Synthesis and some transformations of 4H-pyrano[3,2-d]pyrazoles

Article abstract of DOI:10.1007/BF00522118

The ability of the amide carbonyl group of the pyrazolone ring to participate in the heterocyclization of oxopropyl-5-pyrazolones under the influence of polyphosphoric acid (PPA) or phosphorus polysulfide in dioxane with the formation of 4H-pyrano[ 3,2-d]