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Helvetica Chimica Acta – Vol. 95 (2012)
ꢀ 0.07 (s, 3 H); ꢀ 0.02 (s, 3 H); 0.06 (s, 3 H, minor); 0.09 (s, 3 H, minor); 0.18 (s, 9 H); 0.20 (s, 9 H,
minor); 0.38 (t, J ¼ 5.2, 1 H); 0.55 – 0.62 (m, 1 H, minor); 0.69 (t, J ¼ 5.2, 1 H, minor); 0.90 (s, 9 H); 0.93 (s,
9 H); 1.20 (dd, J ¼ 8.6, 5.2, 1 H, minor); 1.27 (dd, J ¼ 14.3, 5.2, 1 H); 1.56 (dddd, J ¼ 14.3, 9.2, 6.3, 5.2,
1 H); 3.33 (s, 3 H, minor); 3.47 (s, 3 H); 3.52 (dd, J ¼ 10.3, 8.6, 1 H, minor); 3.58 (dd, J ¼ 10.3, 9.2, 1 H);
3.57 – 3.60 (m, 1 H, minor); 3.90 (dd, J ¼ 10.3, 6.3, 1 H); 4.54 (s, 2 H, minor); 4.61 (d, J ¼ 11.5, 1 H); 4.64
(d, J ¼ 11.5, 1 H); 4.69 (d, J ¼ 6.3, 1 H, minor); 4.72 (d, J ¼ 6.3, 1 H, minor); 4.80 (d, J ¼ 6.9, 1 H); 4.83 (d,
J ¼ 6.9, 1 H); 5.03 (s, 1 H); 5.17 (s, 1 H, minor); 6.72 (d, J ¼ 7.5, 1 H); 6.74 (d, J ¼ 7.5, 1 H, minor); 6.79 (d,
J ¼ 7.5, 1 H); 6.80 (d, J ¼ 7.5, 1 H, minor); 7.27 – 7.37 (m, 7 H þ 7 H (minor)). 13C-NMR (125 MHz,
CDCl3): ꢀ 4.2 (minor); ꢀ 4.0; ꢀ 3.1 (minor); ꢀ 3.0; 1.0; 1.4 (minor); 10.0; 14.2 (minor); 16.8; 18.3; 20.0
(minor); 22.0; 22.6 (minor); 25.9; 26.0 (minor); 31.6 (minor); 54.1; 54.3 (minor); 68.7 (minor); 68.8; 69.3
(minor); 69.4; 79.6 (minor); 79.9; 94.37; 94.43 (minor); 95.2 (minor); 95.5; 100.9; 101.0 (minor); 110.4;
110.7 (minor); 116.3; 116.5 (minor); 122.2; 122.3 (minor); 127.6 (minor); 127.76; 127.82 (minor); 128.4;
137.87 (minor); 137.94; 141.3 (minor); 141.45; 141.50; 141.7 (minor); 147.76; 147.77 (minor). Anal. calc.
for C31H46O6Si2: C 65.22, H 8.12; found: C 64.96, H 7.90.
rac-{2-[(6S,7R)-6-{[tert-Butyl(dimethyl)silyl]oxy}-6,7-dihydro-7-methoxycyclobuta[e][1,3]benzo-
dioxol-7-yl]-2-(trimethylsilyl)cyclopropyl}methanol (29). A flask, purged with Ar, was charged with 20%
Pd(OH)2/C (350 mg), to which was added a soln. of 28 (1.08 g, 1.89 mmol) in AcOEt (18 ml). The
atmosphere was changed from Ar to H2 (1 atm), and the mixture was stirred for 45 min at r.t. After
changing the atmosphere from H2 to Ar, the mixture was filtered through a Celite pad (washed with
AcOEt) and concentrated in vacuo. The residue was purified by FC (SiO2; hexane/AcOEt 9 :1 to 4 :1) to
give rac-[(1R,2R)-2-[(6S,7R)-6-{[(tert-butyl)(dimethyl)silyl]oxy}-6,7-dihydro-7-methoxycyclobu-
ta[e][1,3]benzodioxol-7-yl]-2-(trimethylsilyl)cyclopropyl]methanol (b-29; 652 mg, 64%), and a mixture
of rac-[(1S,2S)-2-[(6S,7R)-6-{[(tert-butyl)(dimethyl)silyl]oxy}-7-methoxy-6,7-dihydrocyclobuta[e][1,3]-
benzodioxol-7-yl]-2-(trimethylsilyl)cyclopropyl]methanol (a-29) and rac-[(1R,2S)-2-[(6S,7R)-6-{[(tert-
butyl)(dimethyl)silyl]oxy}-7-methoxy-6,7-dihydrocyclobuta[e][1,3]benzodioxol-7-yl]-2-(trimethylsilyl)-
cyclopropyl]methanol (29’; 204 mg, 20%) as a colorless oil. Anal. samples of a-29 and 29’ were prepared
by separation of the mixture by PTLC (hexane/acetone 4 :1) to afford pure a-29 and 29’ as colorless oils.
Data of b-29. Rf (hexane/AcOEt 4 :1) 0.25. IR (neat): 3363, 2953, 2934, 2895, 2857, 1457, 1404, 1376,
1
1251, 1208, 1169, 1114, 1047, 837. H-NMR (400 MHz, CDCl3): ꢀ 0.09 (dd, J ¼ 8.6, 4.6, 1 H); ꢀ 0.05 (s,
3 H); ꢀ 0.01 (s, 3 H); 0.17 (s, 9 H); 0.32 (t, J ¼ 4.6, 1 H); 0.89 (s, 9 H); 1.26 (s, 1 H); 1.49 (dddd, J ¼ 8.6,
8.4, 6.6, 4.6, 1 H); 3.44 (s, 3 H); 3.58 (dd, J ¼ 11.2, 8.4, 1 H); 3.87 (dd, J ¼ 11.2, 6.6, 1 H); 5.02 (s, 1 H); 5.93
(d, J ¼ 1.2, 1 H); 6.00 (d, J ¼ 1.2, 1 H); 6.71 (d, J ¼ 7.8, 1 H); 6.80 (d, J ¼ 7.8, 1 H). 13C-NMR (100 MHz,
CDCl3): ꢀ 4.1; ꢀ 3.0; 1.1; 9.7; 14.1; 17.4; 18.3; 22.6; 25.0; 25.9; 31.6; 54.3; 63.8; 80.0; 95.4; 101.0; 110.5;
116.3; 122.2; 141.4; 141.6; 147.8. HR-MS (FAB þ , 3-NBA): 451.2334 ([M þ H]þ, C23H39O5Si2þ ; calc.
451.2336).
Data of a-29. Rf (hexane/AcOEt 4 :1) 0.22. IR (neat): 3388, 2952, 2929, 2895, 2857, 1457, 1252, 1214,
1
1167, 1113, 1048, 1031, 932, 836, 776. H-NMR (500 MHz, CDCl3): 0.05 (s, 3 H); 0.07 (s, 3 H); 0.18 (s,
9 H); 0.57 (dddd, J ¼ 8.6, 8.0, 6.8, 4.6, 1 H); 0.63 (t, J ¼ 4.6, 1 H); 0.90 (s, 9 H); 1.15 (dd, J ¼ 8.6, 4.6, 1 H);
1.64 (s, 1 H); 3.31 (s, 3 H); 3.50 (dd, J ¼ 10.9, 8.0, 1 H); 3.57 (dd, J ¼ 10.9, 6.8, 1 H); 5.13 (s, 1 H); 5.89 (d,
J ¼ 1.2, 1 H); 5.95 (d, J ¼ 1.2, 1 H); 6.73 (d, J ¼ 7.8, 1 H); 6.79 (d, J ¼ 7.8, 1 H). 13C-NMR (125 MHz,
CDCl3): ꢀ 4.3; ꢀ 3.2; 1.4; 13.6; 17.3; 18.1; 23.2; 25.8; 54.3; 63.5; 79.6; 95.1; 101.0; 110.4; 116.5; 122.4;
141.2; 141.5; 147.7. HR-MS (FAB þ , 3-NBA): 450.2268 (Mþ, C23H38O5Si2þ ; calc. 450.2258).
Data of 29’. Rf (hexane/AcOEt 4 :1) 0.22. IR (neat): 3428, 2953, 2930, 2896, 2858, 1501, 1455, 1378,
1251, 1208, 1141, 1044, 932, 877, 836, 777. 1H-NMR (500 MHz, CDCl3): ꢀ 0.03 (s, 9 H); 0.12 (s, 3 H); 0.15
(s, 3 H); 0.66 (dd, J ¼ 9.8, 4.6, 1 H); 0.69 (t, J ¼ 4.6, 1 H); 0.90 (s, 1 H); 0.92 (s, 9 H); 1.35 (dddd, J ¼ 9.8,
9.5, 5.8, 4.6, 1 H); 3.29 (s, 3 H); 3.89 (dd, J ¼ 12.1, 9.5, 1 H); 3.95 (dd, J ¼ 12.1, 5.8, 1 H); 5.37 (s, 1 H); 5.95
(d, J ¼ 1.2, 1 H); 5.96 (d, J ¼ 1.2, 1 H); 6.76 (d, J ¼ 8.0, 1 H); 6.87 (d, J ¼ 8.0, 1 H). 13C-NMR (125 MHz,
CDCl3): ꢀ 4.4; ꢀ 3.2; ꢀ 1.0; 13.2; 17.8; 18.1; 24.1; 25.8; 55.1; 62.3; 79.9; 92.1; 101.0; 110.9; 116.6; 124.6;
140.8; 141.5; 148.2. HR-MS (FAB þ , 3-NBA): 492.2353 (Mþ, C23H38O5Si2þ ; calc. 492.2363).
rac-(1R,2R)-2-[(6S,7R)-6-{[(tert-Butyl)(dimethyl)silyl]oxy}-6,7-dihydro-7-methoxycyclobuta[e][1,3]-
benzodioxol-7-yl]-2-(trimethylsilyl)cyclopropanecarbaldehyde (b-30). To a soln. of b-29 (470 mg,
1.04 mmol) in DMSO (10 ml) was added IBX (730 mg, 2.61 mmol). After stirring for 11 h, the reaction
was stopped by adding 10% aq. Na2S2O3 and sat. aq. NaHCO3. The products were extracted with CH2Cl2