A one-pot method for the selective synthesis of twoisomers 4H-chromene and 2,8-dioxabicyclo[3.3.1]nonane derivatives was developed without a catalyst and using EtOH/H2O (4:1, v/v) as the solvent. The reaction was conducted under mild conditions, with forming multiple chemical bonds in one pot and high atom economy, and only a stoichiometric amount of H2O is produced as the byproduct. Its selectivity
开发了一种选择性合成两种异构体 4 H -色烯和 2,8-二氧杂双环 [3.3.1] 壬烷衍生物的一锅法,无需催化剂,使用 EtOH/H 2 O (4:1, v/v)作为溶剂。该反应在温和的条件下进行,一锅形成多个化学键,原子经济性高,副产物仅产生化学计量的H 2 O。其选择性受热力学和动力学控制,并讨论了两种结构发生转变的原因。
A mild efficient iodine-catalyzed synthesis of novel anticoagulants with 2,8-dioxabicyclo[3.3.1]nonane core
作者:Nemai C. Ganguly、Pallab Mondal、Sushmita Roy
DOI:10.1016/j.tetlet.2013.02.092
日期:2013.5
An efficient coupling of 2-hydroxychalcones/alpha,beta-enones with 4-hydroxycoumarin/5,5-dimethylcyclohexyl-1,3-dione (dimedone) has been accomplished to provide access to a novel class of potential anticoagulants with 2,8-dioxabicyclo[3.3.1]nonane core. The reaction proceeds by Michael-bicycloketalization sequence under iodine catalysis (10 mol %) in aqueous ethanol under reflux. Good to excellent yields, impressive selectivity, absence of byproduct formation, avoidance of toxic organic solvents, and utilization of metal-free water-compatible mild Lewis acid catalyst are the key attractive features of this protocol. (C) 2013 Elsevier Ltd. All rights reserved.