Trifluoromethanesulfonyl azide as a convenient reagent for synthesis of triazoles

Full text of DOI:10.1023/A:1013911615568

Russian Journal of Organic Chemistry, Vol. 37, No. 12, 2001, pp. 1797 1798. Translated from Zhurnal Organicheskoi Khimii, Vol. 37, No. 12, 2001,
pp. 1877 1878.
Original Russian Text Copyright
2001 by Shainyan, Meshcheryakov.
SHORT
COMMUNICATIONS
Dedicated to Academician M.G.Voronkov on occasion of his 80th birthday
Trifluoromethanesulfonyl Azide as a Convenient Reagent
for Synthesis of Triazoles
B. A. Shainyan and V. I. Meshcheryakov
Irkutsk Institute of Chemistry, Siberian Division, Russian Academy of Sciences,
ul. Favorskogo 1, Irkutsk, 664033 Russia
e-mail: bagrat@irioch.irk.ru
Received February 2, 2001
Trifluoromethanesulfonyl azide CF3SO2N3 (I) is
known to react with various substrates either with
liberation of nitrogen or as a source of nitrene [1 3];
it usually acts as amidating agent or, more rarely, as
of pure triazole II in ethanol also resulted in its trans-
formation into 4-phenyl-1H-1,2,3-triazole (III) due
to high nucleofugicity of the CF3SO2 group. The
hydrolysis of structurally related triazole derived from
diazotizing agent with respect to amino group [4, 5] or p-toluenesulfonyl azide occurs only in 90% sulfuric
azidating agent [6]. There are no published data on
reactions of azide I with alkynes. We were the first
to examine the reaction of trifluoromethanesulfonyl
azide (I) with phenylacetylene, which resulted in
formation 1,2,3-triazole derivatives. Unlike p-toluene-
sulfonyl azide which reacts with phenylacetylene to
give the corresponding triazole in 49% yield under
reflux for 6 days [7], azide I gives rise to 1,3-cyclo-
addition products in a similar yield but under milder
conditions and at a much higher rate (by an order of
magnitude). By heating azide I with phenylacetylene
in ethanol we obtained 4-phenyl-1H-1,2,3-triazole
(III) as the major product; it was formed as a result
of solvolysis of intermediate 4- and 5-phenyl-1-tri-
fluoromethylsulfonyl-1H-1,2,3-triazoles IIa and IIb.
acid [7]. Thus the examined reaction provides a con-
venient method for preparation of difficultly acces-
sible substituted 1H-1,2,3-triazoles.
1
In the H NMR spectrum of triazole II, apart from
signals belonging to the major product IIa, we ob-
served signals at 7.58 (m, p-H, m-H), 8.00 (m, o-H),
and 9.16 ppm (s, CH) at a ratio of 3: 2: 1. Presum-
ably, these signals belong to the minor isomer,
5-phenyl-1-trifluoromethylsulfonyl-1H-1,2,3-triazole
(IIb). The isomer ratio IIa: IIb is 4: 1.
Trifluoromethanesulfonyl azide CF3SO2N3 (I).
13C NMR spectrum (CDCl3), C, ppm: 119.26 q
(1JC, F = 322.5 Hz). 19F NMR spectrum (CDCl3):
76.28 ppm; isotope shift (12C)
(13C) =
0F.13 ppm. 15N NMR spectrum (CDCl3), N, ppm:
136.21 ( N ), 150.96 ( N ), 250.31 (S N ).
4-Phenyl-1-trifluoromethylsulfonyl-1H-1,2,3-tri-
azole (II). To a solution of 2 g (0.02 mol) of phenyl-
acetylene in 20 ml of CH2Cl2 we added a solution of
3.5 g (0.02 mol) of azide I in 10 ml of CH2Cl2, and
the mixture was stirred for 10 15 h at 40 C until the
initial azide disappeared (according to TLC). The
solvent was distilled off, and the liquid residue was
subjected to column chromatography on silica gel
using ether hexane (2: 1) as eluent. Yield 2.7 g (48%),
mp 150 155 C. 1H NMR spectrum (acetone-d6),
, ppm: 7.62 m (3H, p-H, m-H), 8.04 m (2H, o-H),
9.20 s (1H, CH). 13C NMR spectrum (DMSO-d6),
We succeeded in isolating N-substituted triazole II
by carrying out the reaction under mild conditions
which exclude solvolysis (CH2Cl2, 30 40 C). Heating
1
C, ppm: 120.77 q (CF3, JC, F = 322.5 Hz), 125.66
1070-4280/01/3712-1797$25.00 2001 MAIK Nauka/ Interperiodica

1798
SHAINYAN, MESHCHERYAKOV
o
p
m
(C ), 127.14 (C5), 128.25 (C ), 129.01 (C ), 130.18
46 MHz for 15N, and 376 MHz for 19F. Solutions in
CDCl3 or neat substance (15N) were examined. Hexa-
i
(C ), 145.12 (C4). 19F NMR spectrum (CDCl3):
74.79 ppm. Found, %: C 39.16; H 2.52; F 19.84; methyldisiloxane was used as internal reference for
N 14.85; S 11.44. C9H6F3N3O2S. Calculated, %:
C 38.99; H 2.18; F 20.56; N 15.16; S 11.56.
F
1H and 13C. The chemical shifts are given relative to
TMS (1H, 13C), CCl3F (19F), and CH3NO2 (15N).
4-Phenyl-1H-1,2,3-triazole (III). To a solution
of 3.26 g (0.032 mol) of phenylacetylene in 50 ml
of ethanol we added 5.6 g (0.032 mol) of azide I,
and the mixture was heated for 10 h at 70 C under
stirring. It was then cooled and poored into ice water,
and the precipitate was filtered off and recrystallized
from ethanol. Yield 2.3 g (50%), mp 143 145 C.
1H NMR spectrum (DMSO-d6), , ppm: 7.33 t (1H,
p-H, J = 7.4 Hz), 7.43 t (2H, m-H, J = 7.6 Hz),
7.33 d (2H, o-H, J = 7.5 Hz), 8.33 s (1H, 5-H),
11.5 v.br.s (1H, NH). 13C NMR spectrum
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o
(DMSO-d ), C, ppm: 125.62 (C ), 127.28 (C5),
6 p
m
i
128.12 (C ), 128.93 (C ), 130.34 C ), 145.24
(C4).
The NMR spectra were obtained on a Bruker DPX-
400 instrument at 400 MHz for 1H, 100 MHz for 13C,
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RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 37 No. 12 2001