Synthetic routes to benzimidazole-based fused polyheterocycles

Abstract

The review article represents a survey covering the synthetic strategies leading to benzimidazolebased fused polyheterocyclic systems utilizing simple reactive benzimidazole synthons since 1980. The polyheterocyclic systems are classified based on the number of rings; tetra-, penta-, hexa-and hepta-fused ring systems. Among each polyheterocyclic system, further classification according to the number of heterotoms; two-, three-, four-, five-, six-and seven heteroatoms is considered.

Mechanochemical Cascade Cyclization of Cyclopropyl Ketones with 1,2-Diamino Arenes for the Direct Synthesis of 1,2-Disubstituted Benzimidazoles

“…Although these methods are extensively used, they suffer from the formation of stoichiometric amounts of waste because of substrate leaving groups or additives, thus limiting the wide application of these methods. Later, aldehydes, benzyl alcohols, benzylamines, methyl arenes, and nitroaniline have been used as alternative substrates in condensation with o -phenylenediamines. A recent analysis says that benzimidazole is one of the top 25 most frequent nitrogen heterocycles in U.S. FDA-approved drugs .…”

Advances in the Synthesis of Ring-Fused Benzimidazoles and Imidazobenzimidazoles

“…Lastly, there is a section on syntheses, which begin with the benzimidazole moiety (Route E), sub-divided according to reaction (type) conditions. This is not an exhaustive review, and the reader should consult reviews on polycyclic benzimidazoles for comprehensive lists of syntheses [ 30 , 31 , 32 , 33 ]. Since the late 1990s, Aldabbagh et al have worked on the discovery of new ring-fused benzimidazoles and synthetic methods, and the collated articles related to their research are reviewed herein.…”

One-pot synthesis of highly fluorescent polycyclic benzimidazole derivatives

“…During the past decades, several methods for synthesis of a variety of N -heterocyclic compounds have been developed. 10 Liubchak et al synthesized annulated benzimidazoles via Cu( i ) catalyzed cyclocondensation reaction. 11 Yanada group developed microwave-accelerated tandem process delivering benzimidazo [2,1- a ] isoquinolines from 2-bromoarylaldehydes, terminal alkyne, and 1,2-phenylenediamines.…”