Palladium-catalyzed stereoselective (3 + 2) cycloaddition of vinylethylene carbonates with cyclic N-sulfonyl
Xing Gao1, Dongyu Zhu1, Feng Jiang1
1Department of Chemistry and Innovation Center of Pesticide Research, China Agricultural University, Beijing 100193, China. hchguo@cau.edu.cn.
Abstract:
A diastereoselective (3 + 2) cycloaddition of N-sulfonyl ketimines with vinylethylene carbonates (VECs) in the presence of Pd2dba3·CHCl3 and PPh3 has been developed. The reaction of various substituted VECs and diverse cyclic N-sulfonyl ketimines proceeded smoothly under mild conditions, giving highly functionalized oxazolidine frameworks in good to excellent yields with moderate to good diastereoselectivities. With the use of spiroketal-based diphosphine SKP as a chiral ligand, an asymmetric version of the current (3 + 2) cycloaddition was achieved, and chiral products were obtained in >99% ee in most cases.
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