The main part of this book is the efficient regioselective synthesis of functionalized heterocycles (furans, pyrroles, thiophenes, selenophenes) based on the palladium(0)-catalyzed cross-coupling and metal-halide exchanged reactions of brominated heterocycles. The study of the efficient methodologies (regioselectivities, optimization of condition including catalysts, solvent, temperature ?) to functionalize them to give a valuable synthetic procedure for the synthesis of pharmacologically relevant products and of useful intermediates for further synthetic transformations. These simple methodologies were applied to synthesize the sulfur- analogues of pyrrole natural product, such as ningaline A. The second part is oriented synthesis of N,O-heterocycles. The convenient approach to synthesized pyrazole-3-carboxylates and pyrazole-1,5- dicarboxylates by one-pot cyclization of hydrazone dianions with diethyl oxalate and 6-iodo- and 6- bromomethyl-5,6-dihydro-4H-1,2-oxazines by condensation of dilithiated acetophenone-oximes with allylbromide and subsequent regioselective iodine- or NBS-mediated cyclization were shown.