Preparation oxo -vinylionol and o- protected derivative thereof

The present invention relates to a OH wherein R represents hydrogen or a protecting group, e.g. oxo -vinylionol and O- protected derivative group Si (Ra) of formula (I) 3, by the presence of at least one transition metal in which R has the formula previously for formula (I) the meaning (II) compound, i.e. β- -vinylionol (formula (II), R = H) or O- protected derivative thereof (formula (II) , R = OH protecting group) with an oxidizing agent, wherein the oxidizing agent comprises at least one oxygen compound, said compound selected from hydrogen peroxide and organic hydroperoxides.