2-Methoxyethoxymethyl (MEM) and 2-(trimethylsilyl) ethoxymethyl (SEM) groups were used to protect the sn-3-OH of optically active glycerols in the synthesis of 1, 2-di-O-octadecyl-sn- glycero-3-phosphatidylcholine. Both MEM and SEM protective groups had advantages of a classical benzyl group by virtue of (i) the facile preparation of 1, 2-O-isopropylidene-3-O-(2- methoxyethoxymethyl)-sn-glycerol and its sn-3-O-SEM analog as starting materials and (ii ...