Reactivity centres in the dimethoxybenzylidene acetophenone towards attack by active methylene compounds [Part X]: synthesis of five membered ring compounds

While malononitrile and cyanoacetamide react with 2,3-dimethox-y benzylideneacetophenone to give pyridine and pyridone derivatives, through Michael condensation, the reaction with succinic ester condenses in the Stobbe type affording the half-ester [IIa]. This undergoes cyclization to five membered ring compounds via two different routes. The synthesis of isoxazole [IX], oxadiazole [XIa] and thiazole [Xlb] is also described. The biological activity of these compounds is evaluated and discussed