Copper‐Catalyzed Coupling of Arylethynes and Aryltriazenes to Access Libraries of 1,2‐Diketones and Their Efficacy in Synthesis of Triaryloxazoles, Imidazoles and Diaryl‐Diazepines.

Libraries of diaryl‐1,2‐diketones were synthesized by oxidative coupling of 1‐aryl‐ethynes with 1‐aryl‐triazenes, employing tetramethylguanidinium ionic liquid [TMG][CF3COO] and Cu(OAc)2. The synthesized compounds served as scaffolds for facile one‐pot synthesis of diverse libraries of pharmaceutically important heterocycles in ionic liquid solvents. Thus BMIM‐ionic liquid/CuI was utilized for the synthesis of triaryl‐oxazoles, [TMG][HSO4]/NH4OAc was used to prepare triaryl‐imidazoles, and [TMG][OAc] was employed for the synthesis of diaryl‐diazepines. Reactions were performed in fresh as well as in recycled ionic liquids. The reported methods expand the available protocols for the synthesis of diaryl‐1,2‐diketones, and enable facile access to pharmaceutically important nitrogen heterocycles. [ABSTRACT FROM AUTHOR]