SYNTHESIS, REACTIVITY AND APPLICATIONS OF SOME PYRIDYL PYRAZOLONE DERIVATIVES

Abstract

The present work deals with some reactions of3-pyridyl-1-phenyl-2-pyrazolin-5- ones, and it was divided into two parts:.

PART I

The Vilsmeier- Haack reaction of compound I gives 5-chloro-3-pyridyl-1-phenyi­ IH-pyrazole-4-carboxaldehyde II. Knoevenagei condensation of II with p-methyl acetophenone, and acetophenone gives 3-(5-chloro-3-pyridyl- I-phenyi-IH-pyrazol-4- yl)- I -phenyl/p-tolyl-prop-2-en-1-ones illa,b.

Furthermore, the structure of the prepared chalcones IIIa,b was confirmed by the following chemical reactions:

i) Condensation of IIIa,b with phenyl hydrazine in glacial acetic acid gives

4-(1,3-diphenyl/1-phenyl-3-p-tolyl-2-pyrazolin-5-yl)-5-chloro-3-pyridyl-1- phenyl-IH-pyrazoles IVa,b, ii) ii) Bromination of IIIa,b in carbon tetrachloride gives 2,3-dibromo-3-(5- chloro-1-phenyl-3-pyridyl-1H-pyrazol-4yl)- I -phenyVp-tolylpropan-1-one Va,b, iii) iii) The reaction ofVa,b with phenyl hydrazine in acetic acid gives 5-(5-chloro-1- phenyl-3-pyridyl-I-H-pyrazol-4-yl}-1-phenyl-3phenyVp-tolyl-IH-pyrazoles Vla,b.

And also, the nucleophilic substitution reactions of Compound II, was illustrated by the following:

i) With sodium ethoxide in boiling ethanol the corresponding I-phenyl-3- pyridyl-5-ethoxypyrazolo-4-carboxaldehyde VII was obtained