Four component synthesis of highly functionalized pyrano[2,3-c]pyrazoles from benzyl halides

ABSTRACT

N-methylmorpholine N-oxide and silver oxide (Ag₂O) oxidized four component reaction for the preparation of pyranopyrazole with different substituted pattern have been developed which provides rapid access to a library of compounds in good to excellent yields by using benzyl halide, malanonitrile/ethyl cyanoacetate, diethylacetylenedicarboxylate/ethyl acetoacetate and hydrazine hydrate as reactants. This transformation involves the breaking of one C‒O bond and formation of 2 C–C, 2 C–N, and a C‒O bond leading to the formation of a five and six membered ring in one pot operation.

GRAPHICAL ABSTRACT

KEYWORDS:

• Multi component reactions
• N-methylmorpholine N-oxide
• pyran
• pyranopyrazole
• pyrazole
• silver oxide