Epoxidations Using Late Transition Metals

The introduction of chiral bidentate diphosphines allowed for asymmetric epoxidations of terminal alkenes. Screening a number of different chiral diphosphines in the epoxidation of 4-methylpentene using 2 mol% of catalyst and 1 equivalent of aqueous hydrogen peroxide as the terminal oxidant revealed that the catalyst containing S,S-Chiraphos (34) allowed for an efficient chirality transfer from the catalyst to the substrate [141]. With this particular catalyst combination, the U-isomer of 4-methylpentene oxide was obtained in 60% yield and 75% enantiomeric excess. The 

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The coordination properties of phosphine oxides has been explored with late transition-metal (Ru, Co, Rh, Ir, Pd, Pt, Cu, and Au),301 303 305 306 310 316 early transition-metal,317 lanthanide,304,318,319 and actinide307,320 ions. One interesting complex is the palladium(II) complex (148) (Scheme 10) which is an extremely rare example of a ds metal center with a tetrahedral geometry.313 Phosphine oxides have found uses in the extraction of alkali, alkaline earth, and actinide metals in catalysis (hydroformylation of alkenes and epoxides, carbonylation of methanol324) and as a useful crystallization aid (Ph3PO).325... 

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