MAGNETIC RESONANCE IN CHEMISTRY, VOL. 36, 459È460 (1998)
Reference Data
EXPERIMENTAL
1H and 13C NMRÈSpectroscopy of Substituted
1,2,3-Triazoles
Melting points were determined on a KoÑer melting point apparatus
and are uncorrected. MS was performed on an HP-5988A spectrometer
(electron ionization at 70 eV). IR spectra were obtained in KBr discs on
a Nicolet 170SX FT-IR spectrometer.
Xiao-Wen Sun, Peng-Fei Xu and Zi-Yi Zhang*
National Laboratory of Applied Organic Chemistry,
Department of Chemistry,
Lanzhou University,
Lanzhou, 730000,
China
1H NMR spectra were recorded at room temperature at 80 MHz on
a Bruker FT-AC 80 instrument. 13C NMR spectra were obtained at
100.61 MHz on a Bruker AM 400 spectrometer operating in the
complex pulse decoupling (CPD) mode. Spectra were recorded for solu-
tions of about 20 mg of each compound in 0.5 ml of DMSO-d and 5
6
mm NMR tubes were used. All chemical shifts were determined on the
Received 27 October 1997; revised 15 January 1998; accepted 23
January 1998
d scale (ppm) relative to internal TMS.
1H NMR spectra were recorded with spectral width 1362.4 Hz,
acquisition time 1.5 s, pulse width for a 90¡ pulse 3.0 ls and relaxation
delay 1.0 s. Typical conditions for recording 13C NMR spectra were
spectral width 23.8 kHz, acquisition time 0.688 s, pulse width for a 90¡
pulse 5.0 ls, relaxation delay 2.0 s and number of data points 32 K.
The 13C chemical shift assignments were made on the basis of the
additivity e†ects induced by the substituents, the signal intensities and
data reported earlier for related compounds.9h11 Compounds 3aÈl
were prepared as described in the literature;12 six are new compounds.
ABSTRACT: 1-Aryl-4-carboxy-5-methyl-1,2,3-triazoles were prepared
by the condensation of aryl azides with ethyl acetoacetate. The struc-
tures of these compounds were characterized by MS, IR and 1H and
13C NMR spectroscopy. The measured and calculated 13C chemical
shifts of the aromatic carbons were compared.
KEYWORDS: NMR; 1H NMR; 13C NMR; 1,2,3-triazoles
INTRODUCTION
Acknowledgement
We are grateful to the National Natural Science Foundation of China
for Ðnancial support.
1,2,3-Triazole derivatives form an interesting class of compounds on
account of their biological activities and their wide use in medicine,
agriculture and industry.1h4 In the past, we investigated the 13C NMR
spectra of substituted 1,2,4-triazoles.5h7 In connection with our e†orts
in this area, we report now the spectroscopic characterization of substi-
tuted 1,2,3-triazoles. ( 1998 John Wiley & Sons, Ltd.
REFERENCES
1. H. Oehlschlaeger, B. Morcher, L. Rosenhahn, F. Sommer and T.
Stetzer, Ger. O†en. 4 007 731 (1991); Chem. Abstr. 116, 31278q
(1992).
2. K. C. Mitsubishi, Jpn. Pat. 02 02 072 (1990); Chem. Abstr. 112,
236930k (1990).
RESULTS AND DISCUSSION
The condensation of aryl azides (1aÈl) with ethyl acetoacetate (2)
a†orded the corresponding 1-aryl-4-carboxy-5-methyl-1,2,3-triazoles
(3aÈl) (Table 1). The structures of these compounds were conÐrmed by
MS, IR and 1H and 13C NMR and the results are given in Tables 2 and
3. The IR spectra of 3aÈl display an intense peak around 1690 cm~1
due to the CxO function and a broad peak in the region 2566È3097
cm~1 (bonded OH) or a sharp peak around 3500 cm~1 (free OH). The
absorption band in the range 1562È1578 cm~1 is assigned to NxN and
aromatic bonds.
The 1H NMR spectra show the presence of the triazole methyl group
in the range d 2.30È2.51 ppm, whereas the aromatic protons resonate at
d 7.15È7.85 ppm. The 13C NMR spectra exhibit characteristic signals
for C-4 and C-5 of the triazole ring at d 135.85È136.62 and 138.93È
140.37 ppm, respectively. The C-12 signal of the carboxy group is at d
162.43È162.64 ppm.
3. F. Kimura, T. Haga, S. Murai and M. Ikeguchi, Jpn. Pat. 03 157
374 (1991); Chem. Abstr. 115, 256177k (1991).
4. Z. Y. Zhang, Y. Liu, S. Y. Yang and M. Q. Chen, Chem. J. Chin.
Univ. 12, 1344 (1991).
5. Z. Y. Zhang, P. Q. Liu, M. S. Song and H. Yang, Chin. J. Magn.
Reson. 5, 367 (1988).
Table 1. Structures, yields and melting points of 1-aryl-4-
carboxy-5-methyl-1,2,3-triazoles 3a–l
Compound 3i was utilized to determine the inÑuence of the hetero-
cyclic ring on the aromatic carbons. The chemical shift increments
induced by the heterocyclic ring are given in Table 4. The para carbon
resonates at lower Ðeld than ortho and meta carbons, which reÑects the
electron-withdrawing ability of the 1,2,3-triazole group.
Compound 3
Ar
Yield (%)
M.p. (¡C)
By adding the substituent e†ects8 of Cl, Br, CH and CH O to the
a
b
c
d
e
f
g
h
i
p-ClC H
p-CH OC H
80
71
56
64
67
55
58
51
45
50
47
43
200È201
179È180
182È183
201È202
187È188
165È166
185È186
157È158
148È149
169È170
159È160
145È146
3
3
6
4
chemical shifts of 3i, the chemical shifts of the aromatic carbons were
calculated for 3aÈh and 3jÈl. The average error of the prediction was ca.
1 ppm. The larger deviations between the measured and the calculated
shifts are observed for ortho-substituted derivatives due to the steric
hindrance.
3
6
4
4
p-CH C H
3
6 4
p-BrC H
6
4
m-ClC H
6
4
o-ClC H
6
4
Finally, it was found that the C-6 chemical shifts could not be well
correlated with HammettÏs constants of the substituents.
m-BrC H
6
4
o-BrC H
6
4
C H
6
5
* Correspondence to: Z.-Y. Zhang, National Laboratory of Applied Organic
Chemistry, Department of Chemistry, Lanzhou University, Lanzhou 730000,
China.
j
k
l
o-CH OC H
3
6
m-CH C H
3
6 4
6 4
o-CH C H
3
Contract/grant sponsor: National Natural Science Foundation of China.
( 1998 John Wiley & Sons, Ltd.
CCC 0749-1581/98/060459È02 $17.50
Sun, Xiao-Wen
