On the Importance of an Acid Additive in the Synthesis of Pyrido[1,2‐<i>a</i>]benzimidazoles by Direct Copper‐Catalyzed Amination

Abstract

Not just an acid! An expedient and highly modular synthesis of 6-, 7-, and 8-substituted pyrido[1,2-a]benzimidazoles (4) has been developed by a direct intramolecular CH amination of N-phenylpyridin-2-amines (3). Efficient CH 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. CCl aminations in N-(2-chloroaryl)pyridin-2-amines allow access to 9-substituted pyrido[1,2-a]benzimidazoles. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.