Page 21 of 26
The Journal of Organic Chemistry
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1025, 679, 543 cm-1; H NMR (400 MHz, CDCl3) δ 5.67-5.66 (m, 1H), 4.92 (d, J = 3.5 Hz, 1H),
4.47 (s, 1H), 4.31 (dd, J = 11.1, 3.3 Hz, 1H), 4.17 (s, 1H), 3.52 (t, J = 3.5 Hz, 1H), 3.19 (dd, J =
16.0, 3.2 Hz, 1H), 2.85-2.78 (m, 1H), 1.93 (d, 1H); ppm 13C{1H} NMR (100 MHz, CDCl3) δ 166.9,
135.6, 121.1, 63.0, 59.5, 56.2, 55.6, 54.3, 29.0 ppm; HRMS (ESI): calcd for C18H18N2O6Na+
[M+Na+] 381.1057, found 381.1045.
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(2R,4aR,6aS,9R,11aR,13aS)-2,9-di((triisopropylsilyl)oxy)-2,3,4,4a,6a,7,9,10,11,11a,13a,14-
dodecahydro-6H,13H-dioxireno[1,2-a:4,5-a']diindole-6,13-dione (8c). The dimer 8b (50 mg, 74.51
µmmol, 1.0 equiv) was dissolved in dry methanol (10 mL), and then sodium methoxide (45.0 µL,
30 wt% in methanol, 3.0 equiv) was injected into the solvent. The reaction was finished after stirred
for about 4h at room temperature and was quenched with saturated NH4Cl solution. The methanol
was removed under reduced pressure. The resulting solid was dissolved using EtOAc and water.
The mixture was extracted with EtOAc three times. The combined organic layers were washed with
brine, dried over anhydrous Na2SO4 and filtered. The filtrate was concentrated and the residue was
purified by flash column chromatography (silica gel, petroleum ether:EtOAc, 1:4 to 1:2 ) to give 8c
as a white solid (45.0 mg, 90%). 8c: m.p. 160-162 oC; Rf = 0.4 (silica gel, petroleum ether:EtOAc,
1:2); [α]D25 = -45.2 (c = 0.47, CHCl3); IR (film) Vmax, 3693, 2949, 2868, 1677, 1089, 882,682 cm-
1; 1H NMR (400 MHz, CDCl3) δ 5.69 (s, 1H), 4.71 (s, 1H), 4.39 (s, 1H), 4.29 (dd, J = 10.3, 6.9 Hz,
1H), 4.19 (d, J = 3.3 Hz, 1H), 3.38 (t, J = 3.5 Hz, 1H), 2.87-2.81 (m, 1H), 2.75 (dd, J = 14.0, 6.8
Hz, 1H), 1.12 (s, 18H), 1.10 (s, 3H) ppm; 13C{1H} NMR (100 MHz, CDCl3) δ 166.4, 135.2, 122.1,
64.4, 60.8, 55.7, 54.9, 53.8, 33.6, 18.0, 12.4 ppm; HRMS (ESI): calcd for C36H58N2O6Si2Na+
[M+Na+] 693.3726, found 693.3726.
(2R,4aR,6aS,9R,11aR,13aS)-2,9-dihydroxy-2,3,4,4a,6a,7,9,10,11,11a,13a,14-dodecahydro-
6H,13H-dioxireno[1,2-a:4,5-a']diindole-6,13-dione (8c’). Acetic acid (4 mg, 62.59 µmol, 3.0 equiv)
was added dropwise to the solution of dimer 8c (14 mg, 20.86 µmol, 1.0 equiv) in THF (2 mL) at
room temperature and then TBAF (62.59 µmol, 1 N in THF, 3.0 equiv) was added. After stirring at
room temperature for 3 h the solvent was removed under reduced pressure directly and the residue
was purified by flash column chromatography (silica gel, EtOAc:methanol, 1:0 to 10:1 ) to give diol
o
8c’ as a white solid (6.0 mg, 80%). 8c’: m.p. 258-260 C; Rf = 0.2 (silica gel, EtOAc:methanol,
10:1); [α]D25 = -76.9 (c = 0.23, DMSO); IR (film) Vmax; 3723, 3694,2955, 1738, 1521, 1462, 1018
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cm-1, H NMR (400 MHz, DMSO) δ 5.66 (s, 1H), 5.02 (d, J = 7.1 Hz, 1H), 4.48 – 4.41 (m, 2H),
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