Expedient synthesis of β,β-disubstituted α-methylenepropionates
摘要:
Baylis-Hillman alcohols are excellent sources of the allylic halides ArCH=CH(CH2X)(CO2R) (X = Br. Cl: R-1= Me, Et. Bu'). The Z double bond isomers are attained in high isomeric purity (> 14: 1. ZIE). The halides are chemo- and regiospecifically transformed into the acrylates (ArCHR2)C(=CH2)(CO2R1) on treatment with Zn(R-2)(2) (R-2 =Me. Et, CH2TMS, CH(2)SiMe(2)Ome) or PrZnBr- in the presence of catalytic amounts of copper(1) salts (0.5-20 mol%) in high yield. (C) 2004 Elsevier Ltd. All rights reserved.
silica chloride, an eco-friendly heterogeneous catalyst, silica chloride–arenes, and silica chloride–saturated and unsaturatedalcohols as reagent systems are reported. These reactions furnished highly functionalized isomerized Baylis–Hillman derivatives in good yield. The efficiency and necessity of silica chloridecatalyst was compared with thionyl chloride. A plausible mechanism of the reaction is proposed
AN EFFICIENT AND STEREOSELECTIVE SYNTHESIS OF (Z)-ALLYL CHLORIDES FROM BAYLIS-HILLMAN ADDUCTS USING VILSMEIER-HAACK REAGENT
作者:Y. Liu、H. Zheng、D. Xu、Z. Xu、Y. Zhang
DOI:10.1080/00304940709356011
日期:2007.4
catalytic process?-9 The adducts, 3-hydroxy-2-methyl enealkanoates (derived from acrylate esters), have been utilized as important precursors for stereoselective synthesis of different multifunctional molecules?-9 Among these transformations, the preparation of 2-(halomethyl)-2-alkenoates fromBaylis-Hillmanadducts has drawn much attention as these compounds are useful in the synthesis of various naturally
Mapping the Mechanism of Nickel-Ferrophite Catalysed Methylation of Baylis-Hillman-Derived S<sub>N</sub>2′ Electrophiles
作者:Andrew Novak、Maria José Calhorda、Paulo Jorge Costa、Simon Woodward
DOI:10.1002/ejoc.200801029
日期:2009.2
presence of ferrophite ligands has been investigated computationally and experimentally. The sense and degree of enantioselectivity attained is independent of both the leaving group and the isomeric structure of the initial allylic halide. DFT studies support the selective formation of a limited number of energetically favoured anti and syn π-allyl intermediates. The observed regio- and enantioselectivity
A new and convenient stereoselective synthesis of (Z)-2-(chloromethyl)alk-2-enoates has been achieved from Baylis–Hillman adducts by treatment with PPh3/Cl3CCONH2 at room temperature. The synthesis can proceed under mild and acid-free conditions to form the products in high yields.