Reactions of phosphine with ketones: A route to primary phosphine oxides

Earlier work on the reaction of phosphine with carbonyl compounds is reviewed and new information is provided on the reaction of phosphines with ketones. Primary phosphine oxides (X) and 1-hydroxy secondary phosphine oxides (XI) are formed in strongly acidic media and the ratio of the two products is determined by steric factors; the former predominate with more hindered ketones. The primary phosphine oxides are a novel class of compounds. They have limited thermal stability in a concentrated state but are sufficiently stable in solution to be useful as intermediates. The mechanism of the oxygen transfer step in this and other phosphine-carbonyl reactions is discussed.