Fused Imidazopyrazoles: Synthetic Strategies and Medicinal Applications

Rizk E Khidre,Bakr F Abdel-Wahab,Othman Y Alothman

doi:10.1155/2014/217596

Rizk E Khidre, Bakr F Abdel-Wahab + Show 1 more

Open Access

https://doi.org/10.1155/2014/217596

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Abstract

The current review summarizes the known synthetic routes of fused imidazopyrazoles. This review is classified into two main categories based on the type of annulations, for example, annulation of the imidazole ring onto a pyrazole scaffold or annulation of the pyrazole ring onto an imidazole scaffold. Some medicinal applications of imidazopyrazoles are mentioned.

Highlights

Over the past two decades, imidazopyrazole and related drugs have been attracting the attention of the medicinal chemists due to their considerable biological and pharmacological activities
Medicinal properties of imidazopyrazole derivatives include anticancer [1,2,3,4,5,6,7,8,9,10,11]; for example, 2,3-dihydro-1H-imidazo[1,2-b]pyrazoles have in vivo effects on the proliferation of mouse leukemic [1], and the same compound has antiviral activity in herpes simplex virus type 1-infected mammalian cells [12], and substituted imidazo[1,2b]pyrazole is used as antimicrobials [13,14,15]
5-amino-1-(5-Otert-butyldimethylsilyl-2,3-O-isopropylidene-β-D-ribofuranosyl)-4-(1,2,4-oxadiazol-3-yl)imidazole 123, synthesized from treatment of 5-amino-1-(β-D-ribofuranosyl)imidazole4-carboxamide 122 with sodium ethoxideat room temperature followed by reaction with ethyl acetate at reflux temperature, underwent the mononuclear heterocyclic rearrangement (MHR) with sodium hydride in DMF or DMSO to afford the corresponding 3-acetamidoimidazo[4,5-c]pyrazole nucleosides 124 in good yields

Summary

Introduction

Over the past two decades, imidazopyrazole and related drugs have been attracting the attention of the medicinal chemists due to their considerable biological and pharmacological activities. In view of the above fact and in connection to our previous review articles about biologically active heterocyclic systems [20,21,22,23,24,25], we decided to prepare this review to present for the reader a survey of the literature of the different azoles linked directly with imidazole nucleus; some of the medicinal applications are mentioned. Fused imidazopyrazole refers to three isomers according to the conjunction between imidazole and pyrazole nucleus. (b) annulation of the pyrazole ring onto an imidazole scaffold

Synthesis by Annulation of the Imidazole Ring onto a Pyrazole Scaffold

Syntheses by Annulation of the Pyrazole Ring onto an Imidazole Scaffold

H CH2CO2R2

Miscellaneous Methods

Conclusions