Helvetica Chimica Acta – Vol. 97 (2014)
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(1R)-1,2-Anhydro-3,5-dideoxy-1-ethenyl-4-O-{(3S)-3-[(4-methoxybenzyl)oxy]pent-4-enoyl}-d-
threo-pentitol (2) [5][16a]. To a stirred soln. of 3 (100 mg, 0.78 mmol) in CH2Cl2 (10 ml) were added
DCC (402 mg, 1.95 mmol) and DMAP (190 mg, 1.56 mmol) at 08. The mixture was stirred for 30 min, and
then 4 (221 mg, 0.93 mmol) was added. The mixture was stirred for 10 h, and then the volatiles were
evaporated under reduced pressure.The resulting crude product was adsorbed on silica gel and purified
by flash CC (SiO2, 6% AcOEt in hexane) to give 2 (216 mg, 80%). Colorless oil. [a]2D5 ¼ ꢀ15.0 (c ¼ 0.5,
CHCl3). IR (neat): 2923, 2853, 1733, 1462, 1219, 772. 1H-NMR (300 MHz, CDCl3): 7.22 (d, J ¼ 8.6, 2 H);
6.85 (d, J ¼ 8.6, 2 H); 5.84 – 5.61 (m, 2 H); 5.52 – 5.21 (m, 4 H); 5.17 – 5.03 (m, 1 H); 4.50 (d, J ¼ 11.1,
1 H); 4.31 (d, J ¼ 11.3, 1 H); 4.27 – 4.19 (m, 1 H); 3.79 (s, 3 H); 3.45 – 3.38 (m, 1 H); 3.20 – 3.08 (m, 1 H);
2.68 – 2.56 (m, 1 H); 2.51 – 2.41 (m, 1 H); 1.85 – 1.66 (m, 2 H); 1.30 (d, J ¼ 6.4, 3 H).13C-NMR (75 MHz,
CDCl3): 170.2; 159.1; 137.3; 132.2; 129.3; 120.4; 117.9; 113.7; 76.8; 70.2; 68.9; 56.7; 55.4; 55.2; 41.3; 34.2;
20.2. ESI-MS: 369 ([M þ Na]þ).
(1S,3R,7S,8Z,10R)-7-[(4-Methoxybenzyl)oxy]-3-methyl-4,11-dioxabicyclo[8.1.0]undec-8-en-5-one
(18) [5]. To a stirred soln. of 2 (0.12 g, 0.35 mmol) in CH2Cl2 (100 ml) was added 10 mol-% Grubbs II
catalyst. The resulting mixture was stirred at reflux for 12 h under N2. The solvent was then distilled off,
and the residual soln. was stirred at r.t. for 2 h under air bubbling in order to decompose the catalyst. The
remaining solvent was evaporated to dryness to give the brown-colored residue which was purified by CC
(SiO2; 5% AcOEt in hexane) to give 18 (71 mg, 65%). [a]2D5 ¼ ꢀ63.0 (c ¼ 0.3, CHCl3). IR (neat): 3450,
1
2925, 2854, 1731, 1513, 1248. H-NMR (300 MHz, CDCl3): 7.14 (d, J ¼ 8.4, 2 H); 6.77 (d, J ¼ 8.7, 2 H);
5.64 (ddd, J ¼ 1.8, 8.3, 11.7, 1 H); 5.49 – 5.42 (m, 1 H); 5.19 (ddq, J ¼ 1.8, 8.3, 11.7, 1 H); 4.49 (d, J ¼ 11.3,
1 H); 4.40 – 4.31 (m, 2 H); 3.75 – 3.69 (m, 4 H); 3.24 (m, 1 H); 2.83 (dt, J ¼ 3.3, 10.5, 1 H); 2.60 (dd, J ¼
3.3, 10.3, 1 H); 2.28 (t, J ¼ 10.5, 1 H); 2.11 – 2.05 (m, 1 H); 1.23 (d, J ¼ 6.7, 3 H). 13C-NMR (75 MHz,
CDCl3): 169.2; 159.2; 133.6; 130.0; 129.7; 114.2; 76.9; 71.9; 70.0; 66.8; 55.4; 54.4; 53.9; 41.2; 32.9. LC/MS:
341 ([M þ Na]þ).
Decarestrictine I (¼(1S,5R,7S,8S)-7-Hydroxy-5-methyl-4,11-dioxabicyclo[6.2.1]undec-9-en-3-one; 1)
[5]. To a stirred soln. of 2 (0.07 g, 0.2 mmol) in CH2Cl2/H2O (2 ml, 19 :1) was added DDQ (0.042 g,
0.33 mmol). The mixture was stirred at r.t. for 1 h. After completion, the reaction was quenched with sat.
aq. NaHCO3 soln. (2 ml), and the mixture was filtered through Celite and then washed with CH2Cl2
(20 ml). The filtrate was washed again with H2O (15 ml), followed by brine (5 ml), and dried (Na2SO4).
Removal of the solvent under reduced pressure followed by purification by CC (SiO2; 15% AcOEt and
hexane), gave 1 (0.030 g, 70%). [a]2D5 ¼ ꢀ129.1 (c ¼ 0.3, MeOH). IR (neat): 3405.5, 2956.3, 2854, 1710,
1431.2, 1385, 1070. 1H-NMR (300 MHz, CDCl3): 5.95 – 5.82 (m, 2 H); 5.10 – 4.95 (m, 2 H); 4.92 – 4.85 (m,
1 H); 3.90 (dt, J ¼ 4.6, 10.9, 1 H); 2.76 – 2.54 (m, 1 H); 2.01 (dd, J ¼ 2.3, 3.1, 2 H); 1.68 – 1.60 (m, 1 H);
1.40 – 1.37 (m, 1 H); 1.25 (d, J ¼ 6.2, 3 H). 13C-NMR (75 MHz, CDCl3): 171.5; 132.2; 127.5; 92.6; 81.6;
73.7; 71.2; 42.5; 39.9; 21.9. LC/MS: 221 ([M þ Na]þ).
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