Catalytic Synthesis of Pyrazolo[3,4-d]pyrimidin-6-ol and Pyrazolo[3,4-d]pyrimidine-6-thiol Derivatives Using Nanoparticles of NaX Zeolite as Green Catalyst

An efficient and environmental benign method is reported for the synthesis of some pyrazolopyrimidine derivatives using 3-methyl-1-phenyl-5-pyrazolone with carbonyl compounds in the presence of nanozeolite Nax catalysts, solvent-free and at reflux conditions. It is noteworthy to mention that this method of the synthesis requires less time, less temperature, and better yield. 1. Introduction Pyrazolopyrimidine derivatives have received a great deal of attention due to their pharmacological activities. Pyrazolopyrimidine derivatives have demonstrated promising antimicrobial activity against gram-positive bacteria [1]. Synthesis of such biologically important compounds assumes great importance. Pyrazolopyrimidine derivatives are purine analogues, and as such they have useful properties as antimetabolites in purine biochemical reaction [2]. Moreover, these compounds also display marked antitumor and antileukemic activities [3]. Pyrazolopyrimidine derivatives have received a great deal of attention due to their pharmacological activity [4], such as allopurino [5], which is still the drug of choice for the treatment of hyperuricemia and gouty arthritis [6]. 1-Phenyl-3-methyl-4-arylmethylene-5-pyrazolones are very useful intermediates in the synthesis of substituted pyrazolones, generally, which were prepared by the condensation of 3-methyl-1-phenyl-5-pyrazolone with aromatic aldehydes [7]. The incorporation of another heterocyclic moiety in pyrans either in the form of a substituent or as a fused component changes its properties and converts it into an altogether new and important heterocyclic derivative. Pyrazoles have attracted particular interest over the last few decades due to the use of such ring system as the core nucleus in various drugs. They are well known for their popular pharmacological activities. Considering the importance of pyrazolone derivatives, it was thought worthwhile to synthesize new compounds incorporating both these moieties. All the compounds synthesized in the present study were screened for their antibacterial activity against some bacteria (both gram-negative and gram-positive) namely, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus subtilis, and C. albicans by filter paper disc technique. Zeolite X is a highly versatile molecular sieve from the faujasite family of zeolites whose 7.4？？, three-dimensional pore structure and solid acidity make it useful as a catalyst, adsorbent, membrane, and others [8–10]. This type of zeolite is used for heavy metal adsorption [11], aromatics from aromatic/alkane