Utilization of 2-ethoxymethylene-3-oxobutanenitrile in the synthesis of heterocycles possessing biological activity

Article abstract of DOI:10.1016/j.tet.2005.03.066

2-Ethoxymethylene-3-oxobutanenitrile is a versatile trifunctional reagent that allows the introduction of a three-carbon moiety to amine-substrates. The reaction of the title compound with hydrazines has been studied leading to appropriate substituted pyrazoles 4-11. Reactions with other dinitrogen nucleophiles were studied giving access to a set of fused pyrimidines 13. All types of compounds displayed biological activity against bacteria, filamentous fungi and tumour HeLa cells, but not for yeasts. Pyrazole 10 and pyrimidine 13d have been found to possess the broadest activity.

Full text of DOI:10.1016/j.tet.2005.03.066

Tetrahedron 61 (2005) 5379–5387
Utilization of 2-ethoxymethylene-3-oxobutanenitrile in the
synthesis of heterocycles possessing biological activity
b,
c
Petra Cernuchova,a,b Giang Vo-Thanh,b Viktor Milata,a, Andre Loupy, Sona Jantova
ˇ
*
c
*
´
´
ˇ
´
´
and Marica Theiszova
a
´
Department of Organic Chemistry, Faculty of Chemical and Food Technology, Slovak Technical University, Radlinskeho 9, SK-812 37
Bratislava, Slovak Republic
bLaboratory of Selective Reactions on Supports, ICMMO, CNRS UMR 8615, Building 410, Paris-South University, 914 05 Orsay-Cedex, France
c
´
Department of Biochemistry and Microbiology, Faculty of Chemical and Food Technology, Slovak Technical University, Radlinskeho 9,
SK-812 37 Bratislava, Slovak Republic
Received 21 December 2004; revised 9 March 2005; accepted 17 March 2005
Available online 11 April 2005
Abstract—2-Ethoxymethylene-3-oxobutanenitrile is a versatile trifunctional reagent that allows the introduction of a three-carbon moiety to
amine-substrates. The reaction of the title compound with hydrazines has been studied leading to appropriate substituted pyrazoles 4–11.
Reactions with other dinitrogen nucleophiles were studied giving access to a set of fused pyrimidines 13. All types of compounds displayed
biological activity against bacteria, filamentous fungi and tumour HeLa cells, but not for yeasts. Pyrazole 10 and pyrimidine 13d have been
found to possess the broadest activity.
q 2005 Elsevier Ltd. All rights reserved.
1. Introduction
Pyrazoles,1–3 pyrimidines4–7 and [1,2,4]triazolo[1,5-a]pyr-
imidines8 have been the subject of chemical and biological
studies due to their interesting pharmacology including
antipyretic,9,10 analgesic,11 antiinflammatory,12 potential
herbicidal,13 fungicidal14,15 and leishmanicidal16,17 proper-
ties. Diethyl ethoxymethylenemalonate (EMME) is an
attractive building block for the synthesis of biologically
relevant heterocyclic or carbocyclic compounds.18–20 Pyra-
zolones can be efficiently prepared by reaction of EMME
with aryl and benzylhydrazines.21 Pyrimidines and triazines
could be easily accessed by reaction of EMME with
aliphatic or aromatic amidines.22 Stimulated by these
findings, we report here on the application of (E)-2-
ethoxymethylene-3-oxobutanenitrile 1, a synthetic equival-
ent of EMME, where the two ester groups were replaced by
ketone and nitrile moieties. The E geometry of 1 was
confirmed by NMR studies. Full characterization of 1H–13C
2. Results and discussion
2.1. Chemistry
The preparation of 2-ethoxymethylene-3-oxobutanenitrile 1
was described earlier by our laboratory.18a,19a In situ
prepared 3-oxobutanenitrile reacted with 3 equiv of triethyl
orthoformate and a catalytic amount of acetic anhydride to
give 1 in good yields (Scheme 1).
1
shifts as well as H–13C coupling constant was recently
reported by our laboratory.23
Scheme 1.
2.2. Reaction of 1 with hydrazines
Keywords: Pyrazoles; Pyrimidines; Biological activity; Aminobenzothia-
zole; Aminobenzimidazole.
Reaction of 1 with various hydrazines can give at least four
different types of pyrazoles, depending on:
*
Corresponding authors. Tel.: C33 1 69 15 7650; fax: C33 1 69 15 4679;
e-mail addresses: viktor.milata@stuba.sk; aloupy@icmo.u-psud.fr
0040–4020/$ - see front matter q 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2005.03.066

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P. Cernuchova et al. / Tetrahedron 61 (2005) 5379–5387
5380
be detected. The structural distinction between 4,5- and 3,4-
disubstituted pyrazoles 5–8 is based on the variation in
chemical shifts Dd (1H NMR) between solvents of different
polarity (CDCl3 and DMSO-d6). As already reported in the
literature,25–27 this variation for the ring proton H5 of
pyrazole (DdZ1.03 ppm) is clearly more important than for
H3 (DdZ0.32 ppm). On the other hand, careful recrystalli-
sation of pyrazole 5 allowed its analysis by X-ray
diffraction, confirming our previous structural assignments
(Fig. 1).
(i) which one of the nitrogens of hydrazine is implied in the
addition–elimination reaction (way a or b).
(ii) which one of the withdrawing groups (CN or COMe)
reacts during the subsequent intramolecular cyclization
when R0ZH (way c or d) (Scheme 2).24
The main results obtained by reacting 1 with various
substituted hydrazines are given in Table 1 (Scheme 3).
Reactions of 1 with hydrazines under solvent-free con-
ditions were conducted at room temperature for 10 min. On
the other hand, when the starting hydrazines were used as
their hydrochlorides, the reactions were carried out in
refluxing ethanol in the presence of triethylamine. We thus
obtained pyrazoles in all cases (4–11) except for the reaction
of disubstituted hydrazines which led to non-cyclized
products 2 and 3 resulting from attack via pathway a.
In the case of the reaction with methylhydrazine, all the four
possible pyrazoles 5–8 were obtained. They were separated
by column chromatography, except the compound 6 which
could not be isolated as a pure substance. The ratio 5:6Z
73:27 was evaluated by GC-MS and confirmed by 1H NMR
analysis of the crude reaction mixture. Traces of 7 and 8
were successfully isolated and their structures were
attributed by NMR spectra.
Figure 1. X-ray diagram of compound 5.
In all other cases, only products, resulting from addition–
elimination of the primary amino group of hydrazine on 1
(pathway a, Scheme 2), have been detected. Distinction of
the reacting group (pathway c or d, Scheme 2) was based
on the 13C NMR spectra and IR analysis, where the presence
or the absence of the signal for cyano or acetyl groups could
The intermediates resulting from the addition–elimination
reaction (pathway a) were isolated only in the case of
pentafluorophenylhydrazine. After 15 min in refluxing
ethanol, the two isomeric enhydrazines 11a (Z and E)
were observed in a 64:36 ratio as precipitates in the reaction
Scheme 2.
Table 1. Reaction of 1 with hydrazines
R0
R
Conditions
Temperature (8C)
Time (min)
Products (yields%)a
Ph
Me
H
Me
t-Bu
Ph
Ph
Me
H
H
H
HCl, Et3N/EtOH
Solvent-free
Solvent-free
Solvent-free
HCl, Et3N/EtOH
Solvent-free
EtOH
78
25
25
25
78
25
78
25
10
10
10
25
10
240
2 (80)
3 (84)
4 (84)
5 (52), 6 (32)b, 7 (2), 8 (4)
9 (61)
H
H
10 (83)
11 (79)
C6F5
a Yields in isolated products.
b Yields determined by GC and H NMR of the crude reaction mixture.
1

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5381
Scheme 3.
mixture. Two pairs of NH-proton signals confirmed the fact
that the primary amino group is the most reactive (Scheme
2, pathway a) (major isomer: 9.03, 8.14, 8.01, 2.21 ppm;
minor isomer: 10.81, 10.38, 8.88, 2.31 ppm). By extending
the reaction time up to 4 h, the cyclic product 11 was
obtained in satisfactory yield (79%).
On the other hand, when reactions were carried out between
N,N-disubstituted hydrazines and 1, only enhydrazines 2
and 3 with the Z geometry were obtained. The
stereochemistry of the double bond is presumably due
to the formation of a hydrogen bond between the NH
group and the carbonyl function which stabilizes for Z
conformation. This was in fact confirmed by NMR
analysis. The presence of a doublet with a coupling
constant about 11 Hz indicates the antiperiplanar
position between H of the amino group and ethylenic
Scheme 4.
toluene gave the bicyclic triazolo-pyrimidine 15 in 78%
yield. On the other side, the cyclization in the case of 4-
amino-1,2,4-triazole did not occur and only the product of
addition–elimination reaction 14 was isolated in 91% yield.
This behaviour is due to the absence of a nitrogen atom in
position 3 on the triazole ring which is necessary for
cyclization (Scheme 5).
3
H. The J coupling constant about 5.2 Hz, measured by
13C NOE NMR clearly shows, on the other hand, the Z
geometry of the ethylenic H and the cyano group.
Moreover, the stereochemistry in the mechanism of
nucleophilic vinylic substitution was confirmed by
quantum chemical calculations.28
2.3. Reaction of 1 with amidines
We also wish to report a simple method for preparing a set
of 2-aryl-5-cyano-4-methylpyrimidines, by reacting a series
of arylamidines 12a–d with 1 (Scheme 4).
It is worth noting that this reaction was quite sensitive to the
stochiometry of the substrates. An excess of arylamidine
hydrochloride (2 equiv) and triethylamine (4 equiv) was
necessary to ensure that the pyrimidines 13a–d were
obtained in good yields (Table 2).
2.4. Reaction of 1 with aminotriazoles
The reaction of 1 with 3-amino-1,2,4-triazole in boiling
Scheme 5.

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5382
Table 2. Influence of the relative amount of the substrates during the
reaction of 1 with 12a–d
microorganisms available in the department of Biochem-
istry and Microbiology, Slovak University of Technology)
were used. The cytotoxic activity of the prepared derivatives
was studied on the transformed tumor cell line HeLa. The
compounds were used at concentrations of 150, 100, 50, 10,
1 and 0.1 mg/L. Chromatographically pure derivatives were
dissolved in DMSO whose final concentration never
exceeded 1% (v/v) in either control or treated samples.
Compound 13
Yield 13 (%)a Ratio 1: 12: Et3N
1:1:2
1:2:4
a
b
c
56
52
50
65
72 (67)
66 (60)
76 (70)
98 (92)
d
a Yields in crude product, isolated yields are given in brackets.
Antibacterial assay. The antibacterial effect has been
assayed by a microdilution method in 96-well microtitration
plates.29 The bacteria were cultivated on Mu¨ller–Hinton
medium at 30 8C. An overnight inoculum was prepared 12–
16 h before the test. The growing inoculum was filtered and
a 1.5% suspension of bacteria was prepared for the
experiments. This suspension (180 mL) was added to
20 mL of the tested complex solution and cultured for 6 h
on a reciprocal shaker in a thermostat at 30 8C. The time
course of absorbance (A630) has been then determined in
three parallel runs. To compare the antimicrobial activity,
ampicillin at concentrations of 100, 50, 10, 1, and 0.1 mg/L
and amphothericine at concentrations of 250, 150, 100, 50,
10, 1 and 0.1 mg/L have been used as standard.
2.5. Reaction of 1 with heteroarylamines
Finally, the reactivity of 1 was studied in the addition–
elimination reaction with aminopyridine derivatives, ani-
line, aminobenzothiazole and aminobenzimidazole
(Scheme 6). In the case of 2-aminobenzimidazole (two
hydrogen atoms are present on the amino group and one on
the cycle), condensed pyrimidines 20 were obtained. If only
two hydrogen atoms are present on amino group, the
cyclization producing fused product did not occur and only
addition–elimination products 16a–d and 19 were isolated.
Satisfactory yields (81–88%) were obtained within a very
short reaction time (2–10 min) at 70–80 8C.
Aniline produced the corresponding anilinomethylene
derivative 17 which could be cyclized using aluminum
chloride to 1-(4-aminoquinolin-3-yl)-ethanone 18.
Effects on yeasts. The yeasts have been cultivated on
Sabourand-glucose medium at 28 8C.30 7 mL of culture
medium have been inoculated with 0.5 mL of culture
growing overnight and 75 mL solution of the tested
compounds. The cultures of yeasts were then cultured for
6 h on a reciprocal shaker in a thermostat at 28 8C. The A650
of triplicate sets of tubes were measured at 2 h intervals.
3. Biological activity
3.1. Materials and methods
Antifungal assay. The effect on filamentous fungi was tested
during static culturing. 0.05 mL DMSO solution of the
tested compounds has been added into petri dishes (diameter
50 mm) immediately before pouring 5 mL of Sabourand-
glucose agar to obtain desired concentrations of inhibitors.
The solidified plates were then inoculated in the center with
5 mL of the spore suspension. Triplicate sets of agar plates
Materials. Bacterial strains Escherichia coli CCM 3988,
Pseudomonas aeruginosa CCM 3955, Bacillus subtilis
CCM 1718, Staphylococcus aureus CCM 3953, the yeasts
Candida albicans 1696, Candida parapsilosis and the
filamentous fungi Rhizopus oryzae, Mucor sp., Aspergillus
niger CCM F-237 (obtained from the collection of
Scheme 6.

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P. Cernuchova et al. / Tetrahedron 61 (2005) 5379–5387
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5383
were incubated at 25 8C and the diameter of growing
colonies was measured at intervals.
was higher than that of GK bacteria. None of the derivatives
influenced the GK Pseudomonas aeruginosa and the tested
yeasts. Most effective against filamentous fungi were
derivatives 19, 13d, 10 and 2, as IC50 values have been
lower than for amphotericin.
The antimicrobial effect was determined by IC50 values, i.e.
the minimal concentration of a substance which inhibits
bacterial, yeast and fungal growth by 50% relative to the
control, and MIC values, i.e. the minimal concentration of a
substance which totally inhibits the bacterial, yeast and
fungal growth. The IC50 and MIC values have been
determined from toxicity curves.
The cytotoxic activities of the tested derivatives were
studied on human tumour cell line HeLa. The compound
13d (IC50Z11.9 mg/L) has manifested the highest activity.
A certain effect was demonstrated by derivatives 13a, 19,
13b, 10 and 9, their values were IC100%100 mg/L. The
other tested molecules were inactive.
Cytotoxic assay. A three-day culture of HeLa cells has been
trypsinized and than used to prepare a suspension with
concentration 5.0!104 cells/200 mL. The experiments have
been carried out in 96-well plates into which 200 mL/well of
the above-mentioned suspension were pipetted. After 24 h
of static culturing at 37 8C, the culture medium has been
emptied and then was added 200 mL of medium containing
the appropriate concentration of test derivatives. After 48 h,
the intensity of growth of the HeLa cells has been evaluated
using the Kenacid blue assay31 determination of the total
cell protein content. The cytotoxic activity of the tested
derivatives was determined from the inhibitory concen-
trations IC50 and IC100 (i.e., such concentration of a
derivative which, in comparison to the control, inhibited
the contents of total cell proteins by 50 or 100%,
respectively) which were read from the toxicity curves.
There is no clear relation between structure and biological
activity of the studied compounds. Represented were almost
all of pyrimidines (3 from 4 synthesized), two pyrazoles and
four enaminonitriles, one of them possessing 2-aminoben-
zothiazole moiety. The most potent compounds against
bacteria, filamentous fungi and HeLa cells are 13d—
containing two potentially biologically active sub-units: a
nitro group in position 3 on the phenyl ring and pyrimidine
one, and the second, 10 bears a pyrazole ring, which could
explain the results we obtained.
5. Conclusion
2-Ethoxymethylene-3-oxobutanenitrile 1 represents a very
versatile and reactive group of enol ethers which can be
widely used in the synthesis of heterocycles. Its reaction
with hydrazines or amidines led to new pyrazolic or
pyrimidinic compounds. Reactions with other dinitrogen
nucleophiles gave access to fused pyrimidines. All these
products as well as some intermediates have been tested for
biological activities against bacteria, filamentous fungi,
yeasts and tumor HeLa cells. Compounds 10 and 13d
displayed the broadest biological activity, 2 and 10 are the
more active against fungi in some cases like standard
Amphotericin used.
4. Results and discussion
The biological activities of the tested derivatives against
selectedorganisms(IC50 andMIC)are summarizedinTable3.
The widest antimicrobial activity has been manifested by
the derivative 13d, which was effective against bacteria
Bacillus subtilis, Staphylococcus aureus and with filamen-
tous fungi Aspergillus niger (IC50Z150 mg/L for B. subtilis
and S. aureus and IC50Z50 mg/L for A. niger). The
broadest antibacterial effect was found with derivatives
13b and 16c, which was effective against GC and GK
bacteria (IC50Z150 mg/L for B. subtilis and S. aureus and
IC50Z100 mg/L or 150 mg/L for E. coli). The derivative
13d influenced GC Bacillus subtilis and Staphylococcus
aureus (IC50Z150 mg/L). A certain antibacterial effect on
GC was demonstrated for derivatives 10, 3 and 9, which
were effective against bacteria Bacillus subtilis (IC50Z
150 mg/L). The sensitivity of GC bacteria to the derivatives
6. Experimental
Melting points were measured with a Kofler bank. NMR
spectra were recorded in CDCl3 or DMSO-d6. H NMR
1
spectra were recorded at 200, 250 or 300 MHz. Chemical
shifts (d) are reported in ppm relative to TMS as internal
standard. J values are given in Hz. 13C NMR spectra were
Table 3. Biological activity of the tested derivatives (IC50, mg/l)a
Compound
B. subtilis
S. aureus
E. coli
P. aeruginosa
Rhizopus oryzae
Mucor sp.
Aspergillus niger
HeLa
2
3
9
10
13a
13b
13d
16c
19
Ampicillin
Amphotericin
150
150
150
O150
O150
O150
O150
O150
O150
O150
O150
O150
O100
—
O100
100
O100
O100
O100
84
O100
O100
O100
—
24.8
100
O100
O100
O100
150
O100
O100
O100
50
O100
O100
O100
O100
O100
—
O100
100
100
100
65.1
100
11.9
O100
100
—
O150
O150
150
150
150
O150
150
150
0.7
—
O150
O150
150
O150
O150
O150
100
O150
O150
O150
O150
0.28
150
O150
O150
O150
O150
0.015
—
24.8
O100
O100
—
—
182.9
250
152.5
—
a The values IC50 of other derivatives tested were higher than 150 mg/L. All derivatives were inactive on the yeasts Candida albicans and Candida
parapsilosis.

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5384
recorded at 75, 62.5 or 50 MHz, respectively. IR spectra
were registered on a FT-IR Perkin–Elmer instrument. X-ray
data recordings at room temperature were obtained with a
Bruker-AXS X8-Apex2 area detector diffractometer using
yellowish crystals. Mp 141–142 8C (lit.32: 142 8C). 1H NMR
(300 MHz, CDCl3) d 2.50 (s, 3H), 7.86 (s, 1H); 13C NMR
(75 MHz, CDCl3) d 11.0, 91.9, 113.7, 139.4, 148.4; IR
(cmK1): n~Z3197, 3163, 3119, 3059, 2878, 2235, 1597,
1570, 1519, 1445; Anal. Calcd. for C5H5N3: C, 56.07; H,
4.71; N, 39.23; Found C, 55.57; H, 4.76; N, 39.42.
˚
graphite-monochromated Mo Ka radiation (0.71073 A).
Crystallographic data for the structure reported have been
deposited in the Cambridge Crystallographic Data Center
(CCDC 252735).33 TLC was carried out with 0.2 mm thick
silica gel plates (GF254). Visualisation was accomplished by
UV light or phosphomolybdic acid solution or KMnO4
stain. The columns were hand packed with silica gel 60
(200–300 mesh).
6.1.4. 1,5-Dimethyl-1H-pyrazole-4-carbonitrile 5. Purifi-
cation by flash chromatography (hexane/AcOEtZ9/1) gave
5 (0.63 g, 52%) as colorless crystals. Mp 80 8C. H NMR
1
(200 MHz, CDCl3) d 2.36 (s, 3H), 3.76 (s, 3H), 7.58 (s, 1H);
1H NMR (200 MHz, DMSO-d6) d 2.38 (s, 3H), 3.78 (s, 3H),
7.89 (s, 1H); Dd (DMSO-d6 CDCl3)Z0.31 ppm; 13C NMR
(50 MHz, CDCl3) d 10.3, 36.8, 91.8, 114.0, 140.6, 144.9; IR
(cmK1): n~Z3117, 2952, 2228, 1549, 1505, 1451; Anal.
Calcd. for C6H7N3: C, 59.49; H, 5.82; N, 34.69; Found C,
59.29; H, 5.86; N, 34.53.
All reagents and solvents were purchased from commercial
sources (Acros or Aldrich) and were used without any
further purification.
6.1. General procedure for the reaction of 1 with
hydrazines
6.1.5. 1-(5-Amino-1-methyl-1H-pyrazol-4-yl)-ethanone
7. Purification by flash chromatography (AcOEt) gave 7
(30 mg, 2%) as colorless crystals. 1H NMR (300 MHz,
CDCl3) d 2.34 (s, 3H), 3.61 (s, 3H), 5. 57 (s, 1H), 7.59 (s,
1H); 1H NMR (300 MHz, DMSO-d6) d 2.20 (s, 3H), 3.50 (s,
3H), 6.63 (s, 1H), 7.65 (s, 1H); 13C NMR (75 MHz, CDCl3)
d 27.0, 33.7, 106.3, 139.4, 149.0, 192.7.
Method A (compounds 3–8, 10). Hydrazine derivative
(10 mmol) was added to compound 1 (1.39 g, 10 mmol)
and the mixture was stirred at room temperature for 10 min.
After evaporation of EtOH formed during the reaction, the
residue was purified by flash chromatography or
recrystallized.
6.1.6. 1-(3-Amino-1-methyl-1H-pyrazol-4-yl)-ethanone
8. Purification by flash chromatography (AcOEt) gave 8
(60 mg, 4%) as colorless crystals, 1H NMR (300 MHz,
CDCl3) d 2.33 (s, 3H), 3.73 (s, 3H), 5.10 (s, 1H), 7.54 (s,
1H); 13C NMR (75 MHz, CDCl3) d 27.4, 39.0, 108.7, 133.0,
156.5, 192.4.
Method B (compounds 2, 9). A solution of 1 (1 g,
7.19 mmol), hydrazine hydrochloride (7.19 mmol) and
triethylamine (1.1 mL, 0.8 g, 7.91 mmol, 1.1 equiv) in
ethanol (15 mL) was refluxed for 25 min. The solvent was
evaporated, water (15 mL) was added and the resulting
precipitate was filtered. The crude product was purified by
recrystallization.
6.1.7. 1-(5-Amino-1-tert-butyl-1H-pyrazol-4-yl)-etha-
none 9. Purification by recrystallization (water) gave 9
(0.8 g, 61%) as colorless crystals. Mp 130–131 8C. 1H NMR
(200 MHz, CDCl3) d 1.63 (s, 9H), 2.33 (s, 3H), 5.88 (s, 2H),
7.57 (s, 1H); 1H NMR (200 MHz, DMSO-d6) d 1.46 (s, 9H),
2.15 (s, 3H), 6.61 (s, 2H), 7.56 (s, 1H); Dd (DMSO-d6-
CDCl3)ZK0.002 ppm; 13C NMR (75 MHz, CDCl3) d 26.9,
28.7, 58.7, 106.9, 138.1, 148.8, 192.9; IR (cmK1): n~Z3418,
3314, 1627, 1540, 1504; Anal. Calcd. for C9H15N3O: C,
59.64; H, 8.34; N, 23.19; Found C, 59.19; H, 8.25; N, 23.11.
Method C (compound 11). A solution of 1 (1 g, 7.19 mmol)
and pentafluorophenylhydrazine (1.4 g, 7.19 mmol) in
ethanol (15 mL) was refluxed for 4 h. The reaction mixture
was cooled to room temperature. Solvent was evaporated
and the residue was recrystallized from toluene to give 11.
6.1.1. (Z)-2-N,N-diphenylhydrazinomethylene -3-oxobu-
tanenitrile 2. Purification by recrystallization (EtOH/
H2OZ9/1) gave 2 (1.59 g, 80%) as pale green crystals. Mp
138–139 8C.1HNMR(300 MHz,CDCl3)d2.32(s, 3H),7.02–
7.36 (m, 10H), 7.58 (d, JZ11 Hz, 1H), 11.77 (d, JZ11 Hz,
1H), 13C NMR (75 MHz, CDCl3) d 27.9, 83.4, 118.9, 120.2,
124.8, 129.6, 145.8, 159.2, 196.3; IR (cmK1): n~Z3181, 3040,
2206, 1646, 1600; Anal. Calcd. for C17H15N3O: C, 73.63; H,
5.45; N, 15.15; Found C, 73.51; H, 5.43; N, 15.02.
6.1.8. 5-Methyl-1-phenyl-1H-pyrazole-4-carbonitrile 10.
Purification by flash chromatography (hexane/AcOEtZ9/1)
gave 10 (1.5 g, 83%) as brown solid. Mp 43–46 8C (lit.27:
1
46–48 8C). H NMR (200 MHz, CDCl3) d 2.50 (s, 3H),
7.41–7.55 (m, 5H), 7.88 (s, 1H); 1H NMR (200 MHz,
DMSO-d6) d 2.38 (s, 3H), 7.50 (m, 5H), 8.13 (s, 1H); Dd
(DMSO-d6-CDCl3)Z0.25 ppm; 13C NMR (75 MHz,
CDCl3) d 11.5, 93.4, 113.6, 124.8, 128.9, 129.3, 138.1,
141.6, 145.3; IR (cmK1): n~Z3069, 2973, 2230, 1598, 1553,
1507; Anal. Calcd. for C11H9N3: C, 72.11; H, 4.95; N,
22.94; Found C, 71.83; H, 4.97; N, 22.66.
6.1.2. (Z)-2-N,N-dimethylhydrazinomethylene-3-oxobu-
tanenitrile 3. Purification by recrystallization (hexane/
AcOEtZ9/1) gave 3 (1.29 g, 84%) as dull crystals. Mp
115 8C. 1H NMR (300 MHz, CDCl3) d 2.26 (s, 3H), 2.59 (s,
6H), 7.53 (d, JZ11 Hz, 1H), 10.73 (d, JZ11 Hz, 1H); 13C
NMR (75 MHz, CDCl3) d 28.0, 48.7, 80.5, 120.0, 157.5,
196.6; IR (cmK1): n~Z3196, 2963, 2878, 2203, 1651, 1599;
Anal. Calcd. for C7H11N3O: C, 54.89; H, 7.24; N, 27.43.
Found C, 54.65; H, 7.21; N, 27.66.
6.1.9. 1-(5-Amino-1-pentafluorophenyl-1H-pyrazol-4-
yl)-ethanone 11. Purification by recrystallization (toluene)
gave 11 (1.65 g, 79%) as white powder. Mp 160–161 8C. 1H
NMR (200 MHz, CDCl3) d 2.41 (s, 3H), 5.84 (s, 2H), 7.88
(s, 1H); 1H NMR (200 MHz, DMSO-d6) d 2.31 (s, 3H), 7.17
(s, 2H), 8.07 (s, 1H); Dd (DMSO-d6-CDCl3)Z0.19 ppm;
13C NMR (50 MHz, DMSO-d6) d 26.9, 103.8, 112.4, 135.6,
6.1.3. 3-Methyl-1H-pyrazole-4-carbonitrile 4. Purifi-
cation by recrystallization (toluene) gave 4 (0.9 g, 84%) as

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5385
139.5, 142.2, 143.4, 146.2, 151.8, 191.1; IR (cmK1):
n~Z3499, 3411, 3357, 1629, 1549, 1518; Anal. Calcd. for
C11H9N3: C, 45.37; H, 2.08; F, 32.62 N, 14.43; Found C,
45.23; H, 2.08; F, 32.42; N, 14.43.
6.3.1. 2-Acetyl-3-([1,2,4]triazol-4-ylamino)-acrylonitrile
14. Purification by recrystallization (DMSO/waterZ9/1)
gave 14 (1.16 g, 91%) as dark pink powder. Mp 258–
260 8C. 1H NMR (300 MHz, DMSO-d6) d 2.19 (s, 3H), 8.58
(s, 1H), 9.38 (s, 2H); 13C NMR (75 MHz, DMSO-d6) d 24.6,
80.6, 118.6, 139.6, 159.5, 187.6; IR (cmK1): n~Z3097,
3038, 2239, 1614, 1544, 1523, 1431, 1374; Anal. Calcd. for
C7H7N5O: C, 47.46; H, 3.98; N, 39.53; Found C, 46.88, H
3.98; N, 39.49.
6.2. General procedure for the reaction of 1 with
amidines (compounds 13a–d)
To a solution of 1 (0.7 g, 5 mmol) in ethanol (10 mL) were
added benzamidine hydrochloride derivatives (10 mmol)
and triethylamine (2.8 mL, 20 mmol). The mixture was
refluxed for 5 min. The reaction mixture was cooled to room
temperature and the precipitate products 13a–d were filtered
and recrystallized from DMF.
6.3.2. 7-Methyl-[1,2,4]triazolo[1,5-a]pyrimidine-6-car-
bonitrile 15. Purification by recrystallization (toluene)
gave 15 (0.9 g, 78%) as orange powder. Mp 145–146 8C.
1H NMR (300 MHz, DMSO-d6) d 3.00 (s, 3H), 8.85 (s, 1H),
9.13 (s, 1H); 13C NMR (75 MHz, DMSO-d6) d 16.61, 97.4,
114.4, 154.4, 155.1, 155.3, 157.2; IR (cmK1): n~Z3134,
3102, 3026, 2214, 1571, 1416, 1396; Anal. Calcd. for
C7H7N5: C, 52.83; H, 3.17; N, 44.01; Found C, 52.42; H,
3.19; N, 43.97.
6.2.1. 4-Methyl-2-phenylpyrimidine-5-carbonitrile 13a.
13a (0.65 g, 67%) as white crystals. Mp 173–174 8C. H
1
NMR (300 MHz, DMSO-d6) d 2.78 (s, 3H), 7.49–7.57 (m,
3H), 8.48 (d, JZ7 Hz, 2H), 9.03 (s, 1H); 13C NMR
(75 MHz, DMSO-d6) d 22.2, 104.8, 113.9, 127.3, 127.6,
130.8, 134.5, 158.9, 163.6, 168.6; IR (cmK1): n~Z3063,
2225, 1574, 1531; Anal. Calcd. for C12H9N3: C, 73.83; H,
4.65; N, 21.52; Found C, 73.43; H, 4.58; N, 21.49.
6.4. General procedure for the reaction of 1 with
arylamines (compounds 16a-d, 17–20)
A solution of 1 (1 g, 7.19 mmol) and arylamine (7.19 mmol)
in ethanol (15 mL) was refluxed for 10 min. The reaction
mixture was then cooled to room temperature and the
resulting precipitate was filtered and recrystallized.
6.2.2. 2-(4-Chlorophenyl)-4-methylpyrimidine-5-carbo-
nitrile 13b. 13b (0.48 g, 42%) as white crystals. Mp
170 8C. 1H NMR (300 MHz, DMSO-d6) d 2.72 (s, 3H), 7.63
(d, JZ7 Hz, 2H), 8.41 (d, JZ7 Hz, 2H), 9.24 (s, 1H); 13C
NMR (75 MHz, DMSO-d6) d 23.3, 106.3, 115.4, 129.0,
130.2, 134.4, 137.2, 160.8, 163.0, 170.3; IR (cmK1):
n~Z3048, 2227, 1579, 1568; Anal. Calcd. for C12H8ClN3:
C, 62.76; H, 3.51; N, 18.30; Cl, 15.44; Found C, 62.53; H,
3.49; N, 18.33; Cl, 15.63.
6.5. Preparation of compound 16c
6-Methylpyridin-2-ylamine (0.78 g, 7.19 mmol) was added
to 1 (1 g, 7.19 mmol) and the mixture was stirred at 80 8C
for 10 min. After cooling, ethanol (15 mL) was added, the
precipitated was filtered and purified by recrystallization
from toluene to give 16c.
6.2.3. 4-Methyl-2-p-tolylpyrimidine-5-carbonitrile 13c.
13c (0.73 g, 70%) as white crystals. Mp 194–195 8C. H
1
NMR (300 MHz, DMSO-d6) d 2.39 (s, 3H), 2.69 (s, 3H),
7.36 (d, JZ8 Hz, 2H), 8.30 (d, JZ8 Hz, 2H), 9.17 (s, 1H);
13C NMR (75 MHz, DMSO-d6) d 20.8, 23.0, 106.0, 115.4,
128.3, 129.3, 132.6, 142.2, 160.4, 168.2, 169.8; IR (cmK1):
n~Z2925, 2957, 2220, 1570, 1525; Anal. Calcd. for
C13H11N3: C, 74.62; H, 5.30; N, 20.08; Found C, 74.61;
H, 5.33; N, 20.01.
6.6. Preparation of compounds 17, 18
Aniline (2 g, 21.6 mmol) and 1 (3 g, 21.6 mmol) were
heated at 70 8C for 2 min. The reaction mixture was cooled
to room temperature, EtOH formed during the reaction was
evaporated and the product was then recrystallized from
toluene to give 17.
6.2.4. 3-Methyl-2-(3-nitrophenyl)-pyrimidine-5-carboni-
trile 13d. 13d (1.1 g, 92%) as dull crystals. Mp 223–226 8C.
1H NMR (300 MHz, DMSO-d6) d 2.75 (s, 3H), 7.83 (t, JZ
8.1 Hz, JZ7.8 Hz, 1H), 8.40 (d, JZ8.1 Hz, 1H), 8.74 (d,
JZ7.5 Hz, 1H), 9.03 (s, 1H), 9.29 (s, 1H); 13C NMR
(75 MHz, DMSO-d6) d 23.4, 107.3, 115.3, 122.7, 126.6,
130.8, 134.4, 137.2, 148.3, 161.1, 170.8; IR (cmK1):
n~Z3081, 2862, 2230, 1574, 1526, 1346; Anal. Calcd. for
C12H8N4O2: C, 60.00; H, 3.36; N, 23.32; Found C, 59.87;
H, 3.28; N, 23.36.
Aluminum chloride (2.1 g, 16.14 mmol) was added to 17
(1 g, 5.38 mmol) and the mixture was stirred at 180 8C for
1 h. The reaction mixture was poured into ice, saturated with
K2CO3 powder and extracted with dichloromethane (3!
20 mL). After evaporation, the residue was purified by flash
chromatography (Hexane/AcOEtZ8/2 then AcOEt) to give
18.
6.6.1. 2-Acetyl-3-(pyridin-2-ylamino)-acrylonitrile 16a.
Purification by recrystallization (ethanol) gave 16a (1.16 g,
1
86%) as white crystals. Mp 165 8C. H NMR (300 MHz,
6.3. General procedure for the reaction of 1 with
aminotriazoles (compounds 14, 15)
DMSO-d6) two isomers E and Z were observed E/ZZ80/20;
d 2.30 (s, 3H, (E)), 2.32 (s, 3H, (Z)), 7.15–7.24 (m, 1H), 7.35
(d, JZ8 Hz, 1H, (E)), 7.53 (d, JZ8 Hz, 1H, (Z)), 7.79–7.85
(m, 1H), 8.36 (d, JZ5 Hz, 1H), 8.61 (d, JZ12 Hz, 1H, (Z)),
9.06 (s, 1H, (E)), 11.22 (s, 1H, (E)), 12.00 (d, JZ11 Hz, 1H,
(Z)); 13C NMR (75 MHz, DMSO-d6) d 26.7 (E), 28.4 (Z),
85.2 (Z), 87.1 (E), 112.6 (Z), 113.0 (E), 116.6, 120.2 (E),
121.0 (Z), 139.1 (E), 139.2 (Z), 148.2 (E), 148.3 (Z), 149.0
A solution of 1 (1 g, 7.19 mmol) and the appropriate
aminotriazole (0.60 g, 7.19 mmol) in toluene (15 mL) has
been refluxed for 30 min. After cooling the reaction
mixture, the precipitate formed was filtered and recrystal-
lized to afford 14 or 15 as a solid.

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P. Cernuchova et al. / Tetrahedron 61 (2005) 5379–5387
5386
(E), 149.8 (E), 149.9 (Z), 150.4 (E), 191.5 (E), 195.7 (Z); IR
(cmK1): n~Z3183, 3052, 2201, 1646, 1599, 1554; Anal.
Calcd. for C10H9N3O: C, 64.16; H, 4.85; N, 22.45; Found C,
64.01; H, 4.81; N, 22.55.
6.6.6. 3-(4-Aminoquinolin-3-yl)-ethanone 18. Purification
by flash chromatography (hexane/AcOEtZ8/2, then
AcOEt) gave 18 (0.45 g, 45%) as brown powder. Mp
217–219 8C. 1H NMR (200 MHz, DMSO-d6) d 2.65 (s, 1H),
7.51 (t, JZ8 Hz, 1H), 7.75–7.85 (m, 2H), 8.41 (d, JZ8 Hz,
1H), 8.99 (s, 1H); 13C NMR (62.5 MHz, DMSO-d6) d 27.8,
107.9, 118.4, 123.4, 124.9, 129.0, 131.5, 148.5, 153.1,
153.6, 199.5; IR (cmK1): n~Z3302, 3053, 1623, 1612, 1584;
MS (Da): 186; Anal. Calcd. for C11H10N2O: C, 70.95; H,
5.41; N, 15.04; Found C, 70.80; H, 5.50; N, 14.36.
6.6.2. 2-Acetyl-3-(5-methyl-pyridin-2-ylamino)-acryloni-
trile 16b. Purification by recrystallization (DMF/waterZ9/
1) gave 16b (1.27 g, 88%) as white crystals. Mp 173 8C. 1H
NMR (300 MHz, DMSO-d6) two isomers E and Z were
observed E/ZZ78/22, d 2.23 (s, 3H), 2.28 (s, 3H, (E)), 2.30
(s, 3H, (Z)), 7.23 (d, JZ9 Hz, 1H, (E)), 7.40 (d, JZ8 Hz,
1H, (Z)), 7.61 (d, JZ9 Hz, 1H), 8.16 (s, 1H), 8.53 (d, JZ
13 Hz, 1H, (Z)), 8.99 (s, 1H, (E)), 11.13 (s, 1H, (E)), 11.97
(d, JZ13 Hz, 1H, (Z)); 13C NMR (75 MHz, DMSO-d6) d
17.1, 26.7 (E), 28.3 (Z), 84.7, 86.5 (Z)C(E), 112.1 (Z),
112.5 (E), 116.8, 129.4 (E), 130.3 (Z), 139.4, 147.9, 148.1
(E)C(Z), 148.3, 148.9 (E), 149.8 (Z), 191.4 (E), 195.6 (Z);
IR (cmK1): n~Z3188, 3052, 2204, 1657, 1602, 1558; Anal.
Calcd. for C11H11N3O: C, 65.66; H, 5.51; N, 20.88; Found
C, 65.56; H, 5.44; N, 20.87.
6.6.7. 2-Acetyl-3-(6-methoxybenzothiazol-2-ylamino)-
acrylonitrile 19. Purification by recrystallization (DMSO/
waterZ8/2) gave 19 (1.7 g, 88%) as pale green powder. Mp
227–228 8C. 1H NMR (300 MHz, DMSO-d6) d 2.33 (s, 3H),
3.78 (s, 3H), 7.01 (d, JZ9 Hz, 1H), 7.51 (s, 1H), 7.64 (d,
JZ9 Hz, 1H), 8.68 (s, 1H), 12.17 (s, 1H); 13C NMR
(75 MHz, DMSO-d6) d 26.7, 55.5, 89.9, 105.2, 114.9, 115.8,
121.2, 133.3, 143.6, 149.1, 156.3, 158.0, 191.4; IR (cmK1):
n~Z3096, 2969, 2213, 1652, 1597; Anal. Calcd. for
C13H11N3O2S: C, 57.13; H, 4.06; N, 15.37; Found C,
57.03; H, 4.07; N, 15.27.
6.6.3. 2-Acetyl-3-(6-methyl-pyridin-2-ylamino)-acryloni-
trile 16c. Purification by recrystallization (toluene) gave
1
16c (1.24 g, 86%) as white crystals. Mp 169–171 8C. H
6.6.8. 4-Methyl-benzo[4,5]imidazo[1,2-a]pyrimidine-3-
carbonitrile 20. Purification by recrystallization (DMF)
gave 20 (1.27 g, 85%) as pale red powder. Mp: O300 8C. 1H
NMR (250 MHz, DMSO-d6) d 3.27 (s, 1H), 7.53 (t, JZ
8 Hz, 1H), 7.69 (t, JZ8 Hz, 1H), 7.96 (d, JZ8 Hz, 1H),
8.35 (d, JZ8 Hz, 1H), 9.00 (s, 1H); 13C NMR (62.5 MHz,
DMSO-d6) d 19.9, 116.8, 119.6, 122.9, 127.0, 149.2, 154.8,
176.3; IR (cmK1): n~Z3091, 3070, 3052, 2926, 2231, 1621,
1595; Anal. Calcd. for C12H8N4: C, 69.22; H, 3.87; N,
26.91; Found C, 69.23; H, 3.85; N, 27.01.
NMR (200 MHz, DMSO-d6) two isomers E and Z were
observed E/ZZ86/14, d 2.29 (s, 3H, (E)), 2.31 (s, 3H, (Z)),
2.43 (s, 3H), 7.02 (d, JZ7 Hz, 1H), 7.14 (d, JZ8 Hz, 1H,
(E)), 7.32 (d, JZ8 Hz, 1H, (Z)), 7.69 (t, JZ8 Hz, JZ7 Hz,
1H), 8.60 (d, JZ13 Hz, 1H, (Z)), 9.04 (d, JZ13 Hz, 1H
(E)), 11.18 (d, JZ14 Hz, 1H, (E)), 11.94 (d, JZ13 Hz, 1H,
(Z)); 13C NMR (62.5 MHz, DMSO-d6) d 23.7 (Z), 23.9 (E),
26.9 (E), 28.4 (Z), 84.9, 86.5 (Z)C(E), 109.4 (Z), 110.0 (E),
116.0 (Z), 116.9 (E), 119.6 (E), 120.4 (Z), 139.2 (E), 139.4
(Z), 148.9 (E), 149.0, 149.7 (Z), 157.1 (E), 157.3 (Z),
191.4 (E), 195.7 (Z); IR (cmK1): n~Z3194, 3091, 3058,
2204, 1655, 1608, 1559; Anal. Calcd. for C11H11N3O: C,
65.66; H, 5.51; N, 20.88; Found C, 65.75; H, 5.44; N, 21.04.
Acknowledgements
This work was realized within the frame of a convention of
co-supervised thesis between Paris-South University and
Slovak Technical University supported by French Embassy
in Bratislava. We thank sincerely these organisations as well
as the Slovak Grant Agency (1/9254/02, 1/0058/03 and
1/1173/04) for additional financial help in Slovakia. Dr.
6.6.4. 2-Acetyl-3-(pyridin-4-ylamino)-acrylonitrile 16d.
Purification by recrystallization (DMF/waterZ9/1) gave
16d (1.24 g, 81%) as dull powder. Mp 206–209 8C. 1H
NMR (200 MHz, DMSO-d6) two isomers E and Z were
observed E/ZZ75 / 25, d 2.32 (s, 3H, (Z)), 2.34 (s, 3H, (E)),
7.47 (d, JZ6 Hz, 2H, (E)), 7.53 (d, JZ6 Hz, 2H, (Z)), 8.46–
8.51 (m, 3H, (ECZ)); 13C NMR (62.5 MHz, DMSO-d6) d
26.4 (E), 28.5 (Z), 85.9 (Z), 89.2 (E), 112.2 (E), 112.3(Z),
116.0 (E), 119.5 (Z), 145.2 (Z), 146.5 (E), 150.5 (E), 150.7
(Z), 151.3 (E), 152.0 (Z), 191.8 (E), 196.0 (Z); IR (cmK1):
n~Z3197, 3068, 2210, 1686, 1664, 1626, 1592, 1595, 1565;
Anal. Calcd. for C10H9N3O: C, 64.16; H, 4.85; N, 22.45;
Found C, 63.58; H, 4.81; N, 22.31.
´
Regis Guillot (ICMMO, Paris-South University) is warmly
acknowledged for X-ray recording.
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