A new synthesis of 2,8-disubstituted pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidines
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A practical synthesis of pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidines, which are key intermediates inthe preparation of adenosine receptor antagonists, is developed. The method allows introduction of avariety of aryl substituents at position 2 of the pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidine systemvia cyclocondensation of 5-amino-4-iminopyrazolo[3,4-d]pyrimidine with benzaldehydes accompaniedwith oxidation by iodobenzene diacetate. Some unexpected reactions are observed and the structuresof the products are confirmed using NMR spectroscopy and X-ray crystallography.
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Does the combination of optimal substitutions at the C2-, N5- and N8-positions of the pyrazolo-triazolo-pyrimidine scaffold guarantee selective modulation of the human A3 adenosine receptors?Cheong, S.; Dolzhenko, Anton; Paoletta, S.; Lee, E.; Kachler, S.; Federico, S.; Klotz, K.; Dolzhenko, A.; Spalluto, G.; Moro, S.; Pastorin, G. (2011)In an attempt to study the optimal combination of a phenyl ring at the C2-position and different substituents at the N5- and N8-positions towards the selective modulation of human A3 adenosine receptors (hA3AR), we ...
The significance of 2-furyl ring substitution with a 2-(para-substituted) aryl group in a new series of pyrazolo-triazolo-pyrimidines as potent and highly selective hA3 adenosine receptors antagonists: new insights into structure-affinity relationship and receptor-antagonist recognitionCheong, S.; Dolzhenko, A.; Kachler, S.; Paoletta, S.; Federico, S.; Cacciari, B.; Dolzhenko, Anton; Klotz, K.; Moro, S.; Spalluto, G.; Pastorin, G. (2010)Among the heterocyclic structures identified as potent human A3 (hA3) adenosine receptor’s antagonists, we have demonstrated that the new pyrazolo-triazolo-pyrimidines, bearing an aryl group in replacement of the C2-furyl ...
Regioselective synthesis of pyrimido [1,2-a][1,3,5]triazin-6-ones via reaction of 1-(6-oxo-1,6-dihydropyrimidin-2-yl)guanidines with triethylorthoacetate: Observation of an unexpected rearrangementSachdeva, N.; Dolzhenko, Anton; Chui, W. (2012)A novel thermal rearrangement, involving pyrimidine ring opening and subsequent ring closure leading to recyclization of the system, was identified in the reaction of (6-oxo-1,6- dihydropyrimidin-2-yl)guanidines 3 (where ...