Synthesis of carbazoles and 1,2-dihydrocarbazoles by domino ‘twofold Heck/6π-electrocyclization’ reactions of di-, tri- and tetrabromoindoles
作者:Munawar Hussain、Serge-Mithérand Tengho Toguem、Rasheed Ahmad、Đặng Thanh Tùng、Ingo Knepper、Alexander Villinger、Peter Langer
DOI:10.1016/j.tet.2011.05.014
日期:2011.7
palladium(0)-catalyzed Heck cross-coupling reactions of di-, tri- and tetrabromo-N-methylindoles. The reactions were carried out at 90 °C using a novel biaryl monophosphine ligand developed by Buchwald and co-workers. 1,2-Dihydrocarbazoles were formed by a domino ‘twofold Heck/6π-electrocyclization’ when the reaction was carried out at higher temperature. The regioselectivity of the Heck reaction of 2,3,6-tr
二,三和四烯基吲哚是通过钯(0)催化的二,三和四溴-N-甲基吲哚的Heck交叉偶联反应制备的。使用Buchwald及其同事开发的新型联芳基单膦配体在90°C下进行反应。当在较高温度下进行反应时,通过多米诺“双重Heck /6π-电环化”形成1,2-二氢咔唑。2,3,6-三溴-N-甲基吲哚的Heck反应的区域选择性有利于碳原子C-2和C-3。通过Pd / C催化的脱氢,将1,2-二氢咔唑高产率地转化为相应的咔唑。