Catalytic Asymmetric Synthesis of Acyclic Arrays by Tandem 1,4-Addition-Aldol Reactions
作者:Gareth P. Howell、Stephen P. Fletcher、Koen Geurts、Bjorn ter Horst、Ben L. Feringa
DOI:10.1021/ja0651862
日期:2006.11.1
Herein, we report efficient acyclic stereocontrol in tandem 1,4-addition-aldol reactions triggered by catalytic asymmetric organometallic addition. Grignard reagents add to alpha,beta-unsaturated thioesters in a 1,4-fashion and the resulting magnesium enolates are trapped with aromatic or aliphatic aldehydes. The process provides a range of tandem products bearing three contiguous stereocenters with
在此,我们报告了由催化不对称有机金属加成引发的串联 1,4-加成-羟醛反应中的有效无环立体控制。格氏试剂以 1,4-方式添加到 α,β-不饱和硫酯中,生成的烯醇镁被芳香族或脂肪族醛捕获。该过程提供了一系列串联产品,这些产品具有三个连续的立体中心,具有出色的相对和绝对立体化学控制。使用单晶 X 射线分析对各种非对映体产品进行了充分表征,并讨论了该串联协议中立体控制的起源。这种方法的多功能性和效率在第一次催化不对称合成 (-)-菜豆酸的过程中得到了证明,通过一条简短而简洁的路线以 54% 的总产率合成。
The Reaction of Cyclopropenethione with Carbonyl-stabilized Phosphonium Methylides to Yield 2<i>H</i>-Pyran-2-thione
The reaction of diphenylcyclopropenethione with carbonyl-stabilized triphenylphosphonium methylides (2) to yield 2H-pyran-2-thiones was studied. It was clarified that electron-releasing substituents increased the reactivity of 2.
A convenient synthesis of perfluoro- and polyfluoroacetylenic thiolesters
作者:Yanchang Shen、Jianhua Zheng
DOI:10.1016/s0022-1139(00)81998-3
日期:1987.4
An intramolecular Wittig reaction has been successfully applied to the synthesis of perfluoro- and polyfluoroacetylenic thiolesters in excellent yields. These thiolesters would be expected to be good dipolarophiles and dienophiles and useful species for the synthesis of fluorinated heterocyclic compounds.