Asymmetric Synthesis of Enantioenriched 2-Aryl-2,3-Dihydrobenzofurans by a Lewis Acid Catalyzed Cyclopropanation/Intramolecular Rearrangement Sequence

Rameshwar Prasad Pandit; Seung Tae Kim; Do Hyun Ryu

doi:10.1002/anie.201906954

Asymmetric Synthesis of Enantioenriched 2-Aryl-2,3-Dihydrobenzofurans by a Lewis Acid Catalyzed Cyclopropanation/Intramolecular Rearrangement Sequence

Angew Chem Int Ed Engl. 2019 Sep 16;58(38):13427-13432. doi: 10.1002/anie.201906954. Epub 2019 Aug 8.

Authors

Rameshwar Prasad Pandit¹, Seung Tae Kim¹, Do Hyun Ryu¹

Affiliation

¹ Department of Chemistry, Sungkyunkwan University, 300, Cheoncheon, Jangan, Suwon, 16419, Korea.

PMID: 31309680
DOI: 10.1002/anie.201906954

Abstract

A cyclopropanation/intramolecular rearrangement initiated by the Michael addition of in situ generated ortho-quinone methides (o-QMs) has been developed for the enantioselective synthesis of 2-aryl-2,3-dihydrobenzofurans containing two consecutive stereogenic centers, including a quaternary carbon atom. In the presence of a chiral oxazaborolidinium ion catalyst, the reaction proceeded in excellent yields (up to 95 %) with excellent stereoselectivity (up to >99 ee, up to >20:1 d.r.).

Keywords: 2,3-dihydrobenzofuran; diazoester; ortho-quinone methide; quaternary carbon atoms; rearrangement.

Abstract

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