THE EFFECT OF TRIFLATE ADDITIVES IN PLATINUM-CATALYZED ENANTIOSELECTIVE HYDROFORMYLATION

Styrene was hydroformylated in the presence of platinum containing in situ catalysts formed in the reaction of PtCl2(diphosphine), tin(II)ch loride, and tin(II)triflate (or silver triflate). The reaction resulte d in both linear and branched formyl regioisomers, achiral 5-phenyl-pr opanal and chiral 2-phenyl-propanal, respectively. Using the optically active Pt-bdpp (bdpp = (2S,4S)-2,4-bis(diphenylphosphino)pentane) sys tems high ee-s were achieved, which were decreased substantially in th e presence of triflate anion. The activity of the catalyst was reduced by the addition of silver triflate and its application in excess resu lted in the formation of inactive systems. However, regioselectivity t owards chiral branched aldehyde (2-phenylpropanal) was increased both with achiral and chiral bidentate phosphine-containing catalysts upon addition of silver triflate. In the presence of platinum-phosphine-tin (II)chloride in situ systems containing tin(II)triflate consecutive hy drogenation of the aldehyde regioisomers formed in hydroformylation of styrene took also place.