Rhodium(I)/Zn(OTf)2 -Catalyzed Asymmetric Ring Opening/Cyclopropanation of Oxabenzonorbornadienes with Phosphorus Ylides

Tao Chen; Lifei Gan; Ran Wang; Yuhua Deng; Fangzhi Peng; Mark Lautens; Zhihui Shao

doi:10.1002/anie.201909596

Rhodium(I)/Zn(OTf)₂ -Catalyzed Asymmetric Ring Opening/Cyclopropanation of Oxabenzonorbornadienes with Phosphorus Ylides

Angew Chem Int Ed Engl. 2019 Oct 28;58(44):15819-15823. doi: 10.1002/anie.201909596. Epub 2019 Sep 19.

Authors

Tao Chen¹, Lifei Gan¹, Ran Wang¹, Yuhua Deng¹, Fangzhi Peng¹, Mark Lautens², Zhihui Shao¹

Affiliations

¹ Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education, School of Chemical Science and Technology, State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan University, Kunming, 650091, China.
² Davenport Laboratories, Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, ON, M5S 3H6, Canada.

PMID: 31489736
DOI: 10.1002/anie.201909596

Abstract

The strong binding ability of P-ylides with transition metals limits the utilization of stabilized P-ylide as nucleophiles in asymmetric organometallic catalysis. Herein we describe the first rhodium-catalyzed asymmetric ring-opening reaction of P-ylides utilizing oxabicyclic alkenes as the electrophilic partner. Various P-ylides including ester-, ketone- and amide-style P-ylides are all applicable. This asymmetric reaction occurs through the cleavage of two bridgehead C-O bonds and the formation of two C-C bonds, and oxabenzonorbornadienes are used as 1,4-biselectrophiles, thus providing access to benzonorcaradienes in good yields with high enantioselectivity and perfect diastereoselectivity. The present protocol also constitutes the first highly enantioselective direct catalytic asymmetric cyclopropanation of stabilized P-ylide nucleophiles.

Keywords: 1,4-biselectrophiles; asymmetric catalysis; oxabenzonorbornadienes; phosphorus ylides; rhodium.