STUDIES ON VILSMEIER-HAACK REACTION - A VERSATILE NEW SYNTHESIS OF 5-CHLORO-3-METHYLPYRAZOLE-4-CARBOXALDEHYDE, -CHLORO-3-METHYL-1-PHENYLPYRAZOLE-4-CARBOXALDEHYDE AND RELATED FUSED HETEROCYCLIC-COMPOUNDS AND HETEROCYCLIC SCHIFFS BASES

3-Methyl-(I)- and 3-methyl-l -phenyl-(II) -pyrazol-5(4H)-ones on formy lation using Vilsmeier-Haack reagent (VR) yield a versatile intermedia tes 5-chloro-3-methyl-(III)-and 3-methyl-l-phenyl-(IV)-pyrazole-4-carb o-xaldehydes respectively. The chloroaldehydes III and IV react with v arious amines to give heterocyclic compounds (V-IX, XIII-XVII) and sch iff bases (X-XII, XVIII-XX). Some (III, IV, V, VII, XI, XII, XIII, XV and XIX) of these compounds show in vitro antibacterial activity.