Yb(<scp>OTf</scp>)<sub>3</sub>‐Catalyzed Asymmetric [3+3] Cycloaddition of <i>N</i>‐Vinyl Nitrones with Activated Cyclopropanes to Prepare 1,2‐Oxazines
Yu‐Zheng Wu, Yue Leng, Yixin Chen, Shi‐Qiu Huang, Ning Zou, Chunhua Chen, Dong‐Liang Mo
Abstract
Comprehensive Summary We described a Yb(OTf) 3 combined with Pybox ligand catalyzed asymmetric [3+3] cycloaddition of N ‐vinyl cinnamaldehyde nitrones with activated cyclopropanes to prepare various functionalized 1,2‐oxazines in 24%—95% yields and 22%—96% ee. Experimental results revealed that the reaction underwent a domino [3+3] cycloaddition, dealkenylation, and aza‐1,4‐addition in three steps. The chiral 1,2‐oxazine could be obtained in gram scales and easily converted into various 1,2‐oxazine scaffolds. The present method features broad substrate scope, good functional group compatibility, three‐component domino reaction, and asymmetric [3+3] cycloaddition of N ‐vinyl nitrones with activated cyclopropanes.