Reaktionen mit phosphororganischen verbindungen—XV

Osmium tetraoxide cis hydroxylation of unsaturated substrates

“…188 The oxidation of (ßoxoalkylene)phosphoranes ( 40 More recently Grieco and co-workers187 in their total synthesis of the Prelog-Djerassi lactone used osmium tetraoxide in con-barium chlorate yields the corresponding -diketones.189 This reaction is thought to proceed via formation of an osmium(VI) ester complex (41) which on hydrolysis yields the corresponding dione together with triphenylphosphine which is oxidized to the oxide by osmium tetraoxide. 189 The use of Hofmann's reagent in the synthesis of polyalcohols, particularly in carbohydrate chemistry, has been of great success. [190][191][192][193][194] Sodium perchlorate has also been used as a secondary oxidant with osmium tetraoxide.…”