Polymerized ionic amphiphiles: Synthesis and effects in the enantioselective hydrogenation of an amino acid precursor

Full Paper: A number of polymerizable ionic amphiphiles has been polymerize d in water at various concentrations above their critical micelle concentra tion (cmc). Oligomeric and polymeric species are formed upon photochemical initiation. Depending on the position of the double bond within the monomer and polymerization conditions (temperature, concentration, use of radical starters) polymeric assemblies were obtained of different size and hence wa ter-solubility. After separation of low-molecular components by dialysis wa ter-soluble polymers have been characterized by their molecular weights (me mbrane and vapor pressure osmometry) and transmission electron microscopy ( TEM). They showed different efficiency as promotors in the rhodium complex- catalyzed asymmetric hydrogenation of (Z)-methyl alpha -acetamidocinnamate in water and have been compared with their monomeric counterparts. As was d emonstrated in one case, associates formed by intramicellar polymerization display an enhanced catalytic efficiency whereas clustered assemblies are i nactive.