With the aim to find new applications for gold or either to improve known gold catalyzed processes, three new gold(III) chiral complexes were synthesized from the inorganic salt NaAuCl4.2H2O and different chiral ligands of bis(oxazoline) type. 
One of the bis(oxazoline) ligands underwent a complete opening of both two five-membered rings under synthetic conditions. For the other two bis(oxazoline) ligands only one of two oxazoline rings opened up under similar experimental conditions, therefore losing in these two cases the C2-symmetry.
These three new synthesized gold complexes were active as catalysts in the intermolecular hydroamination of alkynes as well as in the enantioselective epoxidation and cyclopropanation reactions. 
     In the hydroamination reaction of alkynes, the regioselective Markovnikov addition of the aromatic amine to the acetilenic bond led to formation of the Markovnikov imine as major product. In this case, terminal alkynes and aromatics amines were the substrates of preference.
     Similarly, the gold(III) catalyzed asymmetric epoxidation of alkenes afforded moderate yields of epoxide together with moderate enantioselectivity values. In this case, the epoxidation reaction took place with classical oxidants such as NaOCl and PhIO in combination with molecular oxygen. Isotopic labelling experiments with 18O2 showed that the oxygen in the epoxide came from two different sources: a) the classical oxidant (NaOCl or PhIO) and b) the molecular oxygen. In this case a dual mechanism was proposed in order to explain the incorporation of oxygen in the epoxide: a) a less selective radical pathway and b) a second and more selective one that led to the preferential formation of the epoxide.
     With respect to the asymmetric cyclopropanation of olefins, different aromatic and aliphatic alkenes were used as model substrates whereas ethyl diazoacetate (EDA) was employed as source of carbene ion.  In this case, the new prepared gold(III) catalysts led to the formation of cyclopropanecarboxylates as major products, albeit with low values of enantioselectivity.

     On the other hand, new gold heterogeneous catalysts were prepared. These catalysts consisted on gold nanoparticles supported on a biopolymer (quitosan), which in turn it was deposited onto silica. In this case two gold catalysts with different biopolymer/silica ratio were prepared.
     Both heterogeneous catalysts were active in the hydroamination reaction of alkynes, showing higher activity than other known heterogeneous gold catalyst such as Au/SiO2, Au/CeO2, Au/Fe2O3 and Au/TiO2. This fact is probably due to the interaction between the NH and OH groups of chitosan and the metal particles. Effectively, this interaction may lead to an excellent dispersion of gold on the support as well as to a better stabilization against metal agglomeration and leaching. The catalyst with lower ratio biopolymer/silica ratio was used up to six times without loss of activity.
 	These catalysts, showed activity in the asymmetric epoxidation of alkenes using PhIO/O2 as oxidant under the same experimental conditions than those employed with the homogeneous gold(III) catalysts. However, with gold nanoparticles supported on quitosan, the enantioselectivity values were lower than those obtained for the homogeneous gold(III) complexes. The catalyst with higher biopolymer/silica ration was used up to four times without loss of activity.
	Finally, the heterogeneous catalyst also showed activity in the asymmetric cyclopropanation reaction of olefins. In this case the yields of cyclopropanecarboxylates were comparable to those obtained with the homogeneous gold(III) catalysts. The gold heterogeneous catalyst was recovered and reused without lost of activity up to two times.