52
3 Experimental Section
(C
12 ), 52.1 (C
18 ), 48.3 (C
5 ), 45.4 (C
17 ), 44.1 (C
4 ), 44.1 (C
9 ), 43.2 (C
14 ),
42.2 (C
8 ), 39.9 (C
19 ), 37.4 (C
1 ), 36.2 (C
10 ), 34.0 (C
21 ), 33.7 (C
7 ), 33.4 (C
29 ),
32.0 (C
20 ), 29.9 (C
11 ), 29.0 (C
15 ), 27.6 (C
22 ), 23.7 (C
30 ), 21.4 (C
16 ), 21.2
(C
34 ), 20.4 (C
2 ), 20.2 (C
32 ), 20.1 (C
27 ), 19.0 (C
6 ), 18.9 (C
24 ), 18.6 (C
26 ),
17.1 (C
25 ). IR (neat) 2941, 2869, 1771, 1743, 1466. HRMS (ESI-TOF)
m/z: [M + Na]
+ Calcd for C 34 H 50 ClNNaO 6
+ 626.3219; Found 626.3208.
3.2.9 23-Acetoxy-3-(acetoxyimino)-12α-bromo-olean28,13β-olide (7b)
N
H
H
H
Br
O
O
O
O
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
31
32
33
34
A round bottom flask, equipped with magnetic stirring bar, was charged
with a suspension of 6b (19.7 mmol, 10.805 g, 1 equiv) in a mixture of Ac 2 O
(512 mmol, 48.4 ml, 26 equiv) and AcOH (49.25 ml). The flask was immersed
into a preheated oilbath (40 °C), and the mixture was left stirring at 40 °C for
2 h. Pd(OAc) 2 (2.95 mmol, 663.0 mg, 0.15 equiv) and PhI(OAc) 2 (31.5 mmol,
10.150 g, 1.6 equiv) were added subsequently and the reaction was left stirring
at 40 °C for 16 h. After cooling to room temperature, MeOH (49.25 ml) was
added and the resulting mixture was left stirring at room temperature for
30 min. Solvents were removed under reduced pressure at 50 °C. Purification
by column chromatography (silica gel, heptane/EtOAc = 4:1) gave the target
compound as colourless solid (9.4 mmol, 6.100 g, 48 %; dr 75:25).
1 H-NMR (600 MHz, CDCl 3 , major): δ 4.31 (dd, J = 3.9, 2.3 Hz, 1 H,
H
12 ), 4.22 (d, J = 11.0 Hz, 1 H, H
23a ), 4.10 (d, J = 11.0 Hz, 1 H, H
23b ), 2.74–
2.63 (m, 1 H, H
2a ), 2.46–2.35 (m, 1 H, H
11a ), 2.34–2.26 (m, 2 H, H
2b,19a ),
2.20–2.13 (m, 4 H, H
16a,32 ), 2.08 (s, 3 H, H
34 ), 2.01–1.98 (m, 2 H, H
18,19b ),
3 Experimental Section
(C
12 ), 52.1 (C
18 ), 48.3 (C
5 ), 45.4 (C
17 ), 44.1 (C
4 ), 44.1 (C
9 ), 43.2 (C
14 ),
42.2 (C
8 ), 39.9 (C
19 ), 37.4 (C
1 ), 36.2 (C
10 ), 34.0 (C
21 ), 33.7 (C
7 ), 33.4 (C
29 ),
32.0 (C
20 ), 29.9 (C
11 ), 29.0 (C
15 ), 27.6 (C
22 ), 23.7 (C
30 ), 21.4 (C
16 ), 21.2
(C
34 ), 20.4 (C
2 ), 20.2 (C
32 ), 20.1 (C
27 ), 19.0 (C
6 ), 18.9 (C
24 ), 18.6 (C
26 ),
17.1 (C
25 ). IR (neat) 2941, 2869, 1771, 1743, 1466. HRMS (ESI-TOF)
m/z: [M + Na]
+ Calcd for C 34 H 50 ClNNaO 6
+ 626.3219; Found 626.3208.
3.2.9 23-Acetoxy-3-(acetoxyimino)-12α-bromo-olean28,13β-olide (7b)
N
H
H
H
Br
O
O
O
O
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
31
32
33
34
A round bottom flask, equipped with magnetic stirring bar, was charged
with a suspension of 6b (19.7 mmol, 10.805 g, 1 equiv) in a mixture of Ac 2 O
(512 mmol, 48.4 ml, 26 equiv) and AcOH (49.25 ml). The flask was immersed
into a preheated oilbath (40 °C), and the mixture was left stirring at 40 °C for
2 h. Pd(OAc) 2 (2.95 mmol, 663.0 mg, 0.15 equiv) and PhI(OAc) 2 (31.5 mmol,
10.150 g, 1.6 equiv) were added subsequently and the reaction was left stirring
at 40 °C for 16 h. After cooling to room temperature, MeOH (49.25 ml) was
added and the resulting mixture was left stirring at room temperature for
30 min. Solvents were removed under reduced pressure at 50 °C. Purification
by column chromatography (silica gel, heptane/EtOAc = 4:1) gave the target
compound as colourless solid (9.4 mmol, 6.100 g, 48 %; dr 75:25).
1 H-NMR (600 MHz, CDCl 3 , major): δ 4.31 (dd, J = 3.9, 2.3 Hz, 1 H,
H
12 ), 4.22 (d, J = 11.0 Hz, 1 H, H
23a ), 4.10 (d, J = 11.0 Hz, 1 H, H
23b ), 2.74–
2.63 (m, 1 H, H
2a ), 2.46–2.35 (m, 1 H, H
11a ), 2.34–2.26 (m, 2 H, H
2b,19a ),
2.20–2.13 (m, 4 H, H
16a,32 ), 2.08 (s, 3 H, H
34 ), 2.01–1.98 (m, 2 H, H
18,19b ),