A functionalizedpolymer-lnmndRh6 cluster complex showed high catalytic activity for chemoselectivereductionof aldehydesin the presenceof CO and H20. The reactionsystemconsistsof the triphase,whichmakeswork-upprocedoresimple.O 1997Elsevier ScienceLtd. Immobilization of metal cluster complexes onto organic or inorganic polymers has been extensively developed for preparation of new type catafysts, which has been expeeted to show novel catalysis based on interactions between supports and metals.1 We found that homogeneous catalyst systems consisting of Rh6(CO)16 and amines had high activities for the water-gas shift reaction (WGSR), reduction of aldehydes, and deoxygenation of various N-O bonds under the WGSR conditions.' Recently, it is very interesting for organic syntheses to use water as a hydrogen source in place of molecular hydrogen, since water is a safety and cheap materiaL3 Using aminated polystyrene, the above Rh6(CO)16-aminesystems could be heterogenized to form polymer-bound Rb cluster complexes. ' Selective reduction of one carbonyl group in the presence of other functional groups isafundamental process inorganic syntheses. Here, wewishtoreportthe highly chemoselective reduction of aldehyde function catalyzed by a polymer-bound Rh6 cluster complex (Eq. 1). The above