Synthesis and characterization of fluorescent atropoisomeric bis-arylboryl-carbazoles

This thesis project presents a work based on the study of bis-arylboryl-carbazoles a particular class of aminoboranes. The peculiarity of these compounds is the -B=N+ chemical moiety and their conformational behaviour coming from the combination of steric constrain and conjugation of the B-N bond. Our work is focused on three products: 9-(mesityl(naphthalen-1-yl)boraneyl)-9H-carbazole 1a, 9-(mesityl(2-methylnaphthalen-1-yl)boraneyl)-9H-carbazole 1b and 9-(anthracen-9-yl(mesityl)boraneyl)-9H-carbazole 1c. We firstly focused our attention on the synthesis optimizing conditions. Then the products were synthetized and characterized with NMR. The products were eventually analysed through conformational studies, by a theoretical approach with DFT calculations and by experimental techniques, such as standard kinetic and EXSY. In the end of this work the products were characterized through fluorescence studies both by DFT, TD-DFT calculations and experimentally by emission spectroscopy.

Organocatalytic tandem reactions of polyfunctional compounds for the synthesis of enantioenriched heterocycles. Reazioni tandem organocatalitiche di composti polifunzionali per la sintesi di eterocicli enantioarricchiti.

In questo lavoro di tesi sono state sviluppate reazioni domino, tandem e procedure one-pot per ottenere eterocicli enatioarricchiti. Lo sviluppo di queste metodologie sintetiche è molto importante perché permettono di ottenere molecole complesse partendo da prodotti semplici, senza effettuare ripetuti passaggi di purificazione (stop-and-go or step-by-step synthesis). Lo scopo di questo lavoro è di ottenere derivati tetraidrofuranici modificati e derivati ossoazzolinici enantioarrichiti tramite reazioni SN2-Michael o tramite reazioni aldolica-ciclizzazione-Michael usando la catalisi asimmetrica a trasferimento di fase (PTC). Come catalizzatori PTC per imprimere enantioselezione sono stati utilizzati sali di ammonio quaternario derivati dagli alcaloidi della Cinchona. Sono state ottimizzate le condizioni di reazione (base inorganica, temperatura, solvente, tempo di reazione) per i diversi substrati presi in considerazione. I prodotti target sono stati ottenuti con buone rese, ottime diastereoselezioni ma con bassa enantioselezione. I risultati ottenuti richiedono un’ulteriore ottimizzazione e dovranno essere valutate variazioni strutturali dei nucleofili utilizzati. In this thesis were developed domino, tandem reactions and one-pot procedures to obtained enantioenriched heterocycles. The development of these methodologies is very fundamental because they allow to obtain complex molecules starting from raw materials, without carrying out repeated purification steps (stop-and-go or step-by-step synthesis). The purpose of this work is to obtain enantioenriched tetrahydrofuran and oxazoline derivatives through a SN2-Michael reaction or a aldol- cyclization-Michael reaction using the phase-transfer asymmetric catalysis (PTC). For imprint enantioselection we used Cinchona alkaloids quaternary ammonium salts derivatives. The reaction conditions (inorganic base, temperature, solvent, reaction time) were optimised for the different substrates taken into account. The target products were obtained with good yields, excellent diastereoselections but with low enantioselections. The obtained results require further optimization and structural changes in the nucleophiles used must be evaluated.