Synthetic approaches towards dendrimeric catalysts.

Abstract

This thesis describes the different synthetic routes carried out towards a dendritic catalyst. Various dendrimers were investigated as possible starting points for the exterior portion of the catalyst. These dendrimers were synthesised as well as their modified versions. The attachment of a phosphine-containing moiety was thought to be crucial for high activity of these catalysts, in the hydroformylation of olefins. Different methods were investigated to affect the incorporation of a bis-phosphine. The tetra-phosphine, 4,5-bis(bis[{diphenyl-phosphanyl}methyl]aminomethyl)-2,2-dimethyl-[1,3]dioxolane, and the bis-phosphine, N,N'-Bis-(2-benzyloxyethyl)- N,N'-bis[(diphenylphosphanyl)methyl]-ethane-1,2-diamine, were both synthesised and their rhodium(I) complexes were used successfully in the hydroformylation of m different olefins. Suggested pathways to bring together these exterior and interior pieces were then investigated. During the synthesis of one of the core units a phosphine oxide compound, (diphenylphosphinoyl)phenyl-methanol was prepared. This compound is an excellent ligand in rhodium-catalysed hydroformylation reactions. As the phosphine oxide contained a chiral centre, it was resolved and employed in the enantioselecove hyrdoformylation reactions of olefinic substrates.