This doctoral thesis describes the development of environmentally sustainable chemical 
processes, focusing on the search for new strategies of synthesis and recovery of homogenous 
catalysts with the aim to extend their lifetime. From another side, it emphasizes the design of 
multifunctional catalysts for application in domino reactions. With this type of process is 
possible to perform multiple transformations in a single synthetic operation, resulting in energy 
savings and a significant reduction in waste generation as well as hazardous substances.
     In both cases it has been studied the applicability of different gold catalysts based on both 
metal nanoparticles and Au(I) and Au(III) salts to generate products of interest in chemical and 
pharmaceutical industry. All these concepts are addressed in a first chapter as a general 
introduction.
     The second chapter discusses the general objectives of the dissertation.
     A third chapter describes the synthesis of phosphine gold (I) complexes, and their 
application in the intermolecular hydroalkoxylation of alkynes to form enol ethers and ketals. 
By an appropriate choice of the phosphine ligand, the Z or E isomer vinyl ether can be 
selectively obtained, controlling also the formation of the ketal.
     The fourth chapter collects the main results concerning the transformation of alkynes into 
cyclic acetals and thioacetals catalyzed by the system  AuPPh3Cl/AgBF4. Besides this, a 
comparative study on the catalytic activity of the system AuPPh3Cl/AgBF4 and a Brønsted acid 
such as p-TsOH has been carried out. This reaction allows us to synthesize a fragrance with 
blossom orange scent.
     The fifth chapter, introduces the need for processes to recover glycerol. In this regard, the 
valorization (Law 10/1998 on waste) of pure glycerol and glycerol in water has been achieved 
by reaction with aldehydes to form valuable acetals. While soluble p-TsOH is more active than 
solid Brønsted acids (zeolites and resins) when reacting with pure glycerol, the synthesis of a 
hydrophobic zeolite with the adequate ratio of polarity/acidity leads to a better catalyst when 
reacting with glycerol–water mixtures. Nonetheless, the best results were obtained with gold as 
Lewis acid catalysts under very mild reaction conditions. The preparation of a recoverable and 
reusable gold catalyst allows achieving high turnover numbers.
     The sixth chapter, explores different “one-pot” routes for the synthesis of benzimidazole 
derivatives in the presence of a bifunctional solid catalyst. The process is illustrated by the 
synthesis of 1,2-disubstituted benzimidazole with antiviral activity (anti-HIV-1). This 
benzimidazole derivative have been prepared by a one-pot four step process with a solid catalyst 
containing basic and oxidation sites. The four steps refer to: (a) oxidation of an alcohol; (b) 
cyclocondensation of the aldehyde formed with ortho-phenylenediamines, (c) oxidation of the 
carbon–nitrogen bond, (d) N-alkylation reaction. 
Besides this, the synthesis of the bencimidazole derivative with antitumoral activity Ho33342 
has been carried out by means of a synthetic route based on the use of the same previous metal 
catalysts.