Síntese multicomponente de 3-estiril-1h-quinoxalina-2-onas em meio aquoso

Abstract

Nitrogen heterocycles compounds are of great relevance due their applications in many scientific areas, notablyin the development of new materials of technological interest, as well as therapeutic agents and other biological active compounds. Recently, application of green chemistry concepts highlighted the relevance of multicomponent reactions (MCR) in aqueous medium to organic synthesis. This work reports the synthesis of 3- styryl-1H-quinoxaline-2-one-based nitrogen heterocycles (SQXO) based in MCR protocol in aqueous medium. The tri-component systems, which involves reaction of ophenylenediamine sodium pyruvate and different aldehydes, were carried out in 20% aqueous acetic acid, and in the presence of sodium acetate. Fourteen SQXO derivatives, including eight new compounds, were obtained in 65-92% in 8-14 hours. Products were properly characterized by melting point as well as infrared and nuclear magnetic resonance ( 1H and 13C) spectroscopies. Reactions are supposed to proceed via mechanism involving initial condensation of aromatic diamine and sodium pyruvate, to afford 3- methyl-1H-quinoxaline-2-one, which reacts with different aldehydes via aldol-type condensation. It is important to point out that only water molecules are released to the medium during all stages. This green synthetic protocol becomes especially attractive due the applications of SQXO derivatives in many areas, notably those associated to biological and materials fields.