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Secondary Alkylation of Arenes via the Borono-Catellani Strategy
Haiyun Peng1, Dandan Wang1, Jinxiang Ye1
1Engineering Research Center of Organosilicon Compounds & Materials (Ministry of Education), Hubei Key Lab on Organic and Polymeric OptoElectronic Materials, College of Chemistry and Molecular Sciences, and TaiKang Center for Life and Medical Sciences, Wuhan University, Wuhan 430072, China.
Abstract:
A modular platform technology for the synthesis of α-aryl carbonyl derivatives via Borono-Catellani-type secondary alkylation of arenes is presented. This practical method features a broad substrate scope regarding aryl boronic acid catechol esters, secondary alkyl bromides, and diversified terminating reagents (e.g., olefins, alkynes, and Zn(CN)2), mild reaction conditions, and good functional-group tolerance. Importantly, the asymmetric version based on a dynamic kinetic asymmetric transformation (DyKAT) has also been realized by introducing the 1:1 diastereomeric mixture of α-bromo carboxamides bearing an Evans chiral auxiliary as the electrophiles, and constantly excellent diastereoselectivities (>20:1 d.r.) are obtained. Notably, the obtained chiral products can be readily transformed into diversified enantioenriched α-aryl propionic acid derivatives, laying a solid foundation for the discovery of new NSAIDs. Through mechanistic studies and DFT calculations, a critical stereoretentive oxidative addition step is revealed in this Borono-Catellani secondary alkylation reaction, and the origins of stereodiscrimination of this DyKAT are well explained.
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