New one‐step synthesis of pyrazolo[1,5‐a]pyrimidine and pyrazolo[1,5‐a]quinazoline derivatives via multicomponent reactions

Abstract

A series of pyrazolopyrimidine and pyrazoloquinozoline derivatives has been synthesized in one step by multicomponent reactions using, 5-aminopyrazole, p-substitutedbenzoylacetonitrile/dimedone and triethylorthoesters. pyrazolopyrimidine derivatives were also studied for their absorption and fluorescence maxima.

Regioselectivity in the multicomponent reaction of 5-aminopyrazoles, cyclic 1,3-diketones and dimethylformamide dimethylacetal under controlled microwave heating

“…In addition, the nature of the catalyst plays an important role [ 20 ]. A one-pot three component reaction of 5-amino-1 H -pyrazole-4-carbonitrile, dimedone and triethylorthoesters in toluene under reflux was recently reported to afford the corresponding pyrazolo[1,5- a ]-quinazolin-6-one derivatives [ 21 ]. Although it is well established that 5-amino-pyrazoles have nonequivalent nucleophilic reaction centres in the aminopyrazole scaffold (N1, C4, NH 2 ), which can lead to the formation of several different tricyclic reaction products, no general basis on which to determine the preferred tautomeric form of the final product has been established.…”

Orthoesters: Multiple Role Players in Organic Synthesis

“…Multicomponent reactions of 5‐amino‐1 H ‐pyrazole‐4‐carbonitriles with p ‐substituted benzoylacetonitriles and triethyl orthoesters of TEOF , TEOA , and TEOP produced 7‐(4‐aryl)pyrazolo[1,5‐ a ]pyrimidine‐3,6‐dicarbonitriles 98 and 7‐amino‐6‐(4‐aroyl)pyrazolo[1,5‐ a ]pyrimidine‐3‐carbonitriles 99 from intermediate 97 , depending on the choice of solvent as well as catalyst . Execution of the reaction in the presence of Et 3 N and pyrimidine in refluxing toluene produced dicarbonitrile 98 .…”

“… Synthesis of 7‐(4‐aryl) pyrazolo[1,5‐ a ]pyrimidine‐3,6‐dicarbonitriles and 7‐amino‐6‐(4‐aroyl)pyrazolo[1,5‐ a ]pyrimidine‐3‐carbonitriles …”

Design, Multicomponent Synthesis and Characterization of Diversely Substituted Pyrazolo[1,5‐a] Pyrimidine Derivatives

“…Pyrazolopyrimidines have multiple pharmacological activities including hypnotic , anti‐inflammatory , anti‐tumor, antimycobacterial , antidiabetic, antiphlogistic agents, antidepressants, analgesics , and anti‐viral . Several diverse biological activities have been reported for pyrazolopyrimidine ring systems which are described as below.…”