Reactions of 1-aryl-2-bromo-3,4,4-trichlorobut-3-en-1-ones with some nucleophilic reagents

Article abstract of DOI:10.1134/S1070428007110061

Reactions of 2-bromo-1-phenyl- and 2-bromo-1-(4-methylphenyl)-3,4,4- trichlorobut-3-en-1-ones with morpholine and diethylamine are accompanied by prototropic allylic rearrangement, leading to 3-amino-1-aryl-2-bromo-4,4- dichlorobut-2-en-1-ones as mixtures of E and Z isomers. The title compounds react with hydrazine, hydroxylamine, and thiourea to give the corresponding 5-aroyl-4-methoxypyrazoles, 3-aryl-5-hydroxyiminomethyl-4-methoxyisoxazoles, and 2-amino-4-aryl-5-trichlorovinylthiazoles.

Full text of DOI:10.1134/S1070428007110061

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2007, Vol. 43, No. 11, pp. 1622–1627. © Pleiades Publishing, Ltd., 2007.
Original Russian Text © V.I. Potkin, S.K. Petkevich, P.V. Kurman, 2007, published in Zhurnal Organicheskoi Khimii, 2007, Vol. 43, No. 11, pp. 1626–1632.
Reactions of 1-Aryl-2-bromo-3,4,4-trichlorobut-3-en-1-ones
with Some Nucleophilic Reagents
V. I. Potkin, S. K. Petkevich, and P. V. Kurman
Institute of Physical Organic Chemistry, National Academy of Sciences of Belarus,
ul. Surganova 13, Minsk, 220072 Belarus
e-mail: potkin@ifoch.bas-net.by
Received February 2, 2007
Abstract—Reactions of 2-bromo-1-phenyl- and 2-bromo-1-(4-methylphenyl)-3,4,4-trichlorobut-3-en-1-ones
with morpholine and diethylamine are accompanied by prototropic allylic rearrangement, leading to 3-amino-1-
aryl-2-bromo-4,4-dichlorobut-2-en-1-ones as mixtures of E and Z isomers. The title compounds react with
hydrazine, hydroxylamine, and thiourea to give the corresponding 5-aroyl-4-methoxypyrazoles, 3-aryl-5-
hydroxyiminomethyl-4-methoxyisoxazoles, and 2-amino-4-aryl-5-trichlorovinylthiazoles.
DOI: 10.1134/S1070428007110061
Halogen-substituted ketones are widely used in the
synthesis of various practically important products
[1–4]. Chlorovinyl ketones attract specific interest due
to their high reactivity arising from mutual effect of
the conjugated carbonyl and chlorovinyl groups; these
compounds are convenient starting materials for build-
ing up heterocyclic systems [5]. We recently described
a practical method for the synthesis of 1-aryl-2-bromo-
3,4,4-trichlorobut-3-en-1-ones [6] from accessible aryl
trichloroallyl ketones that are capable of readily under-
going prototropic allylic rearrangement into chloro-
vinyl ketones, namely 1-aryl-3,4,4-trichlorobut-2-en-1-
ones [7]. It might be expected that 1-aryl-2-bromo-
3,4,4-trichlorobut-3-en-1-ones could also undergo
analogous rearrangement with formation of isomeric
reactive bromochlorovinyl ketones, 1-aryl-2-bromo-
3,4,4-trichlorobut-2-en-1-ones. The presence of a bro-
mine atom in their molecules gives rise to a new
reaction center, which could considerably extend their
synthetic potential, as compared to their precursors,
1-aryl-3,4,4-trichlorobut-3-en-1-ones.
ment of the initial ketones into isomeric conjugated
bromochlorovinyl ketones Ib and IIb, followed by
replacement of the chlorine atom in position 3 by
amino group. As a result, the corresponding 3-amino-
1-aryl-2-bromo-4,4-dichlorobut-2-en-1-ones III–V
were formed in 74–97% yield (Scheme 1). The ele-
mental analyses of the products unambiguously
showed that just chlorine rather than bromine atom
was replaced. The structure of III–V was assigned on
the basis of their IR, 1H and 13C NMR, and mass spec-
tra. The IR spectra of amino ketones III–V contained
a strong absorption band at 1693–1703 cm–1 due to
stretching vibrations of the carbonyl group, and vibra-
tions of the C=C bond were characterized by absorp-
tion bands in the region 1576–1606 cm–1. In the
1H NMR spectra of III–V we observed signals from
the Cl2CH group and protons in the amine and aro-
matic fragments. However, the number of signals and
their multiplicity suggested that amino ketones III–V
are mixtures of E and Z isomers. For example, the
spectrum contained two singlets at δ 6.6 and 7.2 ppm
with an intensity ratio of about 2:1, which were
assigned to the CHCl2 proton. According to published
1H NMR data for derivatives of β-amino-γ,γ-dichloro-
crotonic acid, signal of the CHCl2 proton in isomers
with cis arrangement of the carbonyl and dichloro-
methyl groups with respect to the double C=C bond
appears in a weaker field that the corresponding signal
of the trans isomers due to formation of intramolecular
hydrogen bond Cl2CH··· O=C in the former [8, 9].
Therefore, the signal at δ 7.2 ppm in the spectra of
The present work was aimed at studying reactions
of 1-aryl-2-bromo-3,4,4-trichlorobut-3-en-1-ones with
mono- and difunctional nucleophiles (such as amines,
hydrazine, hydroxylamine, and thiourea) and elucidat-
ing their potential for the synthesis of heterocyclic
compounds. As substrates we used 2-bromo-3,4,4-tri-
chloro-1-phenylbut-3-en-1-one (Ia) and 2-bromo-
3,4,4-trichloro-1-(4-methylphenyl)but-3-en-1-one (IIa).
The reactions of Ia and IIa with secondary amines
(morpholine and diethylamine) involved rearrange-
1622

REACTIONS OF 1-ARYL-2-BROMO-3,4,4-TRICHLOROBUT-3-EN-1-ONES
1623
Scheme 1.
Cl
Br
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
NR2R3
Cl
R2R3NH, Et2O
O
O
O
R2R3N
O
+
Br
C6H4R1
Br
C6H4R1
Br
C6H4R1
C6H4R1
Ia, IIa
Ib, IIb
(E)-III–(E)-V
(Z)-III–(Z)-V
OMe
H2NNH2, MeOH
C6H4R1
N
N
H
O
VI, VII
R1C6H4
Br
R1C6H4
Cl
2NH2OH·HCl
2AcONa, MeOH
Cl
Cl
+
+
PhCN + PhCOOMe
Ia, IIa
N
N
O
O
Cl
Cl
VIII, IX
R1C6H4
X, XI
OMe
5NH2OH, MeOH
N
O
NOH
XII, XIII
I, III, V, VI, VIII, X, XII, R1 = H; II, IV, VII, IX, XI, XIII, R1 = 4-Me; III, IV, R2R3N = morpholino; V, R2 = R3 = Et.
amino ketones III–V was assigned to the CHCl2
proton in the Z isomers, and that at δ 6.6 ppm, to the
corresponding proton in the E isomer, i.e., E isomers of
III–V predominate in the isomer mixture. We also
recorded the 13C NMR spectrum of morpholinovinyl
ketone III. The spectrum contained two sets of signals,
indicating the presence of two isomers. Using the
DEPT sequence, the signals at δC 55.96 and 69.81 ppm
with an intensity ratio of ~2:1 were assigned to the
nucleophile nature (Scheme 1). As in the reactions
with amines, the condensation of aryl bromotrichloro-
allyl ketones with hydrazine in methanol was accom-
panied by prototropic allylic rearrangement, and it re-
sulted in the formation of pyrazole ring. However, the
cyclization did not involve the carbonyl group but
involved the dichloromethyl fragment which reacted
with hydrazine with replacement of both chlorine
atoms. The other reaction center in the ketone mole-
cule, participating in the heterocyclization process, was
the =CBr moiety. The bromine atom therein was
replaced by the second nucleophilic nitrogen atom of
hydrazine. In addition, the reaction was accompanied
by replacement of the remaining chlorine atom by
methoxy group from the solvent. The final products
were 5-benzoyl-4-methoxy-1H-pyrazole (VI) and
4-methoxy-5-(4-methylbenzoyl)pyrazole (VII) from
ketones Ia and IIa, respectively (yield 54 and 71%).
Interestingly, the reaction of Ia and IIa with hydrazine
in ethanol gave no expected ethoxypyrazoles but
resulted in complete tarring of the reaction mixture.
1
CHCl2 carbon atom. As in the H NMR spectrum, the
minor signal appeared in a weaker field and was
assigned to the Z isomer in which hydrogen bonding is
possible between the C=O and Cl2CH groups.
No molecular ion peaks were observed in the
electron impact mass spectra of amino ketones III–V.
Peaks with the maximal m/z value belong to the
[M – HCl]+ ions; the corresponding isotope ratio (76:
100:24) indicates the presence of one chlorine and one
bromine atoms in these ions [10, 11]. In addition, the
mass spectra contained peaks of ions arising from
elimination of aroyl, aryl, and amino groups and halo-
gen atoms.
Unlike hydrazine, ketones Ia and IIa reacted with
hydroxylamine in methanol in a classical way, i.e.,
with participation of the C=O group of ketones Ib and
Compounds Ia and IIa reacted with difunctional
nucleophiles in peculiar fashions, depending on the
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 43 No. 11 2007

POTKIN et al.
1624
IIb formed by prototropic rearrangement of the initial
ketones. The structure of the final products depends on
the reactant ratio and reaction conditions. At a ketone-
to-hydroxylamine ratio of 1 : 2 we obtained a complex
mixture of products, among which we identified by
GC–MS 3-aryl-4-bromo-5-dichloromethyl-1,2-oxa-
zoles VIII and IX, 3-aryl-4-chloro-5-dichloromethyl-
isoxazoles X and XI, benzonitrile, and methyl ben-
zoate. The mass spectra of these compounds contained
the corresponding molecular ion peaks and fragment
ion peaks. The isotope ratios of the molecular ion
clusters were 61:100:46:6.4 for compounds VIII and
IX and 100:98:32:3.5 for X and XI, in keeping with
the presence of one bromine and two chlorine atoms in
molecules of the former and of three chlorine atoms in
molecules of the latter [10, 11]. The reactions of
ketones Ia and IIa with hydroxylamine were accom-
panied by strong tarring, and the yield of isoxazoles
VIII–XI did not exceed 8–10%. Methyl benzoate and
benzonitrile were likely to be formed as a result of
cleavage of the (Br)C–C(O) bond in molecules of the
initial ketone and ketone oxime, respectively. The
formation of bromo-substituted isoxazoles VIII and
IX might be expected, so that it requires no additional
comments, whereas the formation of chloroisoxazoles
X and XI was quite surprising. We believe that com-
pounds X and XI arise from intramolecular halogen
migration in isomeric ketones Ib and IIb. By carrying
out the reactions of Ia and IIa with hydroxylamine
hydrochloride in methanol in the presence of an equi-
molar (with respect to hydroxylamine) amount of
sodium acetate we succeeded in minimizing tar forma-
tion and obtaining mixtures of 4-bromo- and 4-chloro-
isoxazoles VIII/X and IX/XI at a ratio of ~1:1 in
an overall yield of 25%. Compounds VIII–XI were
not isolated as individual substances, and their struc-
ture was confirmed, apart from the GC–MS data, by
structure [12–14]. We found that bromotrichloroallyl
ketones Ia and IIa react with thiourea in methanol in
a selective fashion, yielding the corresponding substi-
tuted thiazoles. Unlike the reactions with hydrazine
and hydroxylamine, the condensations of Ia and IIa
with thiourea were not accompanied by rearrange-
ments into isomeric structures Ib and IIb, presumably
due to low basicity of thiourea. 2-Amino-4-aryl-5-tri-
chlorovinyl-1,3-thiazoles XIVa and XVa were isolated
in 87 and 92% yield, respectively. In the reactions of
ketones Ia and IIa with N-acetylthiourea we obtained
2-acetylamino-4-aryl-5-trichlorovinylthiazoles XVIa
and XVIIa, respectively, but their yield did not exceed
18% because of concomitant hydrolysis to thiazoles
XIVa and XVa; the latter were isolated in 45–50%
yield. Presumably, the reactions of ketones Ia and IIa
with thiourea derivatives begin with nucleophilic at-
tack by the sulfur atom of thiourea on the electrophilic
CHBr carbon atom with formation of isothiuronium
salts XIVb–XVIIb. The latter undergo intramolecular
ring closure to give the corresponding 1,3-thiazoles as
hydrobromides, and their treatment with sodium
hydrogen carbonate yields thiazoles XIVa–XVIIa
(Scheme 2). The proposed scheme is consistent with
published data [15–17].
Acylaminothiazoles can be obtained in a higher
yield by acylation of preliminarily prepared 2-amino-
thiazoles with carboxylic acid chlorides. For example,
by treatment of aminothiazole XIVa with 3,4,4-tri-
chlorobut-3-enoyl chloride (which is readily available
starting from trichloroethylene dimer [18]) we syn-
thesized 3,4,4-trichloro-N-[4-phenyl-5-trichlorovinyl-
1,3-thiazol-2-yl]but-3-enamide (XVIII) in 87% yield.
The structure of heterocyclic compounds VI, VII,
and XIV–XVIII was determined on the basis of their
1
elemental compositions and IR, H NMR, and mass
spectra. The IR spectra of pyrazoles VI and VII
contained a strong absorption band at 1730 cm–1 due to
stretching vibrations of the ketone carbonyl group and
bands in the region 1615–1620 cm–1 due to vibrations
1
the H NMR spectra of mixtures of 4-chloro and
4-bromo derivatives. The Cl2CH groups therein gave
rise to singlets at δ 6.36, 6.54 and 6.35, 6.37 ppm for
VIII, X and IX, XI, respectively, and protons in the
methyl groups attached to the benzene ring in IX and
XI resonated as singlets at δ 2.41 and 2.45 ppm. When
compounds Ia and IIa were treated with excess hy-
droxylamine as free base (ketone-to-hydroxylamine
ratio 1:5) in methanol, the products were 3-aryl-5-hy-
droxyiminomethyl-4-methoxyisoxazoles XII and XIII,
respectively (yield 35 and 45%).
1
of the C=N bond. In the H NMR spectra of VI and
VII we observed a broadened singlet in the region
δ 8.1–10.0 ppm from the NH proton, multiplet of
aromatic protons, and singlets at δ 3.9 and 7.0 ppm
from the methoxy group and CH proton in the pyrazole
ring. The aromatic methyl protons in compound VII
resonated as a singlet at δ 2.39 ppm. Pyrazoles VI and
VII showed in the electron impact mass spectra the
molecular ion peaks and fragment ion peaks corre-
sponding to elimination of the aryl and methoxy
groups and decomposition of the pyrazole ring.
It is known that chlorovinyl ketones are capable of
reacting with thiourea to give thiazine or thiazole
derivatives, depending on the conditions and ketone
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 43 No. 11 2007

REACTIONS OF 1-ARYL-2-BROMO-3,4,4-TRICHLOROBUT-3-EN-1-ONES
1625
Scheme 2.
Cl
Cl
Cl
Cl
Cl
C6H4R1
O
H2NC(S)NHR4, MeOH
Cl
Ia, IIa
S
C6H4R1
S
N
NH2
Br–
R4NH
NHR4
XIVa–XVIIa
XIVb–XVIIb
Cl
Ph
Cl
Cl
N
Cl
CCl2=CClCH2COCl
R1 = R4 = H
S
Cl
HN
Cl
O
XVIII
I, XIV, XV, R1 = H; II, XV, XVII, R1 = 4-Me; XIV, XV, R4 =H; XVI, XVII, R4 = Ac.
Isoxazoles XII and XIII were characterized by IR
absorption bands in the regions 1600–1640 (ν C=N)
instrument (100 MHz) from solutions in CDCl3 (III–
XI, XIV–XVIII) and acetone-d6 (XII, XIII) using
tetramethylsilane as internal reference. The C NMR
13
1
and 1514–1587 cm–1 (νC=C). Their H NMR spectra
spectrum of a solution of compound III in CDCl3 was
obtained on a Bruker Avance-500 spectrometer; the
chemical shifts were measured relative to the solvent
signal (δC 77.0 ppm). The mass spectra (electron im-
pact, 70 eV) were recorded on a Hewlett–Packard HP
5972 mass-selective detector coupled with an HP 5890
gas chromatograph (HP-5MS capillary column, 30 m×
0.25 mm, film thickness 0.25 μm, stationary phase 5%
of phenylmethylsilicone, injector temperature 250°C).
contained a singlet from the methoxy group at δ 3.40–
3.45 ppm) and a multiplet belonging to aromatic
protons. The exocyclic –CH=N group gave a singlet in
the region δ 8.08–8.12 ppm, the aromatic methyl
protons of compound XIII resonated as a singlet at
δ 2.37 ppm, and a broadened singlet at δ 11.5–11.7 ppm
was assigned to the oxime NOH proton.
Stretching vibrations of the endocyclic C=N bond
in thiazoles XIV–XVIII had an IR frequency of 1604–
1627 cm–1, absorption bands in the region 1516–
1600 cm–1 were assigned to the endo- and exocyclic
C=C bonds, and the amide carbonyl groups in XVI–
XVIII gave rise to absorption bands at 1622–
3,4,4-Trichlorobut-3-enoyl chloride was synthe-
sized from trichloroethylene dimer according to the
procedure described in [18].
2-Bromo-4,4-dichloro-3-morpholino-1-phenyl-
but-2-en-1-one (III). A solution of 0.53 g (6 mmol) of
morpholine in 10 ml of anhydrous diethyl ether was
added dropwise at 15°C to a solution of 1.0 g (3 mmol)
of ketone Ia in 30 ml of anhydrous diethyl ether. The
mixture was stirred for 1 h, and the precipitate was
filtered off, washed with water (3×30 ml), and dried
under reduced pressure. Yield 1.08 g (94%), mp 112–
113°C (decomp.). IR spectrum, ν, cm–1: 928 (CHCl2);
1580, 1593 (C=C); 1696 (C=O). 1H NMR spectrum, δ,
ppm (major Z isomer): 3.23 m (4H, CH2N), 3.38 m
(4H, CH2O), 6.59 s (1H, CHCl2), 7.45 m (3H, Harom),
7.87 m (2H, Harom). 13C NMR spectrum, δC, ppm
(major Z isomer): 50.61 (CH2N), 55.96 (CHCl2), 67.42
(CH2O), 128.90 (2CHarom), 129.77 (2CHarom), 134.61
(CHarom), 188.95 (C=O), 119.40, 134.90, 143.2. Found,
%: C 44.52; H 3.99; Hlg 39.69; N 3.77. [M – HCl]+
341. C14H14BrCl2NO2. Calculated, %: C 44.36; H 3.72;
1
1702 cm–1. In the H NMR spectra of XIV–XVIII,
multiplets from aromatic protons were located in the
region δ 7.2–7.7 ppm, the NH2 protons in XIV and XV
resonated as a broadened singlet at δ 5.5 ppm, and the
amide NH protons in XVI–XVIII were characterized
by chemical shifts δ of 10.6–11.6 ppm. The mass spec-
tra of thiazoles XIV–XVIII contained the molecular
ion clusters with isotope intensity ratios of 100:98:32:
3.5 for compounds XIV–XVII and 51:100:82:35:8.7
for XVIII, indicating the presence of three chlorine
atoms in molecules XIV–XVII and six chlorine atoms
in molecule XVIII [10, 11].
EXPERIMENTAL
The IR spectra were recorded in KBr on a Nicolet
Protege-460 spectrometer with Fourier transform. The
1H NMR spectra were measured on a Tesla BS-567A Hlg 39.78; N 3.69. M 379.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 43 No. 11 2007

POTKIN et al.
1626
Amino ketones IV and V were synthesized in a
3-Aryl-5-hydroxyiminomethyl-4-methoxyisoxa-
zoles XII and XIII (general procedure). A solution of
hydroxylamine, prepared from 2.08 g (30 mmol) of
hydroxylamine hydrochloride and 3.04 g (30 mmol) of
triethylamine in 30 ml of methanol, was added drop-
wise at 15°C to a solution of 6 mmol of ketone Ia or
IIa in 30 ml of methanol. The mixture was heated
to 45°C, stirred for 5 h at that temperature, evaporated
to 1/3 of the initial volume, and poured into water.
An oily material separated and was extracted into
chloroform, the extract was dried over CaCl2, the
solvent was removed under reduced pressure, and the
residue was recrystallized from hexane–CHCl3 (1:5).
4-Methoxy-3-phenylisoxazole-5-carbaldehyde
oxime (XII). Yield 35%, mp 130–132°C. IR spectrum,
ν, cm–1: 1530, 1587 (C=C); 1600, 1618 (C=N); 3311
(O–H). 1H NMR spectrum, δ, ppm: 3.40 s (3H, OCH3),
7.3 m (3H, Harom), 7.6 m (2H, Harom), 8.12 s (1H,
N=CH), 11.50 br.s (1H, OH). Found, %: C 60.82;
H 5.01; N 12.77. [M]+ 218. C11H10N2O3. Calculated,
%: C 60.55; H 4.62; N 12.84. M 218.
similar way from the corresponding ketone and amine.
2-Bromo-4,4-dichloro-1-(4-methylphenyl)-3-
morpholinobut-2-en-1-one (IV). Yield 97%, mp 107–
108°C (decomp.). IR spectrum, ν, cm–1: 929 (CHCl2);
1580, 1606 (C=C); 1693 (C=O). 1H NMR spectrum, δ,
ppm (major Z isomer): 2.44 s (3H, CH3), 2.60 m (4H,
CH2N), 3.34 m (4H, CH2O), 6.59 s (1H, CHCl2),
3
3
7.27 d (2H, Harom, J = 8 Hz), 7.80 m (2H, Harom, J =
8 Hz). Found, %: C 45.62; H 3.79; Hlg 38.57; N 3.70.
[M – HCl]+ 355. C15H16BrCl2NO2. Calculated, %:
C 45.83; H 4.10; Hlg 38.36; N 3.56. M 393.
2-Bromo-4,4-dichloro-3-diethylamino-1-phenyl-
but-2-en-1-one (V). Yield 74%, mp 72–73°C
(decomp.). IR spectrum, ν, cm–1: 923 (CHCl2); 1576,
1
1593 (C=C); 1703 (C=O). H NMR spectrum, δ, ppm
(major Z isomer): 0.67 t (6H, CH3), 2.91 q (4H,
CH2N), 6.60 s (1H, CHCl2), 7.51 m (3H, Harom), 7.85 m
(2H, Harom). Found, %: C 46.47; H 4.59; Hlg 40.99;
N 3.92. [M – HCl]+ 327. C14H16BrCl2NO. Calculated,
%: C 46.06; H 4.42; Hlg 41.31; N 3.84. M 365.
4-Methoxy-3-(4-methylphenyl)isoxazole-5-car-
baldehyde oxime (XIII). Yield 45%, mp 149–151°C.
IR spectrum, ν, cm–1: 1514, 1526 (C=C); 1613, 1640
5-Aroyl-4-methoxy-1H-pyrazoles VI and VII
(general procedure). A solution of 0.61 g (12.2 mmol)
of hydrazine hydrate in 10 ml of methanol was added
dropwise over a period of 30 min under vigorous stir-
ring to a solution of 6 mmol of ketone Ia or IIa in
25 ml of methanol, maintaining the temperature at
10°C. The mixture was stirred for 1 h and poured into
water. The oily material was extracted into methylene
chloride, the extract was dried over CaCl2 and con-
centrated to a volume of 10 ml under reduced pressure,
and the product was isolated by precipitation with
hexane at –5°C and dried under reduced pressure.
1
(C=N); 3305 (O–H). H NMR spectrum, δ, ppm:
2.37 s (3H, CH3), 3.45 s (3H, OCH3), 7.22 d (2H,
H
arom, 3J = 8 Hz), 7.46 d (2H, Harom, 3J = 8 Hz), 8.08 s
(1H, =CH), 11.70 br.s (1H, OH). Found, %: C 62.21;
H 5.19; N 12.45. [M]+ 232. C12H12N2O3. Calculated,
%: C 62.06; H 5.21; N 12.06. M 232.
2-Amino-4-aryl-5-trichlorovinyl-1,3-thiazoles
XIVa and XVa (general procedure). A solution of
4 mmol of ketone Ia or IIa and 0.61 g (8 mmol) of
thiourea in 30 ml of methanol was stirred for 3 h at
40°C. The mixture was poured into 200 ml of water
and treated with sodium hydrogen carbonate to weakly
alkaline reaction. The precipitate was filtered off,
washed with water, and dried under reduced pressure
at 60°C.
4-Phenyl-5-trichlorovinyl-1,3-thiazol-2-amine
(XIVa). Yield 87%, mp 147–148°C (decomp.). IR spec-
trum, ν, cm–1: 1520, 1600 (C=C); 1627 (C=N); 3266,
3464 (NH2). 1H NMR spectrum, δ, ppm: 5.50 br.s (2H,
NH2), 7.4 m (3H, Harom), 7.6 m (2H, Harom). Found, %:
C 43.15; H 2.64; Cl 34.33; N 9.03; S 10.35. [M]+ 304.
C11H7Cl3N2S. Calculated, %: C 43.23; H 2.31; Cl 34.80;
N 9.17; S 10.49. M 305.
5-Benzoyl-4-methoxy-1H-pyrazole (VI). Yield
54%, mp 181–182°C (decomp.). IR spectrum, ν, cm–1:
1492, 1560, 1590 (C=C); 1620 (C=N); 1731 (C=O);
1
3203 (N–H). H NMR spectrum, δ, ppm: 3.85 s (3H,
OCH3), 7.05 s (1H, 3-H), 7.4 m (3H, Harom), 7.7 m (2H,
Harom), 10.0 br.s (1H, NH). Found, %: C 65.39; H 4.93;
N 13.76. [M]+ 202. C11H10N2O2. Calculated, %:
C 65.34; H 4.98; N 13.85. M 202.
4-Methoxy-5-(4-methylbenzoyl)pyrazole (VII).
Yield 71%, mp 194–195°C (decomp.). IR spectrum, ν,
cm–1: 1509, 1560, 1580 (C=C); 1615 (C=N); 1729
1
(C=O); 3200 (N–H). H NMR spectrum, δ, ppm:
2.39 s (3H, CH3), 3.94 s (3H, OCH3), 7.08 s (1H,
=CH), 7.24 d (2H, Harom, 3J = 8 Hz), 7.63 d (2H, Harom
,
4-(4-Methylphenyl)-5-trichlorovinyl-1,3-thiazol-
2-amine (XVa). Yield 92%, mp 156–157°C (decomp.).
IR spectrum, ν, cm–1: 1516, 1537 (C=C); 1604 (C=N);
3J = 8 Hz), 8.1 br.s (1H, NH). Found, %: C 66.47;
H 5.99; N 12.79. [M]+ 216. C12H12N2O2. Calculated,
%: C 66.65; H 5.59; N 12.95. M 216.
1
3241, 3468 (NH2). H NMR spectrum, δ, ppm: 2.39 s
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 43 No. 11 2007

REACTIONS OF 1-ARYL-2-BROMO-3,4,4-TRICHLOROBUT-3-EN-1-ONES
1627
(3H, CH3), 5.50 br.s (2H, NH2), 7.22 d (2H, Harom
,
3.16 s (2H, CH2), 7.48 m (3H, Harom), 7.66 m (2H,
Harom), 10.60 br.s (1H, NH). Found, %: C 37.51;
H 1.76; Cl 44.34; N 5.61; S 6.68. [M]+ 474.
C15H8Cl6N2OS. Calculated, %: C 37.77; H 1.69;
Cl 44.59; N 5.87; S 6.72. M 477.
3
3J = 8 Hz), 7.50 d (2H, Harom, J = 8 Hz). Found, %:
C 45.49; H 2.88; Cl 32.80; N 8.79; S 9.88. [M]+ 318.
C12H9Cl3N2S. Calculated, %: C 45.09; H 2.84; Cl 33.27;
N 8.76; S 10.03. M 319.
This study was performed under financial support
by the Byelorussian Foundation for Basic Research
(project no. Kh07-050).
N-[4-Aryl-5-trichlorovinyl-1,3-thiazol-2-yl)acet-
amides XVIa and XVIIa (general procedure).
A solution of 4 mmol of bromo ketone Ia or IIa and
0.95 g (8 mmol) of N-acetylthiourea in 30 ml of
methanol was stirred for 3 h at 40°C. The mixture was
poured into 200 ml of water, the precipitate was
extracted into chloroform, the extract was dried over
CaCl2 and evaporated under reduced pressure to a vol-
ume of 20 ml, 20 ml of hexane was added, and the
precipitate of aminothiazole XIV or XV was filtered
off (after drying under reduced pressure, the yields
were 45 and 50%, respectively). The filtrate was kept
for 40 h at –5°C, and the precipitate of XVIa or XVIIa
was filtered off, washed with hexane, and dried under
reduced pressure.
N-(4-Phenyl-5-trichlorovinyl-1,3-thiazol-2-yl)-
acetamide (XVIa). Yield 18%, mp 222–224°C. IR
spectrum, ν, cm–1: 1525, 1600 (C=C); 1625 (C=N);
1678 (C=O); 3264, 3449 (N–H). 1H NMR spectrum, δ,
ppm: 1.56 s (3H, CH3), 7.45 m (3H, Harom), 7.7 m
(2H, Harom), 11.60 br.s (1H, NH). Found, %: C 44.83;
H 2.82; Cl 30.55; N 8.03; S 9.20. [M]+ 346.
C13H9Cl3N2OS. Calculated, %: C 44.91; H 2.61;
Cl 30.59; N 8.06; S 9.22. M 347.
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N-[4-(4-Methylphenyl)-5-trichlorovinyl-1,3-thia-
zol-2-yl)acetamide (XVIIa). Yield 10%, mp 188–
190°C. IR spectrum, ν, cm–1: 1523, 1590 (C=C); 1615
1
(C=N); 1622 (C=O); 3240 (NH). H NMR spectrum,
δ, ppm: 1.62 s (3H, CH3), 2.41 s (3H, CH3), 7.20 d
3
3
(2H, Harom, J = 8 Hz), 7.55 d (2H, Harom, J = 8 Hz),
11.50 br.s (1H, NH). Found, %: C 46.83; H 3.15;
Cl 29.38; N 7.35; S 8.55. [M]+ 360. C14H11Cl3N2OS.
Calculated, %: C 46.49; H 3.07; Cl 29.41; N 7.75;
S 8.87. M 361.
12. Levkovskaya, G.G., Bozhenkov, G.V., Larina, L.I.,
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3,4,4-Trichloro-N-(4-phenyl-5-trichlorovinyl-1,3-
thiazol-2-yl)but-3-enamide (XVIII). A mixture of
0.83 g (3.99 mmol) of 3,4,4-trichlorobut-3-enoyl chlo-
ride and 2.44 g (7.98 mmol) of aminothiazole XIVa in
20 ml of anhydrous chloroform was stirred for 5 h at
50°C. The mixture was cooled, 30 ml of anhydrous
diethyl ether was added, the precipitate of initial
aminothiazole hydrochloride was filtered off, the fil-
trate was evaporated to dryness under reduced pres-
sure, and the residue was recrystallized from hexane–
chloroform (1:1). Yield 1.66 g (87%), mp 173–175°C.
IR spectrum, ν, cm–1: 1536, 1598, 1610 (C=C, C=N);
1702 (C=O); 3250 (N–H). 1H NMR spectrum, δ, ppm:
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RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 43 No. 11 2007