Synthesis and chemical reactivity of polyfunctionally substituted pyridazines and pyridazines containing hydroxy substituents

Abstract

In the first part of this thesis, 2-Arylhydrazonals were used as aldehyde components in Baylis Hillman reaction. 2-Arylhydrazonals reacted with acrylonitrile to yield 1,6-dihydropyridazine-4- carbonitrile derivatives and with cyclohexenone to yield tetrahydrocinnoline derivatives.

In the second part of this thesis novel azaenamines incorporated tetrahyderothiophene were prepared. Michael addition reaction of azaenamine with a, -unsaturated nitriles, took place and led to thia-triaza-benzo[a]fluorine derivatives. The condensation with malononitrile resulted in the formation of 11-thia-1,5,11 b-triaza-benzo[a]fluorene-4-carbonitrile. Azaenamines reacted also with aldehydes and piperidine to give Mannich products.

In the appendix (third part), a novel route to the three-component Biginelli-like cyclocondensation reaction of enamines, urea and aldehydes in dioxan-acetic acid efficiently afforded the corresponding 4-unsubstituted 3,4-dihydropyrimidin-2-(lH)-ones in moderate yields. The reaction of azaenamines with aldehydes and urea afforded 6-acetyl-1,2,4-triazin-3-one in moderate yields. Keywords: 2-Arylhydrazonals, Baylis-Hillman, dihydropyridazine, tetrahydrocinnoline, azaenamine, Michael addition, Mannich adduct, enamines Biginelli-like reaction, 5-Aroyl pyrimidine-2-ones.