Pyrazolo -pyrimidines

Acetylenic esters convert aminopyrazolinones (134) into pyrazolo-pyrimidines (138).128... 

Pyrazolo-pyrimidine anilines, (IV), and thiazolecarboxamide derivatives, (V), prepared by Das (4,5), respectively, mediated the production of inflammatory cytokines including TNF, IL-1, IL-6, and COX-II and were used in treating inflammatory bowel disorder. 

In a recent report, Gregg and coworkers outline the use of conventional resin-bound isocyanates in scavenging amines for the synthesis of a large library of aryl pyrazolo-pyrimidine carboxamides (Scheme 8.4). Various primary as well as secondary amines were utilized in the amidation of activated nitro phenyl ester. Subsequent scavenging of amines with polystyrene isocyanate afforded the target... 

Scheme 8.4 Utilization of PS-isocyanate for amine scavenging in pyrazolo pyrimidine library synthesis.

Intramolecular ring-closure of 6-(thiosemicarbazido)uracils (368) to pyrimido-thiadiazines (369) is achieved in 32—75% yield by oxidation with Af-chloro- or N-bromo-succinimide. On heating the thiadiazines, sulphur is extruded and pyrazolo-pyrimidines (370) are formed (Scheme 142). ... 

Feigelson, P., Davidson, J. D. and Robins, R. K. 1957. Pyrazolo-pyrimidines as inhibitors and substrates of xanthine oxidase. 

In this case, Mercapto Pyrazolo Pyrimidine (Thiopurinol) was shown to be completely ineffective for reducing both uricemia and uricuria On the other hand, Allopurinol produced a decrease of uric acid plasma level but the total purine excretion remained unchanged This way of responding to treatment is caracteristic of patients with partial or total HGPRTase deficiency ... 

Anand, N.K. etal. Preparation and structure activity of pyrazolo-pyrimidine derivatives as antitumor agents and kinase modulators. PCX application W02005117909 (2005). 

The palladium-catalysed reaction of the pyrazolo-pyrimidine derivative (141) with 3-bromotoluene may result in arylation at the 3-position in the pyrazole ring or at an sp hybridized site in the 7-methyl side-chain depending on the base and ligands used. After initial insertion of the palladium catalyst into the aryl halide bond, palladation of (141) occurs by a concerted metalation-deprotonation pathway and is followed by reductive elimination. Concerted metalation-deprotonation is also likely in the palladium-acetate-catalysed reaction of imidazo[l,2-a]pyridines with aryl bromides to give 3-substituted derivatives such as (142). A careful mechanistic study of the arylation of pyridine A-oxide by bromotoluene, catalysed by palladium acetate and t-butylphosphine, has shown that direct reactions of an aryl palladium complex with... 

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