3-Oxy-5-phenyl-1H-1,2,3-triazole-4-carboxylic acid. Synthesis, structure, and properties

Article abstract of DOI:10.1007/s11178-005-0209-8

The structure of 3-oxy-5-phenyl-1H-1,2,3-triazole-4-carboxylic acid was determined both experimentally (by the X-ray diffraction method) and by quantum-chemical calculations. Alkylation of 3-oxy-5-phenyl-1H-1,2,3-triazole-4- carboxylic acid (as crystal hydrate) with methyl iodide, depending on the reactant ratio, gives 1-methoxy-4-phenyl-1H-1,2,3-triazole-5-carboxylic acid and methyl 1-methoxy-4-phenyl-1H-1,2,3-triazole-5-carboxylate. Nitration of the title compound under mild conditions occurs at the 5-phenyl group with formation of meta-nitro derivative, while under more severe conditions 3,5-dinitrobenzoic acid is obtained. 3-Oxy-5-phenyl-1H-1,2,3-triazole-4-carboxylic acid was also converted into the corresponding acid chloride and substituted amide.

Full text of DOI:10.1007/s11178-005-0209-8

Russian Journal of Organic Chemistry, Vol. 41, No. 4, 2005, pp. 591–598. Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 4, 2005,
pp. 601–608.
Original Russian Text Copyright © 2005 by Shtabova, Shaposhnikov, Mel’nikova, Tselinskii, Nather, Traulsen, Friedrichsen.
3-Oxy-5-phenyl-1H-1,2,3-triazole-4-carboxylic Acid.
Synthesis, Structure, and Properties
O. V. Shtabova1, S. D. Shaposhnikov1, S. F. Mel’nikova1, I. V. Tselinskii1, Ch. Nather2,
T. Traulsen2, and W. Friedrichsen3
1 St. Petersburg State Institute of Technology, Moskovskii pr. 26, St. Petersburg, 190013 Russia
e-mail: sfm@fromru.com
2 Institute of Inorganic Chemistry, University of Kiel, Kiel, Germany
3 Institute of Organic Chemistry, University of Kiel, Kiel, Germany
Received February 24, 2003
Abstract—The structure of 3-oxy-5-phenyl-1H-1,2,3-triazole-4-carboxylic acid was determined both experi-
mentally (by the X-ray diffraction method) and by quantum-chemical calculations. Alkylation of 3-oxy-5-
phenyl-1H-1,2,3-triazole-4-carboxylic acid (as crystal hydrate) with methyl iodide, depending on the reactant
ratio, gives 1-methoxy-4-phenyl-1H-1,2,3-triazole-5-carboxylic acid and methyl 1-methoxy-4-phenyl-1H-
1,2,3-triazole-5-carboxylate. Nitration of the title compound under mild conditions occurs at the 5-phenyl
group with formation of meta-nitro derivative, while under more severe conditions 3,5-dinitrobenzoic acid is
obtained. 3-Oxy-5-phenyl-1H-1,2,3-triazole-4-carboxylic acid was also converted into the corresponding acid
chloride and substituted amide.
1,2,3-Triazole N-oxide derivatives attract interest
from the viewpoint of synthetic organic chemistry
due to diversity of their reactions. 1H-1,2,3-Triazole
3-oxides, which were formerly assigned the structure
of N-hydroxy-1,2,3-triazoles, were synthesized as early
as 1902 by treatment of diazo ketones with hydroxyl-
amine in aqueous alcohol [1]. The first and the only
review on the synthesis and reactivity of 1H-1,2,3-tri-
azole 3-oxides was published in 1989 [2], and it
stimulated further research in this field. As a result,
methods for the preparation of substituted 4-amino-5-
nitro-1,2,3-triazole 1-oxides via recyclization of 3,4-di-
nitro- and 4-alkylamino-3-nitrofuroxans [3, 4], as well
as of 2-aryl-4,5-dinitro- [5] and mononitro-1,2,3-tri-
azole 1-oxides [6] were developed. A number of
2-methyl-4(5)-nitro-5(4)-R-1,2,3-triazole 1-oxides
were synthesized by nucleophilic substitution of the
nitro group in 2-methyl-4,5-dinitro-1,2,3-triazole
1-oxide [7, 8].
cule [9]. The IR spectrum of N-oxide II contained
absorption bands at 3490, 3371, and 3071 cm–1, typical
of NH and OH groups, carbonyl absorption band at
1747 cm–1, and bands at 1696, 1616, 1164, 1090, and
798 cm–1, which are typical of 1,2,3-triazoles and their
N-oxides [2]. The UV spectrum of a solution of II in
water displayed two maxima at λ 221 and 256 nm.
According to the data of differential thermal analysis,
compound II decomposes in 3 steps two of which are
endothermic, and the third is exothermic. The first
endothermic step starts at 90°C; it corresponds to
slow elimination of water molecule and is complete at
180°C. Next follows melting (which is accompanied
by decarboxylation) and fast exothermic decom-
position.
Scheme 1.
(1) NaOH, H2O, ∆
(2) HCl, ∆
Ph
NOH
Ph
COOH
·H2O
N
HN
N
NOH
O
We previously showed that heating of 4,5-bis-
(hydroxyimino)-3-phenyl-4,5-dihydroisoxazole (I) in
boiling 20% aqueous sodium hydroxide, followed by
treatment with hydrochloric acid, gives 3-oxy-5-
phenyl-1H-1,2,3-triazole-4-carboxylic acid (II)
(Scheme 1); the product was isolated from the reaction
mixture as crystal hydrate containing one water mole-
O
N
I
II
The structure of 3-oxy-5-phenyl-1H-1,2,3-triazole-
4-carboxylic acid was studied theoretically by quan-
tum-chemical methods and was proved by the X-ray
diffraction data. Such compounds can exist as several
1070-4280/05/4104-0591 © 2005 Pleiades Publishing, Inc.

SHTABOVA et al.
592
Table 1. Energies of compounds II–IV and transition states
6-31G(d) basis set gave almost the same results;
here, tautomer IIIa was more stable than IIIb (∆E =
1.9 kcal/mol) and IIIc (∆E = 2.4 kcal/mol, Table 1).
(in hartree)a
Structure no.
E
E + ZPE
Sb
–11.54
0–7.51
–12.85
–10.88
–14.83
–15.99
0–7.95
0–8.73
–15.09
–
–737.00046 –736.84225
–737.00491 –736.84642
IIa
N
N
N
N
N
NH
IIb
HO
O
O
N
N
H
N
–737.01012
–737.00208
–737.00101
–737.01813
–
–
–
–
IIc
IIIa
IIIb
IIIc
IId
IIe
IIf
N
N
N
N
O
O
H
N
N
H
–317.38003 –317.31786
–317.37705 –317.31418
–317.37619 –317.31301
–393.81570 –393.72776
–393.81161 –393.72296
–393.80175 –393.71415
–393.80367 –393.71565
–505.95514 –505.87715
–505.95090 –505.87264
–505.95567 –505.87693
–317.31554 –317.25768
–317.29616 –317.23865
–393.79335 –393.71057
–393.75977 –393.67629
IIIa
H
H
IIIb
O
O
IIIc
H
H
IIId
IIId
IIIe
–
IIIe
–
IIIf
N
N
N
N
O
O
O
H
N
H
N
H
–
IIIg
O
H
0–7.37
0–9.42
–18.90
–
IVa
H
H
IVb
IVc
IIIf
IIIg
TS(IIIa–IIIb)
TS(IIIb–IIIc)
TS(IIId–IIIe)
TS(IIIf–IIIg)
The solvent effect calculation in terms of the
–
Cramer–Truhlar SM5.4 model [22] showed that the
most stable isomer is IIIc (IIIa, 4.8 kcal/mol; IIIb,
5.9 kcal/mol; IIIc, 0.0 kcal/mol; see Table 1). Tauto-
meric transformations IIIa → IIIb → IIIc (proton
migration) in the gase phase were characterized by the
following energies of activation: IIIa → IIIb, ∆E≠ =
40.5 kcal/mol; IIIb → IIIc, ∆E≠ = 50.7 kcal/mol
(Table 1). These values are consistent with the ab initio
energies for intramolecular proton migrations like
IIIa → IIIb in other azoles [8]. Participation of a sol-
vent (in our case, water) strongly reduces the energy
of activation: ∆E≠(IIId → IIIe) = 14.0 kcal/mol,
∆E≠(IIIf → IIIg) = 26.3 kcal/mol. The corresponding
transition states [23] involve simultaneous transfer of
two protons.
–
–
a
B3LYP/6-31G(d).
Solvation energy, kcal/mol (water, Truhlar–Cramer SM5.4).
b
tautomers. We performed calculations in terms of the
density functional theory (DFT) for both parent struc-
tures and substituted derivatives. Prototropic tautomer-
ism of heterocycles has been extensively studied by
both experimental and theoretical methods [10].
Tautomeric equilibria of heterocyclic compounds are
usually described by methods taking into account elec-
tron correlation [11, 12] (e.g., Moeller–Plesset per-
turbation theory) and DFT methods [13–16]. If the
energy difference between tautomers is small, solvent
effects are to be considered [17].
Introduction of a carboxy group into molecule III
changes the energies of tautomers. In this case,
rotamers IVa–IVc are expected to occupy energy
minima. The most stable rotamer of triazole IVa gives
rise to intramolecular hydrogen bond. Interestingly,
Anders et al. in the early study [18] used high-level
calculations (MP4SDTQ/6-31+G*//MP2/6-31+G*) to
obtain the following relative energies of unsubstituted
1-hydroxy-1H-1,2,3-triazoles IIIa–IIIc in the gas
phase: 0.0, 2.57, and 1.95 kcal/mol, respectively.
Guimon et al. [19] assigned structure IIIa to the only
tautomer detected by photoelectron spectroscopy [19].
With account taken of solvent effect (Tomasi’s SCRF
procedure [20]), tautomer IIIc turned out to be es-
sentially stabilized, E(IIIa) – E(IIIc) = 28.89 kcal/mol
(water). The DFT B3LYP calculations [21] using the
H
O
Od
O
c
c
O
O
Od
H
a
b
b
a
H
Hd
N
N
N
N
HN
N
O
O
O
b
a
N
N
N
c
H
IVa
IVb
IVc
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 41 No. 4 2005

3-OXY-5-PHENYL-1H-1,2,3-TRIAZOLE-4-CARBOXYLIC ACID.
593
O2
O3
tautomer IVc has the lowest energy even in the gas
phase. Obviously, this result originates from the
stronger intramolecular hydrogen bond, as compared
to structures IIIa–IIIc.
C3
C2
C9
O1
C8
N1
The barrier to rotation of the carboxy group in IVc
is ∆E = 19.0 kcal/mol, which is considerably higher
than the corresponding barrier found for IVa (∆E =
6.2 kcal/mol). The barrier to rotation of the carboxy
group in IVb is comparable with that in IVc
[∆E(IVb) = 18.0 kcal/mol]. Application of the Cramer–
Truhlar model with water as solvent leads to a strong
shift of the tautomeric equilibrium toward IVc; Erel,
kcal/mol: 7.2 (IVa), 6.5 (IVb); 0 (IVc). Analogous cal-
culations on compounds IIa–IIf showed that rotamer
IIa is less stable than IIb (∆E = 2.8 kcal/mol), but in
going to aqueous solution the reverse order is obtained:
∆[E + S (solvation energy)] = 1.24 kcal/mol in favor of
IIa. Intramolecular hydrogen bond stabilizes rotamer
IIc by ∆E = 5.3 kcal/mol relative to IId. The stabiliz-
ing effect becomes even stronger due to solvation:
∆(E + S) = 7.3 kcal/mol. Analogous pattaern is observ-
ed for structures IIe and IIf: ∆E = 10.7, ∆(E + S) =
11.9 kcal/mol). These data indicate that structure IIf is
the most stable, in keeping with the results of X-ray
diffraction study (Figs.1, 2; Tables 2–4).
C1
C7
C4
N2
C5
C6
N3
Fig. 1. Structure of the molecule of 3-oxy-5-phenyl-1H-
1,2,3-triazole-4-carboxylic acid (II) with atom numbering
according to the X-ray diffraction data. Thermal displace-
ment ellipsoids are shown with a probability of 50%.
influence to some extent the reactivity of triazole
derivative II. Treatment of triazole N-oxide II with
excess nitrating mixture (HNO3–H2SO4) under fairly
mild conditions (50°C) resulted in introduction of
a nitro group mainly into the meta-position of the
benzene ring (compound V), and only traces of the
corresponding para isomer were detected by TLC and
1H NMR spectroscopy. Raising the temperature and
increasing the amount of nitrating mixture led to de-
composition of compound II and formation of 3,5-di-
nitrobenzoic acid VI (Scheme 2).
Comparison of the calculated and experimental
geometric parameters (bond lengths, bond angles, and
dihedral angles) shows that the B3LYP/6-31G(d)
method is applicable to description of the heterocyclic
compounds under study. The only exception was the
N1–O1 bond (exocyclic N–O bond) which turned out to
be considerably longer (1.310 Å) than the calculated
value (1.275 Å); on the other hand, this parameter
insignificantly affects the energy.
Table 2. Coordinates of atoms (×104) and their equivalent
isotropic displacement parameters (×103Å2) in the structure
of 3-oxy-5-phenyl-1H-1,2,3-triazole-4-carboxylic acid (II)
Atom
x
y
z
Ueq
C1
C2
N1
N2
N3
O1
C3
O2
O3
C5
C6
C7
C8
C9
O4
8933(2)
7248(2)
7368(2)
8941(2)
9878(2)
6089(2)
5636(2)
4392(2)
5485(2)
6581(2)
7163(2)
6944(2)
6284(2)
6073(2)
7358(2)
8042(2)
8621(2)
8265(2)
6740(1)
6345(1)
5573(1)
5461(1)
6181(1)
4984(1)
6577(1)
6001(1)
7249(1)
7797(1)
8577(1)
9128(1)
8900(1)
8121(1)
6294(1)
20(1)
21(1)
26(1)
30(1)
25(1)
37(1)
21(1)
30(1)
27(1)
23(1)
28(1)
30(1)
27(1)
21(1)
27(1)
The presence of an N-oxide moiety and a carboxy
group, as well as of crystallization water, should
O
O
O
H
Ph
Ph
Ph
O
O
O
H
H
N
N
N
N
N
N
O
OH
O
N
N
N
H
H
IIa
IIb
IIc
11594(2)0 6937(2)
12361(2)0 6911(2)
11299(2)0 6448(2)
H
O
O
O
H
Ph
Ph
Ph
O
O
O
O
H
9469(2)
8682(2)
3291(2)
5980(2)
6006(2)
4760(2)
N
N
HN
N
HN
N
O
O
N
H
N
N
IId
IIe
IIf
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 41 No. 4 2005

SHTABOVA et al.
594
Table 3. Hydrogen bond parameters in 3-oxy-5-phenyl-1H-1,2,3-triazole-4-carboxylic acid (II) in crystal (D stands for donor,
and A, for acceptor)
D–H bond
d(D–H), Å
d (H···A), Å
d(D···A), Å
A
∠D(H···A), deg
178.86
N3–H1N
O2–H1O
O2–H1O
O4–H3O
O4–H2O
O4–H2O
O4–H2O
0.945
0.929
0.929
0.862
0.889
0.889
0.889
1.734
1.640
1.640
1.933
1.960
2.641
2.687
2.678
2.525
2.525
2.788
2.840
3.459
3.317
O4 [x + 1, y, z]
157.78
O1
O1
157.78
171.11
O3 [–x + 1, y–1/2, –z + 3/2]
O1 [–x + 1, –y + 1, –z + 1]
N1 [–x + 1, –y + 1, –z + 1]
N2 [–x + 1, –y + 1, –z + 1]
170.21
153.64
128.79
Triazole II behaved in a specific fashion in the
alkylation with methyl iodide. The reaction of II with
an equimolar amount of methyl iodide in DMF in the
presence of potassium carbonate involved the N-oxide
oxygen atom to give 1-methoxy-4-phenyl-1H-1,2,3-
triazole-5-carboxylic acid (VII); with 2 equiv of MeI
or more, esterification of the carboxy group occurred
to afford O,O'-dimethyl derivative VIII (Scheme 3).
the signal from the methoxy protons appeared at
δ 3.86 ppm. Our results indicate that the alkylation of
triazole N-oxide II does not involve the N1 atom.
We succeeded in synthesizing 3-oxy-5-phenyl-1H-
1,2,3-triazole-4-carbonyl chloride (X) only by fusion
of II with PCl5; our attempts to effect this transforma-
tion with the use of SOCl2 resulted in removal of
crystallization water. Chloride X is hydrolytically
unstable. Presumably, the rate of hydrolysis is fairly
high, as follows from the results of its reactions with
alcohols. The reaction with methanol gave about 80%
of ester IXa, while with 95% ethanol in the presence
of potassium hydroxide we obtained a mixture of ester
IXb and acid II at a ratio of 3:1. Only acid II was
isolated (instead of the expected amide) in the reaction
of IXa with aqueous ammonia. On the other hand, the
reaction of chloride X with p-toluidine afforded sub-
stituted amide XI in a good yield (80%). Like acid II,
1
The H NMR spectra of compounds VII and VIII
contained signals from the aromatic protons (δ 7.75–
7.35 ppm) and methoxy groups [δ 4.33 ppm (VII);
δ 4.35 (MeON) and 3.87 ppm (MeOC) (VIII)]. The
assignment of the methoxy protons was confirmed by
1
comparison with the H NMR spectrum of methyl
3-oxy-5-phenyl-1H-1,2,3-triazole-4-carboxylate (IXa)
which was synthesized by reaction of carbonyl
chloride X with methanol. In the spectrum of IXa,
Scheme 2.
COOH
·H2O
a
HN
N
O
N
II
HNO3/H2SO4
0
c
b
50°C
75°C
COOH
O2N
COOH
O2N
NO2
Fig. 2. Crystal structure of 3-oxy-5-phenyl-1H-1,2,3-tri-
azole-4-carboxylic acid (II) (projection onto the 010 plane,
hydrogen bonds are shown as dashed lines).
HN
N
O
N
V
VI
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3-OXY-5-PHENYL-1H-1,2,3-TRIAZOLE-4-CARBOXYLIC ACID.
595
Scheme 3.
Ph
COOH
Ph
COOMe
MeI, K2CO3, DMF
MeI, K2CO3, DMF
N
N
N
N
OMe
ROH
OMe
N
N
Ph
COOH
VII
VIII
HN
N
O
N
MeI, K2CO3
DMF
Ph
COCl
Ph
COOR
II
PCl5
HN
N
HN
N
O
O
N
N
X
IXa, IXb
NO2
4-MeC6H4NH2
O2N
Ph
CONHC6H4Me-4
COOR
HN
N
HN
N
O
O
N
N
XI
XII
IX, R = Me (a), Et (b).
the nitration of methyl 3-oxy-5-phenyl-1H-1,2,3-tri-
azole-4-carboxylate (IXa) resulted in formation of
5-(3-nitrophenyl) derivative XII (Scheme 3).
100 g of a 20% solution of sodium hydroxide was
heated to the boiling point, kept for 5 min at that tem-
perature, cooled, and acidified to pH 1–2 with con-
centrated hydrochloric acid. The red precipitate was
filtered off, washed with water, and dispersed in 50 ml
of cold water, 10 ml of concentrated hydrochloric acid
was added, and the mixture was heated at the boiling
point under stirring until it became colorless. The mix-
ture was cooled, and the precipitate was filtered off,
washed with 50 ml of water, and dried in air. Yield
4.2 g (65%), mp 180°C (with decomposition; from
EXPERIMENTAL
The calculations were performed using Gaussian
software [21]. All transition states described in this
paper were characterized by calculations of vibration
frequencies (one imaginary frequency) and by visual
monitoring of the imaginary frequency with the aid of
Gaus View [23]. X-Ray analysis of a single crystal of
3-oxy-5-phenyl-1H-1,2,3-triazole-4-carboxylic acid
(II) was performed on a Nonius CAD-4 diffractometer.
The following unit cell parameters were found: a =
7.372(1), b = 7.506(1), c = 17.468(4) Å; β = 99.76(3)°;
V = 952.6(3) Å3; d = 1.556 g/cm3; space group P21/c;
1
H2O). H NMR spectrum, δ, ppm: 8.93 br.s (2H, OH,
NH), 7.78 d (2H, Harom), 7.46 m (3H, Harom). 13C NMR
spectrum, δC, ppm: 160.1 (C=O); 145.8, 120.9 (C4,
C5); 130.5, 129.8, 129.2, 129.0 (Carom). Found, %:
C 48.49; H 4.00; N 18.23. C9H7N3O3·H2O. Calculated,
%: C 48.43; H 4.06; N 18.83.
1
13
Z = 4; µ = 0.125 mm–1. The H and C NMR spectra
were recorded on a Bruker AC-500 spectrometer in
DMSO-d6 using the solvent as internal reference. The
IR spectra were measured in KBr on a Perkin–Elmer
Spectrum BX 1000 instrument.
5-(3-Nitrophenyl)-3-oxy-1H-1,2,3-triazole-4-car-
boxylic acid (V). A mixture of 5 ml of 98% H2SO4 and
4 ml of HNO3 (d = 1.5 g/cm3) was added dropwise
under stirring at 20°C to a solution of 2 g (9 mmol) of
acid II in 20 ml of 98% H2SO4. The mixture was
heated to 50°C under stirring, stirred for 30 min at that
temperature, cooled, and poured into water. The pre-
cipitate was filtered off, washed with water until
neutral washings, and dried in air. Yield 1.4 g (65%),
mp 190–192°C (with decomposition; from H2O).
4,5-Bis(hydroxyimino)-3-phenyl-4,5-dihydroisoxa-
zole (I) was synthesized as described in [24].
3-Oxy-5-phenyl-1H-1,2,3-triazole-4-carboxylic
acid (II). A solution of 6 g (29.3 mmol) of 4,5-bis-
(hydroxyimino)-3-phenyl-4,5-dihydroisoxazole (I) in
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 41 No. 4 2005

SHTABOVA et al.
596
Table 4. Experimental and calculated bond lengths (d, Å)
and bond angles (ω, deg) in the molecule of 3-oxy-5-phenyl-
1H-1,2,3-triazole-4-carboxylic acid (IIf)
acid, and the precipitate was filtered off and dried in
air. Yield 1.54 g (60%), mp 143–144°C (with decom-
position; reprecipitated from acetone with water).
1H NMR spectrum, δ, ppm: 14.36 s (1H, OH), 7.77 d
(2H, Harom), 7.46 m (3H, Harom), 4.33 s (3H, OCH3).
13C NMR spectrum, δC, ppm: 158.9 (C=O); 146.9,
121.1 (C4, C5); 130.4, 129.6, 129.0, 128.8 (Carom); 69.4
(CH3). Found, %: C 54.87; H 4.21; N 19.15.
C10H9N3O3. Calculated, %: C 54.80; H 4.14; N 19.17.
b
b
Bond
dexp
dcalc
Angle
ωexp
ωcalc
C1–N3 1.347(2) 1.357 N3C1C2 105.0(2)
C1–C4 1.466(2) 1.469 C2C1C4 133.1(2) 135.37
C2–C3 1.474(2) 1.490 N1C2C3 120.8(2)
N1–O1 1.310(2) 1.275 N2N1O1 120.8(2) 121.65
Methyl 1-methoxy-4-phenyl-1H-1,2,3-triazole-5-
carboxylate (VIII). a. Finely powdered potassium
carbonate, 15.5 g (110 mmol), and methyl iodide, 16 g
(110 mmol), were added under vigorous stirring to
a solution of 5 g (22.4 mmol) of acid II in 50 ml of
DMF. The mixture was left to stand for 2 days at room
temperature and diluted with 300 ml of water, and the
precipitate was filtered off and dried in air. Yield 4.1 g
C3–O3 1.210(2)
C4–C5 1.394(2)
C5–C6 1.384(2)
C7–C8 1.385(2)
C1–C2 1.386(2) 1.394 C9C4C1 120.8(2)
C2–N1 1.376(2) 1.399 C5C6C7 120.2(2)
N1–N2 1.306(2) 1.319 C7C8C9 120.2(2)
N2–N3 1.339(2) 1.348 N3C1C4 121.9(2)
C3–O2 1.314(2)
C4–C9 1.397(2)
C6–C7 1.384(2)
C8–C9 1.386(2)
C5–C6 1.384(2)
O1N1C2 125.7(2) 125.64
N2N3C1 113.6(2) 114.95
O3C3C2 122.7(2)
C5C4C9 119.7(2)
1
(75%), mp 70–71°C (from aqueous ethanol). H NMR
spectrum, δ, ppm: 7.75 d (2H, Harom), 7.48 m (3H,
Harom), 4.35 s (3H, 1-OCH3), 3.87 s (3H, COOCH3).
13C NMR spectrum, δC, ppm: 157.8 (C=O); 147.7,
119.9 (C4, C5); 130.1, 129.8, 129.2, 128.8 (Carom); 69.5
(1-OCH3); 53.43 (COOCH3). Found, %: C 56.99;
H 4.79; N 20.62. C11H11N3O3. Calculated, %: C 56.65;
H 4.75; N 20.58.
N1C2C1 104.4(2)
C1C2C3 134.5(2)
N2N1C2 113.5(2)
N1N2N3 103.5(2)
O3C3O2 122.0(2)
O2C3C2 115.3(2)
C5C4C1 119.4(2)
C6C5C4 119.9(2)
C6C7C8 120.1(2)
C8C9C4 119.7(2)
b. Finely powdered potassium carbonate, 2.3 g
(16 mmol), and methyl iodide, 0.76 g (5.3 mmol), were
added to a solution of 1 g (4 mmol) of methyl ester VII
in 10 ml of DMF under stirring at 20°C. The mixture
was left to stand for 24 h and diluted with 50 ml of
water, and the precipitate was filtered off and dried in
air. Yield 0.8 g (80%), mp 70–71°C; no depression
of the melting point was observed on mixing with
a sample prepared as described above in a.
a
For atom numbering, see Fig. 1.
B3LYP/6-31G(d).
b
1H NMR spectrum, δ, ppm: 12.82 (2H, NH, OH),
c. Following method b, compound VIII was syn-
thesized from ester IXa. Yield 83%.
8.97 s (1H, Harom), 8.51 d (1H, Harom), 8.23 d (1H,
H
arom), 7.74 t (1H, Harom). 13C NMR spectrum, δC, ppm:
Methyl 3-oxy-5-phenyl-1H-1,2,3-triazole-4-car-
boxylate (IXa). A solution of 1.9 g (23 mmol) of
potassium hydroxide in a minimal amount of methanol
was added to 2.4 g (11 mmol) of acid chloride X in
50 ml of methanol. The mixture was stirred for 3 h at
room temperature, diluted with 100 ml of water,
acidified to pH 1–2 with concentrated hydrochloric
acid, and extracted with methylene chloride (2×
50 ml). The extract was washed with water (2×20 ml)
and evaporated in air. Yield 1.9 g (77%), mp 122–
123°C (from CCl4–CHCl3, 1:1). 1H NMR spectrum, δ,
ppm: 7.73 d (2H, Harom), 7.46 m (3H, Harom), 3.86 (3H,
CH3). 13C NMR spectrum, δC, ppm: 158.1 (C=O);
146.2, 119.5 (C4, C5); 129.8, 128.9, 128.2, 128.1
160.3 (C=O); 142.9, 119.1 (C4, C5); 148.4, 134.5,
133.1, 130.3, 123.5, 122.8 (Carom). Found, %: C 43.57;
H 2.70; N 22.52. C9H6N4O5. Calculated, %: C 43.21;
H 2.42; N 22.40.
1-Methoxy-4-phenyl-1H-1,2,3-triazole-5-carbox-
ylic acid (VII). Finely powdered potassium carbonate,
4.6 g (33 mmol), was added under stirring to a solution
of 2.5 g (11 mmol) of acid II in 25 ml of DMF, the
mixture was stirred for 10 min, and 1.75 g (12 mmol)
of methyl iodide was added. The mixture was stirred
for 2 days, poured into 75 ml of water, and extracted
with diethyl ether (2×50 ml). The aqueous phase was
acidified to pH 1–2 with concentrated hydrochloric
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 41 No. 4 2005

3-OXY-5-PHENYL-1H-1,2,3-TRIAZOLE-4-CARBOXYLIC ACID.
597
(Carom); 52.8 (COOCH3). Found, %: C 55.00; H 4.56;
N 19.32. C10H9N3O3. Calculated, %: C 54.79; H 4.14;
N 19.17.
H2SO4 and 4 ml of HNO3 (d = 1.5 g/cm3) was added
dropwise to a solution of 2 g (9 mmol) of ester XIa in
20 ml of 98% H2SO4 under stirring at ~20°C. The
mixture was stirred for 2 h at 60°C, cooled, and poured
into water. The precipitate was filtered off, washed
with water until neutral washings, and dried in air.
Yield 1.5 g (64%), mp 159–160°C (with decomposi-
Ethyl 3-oxy-5-phenyl-1H-1,2,3-triazole-4-car-
boxylate (IXb) was synthesized in a similar way using
95% ethanol. During extraction with methylene
chloride, a solid precipitated and was filtered off,
washed with water, and dried in air. Yield 0.6 g (20%),
mp 180°C; the product showed no depression of the
melting point on mixing with acid II. From the
methylene chloride extract we isolated 1.8 g (60%) of
compound IXb, mp 134–135°C (from CCl4). 1H NMR
spectrum, δ, ppm: 11.70 (1H, NH), 7.73 d (2H, Harom),
7.46 m (3H, Harom), 4.32 q (2H, CH2), 1.23 t (3H,
CH3). 13C NMR spectrum, δC, ppm: 157.8 (C=O);
146.2, 119.9 (C4, C5); 130.0, 129.1, 128.4, 128.3
(Carom); 61.9 (OCH2), 13.8 (CH3). Found, %: C 56.72;
H 4.83; N 17.98. C11H11N3O3. Calculated, %: C 56.65;
H 4.75; N 18.02.
1
tion; from H2O). H NMR spectrum, δ, ppm: 11.8
(NH), 8.64 s (1H, Harom), 8.31 d (1H, Harom), 8.22 d
(1H, Harom), 7.78 t (1H, Harom), 3.88 s (3H, CH3).
Found, %: C 45.57; H 2.70; N 22.02. C10H8N4O5. Cal-
culated, %: C 45.46; H 3.05; N 21.21.
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3-Oxy-5-phenyl-1H-1,2,3-triazole-4-carbonyl
chloride (X). Finely powdered acid II, 2.5 g
(11 mmol), was mixed with 4.7 g (23 mmol) of finely
powdered phosphorus pentachloride. The mixture was
slowly heated to 100°C under stirring, kept at that
temperature until it solidified completely, cooled, and
ground in a mortar under a layer of hexane. The solid
substance was filtered off and was used in further
syntheses without additional purification. Yield 2.4 g
(quantitative).
N-(p-Tolyl)-3-oxy-5-phenyl-1H-1,2,3-triazole-4-
carboxamide (XI). A mixture of 1.3 g (12 mmol) of
p-toluidine, 20 ml of pyridine, and 2.7 g (12 mmol) of
chloride IX was heated to the boiling point over
a period of 15 min. The mixture was then cooled to
20°C, diluted with 50 ml of water, and acidified to
pH 2 with concentrated hydrochloric acid. The precip-
itate was filtered off, washed with water until neutral
washings, and dispersed in 70 ml of boiling water. The
suspension was filtered while hot, and the precipitate
was dried in air. Yield 24 g (80%), mp 245–246°C
(decomp.). 1H NMR spectrum, δ, ppm: 12.0 (1H, 1-H),
11.21 (1H, NH, amide), 7.78 (2H, C6H5), 7.56 d (2H,
C6H4.), 7.45 m (3H, C6H5), 7.18 d (2H, C6H4), 2.28 s
(3H, CH3). 13C NMR spectrum, δC, ppm: 155.97
(C=O); 141.65, 119.88 (C4, C5); 135.61, 133.74,
129.95, 129.50, 129.04, 128.82 (Carom); 20.63 (CH3).
Found, %: C 65.36; H 4.73; N 19.12. C16H14N4O2. Cal-
culated, %: C 65.30; H 4.79; N 19.04.
Methyl 5-(3-nitrophenyl)-3-oxy-1H-1,2,3-tri-
azole-4-carboxylate (XII). A mixture of 5 ml of 98%
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