Copper complexes of phosphoramidites efficiently catalyzed asymmetricaddition of arylboron reagents to acyclic enones. Importantly, rare 1,4-insertion of arylcopper(I) was identified which led directly to O-bound copper enolates. The new mechanism is fundamentally different from classical oxidative addition/reductive elimination of organocopper(I) on enones.
亚磷酰胺的铜配合物有效地催化芳基硼试剂向无环烯酮的不对称加成。重要的是,鉴定了稀有的芳基铜(I)的 1,4-插入,这直接导致了与 O 结合的铜烯醇化物。新机制与传统的有机铜(I)在烯酮上的氧化加成/还原消除有着根本的不同。
An efficient synthesis of (E)-α,β-unsaturated ketones and esters with total stereoselectivity by using chromium dichloride
作者:José M. Concellón、Humberto Rodríguez-Solla、Carmen Méjica
DOI:10.1016/j.tet.2006.01.052
日期:2006.4
(E)-α,β-Unsaturatedketones 1 or esters 2 can be obtained with complete stereoselectivity by reaction of different 2-chloro-3-hydroxy ketones 3 or esters 4 and CrCl2. A comparative study of the results of synthesis of ketones 1 with CrCl2 or samarium is performed. A mechanism to explain both β-elimination reactions has been proposed.
[EN] A METHOD FOR PREPARING SULFUR-CONTAINING COMPOUNDS<br/>[FR] PROCÉDÉ POUR LA PRÉPARATION DE COMPOSÉS CONTENANT DU SOUFRE
申请人:ROYAL COLLEGE OF SURGEONS IE
公开号:WO2010066450A1
公开(公告)日:2010-06-17
The invention provides a method for preparing sulfur-containing compounds, the method comprising reacting a donor compound comprising at least one sulfur having at least one lone pair of electrons, with an acceptor compound; wherein the reaction occurs in the presence of an amine, optionally an amine catalyst, capable of activating the sulfur having at least one lone pair of electrons; and wherein the reaction occurs via the formation of an transient intermediate species, optionally a transient intermediate species, between the amine, optionally the amine catalyst and the donor compound; and wherein the donor compound is selected from the group consisting of a sulfurous acid, a sulfenic acid and a sulfinic acid or a salt, ester or amide of a sulfurous acid, a sulfenic acid and a sulfinic acid. The invention also provides sulfur-containing compounds of the formula: wherein R is selected from: (a) 1 -(4-Nitro-phenyl)-3-oxo-3-phenyl-propane; (b) 2-(3-Methyl-4-nitro-isoxazol-5-yl)-1 -phenyl-ethane; (c) 1-(4-Methoxy-phenyl)-2-(3-methyl-4-nitro-isoxazol-5-yl)-ethane; (d) 2-(3-Methyl-4-nitro-isoxazol-5-yl)-1-(4-nitro-phenyl)-ethane; (e) 1-(4-Fluoro-phenyl)-2-(3-methyl-4-nitro-isoxazol-5-yl)-ethane; (f) 1 -(4-Chloro-phenyl)-2-(3-methyl-4-nitro-isoxazol-5-yl)-ethane; and (g) 3-Oxo-cyclohexane. Finally, the invention provides use of chiral sulfur-containing compounds obtainable by the above-mentioned method or chiral sulfur-containing compounds as mentioned above for the resolution of racemic mixtures of amines.
Enantioselective Conjugate Azidation of
<i>α,β</i>
‐Unsaturated Ketones under Bifunctional Organocatalysis by Direct Activation of TMSN
<sub>3</sub>
作者:Jorge Humbrías‐Martín、M. Carmen Pérez‐Aguilar、Rubén Mas‐Ballesté、Antonella Dentoni Litta、Alessandra Lattanzi、Giorgio Della Sala、Jose A. Fernández‐Salas、José Alemán
DOI:10.1002/adsc.201900831
日期:2019.10.22
An enantioselective organocatalytic conjugateazidation of α,β‐unsaturatedketones is presented. A bifunctional organocatalyst activates TMSN3, triggering the nucleophilic addition of the azido group to enones in absence of external promoters and avoiding the direct use or the pre‐formation of highly toxic and explosive hydrazoic acid. This protocol proceeds with excellent enantiocontrol under mild
Stereoselective Synthesis of Polysubstituted Alkenes through a Phosphine-Mediated Three-Component System of Aldehydes, α-Halo Carbonyl Compounds, and Terminal Alkenes
作者:Da-Neng Liu、Shi-Kai Tian
DOI:10.1002/chem.200900177
日期:2009.4.27
mediate the one‐pot Wittig reaction of aldehydes with α‐halo carbonylcompounds for the synthesis of 1,2‐disubstituted and trisubstituted alkenes in an excellent stereoselective fashion. Furthermore, the first one‐pot, three‐component reaction of aldehydes, α‐halo acetates, and terminalalkenes has been developed in the presence of PPh3 to produce trisubstituted alkenes with excellent E selectivity (see