Congratulations Dr. Bugga!

Balakrishna Bugga, PhD student under the supervision of Prof. Anton Vidal, has defended his PhD Thesis entitled ‘Development of P-OP Ligands with New Structural Motifs for Rhodium- and Iridium- Mediated Asymmetric Hydrogenations’ (assigned to the Organic and Analytical Chemistry Department of the Universitat Rovira i Virgili) publicly on September 9th at the ICIQ Library.

The members of the evaluation committee were: Prof. Asunción Barbero (Universidad de Valladolid), Prof. Antonio Frontera (Universitat de les Illes Balears) and Prof. Patrick Gámez (Universitat de Barcelona).

Dr. Bugga with his supervisor, Prof. Anton Vidal, and the evaluation committee

Abstract:

The thesis deals with design and synthesis of enantiopure phosphine-phosphite (P-OP) ligands with new phosphite fragments and coordination studies with rhodium and iridium precursors for asymmetric hydrogenations. The resulting P-OP-rhodium and iridium complexes were efficiently employed in asymmetric hydrogenations of an array of structurally diverse substrates. The synthetic rout of highest performing Rh(P-OP) precatalysts has been optimized by developing a chromatography-free synthesis involving the crystallization of the target [Rh(P-OP)] precatalysts as the purification method. Studies on [Ir(P-OP)]-mediated asymmetric hydrogenations of a variety of seven-membered heterocycles those contain C=N bonds have revealed that these iridium complexes are excellent catalysts (up to full conversion; up to 97% ee). The unexpected inversion in enantioselectivity has been rationalized by means of DFT calculations, which have identified the position of the Cl-ligand in catalytically relevant iridium structures and a number of non-covalent interactions (i.e. N-H···Cl, C-H···π and C-H···H-Ir interactions) as key features in the rationalization of the stereochemical outcome of the reactions. As regards to the hydrogenation of functionalized alkenes, [Rh(P-OP)] precatalysts incorporating new phosphite fragments have been prepared. High catalytic activity (>99% conversion) and excellent enantioselectivity (up to >99%) were achieved.