3-(o-Trifluoroacetamidoaryl)-1-propargylic esters: common intermediates for the palladium-catalyzed synthesis of 2-aminomethyl-, 2-vinylic, and 2-alkylindoles
作者:Ilaria Ambrogio、Sandro Cacchi、Giancarlo Fabrizi、Alessandro Prastaro
DOI:10.1016/j.tet.2009.06.113
日期:2009.10
3-(o-Trifluoroacetamidoaryl)-1-propargylic esters have been used as common synthetic intermediates for the preparation of a variety of 3-unsubstituted 2-substituted indoles. Treating ethyl 3-(o-trifluoroacetamidoaryl)-1-propargylic carbonates unsubstituted or containing an aryl substituent at the propargylic carbon with piperazines and Pd(PPh3)4 in THF at 80 °C affords 2-(piperazin-1-ylmethyl)indoles in excellent yields
3-(邻-三氟乙酰氨基芳基)-1-炔丙基酯已被用作制备各种3-未取代的2-取代的吲哚的常用合成中间体。在80°C下用哌嗪和Pd(PPh 3)4在THF中处理未取代的或在炔丙基碳上包含芳基取代基的3-(邻-三氟乙酰氨基芳基)-1-丙炔碳酸酯,得到2-(哌嗪-1-基甲基)吲哚高产。用其他仲胺也可获得2-氨基甲基吲哚的良好至优异的产率。在炔丙基碳上带有烷基取代基的乙基3-(邻-三氟乙酰氨基芳基)-1-炔丙基碳酸酯和乙基3-(o在炔丙基碳处被二取代的-(三氟乙酰氨基芳基)-1-炔丙基乙酸酯在80°C下的Pd(OAc)2 / PPh 3组合和Et 3 N在THF中的生成2-乙烯基吲哚。2-乙烯基吲哚的形成具有很强的立体选择性,至少在我们研究的底物上会生成反式乙烯基衍生物。在80°C下于MeCN中存在甲酸,Et 3 N和Pd(PPh 3)4的情况下,乙基3-(邻三氟乙酰胺基芳基)-1-炔丙基碳酸酯能以优异的产率获得2-烷基吲哚。