Asymmetric [3 + 2] Cycloaddition of Methyleneindolinones with N,N'-Cyclic Azomethine Imines Catalyzed by a N,N'-Dioxide-Mg(OTf)2 Complex.

@article{Yin2015Asymmetric,
  title={Asymmetric [3 + 2] Cycloaddition of Methyleneindolinones with N,N'-Cyclic Azomethine Imines Catalyzed by a N,N'-Dioxide-Mg(OTf)2 Complex.},
  author={Chengkai Yin and Lili Lin and Dong Zhang and Juhua Feng and Xiaohua Liu and Xiaoming Feng},
  journal={The Journal of organic chemistry},
  year={2015},
  volume={80 19},
  pages={9691-9}
}
A highly efficient chiral N,N'-dioxide-Mg(OTf)2 catalyst system has been developed for the asymmetric 1,3-dipolar cycloaddition between methyleneindolinones and N,N'-cyclic azomethine imines. The desired pyrazolidine products with contiguous quaternary-tertiary stereocenters were obtained in up to 99% yields with up to 99% ee and >19:1 dr under mild reaction conditions.