Chiral Amino Ether-Controlled Catalytic Enantioselective Arylthiol Conjugate Additions to α,β-Unsaturated Esters and Ketones: Scope, Structural Requirements, and Mechanistic Implications
作者:Katsumi Nishimura、Kiyoshi Tomioka
DOI:10.1021/jo015879v
日期:2002.1.1
Asymmetric conjugate addition reaction of 2-trimethylsilylbenzenethiol with enoates and enones is catalyzed by a chiral amino ether-lithium thiolate complex and affords adducts with high enantioselectivity. Both the s-cis conformation and a steric wall at one side of the carbonyl group are structural requirements in substrates yielding adducts with high enantioselectivity. Reactions with tert-butyl
New Methods for Stereoselective Synthesis of α-Alkylidene-γ-butyrolactones Using Monoanion of<i>O</i>-Ethyl<i>S</i>-(Tetrahydro-2-oxo-3-furanyl) Thiocarbonate and Dianion of α-Mercapto-γ-butyrolactone
The lithium enolates of O-ethyl S-(tetrahydro-2-oxo-3-furanyl) dithiocarbonate and thiocarbonate were found to be efficient reagents for the stereoselective synthesis of α-alkylidene-γ-butyrolactones fromcarbonylcompounds. The dianion of α-mercapto-γ-butyrolactone was successfully generated by treatment of α-mercapto-γ-butyrolactone with 2.2 equivalents of lithium diisopropylamide in the presence
A Simple Thiophosphate-Based Method for α-Alkylidenation of Lactones
作者:Ewa Krawczyk
DOI:10.1055/s-2006-926285
日期:——
A variety of α-alkylidene lactones has been synthesized using a one-pot procedure based on the reaction of readily available thiophosphates with aldehydes under basic, mild conditions.
Control elements in the asymmetric tandem alkylation of α-alkylidene-γ-butyrolactone derivatives
作者:Kiyoshi Tomioka、Hisashi Kawasaki、Kenji Koga
DOI:10.1016/s0040-4039(00)98609-x
日期:1985.1
Control elements in the highly selective construction of contiguous tertiary and quaternary carbon centers by the tandem alkylation of α-alkylidene-γ-butyrolactone derivatives were studied. It is clarified that the stereochemical course of the reaction is rationalized by evaluating highly selective 1,2-, 1,3-, and 1,4-asymmetric inductions.
Carbonylation of alkynols catalyzed by Pd(II)/2-PyPPh 2 dissolved in organic solvents and in ionic liquids: a facile entry to α-methylene γ- and δ-lactones
作者:Crestina S Consorti、Gunter Ebeling、Jaı̈rton Dupont
DOI:10.1016/s0040-4039(01)02309-7
日期:2002.1
The carbonylation of terminal 3-alkyn-1-ols and 1-alkyn-4-ols by Pd(OAc)(2) associated with 2-(diphenylphosphino)pyridine (2-PyPPh2) dissolved in organic solvents or in 1-n-butyl-3-methyl imidazolium ionic liquids affords quantitatively and selectively exo-alpha-methylene gamma- and delta-lactones, respectively. In the case of the reactions performed in ionic liquids (biphasic conditions), the lactones were isolated by simple distillation and the ionic catalyst solution can be reused. (C) 2002 Elsevier Science Ltd. All rights reserved.