New insoluble surfactant systems as aids in catalysis. A convenient method for nonbonded immobilization of catalytically active transition metal complexes

New insoluble surface-active substances are described here for the first time. They were synthesized by esterification of the surfactants sodium 11-hydroxy-undecane-1-sulfonate or dodecaethylene glycol monododecyl ether with an aliphatic amino acyl chloride, reaction of the amino group containing ester with the bifunctional reagent 3-(triethoxysilyl) propyl isocyanate, and anchoring the products obtained on silica 100 under mild conditions. The surfactants thus immobilized showed a micellar effect, as proved by their influence on reaction rate and selectivity in the enantioselective hydrogenation of methyl (Z)-alpha-acetamido-cinnamate to methyl N-acetyl-phenylalaninate (R) by means of an optically active rhodium complex in water. The systems were compared with an inorganic ion exchanger with dodecyl sulfate counterions and with sodium dodecyl sulfate adsorbed to alumina. The influence of the immobilized surfactants on reaction rate and selectivity appeared to be dependent on the mobility of the hydrophobic chains.