phase‐transfer reaction system can be applied to highly enantioselectiveconjugateaddition and aldol reactions under the influence of chiral bifunctional ammonium bromides as key catalysts. The structure of the chiral ammonium enolate intermediate is discussed based on the single‐crystal X‐ray structures of relevant ammonium salts and the importance of bifunctional design of catalyst is clearly explained in the
Enantioselective Base-Free Phase-Transfer Reaction in Water-Rich Solvent
作者:Rongjun He、Seiji Shirakawa、Keiji Maruoka
DOI:10.1021/ja906821y
日期:2009.11.25
development of enantioselective phase-transfercatalysis for preparing important natural products or physiologically active compounds is quite attractive and challenging in terms of environmental consciousness. Although quaternary ammonium salts as phase-transfer catalysts are believed to require base additives for phase-transferreactions, we have discovered that even without any base additives, the enantioselective
The field of asymmetric catalysis has been developed by exploring noncovalent interactions, particularly within N-heterocyclic carbene-mediated processes. Despite challenges due to the limited number of compatible electrophiles (predominantly π-acceptors), this study introduces the first asymmetric α-alkylation of 3-aryl oxindoles using Csp3 electrophiles. The innovative protocol integrates diverse
不对称催化领域是通过探索非共价相互作用而发展起来的,特别是在 N-杂环卡宾介导的过程中。尽管由于相容亲电子试剂(主要是 π 受体)数量有限而面临挑战,本研究首次使用 C sp3亲电子试剂对 3-芳基羟吲哚进行不对称 α-烷基化。该创新方案集成了多种羟吲哚和烷基、烯丙基和炔丙基亲电子试剂,实现了高产率和对映选择性。初步的机理探索支持非共价催化机制,增强了构建具有潜在应用的复杂手性分子的工具包。