Trapping of an Ammonium Ylide with Activated Ketones: Synthesis of β-Hydroxy-α-Amino Esters with Adjacent Quaternary Stereocenters - Guo, Xin; Yue, Yongli; Hu, Guoliang; Zhou, Jing; Zhao, Yiqing; Yang, Liping; Hu, Wenhao (Synlett, 2009)