46
3 Experimental Section
(neat) 2953, 2867, 1776, 1704, 1463. HRMS (ESI-TOF) m/z: [M + Na]
+
Calcd for C 30 H 45 ClNaO 3
+ 511.2949; Found 511.2949.
3.2.4 12α-Bromo-3-oxo-olean-28,13β-olide (27b)
O
H
H
H
Br
O
O
1
2
3
4
5
6
7
8
9
10
11
12 13
14
15
16
17
18
19
20
21
22
28
24
23
25
26
29
27
30
A round bottom flask, equipped with magnetic stirring bar, was charged
with a solution of oleanolic acid (5) (1.00 mmol, 457 mg, 1.00 equiv) in DCM
(12 ml) and pyridine (15.2 mmol, 1229 μl, 15.2 equiv). After addition of
NBS (1.05 mmol, 187 mg, 1.05 equiv), the reaction was left stirring at 20 °C
for 60 min. Subsequently, trichloroisocyanuric acid (0.80 mmol, 186 mg,
0.80 equiv) was added, and the mixture was left stirring at 20 °C for 90 min.
Then i-PrOH (1.60 mmol, 122 μl, 1.60 equiv) was added, and the mixture
was left stirring at 20 °C for 30 min. The solution was diluted with DCM
(12 ml), filtered over a glass frit (P 16) and the residue was washed with
DCM (2 × 4 ml). The organics were washed with HCl solution (1 m in H 2 O)
(32 ml). The aqueous phase was extracted with DCM (2 × 16 ml). The
combined organic layers were washed with NaOH solution (1 m in H 2 O)
(32 ml), followed by NH 4 Cl solution (half-saturated in H 2 O) (16 ml). After
drying over MgSO 4 the solution was concentrated under reduced pressure.
The residue was dried in vacuo to give the target compound as pale yellow
foam (quantitative yield). The obtained product was used without further
purification. The spectroscopic data is in accordance with the literature.
[36,41]
1 H-NMR (600 MHz, CDCl 3 ): δ 4.30 (t, J = 2.5 Hz, 1 H, H
12 ), 2.55–
2.46 (m, 2 H, H
2 ), 2.42 (ddd, J = 14.8, 12.5, 3.7 Hz, 1 H, H
11a ), 2.33 (dd,
J = 25.7, 15.2 Hz, 1 H, H
19a ), 2.17 (dt, J = 13.4, 5.6 Hz, 1 H, H
16a ), 2.06–
1.86 (m, 5 H, H
1a,9,15a,18,19b ), 1.84 (bd, J = 14.9 Hz, 1 H, H
11b ), 1.67–1.57
3 Experimental Section
(neat) 2953, 2867, 1776, 1704, 1463. HRMS (ESI-TOF) m/z: [M + Na]
+
Calcd for C 30 H 45 ClNaO 3
+ 511.2949; Found 511.2949.
3.2.4 12α-Bromo-3-oxo-olean-28,13β-olide (27b)
O
H
H
H
Br
O
O
1
2
3
4
5
6
7
8
9
10
11
12 13
14
15
16
17
18
19
20
21
22
28
24
23
25
26
29
27
30
A round bottom flask, equipped with magnetic stirring bar, was charged
with a solution of oleanolic acid (5) (1.00 mmol, 457 mg, 1.00 equiv) in DCM
(12 ml) and pyridine (15.2 mmol, 1229 μl, 15.2 equiv). After addition of
NBS (1.05 mmol, 187 mg, 1.05 equiv), the reaction was left stirring at 20 °C
for 60 min. Subsequently, trichloroisocyanuric acid (0.80 mmol, 186 mg,
0.80 equiv) was added, and the mixture was left stirring at 20 °C for 90 min.
Then i-PrOH (1.60 mmol, 122 μl, 1.60 equiv) was added, and the mixture
was left stirring at 20 °C for 30 min. The solution was diluted with DCM
(12 ml), filtered over a glass frit (P 16) and the residue was washed with
DCM (2 × 4 ml). The organics were washed with HCl solution (1 m in H 2 O)
(32 ml). The aqueous phase was extracted with DCM (2 × 16 ml). The
combined organic layers were washed with NaOH solution (1 m in H 2 O)
(32 ml), followed by NH 4 Cl solution (half-saturated in H 2 O) (16 ml). After
drying over MgSO 4 the solution was concentrated under reduced pressure.
The residue was dried in vacuo to give the target compound as pale yellow
foam (quantitative yield). The obtained product was used without further
purification. The spectroscopic data is in accordance with the literature.
[36,41]
1 H-NMR (600 MHz, CDCl 3 ): δ 4.30 (t, J = 2.5 Hz, 1 H, H
12 ), 2.55–
2.46 (m, 2 H, H
2 ), 2.42 (ddd, J = 14.8, 12.5, 3.7 Hz, 1 H, H
11a ), 2.33 (dd,
J = 25.7, 15.2 Hz, 1 H, H
19a ), 2.17 (dt, J = 13.4, 5.6 Hz, 1 H, H
16a ), 2.06–
1.86 (m, 5 H, H
1a,9,15a,18,19b ), 1.84 (bd, J = 14.9 Hz, 1 H, H
11b ), 1.67–1.57