[252554-72-6] · C20H25OP · (MW 312.39)
(monophosphine ligand for asymmetric catalysis;1 nickel(II) complexes are effective catalyst precursors for enantioselective hydrovinylation with non-coordinating counterions)
Solubility: soluble in THF, diethyl ether, hydrocarbons, and chlorinated solvents.
Analysis of Reagent Purity: 1H NMR, 13C NMR, 31P NMR, and GLC analysis.
Preparative Methods: prepared by the reaction of potassium dianion of 2´-(benzyloxymethyl)phenylphosphane1 and (2S,5S)-hexane-2,5-diol cyclic sulfate. The preparation of the latter reagent is described in the literature.2
Purification: by column chromatography under an inert atmosphere.
Handling, Storage, and Precautions: readily oxidizes to the phospholane oxide upon exposure to atmospheric oxygen. The corresponding (allyl)Ni(BARF) complex is stable upon storage at room temperature for several days under a nitrogen atmosphere.
Heterodimerization of olefins is a reaction of enormous synthetic potential, since it has been demonstrated that excellent yields and selectivities can be achieved under exceptionally mild conditions in many cases (
In the hydrovinylation of styrene using a ligand with a hemilabile atom (e.g. OBn in 1a, 1b), the choice of appropriate counter anion is very important. For example, when 2 and a weakly coordinating anion such as AgOTf is used in the reaction of styrene, the yield of hydrovinylation product is 94%. However, with phospholane ligands having a hemilabile coordinating group (-OR), the externally added coordinating anion (AgOTf) suppresses the reaction, while a non-coordinating anion (NaBAr4, Ar = 3,5-(CF3)2C6H3) completely restores the activity and selectivity (
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