Pyrazoles from 3-formylchromone-ethyl vinyl ether adduct

Department of Chemistry, Aligarh Muslim University, Aligarh-202 002, India

Manuscript received 2 March 1998, revised 28 December 1998, accepted 9 March 1999

Reaction of (E)-ß-(4-oxo-4H-1-benzopyran-3-yl)acrolein (2) with phenylhydrazine yields (E)-ß-(4-oxo-4/1-1-benzopyran-3- yl)acrolein phenylhydrazone (4) and [1-phenyl-5-(2-hydroxyphenyppyrazol-4-yl]acrolein phenylhydrazone (5). 3-RE,E)-5- Oxohexa-1,3-dien-1-y1]-1-benzopyran-4-one-5-phenylhydrazone (6) and phenylhydrazone (7) of 6-[5-(2-hydroxypheny1)-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)pyrazole (8) is obtained from 7 by refluxing in nitrobenzene.