Reaction Steps
Retinyl 4-Methoxybenzyl Ether (3e) was prepared from retinol and 4-methoxybenzyl chloride by the method described for 3c. The ether extract was washed successively with saturated sodium bicarbonate solution and with brine. The crude product was purified by successive chromatographic operations with the column absorbent and eluting solvent as follows: deactivated alumina, pentane and then 95:5 pentane-ethyl acetate; silica gel 60, chloroform; silica gel 60, 4:1 chloroform-pentane; repetition of the last method. The purified product was a yellow syrup: HPLC, 99.3% (340 nm), 100% (254 nm); MS m/z 406 (M), 285 (C20H29O), 269 (C20H29), 255 (C19H27), 121 (4-methoxybenzyl); UV λmax326 nm (ε 51 300), 226 nm (ε 14 000); 1H NMR (CDCl3) δ 7.27 (m, 2H, H2′), 6.88 (m, 2H, H3′), 6.59(dd, 1H, H11, J10,11=11.3 Hz, J11,12=15.0Hz), 6.29 (d, 1H, H12), 6.15 (bd, 1H, H8,J7,8=16.0Hz), 6.11 (d, 1H, H7), 6.09 (d, 11H, H10), 5.68 (t, 1H, H14), 4.45 (s, 2H, H21), 4.15 (d, 2H, H15, J14,15=6.8 Hz), 3.80 (s, 3H, OCH3), 2.01 (t, 2H, H4), 1.95 (s, 3H, H17), 1.82 (s, 3H, H20), 1.71 (s, 3H, H18), 1.65-1.57 (m, 2H, H3), 1.48-1.44 (m, 3H, H2), 1.02 (s, 6H, H16, H17). Anal. Calcd. for C28H38O2.½H2O:C, 80.92; H, 9.46. Found: C, 80.93; H, 9.38.
