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Helvetica Chimica Acta – Vol. 93 (2010)
extracted with AcOEt (3 ꢁ 50 ml), the combined org. layer washed with H2O (2 ꢁ 30 ml) and brine (2 ꢁ
20 ml), dried (Na2SO4), and concentrated, and the residue purified by CC (SiO2): 15 (3.75 g, 89%). Clear
liquid. Rf 0.72 (AcOEt/hexane 3 :7). [a]2D5 ¼ ꢀ41.3 (c ¼ 0.25, CHCl3). IR (neat): 3028, 2936, 2859, 1600,
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1495, 1448, 1364, 1279, 1163, 1101, 1067, 969, 931, 745, 695. H-NMR (200 MHz): 1.35 – 1.60 (m, 10 H);
1.85 (t, J ¼ 7.0, 2 H); 3.50 (t, J ¼ 7.8, 1 H); 4.03 (dd, J ¼ 6.2, 7.8, 1 H), 4.08 – 4.20 (m, 1 H); 4.23 – 4.33 (m,
1 H); 4.39 (d, J ¼ 11.7, 1 H); 4.62 (d, J ¼ 11.3, 1 H); 6.09 (dd, J ¼ 7.8, 16.4, 1 H); 6.55 (d, J ¼ 16.4, 1 H);
7.18 – 7.42 (m, 10 arom.). ESI-MS: 401 ([M þ Na]þ). HR-ESI-MS: 401.2110 ([M þ Na]þ, C25H30NaOþ3 ;
calc. 401.2092).
(2S)-2-[(2S,3E)-2-(Benzyloxy)-4-phenylbut-3-en-1-yl]oxirane (5). To a stirred a soln. of 15 (3.6 g,
9.52 mmol) in MeOH (20 ml) was added a cat. amount of PPTS, and the mixture was stirred at r.t. for ca.
2 h. After evaporation, the crude residue was purified by CC (SiO2): (2S,4S,5E)-4-(benzyloxy)-6-
phenylhex-5-ene-1,2-diol (2.56 g, 90%). Viscous liquid. Rf 0.20 (AcOEt/hexanes 5 :5). [a]2D5 ¼ ꢀ42.84
(c ¼ 0.5, CHCl3). IR (neat): 3302 (br. s, 2 OH), 3027, 2935, 1650, 1599, 1494, 1452, 1385, 1065, 1005, 912,
877, 745, 695. 1H-NMR (200 MHz): 1.64 – 1.97 (m, 2 H); 2.36 (br. s, OH); 3.03 (br. s, OH); 3.40 (dd, J ¼
11.0, 6.6, 1 H); 3.48 – 3.62 (m, 1 H); 3.84 – 4.06 (m, 1 H); 4.17 – 4.30 (m, 1 H); 4.39 (d, J ¼ 11.7, 1 H); 4.64
(d, J ¼ 11.7, 1 H); 6.15 (dd, J ¼ 16.1, 8.0, 1 H); 6.56 (d, J ¼ 16.1, 1 H); 7.06 – 7.41 (m, 10 arom. H).
13C-NMR (75 MHz): 38.7; 66.7; 69.0; 70.4; 77.2; 125.8; 126.5; 127.6; 127.8; 128.4; 128.5; 129.2; 132.5;
132.4; 136.2; 138.1.
To a stirred mixture of the above diol (2.2 g, 7.38 mmol), Et3N (0.74 g, 7.38 mmol) and DMAP
(0.01 g, 10 mol-%) in dry CH2Cl2 (30 ml) at 08, TsCl (1.40 g, 7.38 mmol) in dry CH2Cl2 (8 ml) was added
over 15 min. The mixture was allowed to warm to r.t. and stirred for 4 h. After completion of the reaction
(TLC monitoring), the mixture was quenched with sat. aq. NaHCO3 soln., the org. layer extracted with
CH2Cl2 (3 ꢁ 40 ml), and the combined org. layer washed with H2O (2 ꢁ 30 ml) and brine (2 ꢁ 30 ml),
dried (anh. Na2SO4), and concentrated. The crude residue was directly used in the next reaction without
purification. The residue was dissolved in MeOH (20 ml), K2CO3 (2.04 g, 14.76 mmol) added, and the
mixture stirred for 1 h. The MeOH was evaporated, the residue diluted with AcOEt, the AcOEt phase
washed with H2O (2 ꢁ 30 ml) and brine (2 ꢁ 30 ml), dried (anh. Na2SO4), and concentrated, and the
yellow oily product purified by CC (SiO2): 5 (1.66 g, 81%). Colorless liquid. Rf 0.85 (AcOEt/hexane
2 :8). [a]2D5 ¼ ꢀ72.03 (c ¼ 0.25, CHCl3). IR (neat): 3028, 2923, 2854, 1631, 1494, 1453, 1382, 1067, 1027,
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968, 919, 842, 745, 695. H-NMR (300 MHz): 1.55 – 1.66 (m, 1 H); 1.93 – 2.05 (m, 1 H); 2.39 – 2.50 (m,
1 H); 2.72 – 2.79 (m, 1 H); 3.07 – 3.16 (m, 1 H); 4.17 (td, J ¼ 8.3, 3.8, 1 H); 4.43 (d, J ¼ 11.3, 1 H); 4.65 (d,
J ¼ 11.3, 1 H); 6.11 (dd, J ¼ 7.5, 15.8, 1 H); 6.57 (d, J ¼ 15.8, 1 H); 7.09 – 7.38 (m, 10 arom. H). 13C-NMR
(75 MHz): 39.5; 47.5; 49.5; 70.4; 77.5; 127.5; 127.7; 125.8; 126.5; 128.4; 128.6; 129.6; 132.6; 136.3; 138.4.
ESI-MS: 307.7 ([M þ Na]þ). HR-ESI-MS: 303.1349 ([M þ Na]þ, C19H20NaOþ2 ; calc. 303.1360).
(4R,6S,7E)-6-(Benzyloxy)-8-phenylocta-1,7-dien-4-ol (16). To a stirred soln. of 5 (0.75 g, 2.67 mmol)
and CuI (cat.) in THF (30 ml) was added freshly prepared CH2¼CHMgBr (0.72 ml, 5.35 mmol) at ꢀ 108,
and the mixture was stirred at ꢀ 108 for ca. 1 h, quenched with sat. NH4Cl soln. (5 ml), and extracted
with AcOEt (3 ꢁ 30 ml). The combined org. layer was washed with brine (2 ꢁ 20 ml), dried (Na2SO4),
and concentrated, and the residue purified by CC: 16 (1.66 g, 80%). Thick syrup. Rf 0.65 (AcOEt/hexane
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2 :8). [a]2D5 ¼ ꢀ34.81 (c ¼ 1.5, CHCl3). H-NMR (300 MHz): 1.62 – 1.89 (m, 2 H); 2.10 – 2.25 (m, 2 H);
3.86 – 4.02 (m, 1 H); 4.20 – 4.29 (m, 1 H); 4.40 (d, J ¼ 12.0, 1 H); 4.65 (d, J ¼ 12.0, 1 H); 5.07 (dd, J ¼ 1.5,
12.0, 2 H); 5.71 – 5.88 (m, 1 H); 6.16 (dd, J ¼ 7.5, 15.8, 1 H); 6.57 (dd, J ¼ 8.3, 15.8, 1 H); 7.07 – 7.42 (m,
10 H). 13C-NMR (75 MHz): 39.2; 42.0; 67.6; 70.5; 77.5; 117.5; 126.4; 127.6; 127.7; 128.2; 128.3; 128.5;
129.4; 132.3; 134.7; 136.2; 138.0. HR-ESI-MS: 331.1660 ([M þ Na]þ, C21H24NaO2þ ; calc. 331.1673;
ꢀ 4.2273 ppm error).
(1R,3S,4E)-3-(Benzyloxy)-5-phenyl-1-(prop-2-en-1-yl)pent-4-en-1-yl Prop-2-enoate (4). Acryloyl
chloride (¼ prop-2-enoyl chloride; 0.25 g, 2.8 mmol) was added dropwise under N2 to a a soln. of 16
(0.6 g, 1.94 mmol), Et3N (0.55 ml, 3.9 mmol), and DMAP (10 mol-%) in dry CH2Cl2 (20 ml). The
mixture was stirred at r.t. for 1 h. After completion, the mixture was poured into brine (10 ml) and
extracted with CH2Cl2 (2 ꢁ 20 ml). The org. phase was washed with 1m aq. HCl and brine (1 ꢁ 20 ml),
dried (Na2SO4), and concentrated, and the crude product purified by CC (SiO2): 4 (0.63 g, 89%).
Colorless oil. Rf 0.55 (AcOEt/hexane 2 :8). [a]D25 ¼ ꢀ26.99 (c ¼ 1.25, CHCl3). IR (neat): 3027, 2924, 2856,
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1722, 1638, 1494, 1452, 1404, 1269, 1192, 1050, 982, 917, 749, 696. H-NMR (300 MHz): 1.74 – 1.99 (m,