Synthesis of heterocycles via palladium-catalyzed oxidative addition.

Palladium-catalyzed processes have proven to be a powerful and useful tool for the synthesis of heterocycles. Palladium has found such wide utility because it affects an extraordinary number of very different reactions, including many carbon -carbon bond-forming reactions, under relatively mild reaction conditions. Furthermore, palladium can usually be used in only catalytic amounts and tolerates a wide variety of functional groups, thus avoiding protection group chemistry. Most palladium-based methodology proceeds stereoand regioselectively in excellent yields. Thus, a number of books 1 and major review papers 2 have been published on various aspects of organopalladium chemistry, including one book devoted exclusively to heterocyclic synthesis. 1f