Intramolecular Friedel-Crafts cyclization of nitrogen heterocycles. An expeditious approach to the azaphenanthrene skeleton
作者:Jose Barluenga、Miguel Tomas、Angel Suarez-Sobrino、Eduardo Rubio
DOI:10.1021/jo00055a025
日期:1993.1
The intramolecular Friedel-Crafts type cyclization of several heterocycles prepared from 4-amino-1-azabutadienes leading to the preparation of several azaphenanthrene and azasteroid structures, using phosphoric or trifluoromethanesulfonic acid, is described. The reactions are carried out under mild conditions, and good yields are obtained. In some cases, such as the cyclization of thiazine 5, the reaction is totally regioselective.