Chemistry of Pyrazolopyrimidines

Synthesis, Biological Activity and Cytotoxicity of New Fused Pyrazolo[1,5-<i>a</i>]pyrimidine from 5-Aminopyrazole Incorporated with <i>p</i>-Chloroaniline

“…Various related compounds of pyrazolopyrimidines have antitumor and antileukemic activities [6,7]. Several derivatives such as 4-hydroxypyrazolopyrimidine (allopurin), which are used in the treatment of hyperuricemia and gout, inhibit de novo purine biosynthesis and xanthine oxidase [8]. Cyclization of 5-aminopyrazoles with ketene-S,S and N,S-acetals is the most widely used route for the synthesis of pyrazolopyrimidines [9][10][11][12].…”

Synthesis of Novel 5-(N-Boc-N-Benzyl-2-aminoethyl)-7-oxo- 4,7-dihydropyrazolo[1,5-a]pyrimidin-3-carboxamides and Their Inhibition of Cathepsins B and K

“…1,2 Due to biological activity of many of its derivatives, pyrazolo [1,5-a] pyrimidine is an important heterocycle among 5-6-fused systems. 3,4 The importance of pyrazolo [1,5-a]pyrimidine is reflected in the results of a literature search 5 showing around 150,000 known pyrazolo [1,5-a]pyrimidine derivatives within 6,500 references and with preparation, biological study, and uses as the predominant substance roles. For 2016 alone, 74 references can be found for a term "pyrazolo [1,5-a]pyrimidines".…”

Regio-orientation in condensation of aminopyrazoles with 1,3-difunctional reagents: synthesis of new pyrazolo[1,5-a]pyrimidines; pyrazolo[3,4-d]pyridazines and 2,4-dihydropyrano[2,3-c]pyrazoles

“…[1][2][3] Condensed pyrazoles are generally obtained by combining aminopyrazoles or pyrazolones with 1,3-bifunctional reagents. [4][5][6][7][8][9][10][11] Over the past two decades, several syntheses of condensed pyrazoles in this way were reported. However, this work does not, in light of the limited availability of modern properly spectroscopic techniques, address definite proof for reported regioorientation or predominance of a tautomer.…”