Greener and Environmentally Benign Methodology for the Synthesis of Pyrazole Derivatives

Abstract

Pyrazole and its derivatives are one of the interesting heterocyclic compounds among the other because it has tremendous important bio-medical applications such as anticancer, antimalarial, antimicrobial, antifungal, antitubercular and antihelishmanial. Synthesis of pyrazoles by synthetic route requires harsh reaction conditions such as organic solvent, high temperature, require large time that consume more energy which increase final cost of the synthesis of pyrazoles. Therefore researchers be aware about synthesis and give more attention towards to develop a greener as well as economically favorable method for synthesis of pyrazoles such as microwave irradiation, ultra-sonication assisted, reaction at room temperature, solvent and catalyst free and use of universal solvent that is aqueous medium these techniques are environmentally friendly as well as cost effective. Therefore, these review highlights the greener methodologies for the synthesis of pyrazoles, which are good alternative for synthetic methods that sustains green principles.

Recent advances in nanoparticles towards sustainability and their application in organic transformations in aqueous media

“…84 In these environmentally conscious times, researchers are required to focus on developing green methodologies for organic transformations. 85 To fulfill this requirement, Baig and Varma reported the microwave-assisted nano-ferrite NP-catalyzed Paal–Knorr reaction in water. 54 A variety of nano-ferrites modified by ligands were used to immobilize nanometals such as Pd, Cu, and Ru, which helped in the development of a green and sustainable protocol for azide–alkyne cycloaddition reactions, C–S coupling, O -allylation of phenol, Heck-type reactions, and hydration of nitriles.…”

One‐pot Synthesis of Substituted Pyrazoles from Propargyl Alcohols via Cyclocondensation of in situ‐Generated α‐Iodo Enones/Enals and Hydrazine Hydrate

“…Recently, Zhan's group developed a cascade AgOTf‐catalyzed chemoselective approach to 3,5/1,3‐disubstitued pyrazoles from progargylic alcohols and para‐tolysulfonohydrazide (Scheme 2b) [11] . Although chemists have made great achievements in the synthesis of pyrazoles in the past few decades, [3–6,11] but these methods have more or less defects [3f] . It is still of great significance to develop a simple and efficient method to synthesize them [3f] .…”

“…Although chemists have made great achievements in the synthesis of pyrazoles in the past few decades, [3–6,11] but these methods have more or less defects [3f] . It is still of great significance to develop a simple and efficient method to synthesize them [3f] . Considering this, we described herein the iodo‐intercepted Meyer‐Schuster rearrangement reaction of propargylic alcohols as a new, versatile, and general synthetic method of α‐iodo enones/enals, and the sequential one‐pot synthesis of substituted pyrazoles from propargylic alcohols via the cyclocondensation of hydrazines and α‐iodo enones/enals generated in situ (Scheme 2c).This synthesis route brings together three different building blocks, which makes it ideal for the preparation of small libraries for medicinal chemistry.…”

Green Synthesis of Bis(pyrazol‐5‐ole) and Pyrazolopyranopyrimidine Derivatives through Mechanochemistry Using Chitosan as a Biodegradable Catalyst

“…[28,29] Celebrex, mepirizole, betazole, viagra, and lonazolac are some of the famous drugs having pyrazoles as core. [30] There are many catalysts such as pyridine trifluoroacetate, N-methylimidazolium perchlorate, alpha-casein, triphenylphosphine, ZnO@adn-carbon, etc. in the synthesis of bis (pyrazol-5-ole) and amine@functionalized poly-3,3-bis (chloromethyl) oxetane, meglumine, β-dextrine, etc.…”

“…Pyrazole moiety such as rimonabant suppresses hepatitis B by inhibiting hepatocytes nuclear factor 4 α and also acts as powerful anti‐obesity drug [28,29] . Celebrex, mepirizole, betazole, viagra, and lonazolac are some of the famous drugs having pyrazoles as core [30] . There are many catalysts such as pyridine trifluoroacetate, N ‐methylimidazolium perchlorate, alpha‐casein, triphenylphosphine, ZnO@adn‐carbon, etc.…”