One-pot multicomponent diastereoselective synthesis of novel dihydro-1 H -furo[2,3- c ]pyrazoles

An efficient method was developed for the diastereoselective synthesis of novel fused dihydro-1 H -furo[2,3- c ]pyrazole by a one-pot, four-component reaction of β-keto ester, hydrazine, aromatic aldehyde, and pyridinium ylide in the presence of triethylamine under microwave irradiation in solvent-free conditions in good yields. The merits of this cascade Knoevenagel condensation/Michael addition/cyclization sequence include its high atom economy, good yields, and efficiency of producing three new bonds (two C–C and one C–O) and two stereocenters in a single operation.