C–H Functionalization via Remote Hydride Elimination: Palladium Catalyzed Dehydrogenation of ortho-Acyl Phenols to Flavonoids

Although deprotonation of electron-poor C–H bonds to carbon anions with bases has long been known and widely used in organic synthesis, the hydride elimination from electron-rich C–H bonds to carbon cations or partial carbocations for the introduction of nucleophiles is a comparatively less explored...

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Bibliographic Details
Published in:Organic letters 2017-03, Vol.19 (5), p.976-979
Main Authors: Zhao, Xiaomei, Zhou, Jiabin, Lin, Shuying, Jin, Xukang, Liu, Renhua
Format: Article
Language:English
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Summary:Although deprotonation of electron-poor C–H bonds to carbon anions with bases has long been known and widely used in organic synthesis, the hydride elimination from electron-rich C–H bonds to carbon cations or partial carbocations for the introduction of nucleophiles is a comparatively less explored area. Here we report that the carbonyl β-C­(sp3)–H bond hydrogens of ortho-acyl phenols could be substituted by intramolecular phenolic hydroxyls to form O-heterocycles, followed by dehydrogenation of the O-heterocycle into flavonoids. The cascade reaction is catalyzed by Pd/C without added oxidants and sacrificing hydrogen acceptors.
ISSN:1523-7060
1523-7052
DOI:10.1021/acs.orglett.6b03652