2H‑Chromene-3-carboxylic Acid Synthesis via Solvent-Controlled and Rhodium(III)-Catalyzed Redox-Neutral C–H Activation/[3 + 3] Annulation Cascade

An efficient and redox-neutral synthesis of 2H-chromene-3-carboxylic acids from N-phenoxyacetamides and methyleneoxetanones has been realized via a solvent-controlled and rhodium­(III)-catalyzed C–H activation/unusual [3 + 3] annulation sequence. This transformation represents the first example of u...

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Bibliographic Details
Published in:Organic letters 2018-07, Vol.20 (13), p.3892-3896
Main Authors: Zhou, Zhi, Bian, Mengyao, Zhao, Lixin, Gao, Hui, Huang, Junjun, Liu, Xiawen, Yu, Xiyong, Li, Xingwei, Yi, Wei
Format: Article
Language:English
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Summary:An efficient and redox-neutral synthesis of 2H-chromene-3-carboxylic acids from N-phenoxyacetamides and methyleneoxetanones has been realized via a solvent-controlled and rhodium­(III)-catalyzed C–H activation/unusual [3 + 3] annulation sequence. This transformation represents the first example of using an α-methylene-β-lactone unit as the three-carbon source in transition-metal-catalyzed C–H activations through selective alkyl C–O bond cleavage. Synthetic applications and mechanistic details, including further derivatization of 2H-chromene-3-carboxylic acids, the isolation and identification of a five-membered rhodacycle, as well as the theoretical studies for reasoning a plausible Rh­(III)–Rh­(V)–Rh­(III) process, have also been discussed.
ISSN:1523-7060
1523-7052
DOI:10.1021/acs.orglett.8b01477