On the Importance of an Acid Additive in the Synthesis of Pyrido[1,2‐
<i>a</i>
]benzimidazoles by Direct Copper‐Catalyzed Amination
作者:Kye‐Simeon Masters、Tom R. M. Rauws、Ashok K. Yadav、Wouter A. Herrebout、Benjamin Van der Veken、Bert U. W. Maes
DOI:10.1002/chem.201100574
日期:2011.5.27
8‐substituted pyrido[1,2‐a]benzimidazoles (4) has been developed by a direct intramolecular CH amination of N‐phenylpyridin‐2‐amines (3). Efficient CH amination of 3 could only be achieved in the presence of catalytic copper and an acid additive. The type of acid (pKa) proved to be crucial for the catalysis. CCl aminations in N‐(2‐chloroaryl)pyridin‐2‐amines allow access to 9‐substituted pyrido[1,2‐a]benzimidazoles
不只是酸!一种适宜和的6-,7-高度模块化的合成,和8-取代的吡啶并[1,2一]苯并咪唑(4)已经通过开发的直接分子内Ç H的胺化Ñ -phenylpyridin -2-胺(3)。只有在催化铜和酸添加剂的存在下,才能实现3的高效CH胺化。酸的类型(p K a)被证明对催化至关重要。Ç 氯胺化在ñ - (2- chloroaryl)吡啶-2-胺允许访问9-取代的吡啶并[1,2一]苯并咪唑。