6.60 g of butyl-2,3-epoxypropyl ether and 0.78 g of ethyl-triphenyl-phosphonium bromide are added to a solution of 20.0 g of the product from Example A6 in 200 ml of xylene. That reaction mixture is heated to boiling for 18 h. 0.5 g of activated carbon is then added to the reaction mixture and the resulting mixture is stirred at 25° C. for 1 h. After filtration of the reaction mixture on Hyflo® (kieselguhr; Fluka 56678), the solvent is removed in vac. Chromatography of the residue on silica gel yields the product of melting point: 118–119° C.
