Highly enantioselective ylide-mediated synthesis of terminal epoxides
作者:Alessandro Piccinini、Sarah A. Kavanagh、Stephen J. Connon
DOI:10.1039/c2cc32101g
日期:——
The highly efficient asymmetric epoxidation of aldehydes by methylene transfer is now possible using new sulfonium salts.
使用新型硫onium盐,现在可以实现通过亚甲基转移对醛进行高效率非对称环氧化。
A Concise Enantioselective Strategy to (+)-(R)-Goniothalamin and (+)-(R)-Goniothalamin Oxide by Employing Hydrolytic Kinetic Resolution and Ring-Closing Metathesis as Key Steps
作者:D. Bose、A. V. Reddy、Bingi Srikanth
DOI:10.1055/s-2008-1067175
日期:2008.8
An efficient and general strategy to (R)-goniothalamin and (R)-goniothalamin oxide is described by using Jacobsen’s hydrolytic kinetic resolution of racemic epoxide and ring-closing metathesis (RCM) as key steps, which provided a rapid access to these natural products that display a fascinating array of biological activity. (R)-Goniothalamin oxide was prepared in high yield and diastereomeric excess under various epoxidation conditions.
Enzymatic Resolution of Chlorohydrins for the Synthesis of Enantiomerically Enriched 2-Vinyloxiranes
作者:Mark Lautens、J. McCubbin、Matthew Maddess
DOI:10.1055/s-2007-1000845
日期:2008.1
A series of vinylchlorohydrins are resolved by enzymatic kinetic resolution. The resulting R-alcohols, obtained in up to 99% ee, are stereoselectively converted into vinyloxiranes in high yield. The S-acetates, obtained in up to 99% ee were either deprotected to S-alcohols, or cyclized directly to vinyl oxiranes under basic conditions, with moderate to no loss in ee. The results are consistent with
通过酶动力学拆分来拆分一系列乙烯基氯醇。所得的 R-醇以高达 99% 的 ee 获得,以高产率立体选择性地转化为乙烯基环氧乙烷。以高达 99% ee 获得的 S-乙酸酯要么脱保护为 S-醇,要么在碱性条件下直接环化为乙烯基环氧乙烷,ee 中度至无损失。结果与涉及脱保护过程中醋酸盐可逆迁移的外消旋化机制一致。