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A transition metal‐free iodosobenzene‐promoted direct oxidative 3‐arylation of quinoxalin‐2(H)‐ones was developed using various arylhydrazines under air. The protocol affords a variety of 3‐arylquinoxalin‐2(H)‐one derivatives in moderate to good yields. This method provides a rapid access to biologically interesting benzo[g]quinoxalinones and pyrido[3,4‐b]pyrazinones. The present methodology features high functional group tolerance including base‐sensitive groups as well as allyl‐ and benzyl‐substituted quinoxalin‐2(H)‐ones under mild reaction conditions.magnified image

Magnetically retrievable nano crystalline CuFe 2 O 4 catalyzed multi-component reaction: a facile and efficient synthesis of functionalized dihydropyrano[2,3-c]pyrazole, pyrano[3,2-c]coumarin and 4H-chromene derivatives in aqueous media † Koyel Pradhan, Sanjay Paul and Asish R. Das * CuFe 2 O 4 magnetic nanoparticles were synthesized and recognized as an efficient catalyst for the one-pot synthesis of dihydropyrano[2,3-c]pyrazole, pyrano[3,2-c]coumarin and 4H-chromene derivatives at mild conditions and in excellent yields. The four component reaction (4CRs) of a wide variety of substituted hydrazine derivatives, ethyl acetoacetate, dialkyl acetylenedicarboxylates and alkyl nitrile derivatives (malononitrile and ethyl cyanoacetate) gave the targeted dihydropyrano[2,3-c]pyrazoles. When two equivalents of dialkyl acetylenedicarboxylates were introduced replacing ethyl acetoacetate, a new four-component reaction took place providing another type of dihydropyrano[2,3-c]pyrazole derivatives.An efficient and practical route to pyrano[3,2-c]coumarin and 4H-chromene framework has also been developed by one-pot, three-component reaction (3CRs) of 4-hydroxycoumarin/dimedone/ cyclohexane-1,3-dione, dialkyl acetylenedicarboxylates and alkyl nitriles. CuFe 2 O 4 magnetic nanoparticles were prepared by a simple and effective citric acid complex method and characterized by using XRD, FT-IR, EDX and TEM image. The catalyst was recycled for six cycles with almost unaltered catalytic activity. All reactions were easily performed and proceeded with high efficiency under very simple and mild conditions and gave excellent yields avoiding time-consuming, costly syntheses, and tedious workup and purification of products.