This manuscript covers two main topics. The first part dealt with the organocatalytic conjugate addition of Michael donors to phenyl vinyl selenone. The enantioselective Cinchona alkaloid-catalyzed Michael addition using a-substituted a-nitroacetates has been developed. The synthesis of various a,a-dialkyl a-nitroacetates has been accomplished in excellent yield and good enantioselectivity which were subsequently converted to cyclic and acyclic quaternary a-amino acids, taking advantage of the rich functionalities of the adducts. a-Substituted a-nitroamides have also been utilized as nucleophile. With them, an organocatalytic Michael addition/intermolecular SN2/hydrolysis sequence have been developed for the synthesis of a-lactones in moderate enantioselectivity. The second part of the manuscript focused on the transition-metal-catalysed insertion of isocyanides bearing participating functional group for the synthesis of heterocycles and natural product. On the one hand, the synthesis of 3,5,5-trisubstituted imidazolones using silver-catalyzed reaction of a,a-disubstituted a-isocyanoacetate with primary amine have been developed. To illustrate this methodology, evodiamine and rutaecarpine, two natural products, have been synthesized using methyl o-isocyanobenzoate. The synthesis of 2,3,5,5-tetrasubstituted imidazolones have been also reported using the 3-CR reaction of a,a-dibenzyl a-isocyanoacetate, primary amine and aryl iodide in the presence of a palladium/copper bimetallic system. On the other hand, palladium catalysed isocyanide insertion have been explored. The Pd-catalyzed multicomponent reaction of primary amine, aryl halide and o-cyanobenzonitrile has permitted the construction of 2-substituted quinazolin-4-one. Finally, the Pd-catalyzed domino process isocyanide insertion/C(sp)3-H activation of 3-cyclopropyl-2-isocyanopropanoate furnished C-2 arylated azaspiro[2.4]hept-4-ene.