Chemistry of Heterocyclic Compounds, Vol. 43, No. 4, 2007
SYNTHESIS AND HALOGENATION OF ALLYLTHIOETHERS
OF PYRAZOLO[3,4-d]PYRIMIDINE
M. Yu. Onisko, O. V. Svalyavin, and V. G. Lendel
The interaction of 6-allylthio-4-imino-1-methyl-3-methylthio-5-phenyl-1,5-dihydro-4H-pyrazolo[3,4-d]-
pyrimidine with bromine leads to the formation of 8-bromomethyl-4-imino-1-methyl-3-methylthio-
5-phenyl-4,5,7,8-tetrahydro-1H-pyrazolo[4,3-e][1,3]thiazolo[3,2-a]pyrimidinium tribromide.
Keywords: 6-allylthio-4-iminopyrazolo[3,4-d]pyrimidine, monobromide, pyrazolo[3,4-d]pyrimidine,
tribromide, bromoheterocyclization.
With the aim of obtaining condensed pyrazolo[3,4-d]pyrimidine systems the condensation has been carried
out of a substituted aminopyrazole, which contains a cyano group in the ortho position, with phenyl isothiocyanate
and subsequent heterocyclization of the thiourea obtained. Analogous studies have been carried out using
aminothiophene derivatives containing a cyano or an ethyoxycarbonyl grouping in the ortho position [1, 2].
5-Amino-4-cyano-1-methyl-3-methylthio-1H-pyrazole (1), which corresponds to the structural
requirements, was used as the initial model aminopyrazole. It contains an amino and a cyano group in the ortho
position, which is necessary for the synthesis of the condensed systems including pyrimidine.
A nonpolar high-boiling solvent, such as toluene or a mixture of the xylene isomers, was used as solvent
for obtaining thioureas from aminocyanothiophenes and phenyl isothiocyanate [3]. We obtained thiourea 2 from
pyrazole 1 and phenyl isothiocyanate in boiling ethanol in a yield of 809%. Thiourea 2 was cyclized into
4-iminopyrazolo[3,4-d]pyrimidine-6-thione 4 on heating with a twofold excess of alkali in 90% ethanol with
subsequent neutralization with acetic acid.
Thioether 5 was obtained by the alkylation of potassium salt 3 with allyl bromide in 95% ethanol.
Bromination of thioether 5 with a twofold excess of bromine in chloroform was effected, due to the presence of an
unsaturated substituent and a nucleophilic nitrogen atom in the ortho position to heterocyclization, under the action of
the electrophilic reagent to tribromide 6, which was converted into the monobromide 7 by the action of acetone.
EXPERIMENTAL
1
The H NMR spectra were recorded on a Varian VXR 300 (300 MHz) in a mixture of DMSO-d6 and
CCl4, internal standard was TMS.
1-[1,4-Dimethyl-3-(methylthio)-1H-pyrazol-5-yl]-3-phenylthiourea (2). Phenyl isothiocyanate
(1.62 g, 0.012 mol) was added to a solution of pyrazole 1 (1.86 g, 0.01 mol) in ethanol (25 ml), and the mixture
was boiled for 5 h. The bright yellow solid was filtered off, and recrystallized from ethanol. Yield 81%;
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Uzhgorod National University, Uzhgorod 88000, Ukraine; e-mail: muonysko@list.ru; e-mail:
depchem@univ.uzhgorod.ua. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 602-604. April,
2007. Original article submitted August 3, 2006.
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0009-3122/07/4304-0496©2007 Springer Science+Business Media, Inc.
Onisko
