of the grignard reagent with paraformaldehyde or trioxane preferably with paraformaldehyde is carried out at a temperature below room temperature preferably below 10 u00b0 c under agitated conditions one option is to add the grignard reagent slowly to paraformaldehyde or trioxane optionally under stirring to allow for a rapid and homogenous mixture of the reaction solution another option is to add the paraformaldehyde or trioxane to the grignard reagent optionally under stirring at ambient temperature until the reaction complete step c is completed by quenching the reaction mixture with a suitable quenching agent a preferred quenching agent is aqueous ammonium chloride although other quenching agents known to those skilled in the art may be used including aqueous ethyl acetate aqueous sodium chloride or aqueous hydrochloric acid solution subsequently a solvent exchange from the grignard solvent e g toluene and or thf to a suitable solvent for the hydrogenation e g methanol can be performed suitable workup steps after the addition of the quenching reagent are e g washing with water removal of water from organic phase e g by azeotropic drying solvent exchange to a solvent suitable for hydrogenation the process described above is disclosed in more detail in example 1 of the experimental part of this application another preferred embodiment of the present invention is a method for the preparation of a compound of.