A Simple Synthesis of 6-Phenylpyrano[2,3-c]pyrazol-4(1H)-ones

A novel synthesis of substituted 6-phenylpyrano[2,3-c]pyrazol-4(1H)-ones via reaction of various 2-substituted or 2,5-disubstituted 2,4-dihydro-3H-pyrazol-3-ones with phenylpropyn­oyl chloride using calcium hydroxide in refluxing 1,4-dioxane is described. N-Unsubstituted representatives were obtained by treatment of 4-methoxybenzyl-protected congeners with trifluoroacetic acid.