One-pot sequential coupling reactions as a new practical protocol for the synthesis of unsymmetrical 2,3-diethynyl quinoxalines and 4-ethynyl-substituted pyrrolo[1,2-a]quinoxalines.

One palladium-catalyzed sequential coupling reactions were successfully used as a new protocol for the synthesis of unsymmetrical 2,3-diethynyl quinoxalines and 4-ethynyl-substituted pyrrolo[1,2-a]quinoxalines. The one-pot two coupling reactions of 2,3-dichloroquinoxaline, with two different terminal alkynes, under controlled conditions produced selectively unsymmetrical 2,3-diethynyl quinoxalines with high yields. When one of the two terminal alkynes was 3-propyne-1-ol, in the presence of secondary amines, cyclization occurred and 4-ethynyl-substituted pyrrolo[1,2-a]quinoxalines were successfully formed. All synthesized compounds were tested against the two bacterial strains including Micrococcus luteus and Pseudomonas aeruginosa.