Direct construction of   Chiral Quaternary Dihydropyranones through Highly Enantioselective Organocatalytic   Hetero-Diels–Alder Reactions of Olefinic Azlactones

Tai-Ping Gao, Dan Liu, Jun-Bing Lin, Xiu-Qin Hu,   Zhu-Yin Wang and Peng-Fei Xu*

https://doi.org/10.1039/C6QO00018E