EXPLORING NOVEL SUSTAINABLE SYNTHETIC METHODOLOGIES WITH NITRO COMPOUNDS

The present thesis work is devoted to the study of four different topics, the reduction of nitroolefins employing ammonia borane as reductant, the enantioselective reduction of β,β-disubstituted nitroalkenes in deep eutectic solvents, the preliminary investigation of other enantioselective nitroalkenes reductions catalyzed by chiral organocatalysts and the study of mechanically interlocked molecules as organocatalysts in acylation reactions. In particular, Chapter 1 introduces the concepts of green chemistry and of sustainable chemistry as they are the guiding threads of the whole manuscript. Moreover, the first chapter includes a brief overview about green metrics. The use of ammonia borane as reducing agent for the reduction of nitroolefins to nitroalkanes is described in Chapter 2, exploring the possibility to run the reaction both in traditional solvents and in deep eutectic solvents. The tests about the reuse of the DES in four subsequent reactions are also presented. Chapter 3 reports our findings in the use of deep eutectic solvents as reaction media for the enantioselective reduction of β,β-disubstituted nitroalkenes catalyzed by Jacobsen-like catalysts. This is one of the first examples of a challenging transformation: a reaction in which the substrate, the catalyst and the reagents interact through hydrogen bonding in a reaction medium that is held together thanks to a hydrogen bonding network. The preliminary studies about other enantioselective reduction catalyzed by chiral organocatalysts are the topic of Chapter 4, that reports the investigation of a novel activation mode of ammonia borane, trying to achieve its coordination by an enantiopure organocatalyst via hydrogen bonding to explore the enantioselective reduction of β,β-disubstituted nitroalkenes. Besides, the first findings about the regioselective and enantioselective reduction of nitro ester diene are reported. Chapter 5 describes the work done during the six months period at the University of Southampton, in the group of Professor Stephen M. Goldup. In particular, the optimization of the synthesis of a novel catenane is discussed and the preliminary data about its use as an organocatalyst in acylation reactions are summarized.