AlCl₃-catalyzed chemoselective cascade reactions of 4-anilinocoumarins with 2-furylcarbinols: access to densely functionalized chromeno[4,3-b]pyrrol-4(1H)-one derivatives

Abstract

An unprecedented protocol has been developed for the preparation of highly functionalized chromeno[4,3-b]pyrrol-4(1H)-ones, which are not only valuable architectures of many biologically active molecules, but also key building blocks for...

An Overview of the Synthesis of 3,4-Fused Pyrrolocoumarins of Biological Interest

“…Recently, Guan et al presented the synthesis of chromeno[4,3- b ]pyrrol-4(1 H )-ones 174a – t under AlCl 3 -catalyzed reactions of 4-anilinocoumarins with 2-furylcarbinols 173a – f ( Scheme 56 ). The reaction proceeded via chemoselective intermolecular α-carbon nucleophilic attack/ring-opening of furan ring/Michael addition/deprotonation aromatization processes [ 119 ].…”

“…Wu et al presented the one-pot synthesis of 1-phenylchromeno [3,4-b]pyrrol-4(3H)-one (15a) through the three-component reaction of phenylacetaldehyde, pyrrolidine, and 4-chloro-3-nitrocoumarin (119) in three steps and 78% yield [104]. Similarly, they also synthesized the chromeno [3,4-b]pyrrol-4(3H)-one derivatives 122-124 and 126-128 from compound 125 (Scheme 37).…”

“…They utilized this method for the synthesis of ningalin B. The key step of this reaction was the coupling between the intermediate 1-styrylpyrrolidine A and 4-chloro-3nitrocoumarin (119). Diphenyl derivative 128 exhibits electrochromic properties.…”

Iodine-Catalyzed Diversity-Oriented Synthesis of 3,4-Heterocycle-Fused Coumarins from 4-Aminocoumarins and Aurones in Different Solvent

“…19 Meanwhile, Wang and co-workers reported AlCl 3 -catalyzed cascade reactions of 4-anilinocoumarins with 2-furylcarbinols for the preparation of highly functionalized pyrrolocoumarin derivatives (Scheme 1e). 20 Despite significant advancements in the synthesis of pyrrolocoumarins, most of the strategies still suffer from one or more drawbacks including multistep synthetic procedures, expensive reagents and catalysts, complex structures of substrates, and harsh reaction conditions. Therefore, there is considerable interest in exploring an efficient, simple, cost-effective, and environmentally benign approach for the synthesis of pyrrolocoumarin derivatives.…”

“…Maurya and co-workers developed a novel visible light enabled photocatalyst-free synthetic method to construct pyrrolocoumarins from α-keto vinyl azides (Scheme d) . Meanwhile, Wang and co-workers reported AlCl 3 -catalyzed cascade reactions of 4-anilinocoumarins with 2-furylcarbinols for the preparation of highly functionalized pyrrolocoumarin derivatives (Scheme e) . Despite significant advancements in the synthesis of pyrrolocoumarins, most of the strategies still suffer from one or more drawbacks including multistep synthetic procedures, expensive reagents and catalysts, complex structures of substrates, and harsh reaction conditions.…”