Dibutylphosphine oxide

A mixture of methyl xanthate (0.4 mmol) and Bu2POH (dibutylphosphine oxide, 2.0 mmol) in dry dioxane (3 ml) was refluxed under an argon atmosphere, and then a solution of benzoyl peroxide (0.4 mmol) in dioxane (3 ml) was added dropwise to the mixture. After 90 min, the solvent was removed and the residue was chromatographed on silica gel to give the reduction product [22]. 

The favorable effect of a Brpnsted acid on the addition reaction of HP(0) compounds is also seen in the nickel-diphosphine complex-catalyzed addition of dibutylphosphine oxide to give the branched product as near the sole product (Scheme 40) [43]. 

Scheme 39 Hydrophosphinylative carbocyclization with dibutylphosphine oxide...

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