M. Macias-Alonso et al. / Steroids 76 (2011) 317–323
319
1
J = 7.6 Hz, 3H, H-21), 0.97 (s, 3H, H-19), 0.73 (s, 3H, H-18). 13C NMR
9
4
4
8.3%), identical as described in Ref. [31]. H NMR (300 MHz, CDCl ):
3
.94 (ddd, J = 7.8, 7.8, 4.6 Hz, 1H, H-16), 4.72 (dddd, J = 11.4, 11.4, 4.9,
.9 Hz, 1H, H-3), 2.57 (dd, J = 0.7, 7.5 Hz, 1H, H-20), 2.02 (s, 3H, CH3
(75 MHz, CDCl ): C-1 30.5, C-2 24.9, C-3 70.5, C-4 30.7, C-5 37.1, C-6
3
26.3, C-7 26.2, C-8 35.0, C-9 40.1, C-10 35.0, C-11 20.3, C-12 38.5, C-
13 41.8, C-14 54.7, C-15 33.0, C-16 82.8, C-17 59.1, C-18 13.8, C-19
23.7, C-20 36.0, C-21 18.0, C-22 181.2, CH3 acetyl 21.4, C O acetyl
170.6.
acetyl), 1.31 (d, J = 7.6 Hz, 3H, H-21), 0.94 (s, 3H, H-19), 0.73 (s, 3H,
H-18). 13C NMR: (75.5 MHz, CDCl ): C-1 35.0, C-2 26.6, C-3 74.1, C-4
3
3
1
5
2.2, C-5 41.7, C-6 26.8, C-7 26.5, C-8 35.2, C-9 40.6, C-10 34.7, C-
1 20.1, C-12 38.5, C-13 41.8, C-14 54.7, C-15 33.0, C-16 82.8, C-17
9.2, C-18 13.8, C-19 23.3, C-20 36.1, C-21 18.0, C-22 181.3, CH3
acetyl 21.4, C O acetyl 170.5.
23R,25R)-3␣-acetoxy-16,23:23,26-diepoxy-5-cholestan-
(23R,25S)-3-acetoxy-16,23:23,26-diepoxy-5-cholestan-
22-one (4b) obtained following the procedure described in Ref. [24].
◦
1
Mp.: 169–171 C. H NMR (400 MHz, CDCl ): 5.04 (m, 1H, H-3), 4.34
3
(
(ddd, J = 8.1, 8.1, 6.4 Hz, 1H, H-16), 4.11 (dd, J = 7.7, 7.7 Hz, 1H, H-26
Pro-R), 3.60 (dd, J = 7.9, 7.9 Hz, 1H, H-26 Pro-S), 2.74 (dq, J = 9.8,
6.4 Hz, 1H, H-20), 2.55 (m, 1H, H-25), 2.02 (s, 3H, CH3 acetyl), 1.07
(d, J = 6.4 Hz, 3H, H-21), 1.03 (d, J = 6.7 Hz, 3H, H-27), 0.97 (s, 3H,
◦
2
(
1
2-one (4a) obtained as described in Ref. [28]. Mp.: 184–186 C
from ethyl acetate-hexane). 1H NMR: (300 MHz, CDCl ): 4.71 (m,
3
H, H-3); 4.36 (ddd, 1H, J = 6.3, 8.1, 8.1 Hz, 1H, H-16); 4.13 (dd, 1H,
J = 7.6, 7.6 Hz, H-26 Pro-S); 3.54 (dd, 1H, J = 8.2, 9.0 Hz, H-26 Pro-R);
1
3
H-19), 0.93 (s, 3H, H-18). C NMR (100 MHz, CDCl ): C-1 30.5, C-2
3
2
1
6
2
4
3
1
.79 (m, 1H, H-20); 2.41 (m, 1H, H-25); 2.01 (s, 3H, CH3 acetyl);
24.9, C-3 70.5, C-4 30.6, C-5 37.2, C-6 26.3, C-7 26.3, C-8 35.2, C-9
40.5, C-10 34.9, C-11 20.9, C-12 40.1, C-13 42.9, C-14 53.1, C-15
32.8, C-16 72.1, C-17 57.4, C-18 14.7, C-19 23.8, C-20 39.8, C-21
13.0, C-22 213.2, C-23 107.6, C-24 44.3, C-25 32.7, C-26 76.1, C-27
17.0, CH3 acetyl 21.5, C O acetyl 170.7.
.08 (d, 3H, J = 6.4 Hz, H-21); 1.05 (d, 3H, J = 6.7 Hz, H-27); 0.95 (s,
H, H-18 and H-19). 13CNMR: (75.5 MHz, CDCl ): C-1 35.0; C-2
3
6.5; C-3 74.2; C-4 32.9; C-5 41.8; C-6 26.6; C-7 26.9; C-8 35.5; C-9
0.5; C-10 34.6; C-11 20.7; C-12 40.1; C-13 43.0; C-14 53.2; C-15
2.2; C-16 72.9; C-17 57.7; C-18 14.7; C-19 23.3; C-20 39.9; C-21
2.9; C-22 213.1; C-23 107.9; C-24 43.9; C-25 33.4; C-26 75.3;
When the rearranged ketone (4b) (50 mg, 0.11 mmol) was sub-
mitted to the BF ·Et O-catalyzed BV reaction procedure for 10 min
3
2
C-27 16.5; CH3 acetyl 21.4; C O acetyl 170.6.
the pure lactone 2b (27.2 mg, 0.07 mmol, 63.6%) was produced.
When the rearranged ketone (4a) (50 mg, 0.11 mmol) was sub-
mitted to the BF ·Et O-catalyzed BV reaction for 10 min, the pure
3
2
2.1. Isomerization experiments
lactone 2a (38.9 mg, 0.10 mmol, 90.9%) was produced.
(
25S)-3-acetoxy-5-spirostan-23-one 23-oxosarsasapogenin
BF ·Et O (0.2 mL, 1.6 mmol) was added to a solution of 23-oxo-
3
2
◦
1
acetate (1b) obtained as described in Ref. [31]. Mp.: 168–170 C.
NMR: (300 MHz, CDCl ): 5.06 (m, 1H. H-3), 4.61 (m, 1H, H-16), 4.26
dd, J = 11.2, 2.9 Hz, 1H, H-26 Pro-R), 3.42 (ddd, J = 11.1, 2.1, 2.1 Hz,
H, H-26 Pro-S), 2.89 (m, 1H, H-20), 2.38 (m, 1H, H-25), 2.04 (s, 3H,
CH3 acetyl), 1.07 (d, J = 7.1 Hz, 3H, H-21), 0.98 (s, 3H, H-19), 0.95 (d,
J = 7.0 Hz, 3H, H-27), 0.77 (s, 3H, H-18). C NMR (75.5 MHz, CDCl ):
C-1 30.6, C-2 25.0, C-3 70.7, C-4 30.7, C-5 37.3, C-6 26.4, C-7 26.4,
C-8 35.3, C-9 40.0, C-10 35.0, C-11 20.8, C-12 40.0, C-13 41.2, C-14
6.5, C-15 31.7, C-16 83.6, C-17 61.8, C-18 16.2, C-19 23.9, C-20
5.1, C-21 14.2, C-22 110.7, C-23 202.4, C-24 43.9, C-25 33.7, C-26
4.6, C-27 17.7, CH3 acetyl 21.5, C O acetyl 170.7.
H
3-epismilagenin acetate (1a) (50 mg, 0.11 mmol) in CH Cl (5 mL)
2 2
3
and the solution was stirred for 10 min before addition of water
(
1
(20 mL) and dilution with CH Cl2 (20 mL). The organic layer was
2
washed with water (3 × 25 mL), dried (anh. Na SO ) and evapo-
2
4
rated to afford a 1/3.4 mixture of 1a and 4a (ratio determined by
relative integration of H-26 Pro-R of 1a y H-26 Pro-S of 4a, see Fig. 1
and Supplementary information).
13
3
When the rearranged ketone 4a was submitted to the same pro-
cedure, a 1/2.45 mixture of 1a and 4a was obtained (ratio determined
as described for 1a, see Supplementary information).
When 23-oxosarsasapogenin acetate (1b) was submitted to the
same procedure a 1/10.37 mixture of 1b and 4b was obtained (ratio
determined by relative integration of the H-26 Pro-S of 1b and 4b, see
Fig. 1 and Supplementary information).
When the rearranged ketone 4b was submitted to the same
procedure a 1/9.79 mixture of 1b and 4b was obtained (ratio deter-
mined by relative integration of the H-26 Pro-S of 1b and 4b, see
Supplementary information).
5
3
6
When 23-oxosarsasapogenin acetate (1b) (50 mg, 0.11 mmol)
was submitted to the BF ·Et O-catalyzed BV reaction proce-
3
2
dure for 10 min the pure lactone 2b (31.7 mg, 0.08 mmol, 72.7%)
was produced. 3-Acetoxy-16-hydroxy-5-bisnorcholanoic acid
1
2
(
1
2 → 16 lactone (2b) identical as described in Ref. [31]. H NMR:
300 MHz, CDCl ): 5.05 (m, 1H, H-3), 4.93 (ddd, J = 7.7, 7.7, 4.6 Hz,
3
H, H-16), 2.56 (m, 1H, H-20), 2.03 (s, 3H, CH3 acetyl), 1.30 (d,
Fig. 1. Relative integration of the H-26 Pro-S (4a) and H-26 Pro-R (1a) signals.