A comparative study on the synthesis of 4‐alkyl‐1,3‐diarylpyrazoles using microwave irradiation and conventional thermal methods

Abstract

A convenient synthesis of 4-alkyl-1,3-diarylpyrazoles (2) under microwave irradiation as well as conventional thermal method using Vilsmeier cyclization is reported. Microwave irradiation has resulted in the reduction of time from hours to seconds.

Benign Approaches for the Microwave‐assisted Synthesis of Five‐membered 1,2‐N,N‐heterocycles

“…Another recent application of microwaves in cyclization is the preparation of pyrazoles ( 126 ) from hydrazones ( 125 ) using the Vilsmeier cyclization method by treatment with POCl 3 and DMF . As shown in Scheme , the reaction is speeded up by factors of several 100‐fold.…”

Five‐Membered Heterocycles: 1,2‐Azoles. Part 1. Pyrazoles

“…The reaction time can be reduced from 4-5 h to 35-50 s if microwave irradiation is used instead of conventional heating [118]. An interesting variation of method A consists in the substitution of phosphorus oxychloride by cyanuric chloride (2,4,6-trichloro [1,3,5]triazine, TCT) (method B) [119].…”

Synthesis and studies of pyrazolo[3,4-b]pyridin-4-one derivatives

“…The pyrazole nucleus is present in a wide variety of biologically interesting compounds, which exhibit anti-hyperglycemic, analgesic, anti-inflammatory, antipyretic, antibacterial, hypoglycemic, sedative-hypnotic activity [29][30][31][32][33][34][35][36][37][38][39][40][41][42]. Pyrazoles and their derivatives are widely used as pharmaceutical [43][44][45] and agrochemical agents [46] and consequently a large number of synthetic routes to pyrazoles has been reported [47][48][49][50][51]. However, there is still great interest in finding milder and more efficient methods to these valuable compounds.…”