Azo coupling of 5-substituted furan-2(3H)-ones and 1H-pyrrol-2(3H)-ones with arene(hetarene)diazonium salts

Article abstract of DOI:10.1134/S107042801209014X

5-Substituted furan-2(3H)-ones and 1-phenyl-1H-pyrrol-2(3H)-ones reacted with diazonium salts derived from substituted anilines and 1H-1,2,4-triazol-5- amine to give azo coupling products at the methylene group in the heteroring. The products were found t

Full text of DOI:10.1134/S107042801209014X

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2012, Vol. 48, No. 9, pp. 1229–1232. © Pleiades Publishing, Ltd., 2012.
Original Russian Text © D.N. Gavkus, O.A. Maiorova, M.Yu. Borisov, A.Yu. Egorova, 2012, published in Zhurnal Organicheskoi Khimii, 2012, Vol. 48,
No. 9, pp. 1230–1233.
Azo Coupling of 5-Substituted Furan-2(3H)-ones
and 1H-Pyrrol-2(3H)-ones with Arene(hetarene)diazonium Salts
D. N. Gavkus, O. A. Maiorova, M. Yu. Borisov, and A. Yu. Egorova
Chernyshevskii Saratov State University, ul. Astrakhanskaya 83, Saratov, 410012 Russia
e-mail: Beloousova011@yandex.ru
Received December 30, 2011
Abstract—5-Substituted furan-2(3H)-ones and 1-phenyl-1H-pyrrol-2(3H)-ones reacted with diazonium salts
derived from substituted anilines and 1H-1,2,4-triazol-5-amine to give azo coupling products at the methylene
group in the heteroring. The products were found to exist as hydrazone tautomers.
DOI: 10.1134/S107042801209014X
Compounds having both imino and carbonyl groups
in a single molecule are important for fine organic syn-
thesis. Hydrazones derived from furancarbaldehydes
and their nitrogen-containing analogs were used to
synthesize various acyclic and heterocyclic com-
pounds. N-Substituted furanimines were prepared via
introduction of an imino group into furan ring and
intramolecular cyclization of N-substituted 2-amino-4-
oxobut-2-enoic acids. Furan-2-imines can be obtained
from 2,3-dihydrofuran-2,3-diones [1], as well as by
intramolecular cyclization of imino derivatives of
o-hydroxyphenylglyoxalic acid [2, 3] or 4-R-2,4-di-
oxobutanoic acids [4]. 4-R-2-Imino-4-oxobutanoic
acids undergo spontaneous intramolecular cyclization
on heating or by the action of dehydrating agents
[5, 6]. Syntheses of hydrazones are generally based on
cyclization of acyclic diazocarbonyl compounds [7–9].
In the present article we report on the reactions of
5-substituted furan-2(3H)-ones and 1-phenyl-1H-
pyrrol-2(3H)-ones with diazonium salts. It is known
that azo coupling reactions involve not only arenes
activated by strong electron-donor groups but also
aliphatic compounds possessing an activated meth-
ylene group [10].
4-Nitrobenzenediazonium chloride readily reacted
with furan-2(3H)-ones in alcohol at –5 to 0°C
(Scheme 1). The products were the corresponding aryl-
hydrazones Ia–Ic which were isolated in up to 96%
yield as orange–red crystals whose color is intrinsic to
azo dyes. The reactions of furan-2(3H)-ones witt 1H-
1,2,4-triazole-5-diazonium chloride were characterized
by lower yield (~75%), and hetarylhydrazones IIa and
IIb were colored deep red.
The azo coupling products I and II can exist as
several tautomers (Scheme 2). Their IR spectra lacked
absorption bands assignable to free or H-bonded hy-
Scheme 1.
C6H4NO2-4
NH
N
4-O2NC6H4N2 Cl–
R
R
O
O
Ia–Ic
N
R
O
O
N
N2 Cl–
N
N
N
H
N
N
O
H
N
H
O
IIa, IIb
I, R = Ph (a), C5H11 (b), Bu (c); II, R = Ph (a), 4-MeC6H4 (b).
1229

GAVKUS et al.
1230
Scheme 2.
R'
R'
NH
R'
N
N
N
N
N
R
O
R
O
R
OH
O
O
O
A
B
C
Scheme 3.
Ph
Ph
Ph
N
N
N
NH
N
N
PhN2 Cl–
R
O
R
O
R
O
R
OH
N
N
N
N
Ph
Ph
Ph
Ph
IIIa–IIId
O
N
Ph
N
N
R
D
R = Ph (a), C5H11 (b), Bu (c), 4-MeC6H4 (d).
droxy group, but a broad band was observed in the
region 3320–3200 cm–1. The latter was attributed to
stretching vibrations of NH group involved in intra-
molecular hydrogen bond. The carbonyl absorption
band was displaced toward lower frequencies (1760–
1750 cm–1), and a band at 1690–1675 cm–1 (C=N) was
detected (Scheme 3). The IR spectra of IIIa–IIId
retained carbonyl absorption band at 1765–1770 cm–1
typical of unsaturated lactams; also, absorption bands
belonging to C=N (1650–1640 cm–1) and NH stretch-
ing vibrations (3380–3200 cm–1, broadened) were
present.
1
1
present. The H NMR spectra of these compounds
The H NMR spectra were more informative from
contained no signal from methylene protons on C3 in
the furan ring, while signals from vinylic proton
(δ 6.90–6.93 ppm, s) and aromatic protons (δ 7.30–
7.75 ppm, m) and a broadened signal at δ 8.2–
8.25 ppm (NH) were observed. These data indicated
that compounds I and II exist as hydrazone tautomer B
stabilized by intramolecular hydrogen bond.
the viewpoint of determination of tautomer structure.
1
Compounds IIIa–IIId displayed in the H NMR spec-
tra a singlet at δ 5.98–6.00 ppm from vinylic proton,
signals from the substituent on C5 (δ 0.85–2.02 ppm
for 5-alkyl derivatives IIIb and IIIc). The absence of
a doublet of doublets typical of methylene protons on
C3 in the initial pyrroles and the presence of a broad-
ened NH signal at δ 8.50–8.56 ppm allowed us to con-
clude that benzenediazonium salt reacted with 5-sub-
stituted 1-phenyl-1H-pyrrol-2(3H)-ones at the endo-
cyclic methylene group with formation of azo coupling
products IIIa–IIId as hydrazone tautomer.
Likewise, 5-substituted 1-phenyl-1H-pyrrol-2(3H)-
ones readily reacted with benzenediazonium chloride.
However, the substrate molecule, apart from the C3H2
methylene group, possesses one more center capable of
reacting with diazonium salt, namely the benzene ring
on the nitrogen atom. Therefore, the azo coupling with
the above pyrrole derivatives could take different
pathways.
Judging by the IR and 1H NMR spectra of the prod-
ucts, the azo coupling in ethanol at –5 to 0°C occurred
at the endocyclic methylene group in 5-substituted
1-phenyl-1H-pyrrol-2(3H)-ones with formation of
compounds IIIa–IIId, while no structures like D were
EXPERIMENTAL
The IR spectra were recorded on an IKS-29 spec-
trometer from samples dispersed in mineral oil. The
1H NMR spectra were obtained on a Varian FT-80A
spectrometer (80 MHz) from solutions in CDCl3 using
tetramethylsilane as internal reference. Initial 5-alkyl-
(aryl)dihydrofuran-2(3H)-ones [11] and 5-alkyl(aryl)-
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 48 No. 9 2012

AZO COUPLING OF 5-SUBSTITUTED FURAN-2(3H)-ONES
1231
1-phenyl-1H-pyrrol-2(3H)-ones [12] were synthesized
according to known procedures.
5-Phenyl-3-[2-(1H-1,2,4-triazol-5-yl)hydrazinyli-
dene]furan-2(3H)-one (IIb). Yield 1.72 g (93%),
yellow–orange crystals, mp 199–201°C. IR spectrum,
ν, cm–1: 3276 (NH), 1788 (C=O), 1688 (C=N). 1H NMR
3-[2-(4-Nitrophenyl)hydrazinylidene]-5-phenyl-
furan-2(3H)-one (Ia). A solution of 1 g (6.25 mmol)
of 5-phenylfuran-2(3H)-one was added dropwise under
stirring to a freshly prepared solution of 0.8 g of
(6.25 mmol) of 4-nitrobenzenediazonium chloride,
cooled to –5 to 0°C. The precipitate was filtered off
and recrystallized from hexane–chloroform. Yield
1.57 g (81%), orange–red crystals, mp 139–140°C. IR
spectrum, ν, cm–1: 3274 (NH), 1738 (C=O), 1648
(C=N), 1339 (NO2). 1H NMR spectrum, δ, ppm: 6.90 s
(1H, 4-H), 7.30–7.75 m (9H, Harom), 8.25 s (1H, NH).
13C NMR spectrum, δC, ppm: 92.0, 113.2, 124.7,
127.9, 128.3, 130.3, 137.5, 149.1, 152.6, 153.7, 155.0
Found, %: C 62.54; H 3.90; N 13.56. C16H11Ν3O4. Cal-
culated, %: C 62.14; H 3.56; N 13.59.
spectrum, δ, ppm: 6.91 s (1H, 4-H), 7.20–7.40 m (5H,
13
H
arom), 8.20 s (1H, N1′H), 10.66 s (1H, NH). C NMR
spectrum, δC, ppm: 91.6, 127.9, 128.6, 130.0, 145.0,
147.7, 153.1, 153.8, 155.4. Found, %: C 56.94; H 3.52;
N 27.40. C12H9Ν5O2. Calculated, %: C 56.47; H 3.55;
N 27.44.
1,5-Diphenyl-3-(2-phenylhydrazinylidene)-1H-
pyrrol-2(3H)-one (IIIa). Yield 1.66 g (90%), orange–
yellow crystals, mp 143–145°C. IR spectrum, ν, cm–1:
1
3269 (NH), 1716 (C=O), 1634 (C=N). H NMR spec-
trum, δ, ppm: 5.98 s (1H, 4-H), 7.20–7.75 m (15H,
Ph), 8.56 s (1H, NH). 13C NMR spectrum, δC, ppm:
88.7, 113.9, 122.4, 127.9, 128.1, 128.3, 128.6, 128.9,
129.5, 132.7, 134.2, 143.0, 153.3, 154.6, 161.1. Found,
%: C 77.98; H 5.14; N 12.56. C22H17Ν3O. Calculated,
%: C 77.87; H 5.01; N 12.39.
Compounds Ib, Ic, IIa, IIb, and IIIa–IIId were
synthesized in a similar way.
3-[2-(4-Nitrophenyl)hydrazinylidene]-5-pentyl-
furan-2(3H)-one (Ib). Yield 1.83 g (91%), orange–red
crystals, mp 139–141°C. IR spectrum, ν, cm–1: 3330
(NH), 1715 (C=O), 1629 (C=N), 1335 (NO2). 1H NMR
spectrum, δ, ppm: 0.85–2.05 m (11H, C5H11), 6.90 s
(1H, 4-H), 7.20–7.40 m (4H, Harom), 8.25 s (1H, NH).
13C NMR spectrum, δC, ppm: 14.1, 22.8, 28.4, 30.6,
31.9, 94.1, 113.8, 124.0, 137.9, 149.6, 152.4, 154.7,
171.5. Found, %: C 59.02; H 5.41; N 13.62.
C15H17Ν3O4. Calculated, %: C 59.40; H 5.61; N 13.86.
5-Pentyl-1-phenyl-3-(2-phenylhydrazinylidene)-
1H-pyrrol-2(3H)-one (IIIb). Yield 1.73 g (94%),
orange–yellow crystals, mp 149–151°C. IR spectrum,
ν, cm–1: 3338 (NH), 1723 (C=O), 1625 (C=N). 1H NMR
spectrum, δ, ppm: 0.89–2.02 m (11H, C5H11), 6.00 s
(1H, 4-H), 7.20–7.50 m (10H, Ph), 8.50 s (1H, NH).
13C NMR spectrum, δC, ppm: 13.8, 22.1, 28.6, 32.5,
33.4, 90.8, 114.2, 122.6, 128.0, 128.3, 129.0, 129.4,
138.2, 142.7, 155.3, 157.8, 161.4. Found, %: C 75.62;
H 7.09; N 12.76. C21H23Ν3O. Calculated, %: C 75.67;
H 6.90; N 12.61.
5-Butyl-3-[2-(4-nitrophenyl)hydrazinylidene]-
furan-2(3H)-one (Ic). Yield 1.76 g (95%), orange–red
crystals, mp 140–141°C. IR spectrum, ν, cm–1: 3281
(NH), 1712 (C=O), 1630 (C=N), 1347 (NO2). 1H NMR
spectrum, δ, ppm: 6.93 s (1H, 4-H), 0.87–2.02 m (9H,
C4H9), 7.20–7.50 m (4H, Harom), 8.20 s (1H, NH).
13C NMR spectrum, δC, ppm: 14.5, 22.3, 29.1, 32.9,
94.8, 113.6, 12.1, 137.2, 148.4, 153.2, 155.4, 171.8.
Found, %: C 58.02; H 5.31; N 14.62. C14H15Ν3O4.
Calculated, %: C 58.13; H 5.19; N 14.53.
5-Butyl-1-phenyl-3-(2-phenylhydrazinylidene)-
1H-pyrrol-2(3H)-one (IIIc). Yield 1.60 g (86%),
orange–yellow crystals, mp 151–153°C. IR spectrum,
ν, cm–1: 3321 (NH), 1741 (C=O), 1637 (C=N). 1H NMR
spectrum, δ, ppm: 0.85–1.90 m (9H, C4H9), 6.00 s (1H,
4-H), 7.20–7.48 m (10H, Ph), 8.53 s (1H, NH).
13C NMR spectrum, δC, ppm: 14.2, 22.8, 29.4, 33.7,
91.3, 114.5, 122.1, 127.8, 128.4, 129.0, 129.1, 138.5,
143.2, 155.4, 158.8, 161.2. Found, %: C 75.46; H 7.00;
N 13.36. C20H21Ν3O. Calculated, %: C 75.24; H 6.58;
N 13.17.
5-(4-Methylphenyl)-3-[2-(1H-1,2,4-triazol-5-yl)-
hydrazinylidene]furan-2(3H)-one (IIa). Yield 1.70 g
(92%), yellow–orange crystals, mp 227–229°C. IR
spectrum, ν, cm–1: 3271 (NH), 1766 (C=O), 1596
5-(4-Methylphenyl)-1-phenyl-3-(phenylhydra-
zinylidene)-1H-pyrrol-2(3H)-one (IIId). Yield 1.69 g
(91%), orange–yellow crystals, mp 151–153°C. IR
spectrum, ν, cm–1: 3294 (NH), 1716 (C=O), 1632
1
(C=N). H NMR spectrum, δ, ppm: 2.25 s (3H, CH3),
5.99 s (1H, 4-H), 7.25–7.45 m (4H, Harom), 8.23 s (1H,
N1′H), 10.61 s (1H, NH). 13C NMR spectrum, δC, ppm:
21.3, 92.0, 127.3, 128.9, 130.4, 137.6, 146.5, 147.3,
152.4, 154.0, 155.7. Found, %: C 58.21; H 3.88;
N 26.18. C13H11Ν5O2. Calculated, %: C 57.99; H 4.12;
N 26.01.
1
(C=N). H NMR spectrum, δ, ppm: 2.23 s (3H, CH3),
6.01 s (1H, 4-H), 7.30–7.84 m (14H, Harom), 8.60 s
(1H, NH). 13C NMR spectrum, δC, ppm: 21.4, 88.3,
114.2, 122.8, 128.0, 128.3, 128.4, 128.9, 129.3, 129.4,
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GAVKUS et al.
1232
6. Rubtsov, A.E. and Zalesov, V.V., Khim. Geterotsikl.
Soedin., 2001, p. 1130.
7. Taylor, E.C., Barton, J.W., and Osdene, T.S., J. Am.
Chem. Soc., 1958, vol. 80, p. 421.
132.4, 133.9, 137.6, 143.2, 152.7, 154.0, 160.2. Found,
%: C 75.46; H 7.00; N 13.36. C20H21Ν3O. Calculated,
%: C 75.24; H 6.58; N 13.17.
8. Shawali, A.S., Abdelkader, H., and Eltalbawy, F.,
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