ABSTRACT
Heterocyclic compounds form the central core of several pharmaceutical agents and biologically active natural products, and are applied in corrosion inhibitors and herbicides. Many synthetic methods are employed for the synthesis of 5-, 6-, 7- and 8-membered benzo-fused heterocyclic compounds. The indole is one of the most commonly reported heterocyclic compounds. Indole is present in numerous natural products, which exhibit interesting biological activity, for instance reserpine, is one of the first drugs to treat diseases of central nervous system. Many tandem/cascade reactions which provide five-membered nitrogen-heterocycles involved the insertion of carbon monoxide into palladium (Pd)-carbon bonds. The chloroindoles were obtained in lower yields as compared to fluoroindoles or unsubstituted indoles because oxidative addition of chloroindoles to Pd(0) species occurred under reaction conditions. In oxidative addition to palladium(0) centers the alkenyl halides were highly reactive as compared to aryl halides.
