54
3 Experimental Section
compound as colourless solid (3.83 mmol, 2.105 g, 55 %; dr > 20:1).
1 H-NMR (700 MHz, CDCl 3 ): δ 4.31 (dd, J = 3.9, 2.3 Hz, 1 H, H
12 ), 3.69
(dd, J = 11.2, 6.4 Hz, 1 H, H
23a ), 3.43 (dd, J = 11.3, 6.9 Hz, 1 H, H
23b ), 2.64
(ddd, J = 16.4, 12.4, 7.2 Hz, 1 H, H
2a ), 2.45 (ddd, J = 14.9, 12.3, 3.9 Hz, 1 H,
H
11a ), 2.37 (ddd, J = 16.4, 6.1, 2.9 Hz, 1 H, H
2b ), 2.33 (dd, J = 10.1, 1.9 Hz,
1 H, H
19a ), 2.23 (t, 1 H, H
23-OH ), 2.17 (td, J = 13.4, 5.8 Hz, 1 H, H
16a ), 2.05–
1.94 (m, 4 H, H
1a,15a,18,19b ), 1.92 (dd, 1 H, H
9 ), 1.88 (dt, 1 H, H
11b ), 1.77
(dd, J = 12.1, 2.4 Hz, 1 H, H
5 ), 1.67–1.63 (m, 3 H, H
7a,22ab ), 1.56 (s, 2 H,
H
1b,6a ), 1.46 (s, 3 H, H
27 ), 1.42 (dq, J = 13.3, 3.2 Hz, 1 H, H
6b ), 1.39–1.32
(m, 2 H, H
21ab ), 1.32–1.21 (m, 6 H, H
7b,15b,16b,26 ), 1.09 (s, 3 H, H
25 ), 1.01
(s, 3 H, H
24 ), 1.00 (s, 3 H, H
29 ), 0.91 (s, 3 H, H
30 ).
13 C-NMR (175 MHz,
CDCl 3 ): δ 218.5 (C
3 ), 178.9 (C
28 ), 91.7 (C
13 ), 67.0 (C
23 ), 56.2 (C
12 ), 52.6
(C
4 ), 52.5 (C
18 ), 48.8 (C
5 ), 45.7 (C
17 ), 45.0 (C
9 ), 43.7 (C
14 ), 42.5 (C
8 ), 40.1
(C
19 ), 38.8 (C
1 ), 36.3 (C
10 ), 35.3 (C
2 ), 34.1 (C
7 ), 34.0 (C
21 ), 33.4 (C
29 ), 32.0
(C
2 ), 30.9 (C
11 ), 29.3 (C
15 ), 27.6 (C
22 ), 23.7 (C
30 ), 21.4 (C
16 ), 21.2 (C
27 ),
19.1 (C
26 ), 18.7 (C
6 ), 16.8 (C
25 ), 16.8 (C
24 ). [α]
20
D +53.4 (c 1.0, CDCl 3 );
IR (neat) 3486, 2937, 2869, 1772, 1698, 1461. HRMS (ESI-TOF) m/z:
[M + Na]
+ Calcd for C 30 H 45 BrNaO 4
+ 571.2393; Found 571.2394.
3.2.11 Hederagonic acid
(23-Hydroxy-3-oxo-olean-12-en-28-oic acid) (1)
H
H
H
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
HO
O
OH
O
A round bottom flask, equipped with magnetic stirring bar, was charged
with a solution of 8b (36.4 μmol, 20.0 mg, 1 equiv) and zinc dust (1092 μmol,
71.4 mg, 30 equiv) in AcOH (360 μl). The flask was immersed into a preheated
oilbath (40 °C) and the reaction was left stirring at 40 °C for 2 h. After cooling