Chemistry of Heterocyclic Compounds, Vol. 47, No. 12, March, 2012 (Russian Original Vol. 47, No. 12, December, 2011)
NOVEL METHOD FOR THE SYNTHESIS OF
4-(AZOL-5-YL)-1,2,3-TRIAZOLES
V. A. Bakulev1*, I. V. Efimov1, N. A. Belyaev1, Yu. A. Rozin1,
N. N. Volkova1, and O. S. El'tsov1
Keywords: azides, azoles, isoxazoles, 1,2,3-thiadiazoles, 1,2,3-triazoles, cycloaddition.
We have proposed a novel, general, and efficient method for the synthesis of 4-(azol-5-yl)-1,2,3-tri-
azoles by cycloaddition of azides to 2-azolylenamines. It was shown that the enamines 2, 5, 8 take part in [3+2]
cycloaddition when fused with aromatic azides to give exclusively the bicyclic compounds 3, 6, 9 in high yields.
The regiospecificity of the reaction is evidently due to the "push-pull" character of enamines, the reaction of
which with zwitterionic azides gives one of two possible regioisomers. It should be noted that, in contrast to
condensed 1,2,3-triazoles [1], the bicyclic groups of compounds of type 3, 6, 9 are poorly available [2]. The
transformation described is the first example of cycloaddition of 3-hetarylenamines to azides [1, 3]. The
1
structures of the compounds obtained were confirmed by H and 13C NMR spectroscopic data and elemental
analysis. Assignments in the 13C NMR spectra were made on the basis of 2D HMBC experimental data for
compounds 3 and 8.
The 1H, 13C, and 19F NMR spectra were recorded on a Bruker Avance II 400 spectrometer (400, 100, and
376 MHz respectively) using DMSO-d6 with TMS as internal standard. Elemental analysis for C, H, and N was
performed on an automatic Perkin Elmer 2400 II analyzer. The analysis for sulfur was by titration of sulfate
anion after combustion in oxygen.
Ethyl 5-[(E)-2-(dimethylamino)ethenyl]-1,2,3-thiadiazole-4-carboxylate (2). The Bredereck reagent
[4] (0.553 g, 3 mmol) was added to compound 1 (0.172 g, 1 mmol) and heated for 2 h at 50ºC. The reaction
product was cooled and hexane was added. The precipitate was filtered off, dried, and recrystallized from EtOH.
1
Yield 0.184 g (81%); mp 114-115ºC. H NMR spectrum, , ppm (J, Hz): 1.32 (3H, t, J = 7.0, CH2CH3); 2.99
(6H, s, N(CH3)2); 4.34 (2H, q, J = 7.0, CH2CH3); 6.14 (1H, d, J = 13.0, =CH); 7.41 (1H, d, J = 13.0, =CH). 13C
NMR spectrum, , ppm: 14.2 (CH2CH3 ); 39.5 (N(CH3)2, low intensity); 60.3 (CH2CH3); 84.3 (=CH); 141.1
(C-5); 153.9 (=CH); 161.5 (C=O); 163.6 (C-4). Found, %: C 47.80; H 5.91; N 18.21; S 14.14. C9H13N3O2S.
Calculated, %: C 47.56; H 5.77; N 18.49; S 14.11.
Methyl 5-[(E)-2-(Dimethylamino)ethenyl]-1-(4-fluorophenyl)-1H-1,2,3-triazole-4-carboxylate (5).
Obtained similarly to compound 2. Yield 0.249 g (86%); mp 145-146ºC. 1H NMR spectrum, , ppm (J, Hz): 2.77
(6H, s, N(CH3)2); 3.85 (3H, s, OCH3); 4.82 (1H, d, 2J = 13.4, =CH); 7.62-7.47 (4H, m, H Ar); 7.71 (1H, d, J = 13.4,
13
=CH). C NMR spectrum, , ppm (J, Hz): 39.4 (N(CH3)2); 52.2 (OCH3); 110.7 (=CH); 116.6 (d, JC–F = 23.2,
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*To whom correspondence should be addressed, e-mail: vasiliy.bakulev@toslab.com.
1Ural Federal University named after the first President of Russia B.N.Yeltsin, 19 Mir St., Yekaterinburg
620002, Russia.
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Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1900-1902, December, 2011.
Original article submitted September 24, 2011.
0009-3122/12/4712-1593©2012 Springer Science+Business Media, Inc.
1593
Bakulev
