Identificador: TDX:2884
Autors: Cañellas Román, Santiago
Resum:
The main goal of this thesis is the development of new catalytic processes for the efficient synthesis of relevant chiral organic compounds via organocatalysis and nickel catalysis, either in batch and continuous flow manner. After a general introduction, three research projects are collected in this thesis.
The first one shows the development of a new polystyrene-supported chiral organocatalyst for the enantioselective Robinson annulation reaction. Importantly, this reaction gives rise to several important intermediates for the synthesis of many bioactive compounds. With this new protocol, the representative Wieland-Miescher ketone was prepared in reaction times as short as one hour achieving excellent results. Furthermore, a continuous flow synthesis of these bicyclic enones was performed for the first time using this supported catalyst.
The second project illustrates the synthesis of a new class of C2-symmetric chiral triamines. These compounds were prepared in multigram scale avoiding the need of chromatographic purifications. Then, their catalytic activity was tested on the model aldol reaction of ketones with isatins. Notably, they were able to shorten the reaction times usually needed for this reaction, displaying an improved diastereo- and enantioselectivities in comparison with its non-symmetric counterpart. Additionally, the catalyst was demonstrated to be recoverable by using simple extraction techniques.
Finally, the third project shows the discovery of a new nickel-catalyzed transformation. This reaction, a reductive [2+2] cycloaddition reaction of alkynes to cyclobutenes, was found out due to the use of an unusual aminophosphine ligand. The versatility of the cyclobutene products was showcased by the synthesis of the natural product epi-truxillic acid, as well as some cyclic and acyclic stereodefined products. Furthermore, the mechanistic features of this transformation were also investigated.
Repositori URV