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.