Pyrazoles from 3-formylchromone-ethyl vinyl ether adduct

Reaction of (E)-beta-(4-oxo-4H-1-benzopyran-3-yl)acrolein (2) with phenylhy drazine yields (E)-beta-(4-oxo-4H-1-benzopyran-3-yl)acrolein phenylhydrazon e (4) and [1-phenyl-5-(2-hydroxyphenyl)pyrazol-4-yl]acrolein phenylhydrazon e (5). 3-[(E,E)-5-Oxohexa-1,3-dien-1-yl]-1-benzopyran-4-one-5-phenylhydrazo ne (6) and phenylhydrazone (7) of 6-[5-(2-hydroxyphenyl)-1-phenylpyrazol-4- yl] hexa-3,4,5,6-dien-2-one have been synthesized by the reaction of 3-[(E, E)-5-oxohexa-1,3-dien-1-yl] -1-benzopyran-4-one (3) with phenylhydrazine. 4 -[(E)-2-(3-Methyl-1-phenylpyrazol-5-yl)vinyl]-1-phenyl-5-(2-hydroxyphenyl)p yrazole (8) is obtained from 7 by refluxing in nitrobenzene.