SUPPLEMENTARY MATERIAL
Application of the taraxerane-oleanane rearrangement to the synthesis
of seco-oleanane triterpenoids from taraxerone
Phan Minh Gianga*, Vu Minh Tranga,b, Phan Tong Sona and Katsuyoshi Matsunamic
a
Faculty of Chemistry, VNU University of Science, Vietnam National University, Hanoi,
19 Le Thanh Tong Street, Hanoi, Viet Nam;
b
VNU University of Education, Vietnam
National University, Hanoi, 144 Xuan Thuy Road, Hanoi, Viet Nam; c Graduate School
of Biomedical & Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku,
Hiroshima 734-8553, Japan
* Corresponding author. E-mail: phanminhgiang@yahoo.com
Abstract
Synthetic oleananes and seco-oleananes form a group of promising anti-inflammatory
and cancer chemopreventive agents with an excellent safety profile. These compounds
are usually prepared by semi-synthesis from natural oleanane triterpenoids. Since a
taraxer-14-ene was reported to be rearranged into an olean-12-ene under mild reaction
conditions a rapid synthesis of seco-oleananes from taraxerone, which is a readily
available starting material, was explored by us. Treatment of taraxerone with MCPBA
gave 14,15-epoxy lactones, which underwent the taraxerane-oleanane rearrangement
leading to new seco-oleanane triterpenoids.
Keywords: Taraxerone; Baeyer-Villiger oxidation; Taraxerane-oleanane rearrangement;
3,4-seco-Oleanane
1
Synthesis of 14,15-epoxyepitaraxerol
A mixture of epitaraxerol and taraxerol (200 mg) and m-chloroperoxybenzoic acid (243
mg, 1.41 mmol) in CH2Cl2 (7 ml) was stirred at room temperature for 72 h (Scheme S1).
The mixture was washed with aqueous NaHCO3 and extracted with CH2Cl2 (20 ml  5).
The extract was concentrated under reduced pressure to give a crude product. The crude
product was purified by column chromatography on silica gel using n-hexane-EtOAc
60:1 and 19:1 to give 14,15-epoxyepitaraxerol (27.2 mg, 0.06 mmol).
14,15-Epoxyepitaraxerol: White amorphous powder; 1H NMR (CDCl3): δ 0.79 (3H,
s), 0.84 (3H, s), 0.85 (3H, s), 0.91 (3H, s), 0.93 (3H, s), 1.04 (3H, s), 1.10 (3H, s), 1.13
(3H, s) (23-CH3, 24-CH3, 25-CH3, 26-CH3, 27-CH3, 28-CH3, 29-CH3, 30-CH3), 3.04 (1H,
br d, J = 6.5 Hz, H-15), 3.39 (1H, t, J = 2.5 Hz, H-3); 13C NMR (CDCl3): δ 15.3 (C-25),
17.5 (C-11), 17.8 (C-6), 22.2 (C-24), 23.5 (C-30), 24.5 (C-26), 25.1 (C-2), 28.2 (C-23),
28.9 (C-20), 29.9 (C-28), 30.1 (C-16), 31.2 (C-27), 32.7 (C-7), 33.3 (C-12), 33.6 (C-29),
34.8 (C-21), 35.9 (C-17), 36.7 (C-13), 37.3 (C-10), 37.4 (C-1), 37.7 (C-22), 38.1 (C-4),
39.2 (C-8), 39.8 (C-19), 48.6 (C-18), 49.2 (C-5), 49.4 (C-9), 57.2 (C-15), 68.3 (C-14),
76.2 (C-3).
2
MCBPA, CH2Cl2
room temperature
O
HO
HO
epitaraxerol 3-OH
taraxerol 3-OH
14,15-epoxyepitaraxerol
Scheme S1. Synthesis of 14,15-epoxyepitaraxerol
3
O
H3 C
O
O
HO
H
HMBC
NOESY
Scheme S2. NOESY and HMBC correlations of 4
4
Spectra of methyl 15-hydroxy-3,4-seco-olean-4(23),12-dien-3-oate (3)
IR spectrum of 3
5
EI-MS spectrum of 3
HR-EI-MS spectrum of 3
6
Positive-ion HR-APCI-MS spectrum of 3
7
Positive-ion HR-ESI-MS spectrum of 3
8
1H
NMR spectrum of 3
13C
NMR spectrum of 3
9
Spectra of methyl 14,15-epoxy-4-hydroxy-3,4-seco-taraxeran-3-oate (4)
IR spectrum of 4
10
Positive-ion HR-ESI-MS spectrum of 4
11
1H
NMR spectrum of 4
13C
NMR spectrum of 4
12
HSQC spectrum of 4
13
HMBC spectrum of 4
14
NOESY spectrum of 4
15
Spectra of 4,15-dihydroxy-3,4-seco-olean-12-en-3-oic acid (5)
IR spectrum of 5
16
Positive-ion HR-ESI-MS spectrum of 5
17
1H
13C
NMR spectrum of 5
NMR/DEPT spectrum of 5
18