phase was dried over mgso 4 filtered and evaporated at a temperature below 35 u00b0 c an oily residue 5 75 g was obtained which was dissolved in 35 ml of dichloromethane to this solution p toluenesulfonic acid 0 07 g was added and it was stirred at room temperature for 1 hour then the mixture was evaporated at a temperature below 30 u00b0 c and an oily residue 5 62 g was obtained this residue was dissolved in 15 ml of ethyl acetate at 40 60 u00b0 c and 60 ml of hexane were added thereto then the mixture was stirred for one hour at room temperature and two hours at 0 u00b0 c the precipitate was filtered off and dried 2 18 g 52 of the precipitate were obtained the precipitate was dissolved in 50 ml of methanol active charcoal was added and it was stirred for 30 minutes after filtration of active charcoal additional 50 ml of water were added and it was left to cool at 0 u00b0 c for two hours the product was filtered off and dried in a vacuum dryer for two hours 1 61 g 38 5 of the product were obtained the disadvantage of the process is a considerable opening of the lactone ring up to 10 which requires an additional lactonization step wherein additional impurities such as dimer impurity may appear the quality and the yield of the product are inadequate silylated simvastatin 5 5 mmole was dissolved in tetrahydrofurane 10 ml and tea 3hf.