Enantioselective   Synthesis of Spirorhodanine-Pyran Derivatives via Organocatalytic [3 + 3] Annulation   Reactions between Pyrazolones and Rhodanine-Derived Ketoesters

Dong-Sheng Ji,   Yong-Chun Luo, Xiu-Qin Hu, and Peng-Fei Xu*

https://pubs.acs.org/doi/10.1021/acs.orglett.9b04571