On the Reaction of 3-Cyanochromones with Phenyl- and Methylhydrazines: Structural Revision and a Simple Synthesis of Chromeno[4,3-c]pyrazol-4-Ones

Reactions of 3-cyanochromones with phenylhydrazine gave the corresponding 5-amino-4-salicyloyl-1-phenylpyrazoles, 2-aminochromone-3-carbaldehyde N-phenylhydrazones, and 1-phenylchromeno[4,3-c]pyrazol-4(1H)-one, depending on the reaction conditions. With methylhydrazine, 3-(2-hydroxyaryl)-1-methylpyrazole-4-carbonitriles and 2-methylchromeno[4,3-c]pyrazol-4(2H)-ones were obtained in moderate to high yields.