Synthesis of 5-[(4-methylphenyl)sulfinyl]-and 5-[(4-methylphenyl)sulfonyl]- 1-phenyl-1h-tetrazoles

Full text of DOI:10.1007/s10593-012-1003-5

Chemistry of Heterocyclic Compounds, Vol. 48, No. 2, May, 2012 (Russian Original Vol. 48, No. 2, February, 2012)
SYNTHESIS OF 5-[(4-METHYLPHENYL)SULFINYL]-
AND 5-[(4-METHYLPHENYL)SULFONYL]-1-PHENYL-
1H-TETRAZOLES
U. N. Dmitrieva1, Yu. E. Zevatskii1, S. M. Ramsh1,
T. V. Artamonova1, and L. V. Myznikov1*
Keywords: 5-arylsulfanyltetrazoles, hydrogen peroxide, microwave activation, oxidation.
It is known that the reaction of 5-alkylsulfanyltetrazoles with hydrogen peroxide depends on the
reaction conditions and can give 5-alkylsulfinyl- or 5-alkylsulfonyltetrazoles [1-3]. However, the oxidation of
5-arylsulfanyltetrazoles has not previously been studied, probably because of the difficulty in obtaining these
compounds. We have earlier proposed a method for preparation of 1-substituted 5-arylsulfanyltetrazoles [4]. In
this work we have studied the oxidation of 5-[(4-methylphenyl)sulfanyl]-1-phenyl-1H-tetrazole (1) by hydrogen
peroxide in acetic acid.
We have found that reaction of compound 1 with hydrogen peroxide can yield 5-[(4-methyl-
phenyl)sulfinyl]-1-phenyl-1H-tetrazole (2) and 5-[(4-methylphenyl)sulfonyl]-1-phenyl-1H-tetrazole (3). The
oxidation was carried out under conditions of microwave activation and of convection heating at a temperature
of 55ºC.
O
Ph
S
60% H2O2–AcOH, 1:9
Me
N
N
N
Ph
S
N
Me
2
N
N
N
O
O
N
Ph
S
1
Me
60% H2O2–AcOH, 1:4
N
N
N
N
3
Oxidation duration on convection heating of compound 1 to compound 2 is 3 h. In the course of the
reaction yet before full conversion of compound 1, the product of full oxidation 3 begins to accumulate in the
reaction mixture, that leads to a lowering of the yield and the need to use chromatographic methods for the
_______
*To whom correspondence should be addressed, e-mail: myznikov_lv@mail.ru.
1St. Petersburg State Technological Institute (Technical University), 26 Moscow Ave., Saint Petersburg 190013,
Russia.
_________________________________________________________________________________________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 404-405, February, 2012. Original
article submitted July 15, 2011.
382
0009-3122/12/4802-0382©2012 Springer Science+Business Media, Inc.

purification of compound 2. Lowering the temperature and/or the concentration of hydrogen peroxide leads to a
marked increase of the process time, but still with the observation of sulfone 3 formation. The said problems
were eliminated by the use of microwave activation which resulted in shortening of the reaction time to 1.5 h
and in increase in the selectivity of the oxidation reaction.
Increasing the concentration of hydrogen peroxide, the oxidation of derivative 1 using convection
heating at 55ºC occurs completely to give compound 3 after 10 h. Under microwave activation conditions the
oxidation time can be reduced to 3.5 h and there is an increase in yield to 80% from the 62% yield observed
with convection heating.
IR spectra were recorded on a Shimadzu FTIR-8400S spectrometer using KBr pellets. 1H NMR spectra
were recorded on a Bruker WM-400 spectrometer (400 MHz) using acetone-d6. The residual solvent protons at
2.05 ppm were used as standard. Elemental analysis was carried out on an LECO CHNS-932 analyzer. The
microwave activity reactions were performed using a Milestone MicroSynth P/N 44072 reactor.
5-[(4-Methylphenyl)sulfanyl]-1-phenyl-1H-tetrazole (1) was prepared using method [4].
5-[(4-Methylphenyl)sulfinyl]-1-phenyl-1H-tetrazole (2). A solution of 5-[(4-methylphenyl)sulfanyl]-
1-phenyl-1H-tetrazole (1) (1.00 g, 3.9 mmol) in a freshly prepared mixture of 60% hydrogen peroxide and
acetic acid (1:9) (25 ml) was stirred in the microwave reactor at 55ºC (50 W) for 1.5 h, evaporated in vacuo at
35ºC to the beginning of crystallization, and diluted with fourfold amount of water. The precipitate formed was
filtered off and dried at 40ºC. Yield 0.71 g (64%); mp 121-122ºC (n-BuOH). IR spectrum, , cm-1: 601, 665,
1
674, 763, 818, 1016, 1086, 1108, 1166, 1174, 1296, 1337, 1499, 1592, 2376, 2923, 3035, 3069. H NMR
spectrum, , ppm (J, Hz): 2.41 (3H, s, CH3); 7.36 (2H, d, J = 8.4, H Ar); 7.52 (2H, d, J = 8.4, H Ar); 7.63-7.67
(5H, m, H Ph). Found, %: C 58.89; H 4.12; N 19.55; S 11.32. C14H12N4OS. Calculated, %: C 59.14; H 4.25;
N 19.70; S 11.28.
The reaction with convection heating was conducted similarly. The reaction time was 3 h. The target
compound 2 was separated by column chromatography on silica gel (ethyl acetate–hexane, 1:9). Yield 0.47 g
(42%).
5-[(4-Methylphenyl)sulfonyl]-1-phenyl-1H-tetrazole (3) was prepared similarly to compound 2 using
a freshly prepared mixture of 60% hydrogen peroxide–AcOH (1:4). Reaction time was 3.5 h. Yield 0.94 g
(80%); mp 128-130ºC (2-PrOH). IR spectrum, , cm-1: 620, 689, 722, 763, 811, 922, 968, 1014, 1042, 1063,
1089, 1101, 1167, 1229, 1269, 1289, 1367, 1393, 1418, 1454, 1490, 1500, 1593, 2924, 3025, 3040, 3061.
1H NMR spectrum, , ppm (J, Hz): 2.49 (3H, s, CH3); 7.52 (2H, d, J = 8.3, H Ar); 7.68-7.72 (5H, m, H Ph);
7.74-7.75 (2H, d, J = 8.3, H Ar). Found, %: C 56.22; H 3.95; N 18.88; S 10.41. C14H12N4O2S. Calculated, %:
C 55.99; H 4.03; N 18.65; S 10.68.
The reaction with convection heating was conducted similarly. The reaction time was 10 h. Yield 0.73 g
(62%).
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