TiCl4/t-BuNH2 as the sole catalyst for a hydroamination-based Fischer indole synthesis
摘要:
A system comprising TiCl4 and t-BuNH2 acts as a catalyst for highly regioselective hydroamination reactions of alkynes using hydrazines and at the same time a Lewis acid in the transformation of the generated hydrazones into indole derivatives, while a 1,3-diyne is converted to pyrroles using the same precatalyst. (C) 2004 Elsevier Ltd. All rights reserved.
Annulation of internal alkynes through a hydroamination/aza-Heck reaction sequence for the regioselective synthesis of indoles
作者:Lutz Ackermann、René Sandmann、Amparo Villar、Ludwig T. Kaspar
DOI:10.1016/j.tet.2007.10.117
日期:2008.1
Highly regioselective annulation reactions of unsymmetrically substituted alkynes by primary 2-bromo or 2-chloroanilines are achieved with an efficient one-pot protocol, which relies on a regioselective TiCl4-catalyzed intermolecular hydroamination and a subsequent palladium-catalyzed intramolecular aza-Heck reaction. The use of unsymmetrically substituted alkynes in this strategy enables the synthesis