Shoulei Wang, PhD student under the supervision of Prof. Miquel À. Pericàs (ICIQ), has defended his PhD Thesis entitled “Approaches to Asymmetric Catalysis Mediated by Polymer-Supported and Homogeneous Organocatalysts” (assigned to the Analytical & Organic Chemistry Department of the Universitat Rovira i Virgili) publicly in March the 15th at the ICIQ Auditorium.
The members of the evaluation committee were: Prof. José Luis Vicario – Universidad del País Vasco, UPV/EHU; Prof. Ruben Martin – ICIQ; and Prof. Andrew D. Smith – University of St Andrews.
Dr. Wang at the centre with Prof. Pericàs and Prof. Smith on the left, and Prof. Vicario and Prof. Martín on the right.
Abstract
The discovery and design of organocatalysts with better efficiency, able to promote new transformations and reaching higher turnover numbers has attracted a lot of attention in organocatalysis. This thesis focuses on the synthesis of organocatalysts, especially polymer-supported ones and their application in various asymmetric transformations. Firstly, a H-bond-directing aminocatalyst for the asymmetric [4+2] cycloaddition reactions of alkylidene pyrazolones with enals is described. The more hindered 4-hydroxy dinaphthylprolinol catalyst has been prepared and displayed higher reactivities and enantioselectivities in this [4+2] cycloadditions, affording the tetrahydropyranopyrazole derivatives containing three contiguous stereocenters with good results. Secondly, the present work also encompasses the development of a robust, immobilized isothiourea for a formal [4+2] and [8+2] cycloaddition reactions. The recyclability of this immobilized isothiourea catalyst and its application in continuous flow process are also demonstrated.
Finally, we focus on the cascade deoligomerization/cross-aldol reactions of electron-poor benzaldehydes and η6-benzaldehyde Cr(CO)3 with paraldehyde promoted by a dual catalytic system. This dual catalytic system can be recycled several times by simple filtration of the polymer mixture and mild acidic washing to recover full performance. The application of the resulting diol product was proven by reductive amination reaction, affording the well-known drug (R)-phenoperidine or intermediates of (R)-fluoxetine and (R)-atomoxetine.