Affiliation:
1. Key Laboratory of Medicinal Chemistry for Natural Resource Ministry of Education School of Chemical Science and Technology and State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan Yunnan University Kunming 650500 China
2. Department of Chemistry and Shenzhen Grubbs Institute Guangdong Provincial Key Laboratory of Catalysis Southern University of Science and Technology Shenzhen, Guangdong 518055 China
3. Southwest United Graduate School Kunming 650092 China
Abstract
AbstractHere, we report a strategy enabling triple switchable chemo‐, regio‐, and stereodivergence in newly developed palladium‐catalyzed cycloadditions of allenes. An asymmetric pseudo‐stereodivergent cycloaddition of allenes bearing a primary leaving group at the α‐position, where a dynamic kinetic asymmetric hydroalkoxylation of racemic unactivated allenes was the enantio‐determining step, is realized, providing four stereoisomers [(Z,R), (Z,S), (E,S), and (E,R)] containing a di‐substituted alkene scaffold and a stereogenic center. By tuning reaction conditions, a mechanistically distinctive cycloaddition is uncovered selectively with the same set of substrates. By switching the position of the leaving group of allenes, a cycloaddition involving an intermolecular O‐attack is disclosed. Diverse mechanisms of the cycloaddition reactions of allenes enable rapid access to structurally and stereochemically diverse 3,4‐dihydro‐2H‐1,4‐benzoxazines in high efficiency and selectivity.