An improved process for preparing the R- and S-isomers of 2-hydroxymethyl-2-octadecyloxymethyl-tetrahydrofuran, a critical step of which involves the preparation of the R- and S-isomers of 2-[3-(1-methoxy-1-methylethoxy)]propyl-oxiranemethanol employing metal-catalyzed Sharpless epoxidation. In addition, the invention relates to the use of the R- and S-isomers of 2-hydroxymethyl-2-octadecyloxymethyl-tetrahydrofuran in preparing stereoisomers of pharmacologically active compounds, and to the R- and S-isomers of 2-[3-(1-methoxy-1-methylethoxy)]-propyl-oxiranemethanol as novel compounds.