i e it will not undergo unintentional cleavage in both acidic and alkaline conditions such as allyl benzyl or substituted benzyl preferable benzyl the reaction in step a is preferably carried out as a phase transfer catalysis in the presence of a quaternary ammonium salt alternatively the sodium salt of 4 hydroxybenzophenone can be reacted with the compound of formula ii in dmf the solvent used in step b is preferably tetrahydrofuran as examples of other useful alternatives can be mentioned ethers e g diethyl ether and dimethoxyethane the solvent to be used in step c shall be able to dissolve the compound iv but not to react with the thionyl chloride as suitable solvents can be mentioned toluene and dichloromethane the removal of the protecting group r in step d is preferably carried out by hydrogenation with metal catalyst in appropriate solvent or by selective cleavage of nonaromatic ethers with zn acyl chloride is prepared from benzyl bromide and 2 2 chloroethoxy ethanol by the method described in literature bessodes 1996 the mixture of 4 hydroxybenzophenone 16 7 g 84 7 mmol and 48 aqueous sodium hydroxide solution 170 ml is heated to 80 u00b0 c tetrabutylammonium bromide tbabr 1 6 g 5 1 mmol is added and the mixture is heated to 90 u00b0 c 2 2 chloroethoxy ethoxymethyl benzene 18 g.