Catalysis Today, Vol.48, No.1-4, 279-290, 1999
Carbohydrate-substituted phosphines as new ligands for two-phase catalysis - synthesis and application
The synthesis and catalytic application of a new class of polar hydrophilic phosphines for two-phase catalysis is described in full detail. Contrary to the well-known sulfonated phosphines the hydrophilic character of the ligands is attributed to a neutral carbohydrate moiety. Two general routes for the synthesis of monosaccharide substituted triarylphosphines are presented. In the first procedure protected halopyranoses and OH-substituted triphenylphosphines were combined under phase transfer conditions to generate carbohydrate-substituted phosphines. In a second more efficient protocol, the palladium-catalyzed coupling of suitable haloaryl glycosides with diphenylphosphine constitutes a new access to these ligands. The properties of the ligands in terms of solubility, surfactant activity, and partition between two non-miscible phases are discussed. In addition, superior catalytic performance compared to ionic hydrophilic ligands was demonstrated for important C-C coupling reactions such as the Suzuki, Heck, and hydroformylation reactions.
Keywords:CROSS-COUPLING REACTIONS;HYDROFORMYLATION;PALLADACYCLES;COMPLEXES;DIMERIZATION;EFFICIENT;HALIDES