Dynamic Kinetic Resolution via Dual-Function Catalysis of Modified Cinchona Alkaloids: Asymmetric Synthesis of α-Hydroxy Carboxylic Acids
作者:Liang Tang、Li Deng
DOI:10.1021/ja0255047
日期:2002.3.1
dioxolanediones was realized via a modified cinchona alkaloid-catalyzed alcoholytic opening of the dioxolanedione ring, generating a variety of optically active alpha-hydroxy esters in 91-96% ee and 61-85% chemical yield. In this dynamic kinetic resolution, the modified cinchonaalkaloid was found to serve dual catalytic roles, mediating both the rapid racemization of the 5-aryl dioxolanediones and the enantioselective
Alternating Sequence Controlled Copolymer Synthesis of α-Hydroxy Acids via Syndioselective Ring-Opening Polymerization of <i>O</i>-Carboxyanhydrides Using Zirconium/Hafnium Alkoxide Initiators
challenges until now for lack of suitable catalysts/initiators. In this work, a highly syndioselective ROP of OCAs system as the first stereoselective example in this area is reported using zirconium/hafnium alkoxides as initiators with the highest Pr value up to 0.95. Furthermore, these initiators were successfully applied in the precisely alternating sequence controlled copolymerization of PheOCA and