Synthesis of (25R)-26-hydroxy-15-ketosterols

Article abstract of DOI:10.1016/S0039-128X(99)00065-3

(25R)-3β,26-Dihydroxy-5α-cholest-8(14)-en-15-one (1) and (25R)-3β,26- dihydroxy-5α,14β-cholest-16-en-15-one (2) were synthesized from (25R)- 3β,26-dibenzoyloxy-5α,14α-cholest-16-ene (4). Oxidation of 4 with CrO₃- 3,5-dimethylpyrazole at -20°C g

Full text of DOI:10.1016/S0039-128X(99)00065-3

Steroids 64 (1999) 844–848
Synthesis of (25R)-26-hydroxy-15-ketosterols૾
Hong-Seok Kim*, Dong-Il Kim1
Department of Industrial Chemistry, Kyungpook National University, 1370 Sankyuk-dong, Pook-Ku, Taegu 702-701, South Korea
Received 9 November 1998; received in revised form 30 April 1999; accepted 5 May 1999
Abstract
(25R)-3␤,26-Dihydroxy-5␣-cholest-8(14)-en-15-one (1) and (25R)-3␤,26-dihydroxy-5␣,14␤-cholest-16-en-15-one (2) were synthesized
from (25R)-3␤,26-dibenzoyloxy-5␣,14␣-cholest-16-ene (4). Oxidation of 4 with CrO3-3,5-dimethylpyrazole at Ϫ20°C gave (25R)-3␤,26-
dibenzoyloxy-5␣,14␣-cholest-16-en-15-one (5) along with (25R)-3␤,26-dibenzoyloxy-5␣-cholest-16␣,17␣-epoxide (6). Oxidation of 5 with
selenium dioxide afforded (25R)-3␤,26-dibenzoyloxy-5␣-cholest-8(14),16-dien-15-one (7) and (25R)-3␤,26-dibenzoyloxy-5␣,14␤-cholest-
16-en-15-one (8). Selective hydrogenation of 7 followed by hydrolysis in alcoholic potassium hydroxide yielded (25R)-3␤,26-dihydroxy-
5␣-cholest-8(14)-en-15-one (1). Hydrolysis of 5 and 8 in alcoholic potassium hydroxide provided (25R)-3␤,26-dihydroxy-5␣,14␤-cholest-
16-en-15-one (2). © 1999 Elsevier Science Inc. All rights reserved.
Keywords: 15-Ketosterol; Allylic oxidation; Selenium dioxide; Selective hydrogenation; Hydrolysis
1. Introduction
ity to 1, the difference lying in the position of the double
bond.
(25R)-3␤,26-Dihydroxy-5␣-cholest-8(14)-en-15-one (1)
has been shown to be a major metabolite of 3␤-hydroxy-
5␣-cholest-8(14)-en-15-one (3) after incubation with rat
liver mitochondria [1,2] (Fig. 1). Thus, 1, a major mito-
chondrial metabolite of 3, was found to be highly active in
the suppression of 3-hydroxy-3-methylglutaryl coenzyme A
reductase in cultured mammalian cells and in inhibiting
oleoyl coenzyme A-dependent esterification of cholesterol
in jejunal microsomes [2]. In continuation of our interest in
the synthesis of 15-ketosterols, we investigated an alterna-
tive synthesis of 1. Although compound 1 has already been
synthesized from 3␤,26-dibenzoyloxy-5␣-cholest-8(14)-
ene[2] and 3␤,26-diacetoxy-5␣-cholest-8,14-diene [3], this
compound and its analog 2 are needed for biological eval-
uation. Herein, we wish to report the synthesis of two
(25R)-26-hydroxy-15-ketosterols, 1 and 2, from the same
starting material, 4. Sterol 2 shows close structural similar-
2. Experimental
Melting points were measured by using a Thomas–
Hoover (Thomas Scientific, USA) melting point appara-
tus and are uncorrected. IR spectra were recorded on a
Matton GL-6030E spectrophotometer. Ultraviolet (UV)
spectra were determined in methanol on a Shimadzu
(Shimadzu Scientific Instrument, Kyoto, Japan) UV-2100
spectrophotometer. 1H and 13C NMR spectra were re-
corded on a Bruker AM-300 instrument (Bruker, Bil-
lerica, MA, USA); unless otherwise stated, all NMR were
1
performed in CDCl3 solution. The chemical shifts of H
NMR spectra are given in ppm downfield from tetram-
ethylsilane, and 13C NMR spectra were referenced to
CDCl3 at 77.0 ppm. H and 13C NMR assignments were
1
made from distortionless enhancement by polarization
(DEPT), 1H-1H shift-correlated 2D NMR (COSY),
13C-1H shift-correlated 2D NMR (HETCOR), and by
comparison with spectra of similar sterols [2,3]. Low-
resolution MS were recorded on a Shimadzu QP-1000
spectrometer with electron energy of 70 eV and direct
sample introduction. High-resolution MS were measured
on a JEOL KMS-DX 303 spectrometer. Elemental anal-
* Corresponding author. Tel.: ϩ82-53-950-5588; fax: ϩ82-53-950-
6594.
E-mail address: kimhs@kyungpook.ac.kr (H.-S. Kim)
૾Dedicated to the memory of Prof. George J. Schroepfer Jr., who died
December 11, 1998.
1 Present address: Household & Personal Care Products R&D Institute,
LG Chem./Research Park (W), Taejon, Korea.
0039-128X/99/$ – see front matter © 1999 Elsevier Science Inc. All rights reserved.
PII: S0039-128X(99)00065-3

H.-S. Kim, D.-I. Kim / Steroids 64 (1999) 844–848
845
Fig. 1. Structures of 3␤,26-dihydroxy-5␣-cholest-8(14)-en-15-one (1), 3␤,26-dihydroxy-5␣,14␤-cholest-16-en-15-one (2), and 3␤-hydroxy-5␣-cholest-8(14)-
en-15-one (3).
yses were performed by CSI at Kyungpook National
University. TLC analyses were performed on precoated
0.2 mm HPTLC silica gel 60 plates (Merck, Darmstadt,
Germany); substances were visualized by spraying with
5% ammonium molybdate in 10% H2SO4 followed by
heating. Radial chromatography was performed on a Har-
rison chromatotron (Harrison Research, Palo Alto, CA,
USA), by using Merck silica gel 60 PF254. For routine
column chromatography, Merck silica gel (70–230 mesh)
was used as an adsorbent. Solvents were distilled before
use and were dried, as necessary, by procedures in the
literature [4]. Solutions were dried over anhydrous so-
dium sulfate. 3,5-Dimethylpyrazole (3,5-DMP), CrO3,
imidazole, and SeO2 were purchased from Aldrich (Mil-
waukee, WI, USA) and used as received. Preparation of
(25R)-3␤,26-dibenzoyloxy-5␣-cholest-16-ene 4 will be
described elsewhere.
s, 18-CH3), 0.778 (3H, s, 19-CH3); 13C NMR: ␦ 166.6
and 166.0 (C ϭ O), 132.8 and 132.6 (C4 of Ph), 131.0
and 130.5 (C1 of Ph), 129.5 (C2 of Ph), 128.3 and 128.2
(C3 of Ph), 74.2 (C-3), 73.4 (C-17), 69.7 (C-26), 60.0
(C-16), 54.6 (C-9), 45.0 (C-14), 44.8 (C-5), 42.6 (C-13),
36.7 (C-11), 35.7 (C-10), 35.7 (C-1), 34.1 (C-8), 33.9
(C-22), 33.7 (C-4), 33.5 (C-24), 33.0 (C-25), 31.6 (C-15),
29.2 (C-20), 28.5 (C-7), 27.5 (C-6), 27.4 (C-2), 24.9
(C-23), 20.9 (C-11), 17.0 (C-21), 16.9 (C-27), 16.1 (C-
18), 12.2 (C-19); MS m/z: 626 (38, Mϩ), 611 (6, M-CH3),
608 (5, M-H2O), 504 (23, M-C6H5CO2H), 489 (11,
M-C6H5CO2H-CH3), 486 (8, M-C6H5CO2H-H2O), 393
(79, M-SC), 367 (10, M-2C6H5CO2H-CH3), 271 (16,
M-SC-C6H5CO2H), 253 (11, M-SC-C6H5CO2H-H2O);
high-resolution MS m/z: 626.4004 for C41H54O5 requires
626.3971. Anal. Calcd for C41H54O5: C, 78.56; H, 8.68;
Found C, 78.40; H, 8.72.
Further elution with the same solvent gave 5 (148 mg,
0.24 mmol, 49%) as a white solid. m.p. 49.5–50.5°C
(dichloromethane-methanol). Single component on TLC
in two solvent systems: Rf 0.45 (ethyl acetate/hexane
1:4), 0.24 (ethyl acetate/hexane 1:9). FT-IR (KBr): 2937,
2.1. (25R)-3␤,26-Dibenzoyloxy-5␣,14␣-cholest-16-en-15-
one (5)
3,5-Dimethylpyrazole (1.34 g, 13.97 mmol) was added
to a suspension of chromium trioxide (1.40 g, 13.97
mmol) in dry CH2Cl2 (5 ml) at Ϫ20°C under nitrogen,
and the resulting mixture was stirred at Ϫ20°C for 30
min. A solution of 4 (300 mg, 0.49 mmol) in dry CH2Cl2
(2 ml) was added to the dark red solution. The resulting
mixture was stirred at Ϫ20°C for 1 h. A 5 N sodium
hydroxide solution (2 ml) was subsequently added to the
reaction mixture and stirred at 0°C for 30 min. The
resulting mixture was extracted twice with ethyl acetate
(30 ml), and the extracts were washed sequentially with
10% HCl and water and then dried. The solvent was
evaporated, and the crude product was chromatographed
on silica gel (ethyl acetate/hexane 5:95, v/v). The first
fraction gave (25R)-3␤,26-dibenzoyloxy-5␣,14␣-cho-
lest-16␣,17␣-epoxide (6) (76 mg, 0.12 mmol, 24%). m.p.
120.5–121.5°C (dichloromethane-methanol). Single
component on TLC in two solvent systems: Rf 0.63 (ethyl
acetate/hexane 1:4), 0.43 (ethyl acetate/hexane 1:9).
FT-IR (KBr): 2937, 2859, 1717, 1454, 1273, 1111, 714
1
2859, 1713, 1455, 1273, 1107, 710 cmϪ1; H NMR: ␦
8.03 (2H, m, o of Ph), 7.26–7.57 (3H, m, m, p of Ph),
5.62 (1H, s, 16-H), 4.95 (1H, m, 3␣-H), 4.19 (1H, dd, J ϭ
10.5, 6.0 Hz, 26-Ha), 4.12 (1H, dd, J ϭ 10.5, 6.5 Hz,
26-Hb), 2.74 (1H, d, J ϭ 12.9 Hz, 7␤-H), 2.42 (1H, q, J ϭ
6.8 Hz, 20-H), 1.105 (3H, d, J ϭ 6.7 Hz, 21-CH3), 1.009
(3H, d, J ϭ 6.8 Hz, 27-CH3), 0.993 (3H, s, 18-CH3),
0.927 (3H, s, 19-CH3); 13C NMR: ␦ 207.5 (C-15), 188.3
(C-17), 166.5 and 166.0 (C ϭ O), 132.8 and 132.6 (C4 of
Ph), 130.9 and 130.5 (C1 of Ph), 129.5 (C2 of Ph), 128.3
and 128.2 (C3 of Ph), 124.4 (C-16), 74.0 (C-3), 69.6
(C-26), 63.8 (C-14), 54.9 (C-9), 47.0 (C-13), 44.9 (C-5),
36.6 (C-12), 36.2 (C-1), 35.9 (C-10), 34.0 (C-4), 33.5
(C-24), 33.1 (C-8), 32.7 (C-22), 32.6 (C-25), 32.4 (C-20),
30.4 (C-7), 28.2 (C-6), 27.5 (C-2), 24.9 (C-23), 23.6
(C-21), 21.2 (C-18), 20.5 (C-11), 16.9 (C-27), 12.3 (C-
19); UV ␭max: 229 nm (log ⑀ 4.19); MS m/z: 624 (65, Mϩ),
609 (9, M-CH3), 606 (2, M-H2O), 502 (53, M-C6H5CO2H),
487 (10, M-C6H5CO2H-CH3), 484 (2, M-C6H5CO2H-H2O),
391 (6, M-SC), 365 (4, M-2C6H5CO2H-CH3), 269 (13,
M-SC-C6H5CO2H), 251 (3, M-SC-C6H5CO2H-H2O); high-
resolution MS m/z: 624.3792 for C41H52O5 requires
624.3814. Anal. Calcd for C41H52O5: C, 78.81; H, 8.39;
Found C, 78.54; H, 8.30.
1
cmϪ1; H NMR: ␦ 8.03 (2H, m, o of Ph), 7.25–7.57 (3H,
m, m, p of Ph), 4.93 (1H, m, 3␣-H), 4.19 (1H, dd, J ϭ
10.7, 6.0 Hz, 26-Ha), 4.12 (1H, dd, J ϭ 10.7, 6.5 Hz,
26-Hb), 3.25 (1H, s, 16␤-H), 1.013 (3H, d, J ϭ 6.8 Hz,
21-CH3), 0.908 (3H, d, J ϭ 6.8 Hz, 27-CH3), 0.874 (3H,

846
H.-S. Kim, D.-I. Kim / Steroids 64 (1999) 844–848
2.2. (25R)-3␤,26-Dibenzoyloxy-5␣-cholest-8(14),16-dien-
15-one (7)
19.7 (C-11), 16.9 (C-27), 12.8 (C-19); UV ␭max: 203 nm
(log ⑀ 4.26), 229 nm (log ⑀ 4.49), 265 nm (log ⑀ 4.23); MS
m/z: 622 (100, Mϩ), 607 (3, M-CH3), 500 (21,
M-C6H5CO2H), 485 (12, M-C6H5CO2H-CH3), 389 (4,
M-SC), 363 (3, M-2C6H5CO2H-CH3), 267 (6, M-SC-
C6H5CO2H); high-resolution MS m/z: 622.3682 for
C41H50O5 requires 622.3658. Anal. Calcd for C41H50O5: C,
79.07; H, 8.09; Found C, 79.46; H, 8.21.
A mixture of 5 (98 mg, 0.157 mmol) and selenium oxide
(87 mg, 0.78 mmol) in 2-methyl-2-propanol (5 ml) was
refluxed for 5 h under nitrogen. After removal of insoluble
material by filtration through a pad of celite, the filtrate was
diluted with water (20 ml) and extracted with ethyl acetate
(30 ml). The combined extracts were washed with brine,
dried, and concentrated to give a yellow residue (109 mg).
The crude product was chromatographed on silica gel (ethyl
acetate/hexane 1:4). The first fraction gave 3␤,26-dibenzoy-
loxy-5␣,14␤-cholest-16-en-15-one (8) (22 mg, 0.035 mmol,
22%) as a viscous oil. Single component on TLC in two
solvent systems: Rf 0.41 (ethyl acetate/hexane 1:4), 0.24
(ethyl acetate/hexane 1:9). IR (neat): 2933, 2867, 1717,
1609, 1455, 1316, 1273, 1111, 713 cmϪ1; 1H NMR: ␦ 8.03
(2H, m, o of Ph), 7.26–7.58 (3H, m, m, p of Ph), 5.93 (1H,
16-H), 4.92 (1H, m, 3␣-H), 4.19 (1H, dd, J ϭ 10.7, 6.0 Hz,
26-Ha), 4.11 (1H, dd, J ϭ 10.7, 6.4 Hz, 26-Hb), 2.36 (1H, q,
J ϭ 6.6 Hz, 20-H), 2.33 (1H, 7␤-H), 1.181 (3H, s, 18-CH3),
1.106 (3H, d, J ϭ 6.7 Hz, 21-CH3), 1.016 (3H, d, J ϭ 6.8
Hz, 27-CH3), 0.839 (3H, s, 19-CH3); 13C NMR: ␦ 210.3
(C-15), 191.6 (C-17), 166.6 and 166.0 (CϭO), 132.8 and
132.6 (C4 of Ph), 131.0 and 130.5 (C1 of Ph), 129.5 (C2 of
Ph), 128.5 (C-16), 128.3 and 128.2 (C3 of Ph), 74.2 (C-3),
69.7 (C-26), 57.2 (C-14), 48.4 (C-13), 44.6 (C-5), 44.0
(C-9), 38.1 (C-12), 36.8 (C-10), 36.1 (C-1), 34.0 (C-8), 34.0
(C-4), 33.9 (C-22), 33.5 (C-24), 32.7 (C-25), 32.6 (C-20),
29.7 (C-6), 28.9 (C-7), 27.2 (C-2), 24.9 (C-23), 24.3 (C-18),
21.1 (C-21), 19.2 (C-11), 16.9 (C-27), 10.9 (C-19); MS m/z:
624 (3, Mϩ), 502 (17, M-C6H5CO2H), 487 (6,
M-C6H5CO2H-CH3), 391 (3, M-SC), 365 (2,
M-2C6H5CO2H-CH3), 269 (8, M-SC-C6H5CO2H), 251 (2,
M-SC-C6H5CO2H-H2O), 105 (100); high-resolution MS
m/z: 624.3841 for C41H52O5 requires 624.3814.
Further elution with the same solvent gave 7 (44 mg,
0.071 mmol, 45%) as a white solid. m.p. 158–159°C (di-
chloromethane-methanol). Single component on TLC in
two solvent systems: Rf 0.38 (ethyl acetate/hexane 1:4),
0.16 (ethyl acetate/hexane 1:9). FT-IR (KBr): 2944, 2867,
1717, 1679, 1636, 1601, 1451, 1316, 1277, 1176, 1111, 714
cmϪ1; 1H NMR: ␦ 8.03 (2H, m, o of Ph), 7.26–7.58 (3H, m,
m, p of Ph), 5.93 (1H, 16-H), 5.00 (1H, m, 3␣-H), 4.19 (1H,
dd, J ϭ 10.7, 5.9 Hz, 26-Ha), 4.12 (1H, dd, J ϭ 10.7, 6.3 Hz,
26-Hb), 4.08 (1H, dd, J ϭ 9.9, 2.0 Hz, 7␤-H), 2.39 (1H, q,
J ϭ 6.8 Hz, 20-H), 1.155 (3H, s, 18-CH3), 1.102 (3H, d, J ϭ
6.8 Hz, 21-CH3), 1.013 (3H, d, J ϭ 6.8 Hz, 27-CH3), 0.856
(3H, s, 19-CH3); 13C NMR: ␦ 197.3 (C-15), 186.5 (C-17),
166.6 and 166.0 (CϭO), 145.2 (C-8), 137.9 (C-14), 132.8
and 132.7 (C4 of Ph), 130.8 and 130.5 (C1 of Ph), 129.5 (C2
of Ph), 128.3 and 128.2 (C3 of Ph), 127.5 (C-16), 73.8
(C-3), 69.7 (C-26), 51.2 (C-9), 45.4 (C-13), 44.4 (C-5), 38.9
(C-10), 37.0 (C-12), 36.2 (C-1), 33.7 (C-4), 33.7 (C-22),
33.5 (C-24), 32.8 (C-25), 32.6 (C-20), 30.5 (C-7), 29.3
(C-6), 27.4 (C-2), 25.0 (C-23), 24.8 (C-21), 21.7 (C-18),
2.3. (25R)-3␤,26-Dibenzoyloxy-5␣-cholest-8(14)-en-15-
one (9)
Compound 7 (50 mg, 0.080 mmol) was dissolved in
ethyl acetate (5 ml) and hydrogenated at 1 atmosphere of H2
at room temperature for 3 h in the presence of 5% Pt/C (25
mg). After removal of insoluble material by filtration
through a short pad of celite, the solvent was evaporated to
give a solid, which was chromatographed on silica gel (ethyl
acetate/hexane 1:5) and yielded a white solid 9 (36 mg,
0.058 mmol, 73%). m.p. 165–166°C (dichloromethane-
methanol). Single component on TLC in two solvent sys-
tems: Rf 0.52 (ethyl acetate/hexane 1:4), 0.32 (ethyl acetate/
hexane 1:9). FT-IR (KBr): 2937, 2871, 1713, 1621, 1455,
1277, 1176, 1115, 714 cmϪ1; 1H NMR: ␦ 8.03 (2H, m, o of
Ph), 7.26–7.58 (3H, m, m, p of Ph), 4.99 (1H, m, 3␣-H),
4.21 (1H, dd, J ϭ 10.7, 5.9 Hz, 26-Ha), 4.12 (1H, dd, J ϭ
10.7, 6.5 Hz, 26-Hb), 4.15 (1H, d, J ϭ 16.4 Hz, 7␤-H),
1.021 (3H, d, J ϭ 6.6 Hz, 21-CH3), 1.013 (3H, d, J ϭ 6.7
Hz, 27-CH3), 0.983 (3H, s, 18-CH3), 0.784 (3H, s, 19-CH3);
13C NMR: ␦ 207.8 (C-15), 166.6 and 166.1 (CϭO), 150.2
(C-8), 140.4 (C-14), 132.8 and 132.7 (C4 of Ph), 130.8 and
130.5 (C1 of Ph), 129.5 (C2 of Ph), 128.3 and 128.2 (C3 of
Ph), 73.8 (C-3), 69.8 (C-26), 50.9 (C-9), 50.8 (C-17), 44.1
(C-5), 42.6 (C-13), 42.4 (C-16), 38.8 (C-10), 37.0 (C-12),
36.4 (C-1), 35.8 (C-22), 34.5 (C-20), 33.9 (C-4), 33.8 (C-
24), 32.7 (C-25), 29.1 (C-6), 27.6 (C-7), 27.4 (C-2), 23.2
(C-23), 19.6 (C-11), 19.2 (C-21), 18.8 (C-18), 17.0 (C-27),
12.9 (C-19); UV ␭max: 202 nm (log ⑀ 4.14), 229 nm (log ⑀
4.47), 259 nm (log ⑀ 4.25); MS m/z: 624 (100, Mϩ), 609 (2,
M-CH3), 606 (5, M-H2O), 502 (22, M-C6H5CO2H), 487
(13, M-C6H5CO2H-CH3), 484 (3, M-C6H5CO2H-H2O), 391
(2, M-SC), 365 (9, M-2C6H5CO2H-CH3), 269 (4, M-SC-
C6H5CO2H), 251 (10, M-SC-C6H5CO2H-H2O); high-reso-
lution MS m/z: 624.3843 for C41H52O5 requires 624.3814.
Anal. Calcd for C41H52O5: C, 78.81; H, 8.39; Found C,
78.80; H, 8.30.
2.4. (25R)-3␤,26-Dihydroxy-5␣-cholest-8(14)-en-15-one
(1)
Compound 9 (118 mg, 0.189 mmol) in 1 M 95% ethan-
olic potassium hydroxide solution (10 ml) was refluxed for
10 min. The reaction mixture was diluted with water (30 ml)
and then extracted with chloroform (30 ml). The combined
extracts were washed sequentially with 2% HCl and water,
dried, and concentrated to give a solid residue (75 mg),

H.-S. Kim, D.-I. Kim / Steroids 64 (1999) 844–848
847
which was further purified with chromatotron (1 mm thick
disk, ethyl acetate/hexane 3:7) and afforded a white solid 1
(71 mg, 0.171 mmol, 90%). m.p. 197–198°C (H2O-metha-
nol) (lit. [2] 197–198°C). Single component on TLC in three
solvent systems: Rf 0.30 (ethyl acetate/hexane 1:1), 0.22
(ethyl acetate/hexane/chloroform 4:3:3), 0.25 (diethyl ether/
benzene 1:1); MS m/z: 416 (100, M); high-resolution MS
m/z: 416.3318 for C27H44O3 requires 416.3290.
ecule by introduction of the required functionality in the C
and D rings via allylic oxidation of ⌬16.
The synthesis of 1 described in this report is based on the
well-established synthesis of the parent 15-ketosterol 3 from
5␣-cholest-16-ene [6,7]. This route consists of allylic oxi-
dation to ⌬16-15-one, formation of the ⌬8(14),16-15-one, se-
lective hydrogenation of ⌬16, and hydrolysis to the desired
15-ketosterol (Scheme 1). Thus, allylic oxidation of the
2.5. (25R)-3␤,26-Dihydroxy-5␣,14␤-cholest-16-en-15-one
(2)
Compound 5 (39 mg, 0.063 mmol) in 1 M 95% ethanolic
potassium hydroxide solution (5 ml) was refluxed for 10
min. The reaction mixture was diluted with water (20 ml)
and then extracted with ethyl acetate (20 ml). The combined
extracts were washed sequentially with 2% HCl and water,
dried, and concentrated to give a viscous residue, which was
further purified with chromatotron (1 mm thick disk, ethyl
acetate/hexane 1:2) and afforded a viscous oil 2 (25 mg,
0.060 mmol, 95%). Single component on TLC in two sol-
vent systems: Rf 0.40 (ethyl acetate/hexane 2:1), 0.15 (di-
ethyl ether/benzene 3:1). FT-IR (CHCl3): 3401, 2937, 1685,
1
1453, 1376, 1268, 1051 cmϪ1; H NMR: ␦ 5.92 (1H, s,
16-H), 3.55 (1H, m, 3␣-H), 3.47 (1H, dd, J ϭ 10.5, 6.0 Hz,
26-Ha), 3.40 (1H, dd, J ϭ 10.5, 6.3 Hz, 26-Hb), 1.184 (3H,
s, 18-CH3), 1.095 (3H, d, J ϭ 6.8 Hz, 21-CH3), 0.901 (3H,
d, J ϭ 6.6 Hz, 27-CH3), 0.769 (3H, s, 19-CH3); 13C NMR:
␦ 211.1 (C-15), 192.4 (C-17), 128.2 (C-16), 70.1 (C-3), 68.0
(C-26), 57.1 (C-14), 48.3 (C-13), 44.5 (C-5), 44.0 (C-9),
38.0 (C-12), 37.9 (C-4), 36.7 (C-10), 36.6 (C-22), 36.1
(C-1), 35.5 (C-25), 33.8 (C-8), 33.1 (C-24), 32.3 (C-20),
30.8 (C-2), 29.6 (C-6), 28.9 (C-7), 24.9 (C-23), 24.3 (C-18),
20.9 (C-21), 19.0 (C-11), 16.5 (C-27), 10.8 (C-19); MS m/z:
416 (4, Mϩ), 288 (100, M-SC), 269 (13), 105 (22), 91 (25),
69 (51), 55 (55); high-resolution MS m/z: 416.3287 for
C27H44O3 requires 416.3290.
Scheme 1. Synthetic scheme for the preparation of 3␤,26-dihydroxy-5␣-
cholest-8(14)-en-15-one (1) and 3␤,26-dihydroxy-5␣,14␤-cholest-16-en-
15-one (2).
5␣-⌬16 4 with CrO3-3,5-dimethylpyrazole in dichlorometh-
ane at Ϫ20°C gave a white solid 14␣-⌬16-15-one 5 along
with the 16␣,17␣-epoxide 6 in a 2:1 ratio. Compound 5
shows IR (1713 cmϪ1) and UV [␭max 229 nm (log ⑀ 4.19)]
absorptions characteristic of ⌬16-15-one functionality. Due
to the deshielding by the carbonyl group at the 15 position,
Compound 8 (12 mg, 0.019 mmol) in 1 M 95% eth-
anolic potassium hydroxide solution (3 ml) when reacted
similarly provided 2 (6.4 mg, 0.015 mmol, 79%) as a
viscous oil.
1
the H NMR signal of 7␤-H appears at ␦ 2.74.
Selenium dioxide oxidation of 14␣-⌬16-15-one 5 in
2-methyl-2-propanol yielded products that were a mixture
of ⌬8(14),16-15-one 7 (45%) and a viscous oil 14␤-⌬16-15-
one 7 (22%), which were isolated by silica gel chromatog-
raphy. Oxidized compound 5 was easily isomerized to 8.
The 14-H configurations of compounds 5 and 8 were deter-
mined based on 13C NMR data: i.e. the chemical shift of
18-CH3 for 5 was at ␦ 21.2, and that for 8 was at ␦ 24.3.
These values are in good agreement with those reported for
the corresponding compound [6,7]. Some characteristic fea-
tures of compound 7 included the appearance of infrared
stretching bands at 1679 and 1636 cmϪ1 for the conjugated
carbonyl group as well as the 13C NMR peaks at ␦ 197.3,
186.5, 145.2, 137.9, and 127.5 assignable to C-15, 17, 8, 14,
and 16 atoms, respectively. The addition of the double bond
3. Results and discussion
Our interest in the side chain (25R)-26-hydroxy group in
compound 1 and 2 led us to choose (25R)-3␤,26-dibenzoy-
loxy-5␣-cholest-16-ene 4 as our starting compound. This
compound has a quite similar, yet slightly modified struc-
ture compared with 1 and 2. The synthesis of 1 and 2
involved the Clemmensen reduction of diosgenin, hydroge-
nation of ⌬5 of the resulting cholest-5-ene-3␤,16␤,26-triol,
selective protection of the 3␤,26-hydroxyl groups, and the
elimination of the 16-hydroxyl group [5]. The resulting
compound, in turn, may be transformed to our target mol-

848
H.-S. Kim, D.-I. Kim / Steroids 64 (1999) 844–848
in 7 was confirmed by the bathochromic shift found in 7
(␭max 265 nm; log ⑀ 4.23) compared with that in 5 (␭max 229
nm; log ⑀ 4.19).
In summary, in this work, we prepared two (25R)-26-
hydroxy-15-ketosterols. Studies on the biologic activities of
1 and 2 are now in progress.
Catalytic hydrogenation of ⌬8(14),16-15-one 7 with 5%
platinum on carbon under one atmospheric pressure of hy-
drogen resulted in ⌬8(14)-15-one 9 in 73% yield. Confirma-
tion of the 17-H configuration of the latter was made by
comparing the 13C NMR spectrum with that of the value
reported in the literature [6,7]. The hydrogenation preferen-
tially took place in the less-hindered ␣-direction. Various
spectroscopic data were consistent with the structure of 9.
For instance, 1H NMR showed one deshielded 7␤-proton at
␦ 4.15, and two olefinic carbons appeared at ␦ 140.4 (C-14)
and 150.2 (C-8) on 13C NMR spectrum. The absorption at
259 nm (log ⑀ 4.25) confirms the existence of ⌬8(14)-15-one.
The mass spectrum also revealed a peak at m/z 624 corre-
sponding to the molecular ion.
Acknowledgment
This work was supported by the Center for Biofunctional
Molecules.
References
[1] Schroepfer GJ Jr, Kim HS, Vermilion JL, Stephens TW, Pinkerton
FD, Needleman DK, Wilson WK, St. Pyrek J. Enzymatic formation
and chemical synthesis of an active metabolite of 3␤-hydroxy-5␣-
cholest-8(14)-en-15-one, a potent regulator of cholesterol metabo-
lism. Biochem Biophys Res Commun 1988;151:130–6.
[2] Kim HS, Wilson WK, Needleman DH, Pinkerton FD, Wilson DK,
Quiocho FA, Schroepfer GJ Jr. Inhibitors of sterol synthesis: chem-
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[3] Siddiqui AU, Wilson WK, Schroepfer GJ Jr. Inhibitors of sterol
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solution gave 3␤,26-dihydroxy-5␣-cholest-8(14)-en-15-one
1 in 90% yield. The structure and stereochemistry of 1 were
1
confirmed by comparing the H, 13C NMR, and MS values
reported in the literature [2,3].
To obtain (25R)-3␤,26-dihydroxy-5␣,14␣-cholest-16-
en-15-one, compound 5 was hydrolyzed in 1 M ethanolic
potassium hydroxide solution giving (25R)-3␤,26-dihy-
droxy-5␣,14␤-cholest-16-en-15-one (2) in 95% yield. Un-
der basic conditions, 14␣-H in 5 easily epimerized to
14␤-H. Confirmation of the 14␤ configuration of 2 was
made by comparing the 13C NMR spectrum with that of
compound 8. The chemical shifts of 18-CH3 for both 2 and
8 appeared at exactly same position, ␦ 24.3. Compound 2
also was prepared by hydrolysis of 8 under same conditions
as for 5 in 73% yield.
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