Regioselective synthesis of novel nitroso-pyrazolylquinoxalines via HOAc-mediated cyclocondensation of 2-hydroxyimino-1,3-diketones with hydrazinylquinoxalines

This article describes the regioselective synthesis of novel nitroso-pyrazolylquinoxalines via cyclocondensation of 2-hydroxyimino-1,3-diketones with hydrazinylquinoxalines. Of note, this is the first time that 2-hydroxyimino-1,3-diketones are used as electrophilic reagents to cyclocondensation with hetarylhydrazines. The cyclocondensation proceeded through a hydrazone intermediates formation. A series of novel nitroso-substituted pyrazolylquinoxalines were synthesized by both one-pot and two-step procedures in up to 86% yields. Importantly, a gram-scale synthesis of nitroso-pyrazolylquinoxalines, their oxidation and reduction were successfully accomplished.

Automated summary

This article describes the efficient synthesis of novel nitroso-pyrazolylquinoxalines through regioselective cyclocondensation of 2-hydroxyimino-1,3-diketones with hydrazinylquinoxalines. The use of 2-hydroxyimino-1,3-diketones as electrophilic reagents in cyclocondensation with hetarylhydrazines is reported for the first time. The synthesis of nitroso-substituted pyrazolylquinoxalines was achieved in high yields using both one-pot and two-step procedures, and a gram-scale synthesis, as well as oxidation and reduction reactions, were successfully carried out.