SYNTHESIS AND SPECTRAL STUDIES ON HETEROCYCLIC NITROGEN COMPOUNDS

Abstract

Heterocyclic nngs, like triazolines, quinazolines, oxazolidines, thiazoles, benzoxazoles, oxazines and oxadiazines are reported to exhibit biological activity. The aim of this work was:

(1) The use of p-N-succinimidobenzoyl isothiocyanate to prepare th se heterocycles substituted with pyrrolidine dione hopping to enhance their biological activity.

(ii) The use of a-cyano- -phenylcinnamoyl isothiocyanate as a start for the synthesis of oxazine, pyrimidine as well as quinazoline system. All these systems are substituted with a cyano group and this is expected to increase their biological activity.

Part I

p-N-succinimidobenzoyl isothiocyanate (I) was prepared from its acid chloride by treating its solution in acetone with ammonium thiocyanate. The isothiocyanate obtained in situ was used in heterocyclic synthesis.

Treatment of (I) with phenylhydrazine afforded 2-phenyl-1-H-3-(p­ N-succinimidophenyl)- 3-1,2,4-triazoline-5-thione (V).

Reaction with aroyl hydrazine e.g. benzoylhydrazine and p­ chlorobenzoyl hydrazine gave thiosemicarbazide derivatives (VIIa-b), which have been used as precursors to synthesize 3-aryl-4-(p-N­ succinimidobenzoyl)- 2-1,2,4-triazoline-thiones (VIIIa,b) by cyclization using polyphosphoric acid.