Acetylene based short route from 2,2,6,6-tetramethylpiperidin-4-one oxime to 2-(pyrazol-5-yl)-4,5,6,7-tetrahydropyrrolo[3,2-c]pyridines

Pharmaceutically relevant substituted 2-(pyrazol-5-yl)-4,5,6,7-tetrahydropyrrolo [3,2-c]pyridines have been assembled in good to excellent yields via the reaction of 2,2,6,6-tetramethylpiperidin-4-one oxime with acetylene, cross-coupling of the resulting 4,4,6,6-tetramethyl-4,5,6,7 tetrahydropyrrolo[3,2-c]pyridines with aroylbromoacetylenes, and reaction of the formed 2-(aroylethynyl)-4,4,6,6-tetramethyl-4,5,6,7-tetrahydropyrrolo[3,2-c]pyridines with hydrazine.