[CH2:1]([O:3][CH:4]([O:11][CH2:12][CH3:13])[CH2:5][C:6]([O:8][CH2:9][CH3:10])=[O:7])[CH3:2].C(O)[C:15]1[CH:20]=[CH:19][CH:18]=[CH:17]C=1>O.C1(C)C=CC(S(O)(=O)=O)=CC=1.C1C=CC=CC=1>[CH2:12]([O:11][CH:4]([O:3][CH2:1][C:2]1[CH:17]=[CH:18][CH:19]=[CH:20][CH:15]=1)[CH2:5][C:6]([O:8][CH2:9][CH3:10])=[O:7])[C:13]1[CH:15]=[CH:20][CH:19]=[CH:18][CH:17]=1To a 1000 mL round-bottomed flask was added ethyl 3,3-diethoxypropionate (20.0 g, 0.1051 mole), benzyl alcohol (22.7 g, 0.2102 mole), p-toluenesulfonic acid monohydrate (0.5 g, 0.0026 mole) and benzene (350 mL). Heating the mixture at 80° C., the solvent was distilled from the reaction mixture in 1.5 h period. The resulting residue was dissolved in ether (@ 300 mL) and washed with saturated sodium bicarbonate solution (100 mL) and brine (100 mL). The organic layer was dried over anhydrous magnesium sulfate and the solvent removed in vacuo to give ethyl 3,3-dibenzyloxypropionate (9) as a colorless oil (32.9 g, 99.5% yield): 1H NMR (CDCl3) d 1.22 (t, 3H, J=7.2 Hz), 2.79 (d, 2H, J=5.9 Hz), 4.12 (q, 2H, J=7.2 Hz), 4.60 (d, 2H, J=11.6 Hz), 4.70 (d, 2H, J=11.6 Hz), 5.22 (t, 1H, J=6 Hz), 7.27-7.36 (m, 10H); IR (Neat) 3100, 3080, 3040, 2990, 2940, 2920, 2885, 1740, 1630, 1458, 1375, 1315, 1190, 1120, 1050, 1030, 740, 700. ##STR8##
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