Strong base- or acid-mediated chemoselectivity shifts in the synthesis of 2H-chromene or coumarin derivatives from common Baylis-Hillman adducts
作者:Faridoon、Temitope O. Olomola、Matshawandile Tukulula、Rosalyn. Klein、Perry T. Kaye
DOI:10.1016/j.tet.2015.04.104
日期:2015.7
Reaction of tert-butyl 3-(2-hydroxyphenyl)-2-methylenepropanoate esters with aqueous KOH provides convenient and chemoselective one-pot access to 2H-chromene-3-carboxylic acids, the overall transformation involving tandem conjugate addition, hydrolysis and elimination steps. The methodology complements the chemoselective, acid-catalysed route to 3-substituted coumarins from the same substrates by switching
的反应叔丁基3-(2-羟基苯基)-2- methylenepropanoate酯用含水KOH提供了方便的和化学选择性一锅访问2 ħ色烯-3-羧酸,整体改造涉及串联共轭加成,水解和消除脚步。该方法通过切换环化的区域选择性,补充了化学选择性,酸催化的途径,可从相同的底物生成3取代的香豆素。