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Chapter 4
Synthesis of highly substituted pyrazolopyrimidine
Pushpak Mizar et al. 32 have been described a facile method for the synthesis of
pyrazolo[1,5-a]pyrimidine (Figure-17) by reacting N-substituted or unsubstitutedpyrazol-5(4H)-one,
aryl-oxoketene dithioacetals and alkyl amide.
Figure-17
Recently, Ibtissam Bassoude et al. 33 described one step condensation reaction
of of 5(3)-amino-3(5)-arylpyrazoles with 4-hydroxy-6-methylpyran-2-one leading to
new pyrazolo[1,5-a]pyrimidines(Figure-18).
Figure-18
V. N. Britsun was reported cyclocondensation products of N-aryl-3-
oxobutanethioamides with 5-amino-3-R-4-R 1 -pyrazoles are 4-(arylamino)-2-methyl-
7-R-8-R 1 -pyrazolo[1,5-a]pyrimidine and pyrazolo[1,5-a]pyrimidine-4-thione
derivatives (Figure-19), the ratio of which depends on the nucleophilicity of the
starting 5-amino-3-R-4-R 1 - pyrazoles and the presence of a proton donor solvent. 34
Figure-19
D. V. Kryl’skii et al. 35 has described Three-component condensation of 3-
methyl(or methoxymethyl)-4-phenyl-1H-pyrazol-5-amine with triethylorthoformate
and carbonyl compounds or nitriles containing an activated methylene group
(cyclohexane-1,3-diones, acetoacetanilides, benzoylacetone, ethyl cyanoacetate,
malononitrile, 1H-benzimidazol-2-yl-acetonitrile) gave substituted
pyrazolopyrimidines (Figure-20).
Department of Chemistry, Saurashtra university, Rajkot-360005 129