Esters α-méthyléniques par substitution d'éthers et d'acétates dérivés de l'α-(hydroxyméthyl)acrylate d'éthyle
作者:Hassen Amri、Monique Rambaud、Jean Villiéras
DOI:10.1016/0022-328x(90)87047-h
日期:1990.2
α-(Methylene)alkanoic esters are prepared in high yields by substitution of α-(acetoxymethyl)acrylates using Grignard reagents in the presence of a catalytic amount of copper(I) salt. This reaction can be applied to lithium enolates of esters and ketones and to give functional α-(methylene) alkanoic esters, products of great interest for the synthesis of active biological compounds (sarkomycin, α-(methylene)
An efficient, direct nucleophilic allylicsubstitution of α-, β- and γ-substituted alcohols with enamines, using the Pd(OAc)2/PPh3 catalyst system and ZnBr2 as a promoter in CH2Cl2 at reflux, is reported. The reaction course was dependent on the steric hindrance at the α- or γ-positions with respect to the functionalized α-carbon, selectively affording in moderate to good yields, α- or γ-homoallyl
Abstract An efficient nucleophilic allylic substitution of a variety of Morita–Baylis–Hillman adducts with enamines catalyzed by Pd(OAc)2 in the presence of ZnBr2 as a promoter is described in the present study. The reaction gives SN2-type 1,5-dicarbonyl compounds that may subsequently undergo an intramolecular conjugate addition onto the enone moiety affording the corresponding 1,4-adducts. All the
Unexpected nucleophilic behaviour of free-radicals generated from α-iodoketones
作者:Corinne De Dobbeleer、Jiří Pospíšil、Freija De Vleeschouwer、Frank De Proft、István E. Markó
DOI:10.1039/b901943j
日期:——
The unexpected nucleophilic reactivity of free-radicals generated from α-iodoketones is reported; two different procedures, either employing tin or the more environmentally acceptable ethylsulfone-based coupling reagent 5c have been developed.
Efficient access to functionalised medium-ring systems by radical fragmentation/radical addition to α-iodoketones
作者:Corinne De Dobbeleer、Ali Ates、Jean-Christophe Vanherk、István E. Markó
DOI:10.1016/j.tetlet.2005.03.200
日期:2005.5
Functionalised medium-ring systems of various sizes can be efficiently prepared by a novel approach that embodies a radical-induced fragmentation of bicyclic P-hydroxy ketones, followed by a second radical-coupling reaction. The unexpected reactivity of ot-keto radicals is also discussed. (c) 2005 Elsevier Ltd. All rights reserved.