N), 117.6 (C-2′ and C-6′), 135.9 (C-1′), 151.9 (C-3), 152.2 (C-
4′), 154.8 (CH=N), 155.0 (C-5).
Yellow solid; yield: 268 mg (82%); mp 264–266 °C (MeCN).
IR (ATR): 3419 (N-H), 3170 (N-H), 2915 (C-H), 2206 (C≡N), 1617,
1541, 1434, 1247, 1109 cm–1
.
1H NMR (400 MHz, DMSO-d6): δ = 3.47–3.49 (m, 2 H, CH2), 3.63–3.67
(m, 6 H, (CH2)3), 3.87 (s, 3 H, CH3), 6.83 (td, 4J = 1.9, 3J = 7.1 Hz, 1 H, H-
3′), 6.87 (td, 4J = 1.8, 3J = 7.1 Hz, 1 H, H-5′), 6.95 (br s, 1 H, H-4′), 6.98
(dd, 4J = 1.9, 3J = 7.5 Hz, H-6′), 7.82 (br s, 1 H, NH), 8.18 (s, 1 H, CH),
12.15 (br s, 1 H, NH).
13C NMR (75 MHz, DMSO-d6): δ = 42.5 (CH2), 48.9 (CH2), 55.7 (OCH3),
65.3 (CH2), 66.4 (CH2), 68.5 (C-4), 110.3 (C-3′), 115.2 (C≡N), 115.3 (C-
6′), 119.8 (C-4′), 120.6 (C-5′), 130.9 (C-1′), 146.6 (C-2′), 151.4 (C-3),
154.8 (C-5), 155.1 (CH=N).
Anal. Calcd for C17H20N6O2: C, 59.99; H, 5.92; N, 24.69. Found: C, 59.86
H, 6.12; N, 24.54.
3(5)-[3-(Trifluoromethyl)phenylamino]-5(3)-[(morpholinometh-
ylene)amino]-1H-pyrazole-4-carbonitrile (2p)
Yellow solid; yield: 285 mg (78%); mp 235–237 °C (MeCN).
Anal. Calcd for C16H18N6O2: C, 58.88; H, 5.56; N, 25.75. Found: C,
58.76; H, 5.63; N, 25.67.
IR (ATR): 3332 (N-H), 3113 (N-H), 2978 (C-H), 2205 (C≡N), 1610,
1537, 1434, 1235, 1100 cm–1
.
3(5)-(4-Methoxyphenylamino)-5(3)-[(morpholinomethylene)ami-
no]-1H-pyrazole-4-carbonitrile (2m)
1H NMR (400 MHz, DMSO-d6): δ = 3.48–3.55 (m, 2 H, CH2), 3.64–3.68
(m, 6 H, (CH2)3), 7.11 (d, 1 H, 3JH-F = 7.6 Hz, H-4′), 7.42 (t, 1 H, 3JH-F = 8.0
Hz, H-5′), 7.71 (d, 1 H, 3JH-F = 8.1 Hz H-6′), 7.99 (s, 1 H, H-2′), 8.20 (s, 1
H, CH), 8.99 (br s, 1 H, NH), 12.22 (br s, 1 H, NH).
Yellow solid; yield: 286 mg (88%); mp 224–226 °C (MeCN).
IR (ATR): 3301 (N-H), 3140 (N-H), 2959 (C-H), 2216 (C≡N), 1619,
13C NMR (75 MHz, DMSO-d6): δ = 42.5 (CH2), 48.9 (CH2), 65.3 (CH2),
1538, 1463, 1227, 1109 cm–1
.
66.5 (CH2), 68.5 (C-4), 112.0 (q, 3JC-F = 4.0 Hz, C-2′), 115.3 (C≡N), 115.3
3
1
(q, JC-F = 3.3 Hz, C-4′), 119.6 (C-6′), 124.4 (q, JC-F = 272.1 Hz, CF3),
2
129.4 (q, JC-F = 31.1 Hz, C-3′), 129.5 (C-5′), 143.2 (C-1′), 151.1 (C-3),
155.1 (CH=N), 155.4 (C-5).
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2015, 47, A–F

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F. P. Lim et al.
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Synthesis
Anal. Calcd for C16H15F3N6O: C, 52.75; H, 4.15; N, 23.07. Found: C,
52.58; H, 4.24; N, 22.92.
(9) (a) Cheng, K.-M.; Huang, Y.-Y.; Huang, J.-J.; Kaneko, K.; Kimura,
M.; Takayama, H.; Juang, S.-H.; Wong, F. F. Bioorg. Med. Chem.
Lett. 2010, 20, 6781. (b) Wen, K.-S.; Lin, H.-Y.; Huang, Y.-Y.;
Kaneko, K.; Takayama, H.; Kimura, M.; Juang, S.-H.; Wong, F. F.
Med. Chem. Res. 2012, 21, 3920.
(10) (a) Smurnyy, Y.; Toms, A. V.; Hickson, G. R.; Eck, M. J.; Eggert, U.
S. ACS Chem. Biol. 2010, 5, 1015. (b) Eggert, U. S.; Kiger, A. A.;
Richter, C.; Perlman, Z. E.; Perrimon, N.; Mitchison, T. J.; Field, C.
M. PLoS Biol. 2004, 2, e379.
(11) (a) Kalinin, D. V.; Kalinina, S. A.; Dolzhenko, A. V. Heterocycles
2013, 87, 147. (b) Wang, L.-Y.; Uramaru, N.; Wong, F. F. Tetrahe-
dron 2014, 70, 7439. (c) Bogza, S. D.; Ivanov, A. V.; Dulenko, V. I.;
Kobrakov, K. I. Chem. Heterocycl. Compd. 1997, 33, 69.
(12) Chang, C.-H.; Tsai, H. J.; Huang, Y.-Y.; Lin, H.-Y.; Wang, L.-Y.; Wu,
T.-S.; Wong, F. F. Tetrahedron 2013, 69, 1378.
Acknowledgment
This work is supported by the Ministry of Higher Education, Malaysia
under the Fundamental Research Grant Scheme (FRGS) and by a seed
grant from the Infection and Immunity Cluster of the Tropical Medi-
cine, Biology and Genomics Platform (Monash University Malaysia).
The authors are grateful for the OIDD screening data supplied courte-
sy of Eli Lilly and Company, and which are reported with permission.
Supporting Information
(13) Luo, Y.; Zhong, P.; Zhang, X. H.; Lin, Q. L.; Chen, Y. N. Chin. Chem.
Lett. 2008, 19, 383.
Supporting information for this article is available online at
http://dx.doi.org/10.1055/s-0035-1561616.
S
u
p
p
ortioInfgrmoaitn
S
u
p
p
ortiInfogrmoaitn
(14) Taylor, E. C.; Ehrhart, W. A. J. Org. Chem. 1963, 28, 1108.
(15) Sadek, K. U.; Alnajjar, A.; Mekheimer, R. A.; Mohamed, N. K.;
Mohamed, H. A. Green Sustainable Chem. 2011, 1, 92.
(16) Patil, D. R.; Dalal, D. S. Chin. Chem. Lett. 2012, 23, 1125.
(17) Lin, C.-H.; Tsai, C.-H.; Chang, H.-C. Catal. Lett. 2005, 104, 135.
(18) Sheykhan, M.; Mohammadquli, M.; Heydari, A. J. Mol. Struct.
2012, 1027, 156.
(19) Khaksar, S.; Heydari, A.; Tajbakhsh, M.; Vahdat, S. M. J. Fluorine
Chem. 2010, 131, 1377.
(20) Azizi, N.; Gholibeglo, E.; Babapour, M.; Ghafuri, H.;
Bolourtchian, S. M. C. R. Chim. 2012, 15, 768.
(21) Dar, B. A.; Ahmad, S. N.; Wagay, M. A.; Hussain, A.; Ahmad, N.;
Bhat, K. A.; Khuroo, M. A.; Sharma, M.; Singh, B. Tetrahedron
Lett. 2013, 54, 4880.
(22) Hollo, B.; Leovac, V. M.; Bombicz, P.; Kovacs, A.; Jovanovic, L. S.;
Bogdanovic, G.; Kojic, V.; Divjakovic, V.; Joksovic, M. D.;
Szecsenyi, K. M. Aust. J. Chem. 2010, 63, 1557.
(23) Balog, J.; Riedl, Z.; Hajos, G. Tetrahedron Lett. 2013, 54, 5338.
(24) Huang, Q.; Richardson, P. F.; Sach, N. W.; Zhu, J.; Liu, K. K. C.;
Smith, G. L.; Bowles, D. M. Org. Process Res. Dev. 2011, 15, 556.
(25) Tominaga, Y.; Honkawa, Y.; Hara, M.; Hosomi, A. J. Heterocycl.
Chem. 1990, 27, 775.
(26) Alvim-Gaston, M.; Grese, T.; Mahoui, A.; Palkowitz, A. D.;
Pineiro-Nunez, M.; Watson, I. Curr. Top. Med. Chem. 2014, 14,
294.
References
(1) Dunn, P. J. In Comprehensive Organic Functional Group Transfor-
mations II; Vol. 5; Katritzky, A. R.; Taylor, R. J. K., Eds.; Elsevier:
Amsterdam, 2005, 655–699.
(2) (a) Czyz, M.; Szulawska, A.; Bednarek, A. K.; Duechler, M. Bio-
chem. Pharmacol. 2005, 70, 1431. (b) Szulawska, A.; Arkusinska,
J.; Czyz, M. Biochem. Pharmacol. 2007, 73, 175. (c) Jakubowska,
J.; Wasowska-Lukawska, M.; Czyz, M. Eur. J. Pharmacol. 2008,
596, 41. (d) Jin, Z.; El-Deiry, W. S. Cancer Biol. Ther. 2005, 4, 139.
(3) Krawczyk, M.; Wasowska-Lukawska, M.; Oszczapowicz, I.;
Boguszewska-Chachulska, A. M. Biol. Chem. 2009, 390, 351.
(4) Balog, J.; Riedl, Z.; Hajos, G.; Miskolczy, Z.; Biczok, L. Tetrahedron
Lett. 2011, 52, 5264.
(5) (a) Diaz, D. D.; Lewis, W. G.; Finn, M. G. Synlett 2005, 2214.
(b) Porcheddu, A.; Giacomelli, G.; Piredda, I. J. Comb. Chem.
2009, 11, 126. (c) Diaz, D. D.; Finn, M. G. Chem. Commun. 2004,
2514.
(6) (a) Han, Y.; Cai, L. Tetrahedron Lett. 1997, 38, 5423. (b) Cai, L.;
Han, Y.; Ren, S.; Huang, L. Tetrahedron 2000, 56, 8253.
(7) Kwak, S. H.; Gong, Y.-D. Tetrahedron 2013, 69, 7107.
(8) Mekhalfia, A.; Mutter, R.; Heal, W.; Chen, B. Tetrahedron 2006,
62, 5617.
(27) Ouyang, W.; Kolls, J. K.; Zheng, Y. Immunity 2008, 28, 454.
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2015, 47, A–F