Thermal transformation of 5-substituted 2-trityltetrazoles

Full text of DOI:10.1023/A:1013801413344

Russian Journal of Organic Chemistry, Vol. 37, No. 11, 2001, pp. 1672 1673. Translated from Zhurnal Organicheskoi Khimii, Vol. 37, No. 11, 2001,
pp. 1742 1743.
Original Russian Text Copyright
2001 by Artamonova, Myznikov, Koldobskii.
SHORT
COMMUNICATIONS
Thermal Transformation of 5-Substituted 2-Trityltetrazoles*
T. V. Artamonova, L. V. Myznikov, and G. I. Koldobskii
St. Petersburg State Institute of Technology, Moskovskii pr. 26, St. Petersburg, 198013 Russia
e-mail: koldobsk@tu.spb.ru
Received May 30, 2001
Thermolysis of 2,5-disubstituted tetrazoles is
a classical example of generation of 1,3-dipoles. Such
intermediates are readily involved in 1,3-dipolar
cycloaddition reactions and are capable of undergoing
1,5- and 1,7-electrocyclizations. They are widely used
in the synthesis of various heterocyclic compounds
[1 6]. In continuation of our studies on thermal trans-
formations of 2,5-disubstituted tetrazoles [7], we
In the first stage, cleavage of the tetrazole ring and
elimination of nitrogen molecule gives 1,3-dipole A
which undergoes 1,6-electrocyclization with formation
of 1,4-dihydrophthalazine B. o-Quinodimethane II
is formed in the final stage as a result of thermal frag-
mentation of 1,4-dihydrophthalazine. This reaction is
well known and is frequently used for generation of
o-quinodimethanes having various structures [8, 9].
examined thermolysis of 5-substituted 2-trityltetra- Thus the thermolysis of 5-substituted 2-trityltetrazoles
zoles in dodecane at 170 180 C and found that the
process follows a mechanism which differs essentially
from the generally accepted mechanism of such
reactions. The thermolysis products were the corre-
sponding o-quinodimethanes which were obtained in
35 68%. A possible reaction scheme is shown below:
can be regarded as a method for preparation of stable
o-quinodimethanes.
5-Phenyl-2-trityltetrazole (Ic). A mixture of
2.5 mmol of 5-phenyltetrazole, 0.2 mmol of tetra-
butylammonium bromide, 10 ml of 10% aqueous
sodium hydroxide, and 10 ml of chloroform was
stirred for 15 min at 20 C. A solution of 3 mmol of
chlorotriphenylmethane in 20 ml of chloroform was
added, the mixture was stirred for 2 h at 20 C, and
the organic phase was separated, washed with 5 ml of
10% aqueous sodium hydroxide and water (2 10 ml),
dried over sodium sulfate, and evaporated to dryness.
Yield 0.9 g (93%), mp 155 156 C (from butyl
acetate); published data [10]: mp 158 160 C. IR spec-
1
trum, , cm : 930, 1005, 1030, 1050, 1160, 1195,
1285, 1330, 1380, 1455, 1480, 1500, 1605, 2870,
1
2930, 3050, 3075. H NMR spectrum, , ppm: 7.08
7.48 m (18H, Harom), 8.03 m (2H, Harom). Found, %:
C 80.32; H 5.12; N 14.52. C26H20N4. Calculated, %:
C 80.41; H 5.15; N 14.43.
Tetrazoles Ia, Ib, and Id were synthesized in
a similar way.
5-Methyl-2-trityltetrazole (Ia). Yield 60%,
mp 178 C [11] (from ethyl acetate). IR spectrum, ,
1
cm : 890, 910, 930, 1010, 1030, 1040, 1090, 1170,
1190, 1290, 1330, 1360, 1390, 1450, 1500, 1520,
1600, 2970, 3040, 3070. H NMR spectrum, , ppm:
3.1 s (3H, CH3), 6.9 7.2 m (6H, Harom), 7.3 7.45 m
(9H, Harom). Found, %: C 77.22; H 5.60; N 16.91.
C21H18N4. Calculated, %: C 77.30; H 5.52; N 17.18.
1
R = Me (a), 4-MeOC6H4 (b), Ph (c), 4-ClC6H4 (d).
____________
*
This study was financially supported by the INTAS program
(grant no. 97-1289).
1070-4280/01/3711-1672$25.00 2001 MAIK Nauka/Interperiodica

THERMAL TRANSFORMATION OF 5-SUBSTITUTED 2-TRITYLTETRAZOLES
1673
5-(4-Methoxyphenyl)-2-trityltetrazole (Ib). Yield
Harom). Found, %: C 89.75; H 6.20. C27H22O. Cal-
culated, %: C 89.50; H 6.08.
55%, mp 186 C (from ethyl acetate). IR spectrum, ,
1
cm : 910, 940, 1000, 1040, 1070, 1100, 1150, 1170,
-(4-Chlorophenyl)- , -diphenyl-o-quinodi-
methane (IId). Yield 35%, mp 127 C (from 2-prop-
1190, 1230, 1280, 1300, 1330, 1390, 1450, 1500,
1
1
1580, 1600, 2900, 2950, 2990, 3050. H NMR spec-
anol). IR spectrum, , cm : 830, 870, 900, 1010,
trum, , ppm: 3.82 s (3H, CH3O), 6.95 7.4 m (17H,
Harom), 8.0 m (2H, Harom). Found, %: C 77.56;
H 5.48; N 13.44. C27H22N4O. Calculated, %: C 77.51;
H 5.26; N 13.40.
1080, 1100, 1360, 1410, 1495, 1610, 1650, 3040,
1
3080. H NMR spectrum, , ppm: 6.15 m (1H, CH),
6.25 7.40 m (18H, Harom). Found, %: C 84.95;
H 5.15. M+ 367. C26H19Cl. Calculated, %: C 85.13;
H 5.18. M 366.5.
5-(4-Chlorophenyl)-2-trityltetrazole (Id). Yield
51%, mp 187 C (from ethyl acetate). IR spectrum, ,
cm : 910, 940, 1010, 1020, 1040, 1100, 1160, 1200,
The IR spectra of compounds Ia Id, IIa, IIb, and
IId were measured on a UR-20 spectrometer in KBr,
and the IR spectrum of IIc was obtained on a Perkin
Elmer Spectrum-1000 instrument. The electron spec-
trum of IIc was recorded on a Perkin Elmer Lambda
40 spectrophotometer. The mass spectra (70 eV) were
1
1270, 1330, 1420, 1450, 1500, 1610, 2860, 2940,
1
3030, 3070. H NMR spectrum, , ppm: 7.1 7.5 m
(15H, Harom), 8.2 m (4H, Harom). Found, %: C 80.31;
H 5.20; N 14.49. C26H19N4. Calculated, %: C 80.62;
H 4.91; N 14.47.
1
run on an MKh-1321 instrument. The H and 13C
,
,
-Triphenyl-o-quinodimethane (IIc).
NMR spectra were recorded on a Bruker AC-200
spectrometer in CDCl3 (IIc, IId) and DMSO-d6
(Ia Id, IIa, IIb).
A mixture of 2.6 mmol of 5-phenyl-2-trityltetrazole
and 10 ml of dodecane was heated for 3 h at 170
180 C and evaporated to dryness, and the solid tarry
residue was treated with petroleum ether (3 10 ml).
Yield 0.59 g (68%); yellow substance, mp 107 108 C
(from 2-propanol). IR spectrum, , cm : 755, 859,
907, 1043, 1069, 1352, 1440, 1490, 1559, 1600,
1636, 3013. UV spectrum (ethanol), max, nm (log ):
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RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 37 No. 11 2001