purification. An analytical sample was purified by flash chromatography on silica gel (15 cm X 2.5 cm i.d.) eluted with hexane/EtO Ac (9:2): IR (film) 3340,1100 cm"1; NMR (CDC13) 0.05 (s, 6 ), 0.90 (s, 9 ), 1.18 (d, 3 H, J = 5.5 Hz), 1.23-1.65 (m, 14 H), 1.95 (br s, 1 ), 2.10-2.20 (m, 4 H), 3.62 (t, 2 H, J = 6.5 Hz), 3.75-3.85 (m, 1 H); mass spectrum, m/e (relative intensity) 283 (17), 189 (10), 95 (78), 75 (100), 45 (52); high-resolution mass spectrum caled for ^ ^ ^ m/e 340.2797, obsd 340.2785; [a]31D + 3.6°(c 1.82, CHCI3).Preparation of (13S)-13-[(2-Methoxyethoxy)methoxy]-(Z)-5-tetradecen-1 -ol ((13S)-17). The hydroxyl function of (13S)-14 was protected as the MEM ether, via standard procedures.18 The crude product was flash chromatographed in three batches on silica gel (20 cm X 5 cm i.d.) eluted with hexane/EtOAc (9:1), giving (13S)-15: 14.8 g (78%); IR (film) 1100, 1039 cm"1;