I₂-DMSO mediated dual α,β-C(sp²)–H functionalization/bicyclization of o-hydroxyphenyl enaminones to construct C2,C3-disubstituted chromone derivatives: chromeno[2,3-b]pyrrol-4(1H)-ones

Abstract

An unprecedented dual α,β-C(sp2)-H functionalization/bicyclization strategy of o-hydroxyphenyl enaminones for the preparation of chromeno[2,3-b]pyrrol-4(1H)-ones has been established. The multi-component cascade reaction achieves dual α,β-C(sp2)-H functionalization of o-hydroxyphenyl enaminones to construct...

Review of application of the I2 and dimethyl sulfoxide combined reagent system to aryl methyl ketones for diverse transformations

“…To our delight, we successfully developed a new method for constructing chromeno[2,3- b ]pyrrole-4(1 H )-ones via I 2 –DMSO-mediated difunctionalization/cyclization of o -hydroxyphenyl enaminones (Scheme 47A). 57 A mechanism study showed that phenylketoaldehyde is nucleophilically attacked by o -hydroxyphenyl enaminone 47-1 to produce imine ion intermediate 47-2 , which is then converted to intermediate 47-3 by intramolecular cyclization. The chromone C2-substituted intermediate 47-4 is then immediately produced with the elimination of HNMe 2 , which can be oxidized to by-product 47-5 .…”

Selective synthesis of pyridazine-fused chromones and 3-pyridazinyl chromones through intermolecular chromone annulation of o-hydroxyphenylenaminones with aryldiazonium salts

“…Very recently, only one study from Wu's group disclosed a dual α,β-C(sp 2 )–H functionalization/bicyclization of o -HPEs for the construction of chromeno[2,3- b ]pyrrol-4(1 H )-ones through the above-mentioned traditional intramolecular chromone annulation strategy (Scheme 1c). 15 However, both the above-mentioned chromone construction strategies and the fused chromone construction strategy are traditional intramolecular chromone annulation processes from one molecule of o -HPE by first forming α-functionalized enaminone intermediates and then realizing chromone annulation with the hydroxyl group. To the best of our knowledge, a new intermolecular chromone annulation strategy of o -HPEs for the synthesis of (fused) chromone skeletons, especially using multiple molecules of o -HPEs to construct the chromone skeleton, still remains unexplored and very challenging (Scheme 1d).…”

Electrochemical-induced solvent-tuned selective C(sp3)–H bond activation towards the synthesis of C3-functionalized chromone derivatives

“…Enaminones have lately been known as utility and valuable reaction intermediates owing to the ambident nucleophilic and electrophilic characteristics of the enamine and enone groups, respectively, which were exploited by many synthetic chemists towards the synthesis of various biologically important heterocycles, such as some C3-functionalized chromones. 14–20 In particular, Yang and coworker reported the metal-free synthesis of difluoro/trifluoromethyl carbinol-containing chromones using o -hydroxyaryl enaminones as reaction substrates. 20 At the same time, photoredox catalysis and enzyme catalysis are also utilized to synthesize C3-functionalized chromones via the activation of the C(sp 3 )–H bond (Scheme 1).…”