TiCl4   Promoted Formal [3 + 3] Cycloaddition of Cyclopropane 1,1-   Hydrogen-Bond-Directed Formal [5+1] Annulations of Oxindoles with   Ester-Linked Bisenones: Facile Access to Chiral Spirooxindole δ-Lactones

Shuai   Zhao, Jun-Bing Lin, Yuan-Yuan Zhao, Yong-Min Liang,* and Peng-Fei Xu*

https://doi.org/10.1021/ol500547e