P. Purushottamachar, V.C.O. Njar / Steroids 77 (2012) 1530–1534
1531
OH
OH
18
OH
12
17
5 -reductase
5 -reductase
β
11
α
H
H
19
13
14
16
H
8
1
9
2
H
H
15
H
H
10H
6
H
3
O
O
7
5
H
O
H
4
5 -DHT (1)
α
Testosterone (T)
5 -DHT (2)
β
Chart 1. Structures of testosterone, 5a-dihydrotestosterone and 5b-dihydrotestosterone.
sla APEX-Qe FTICR-MS by positive ion ESI mode by Susan A. Hatcher,
20.25 mmol) was added tert-butyldimethylsilyl chloride (2.03 g,
13.5 mmol) and stirred at rt. under argon. Within 20 min, a dense
white precipitate observed. The reaction continued for one more
hour, followed by dilution with water (150 mL) and then extracted
with diethyl ether. The organic phase washed with water, brine
and dried with CaCl2. Upon removal of solvent under reduced pres-
sure and air drying resulted in a white solid of 16 (2.9 g, 96%): mp
119–121 °C; Rf = 0.77 (2% EtOH in MDC); IR (neat) 1736, 1240,
1195, and 1026; 1H NMR (500 MHz, CDCl3) d 0.010 and 0.016 (s,
6H, Si(CH3)2), 0.699 (s, 3H, 18-CH3), 0.838 (s, 3H, 19-CH3), 0.886
Facility Director, College of Sciences Major Instrumentation Cluster,
T
D
Old Dominion University, Norfolk, VA. Values of [
a]
were deter-
mined with Rudholph Res Analytical: Autopol III automatic polarim-
eter. Flash Column chromatography (FCC) was performed using
silica gel (230–400 mesh, 60 Å), and progress of reactionswere mon-
itored by TLC analysis on silica gel plates (Merck F254) (detection by
charring reagent of conc. H2SO4 in ethanol 5% w/v). The starting
material 3b-hydroxy-5a-androstan-17-one and other reagents
were purchased from Sigma Aldrich.
(s, 9H, tert-C4H9), 2.03 (s, 3H, 3b-OAc), 3.55(m, 1H, 17
a-H), 4.68
(m, 1H, 3
a
-H); 13C NMR (500 MHz, CDCl3) d 170.89 (CO), 82.01
2.2. 5a-Androstan-3b-acetoxy-17-one (14)
(C-17), 73.91 (C-3), 54.73 (C-9), 50.82 (C-14), 44.95 (C-13), 43.50
(C-5), 37.35 (C-12), 37.00 (C-1), 35.76 (2Â, C-8 and C10), 34.23
(C-4), 31.80 (C-7), 31.12 (C-16), 28.69 (C-6), 27.61 (C-2), 26.06
(3Â, CH3)3), 23.72 (C-15), 21.66 (COCH3), 21.04 (C-11), 18.30
(C(CH3)3), 12.44 (C-19), 11.59 (C-18), À4.29 and À4.6 (SiCH3);
To an ice cold solution of commercially available 3b-hydroxy-
5a-androstan-17-one (2.5 g, 8.6 mmol) in pyridine (15 ml) was
added acetic anhydride (2.64 g, 25.8 mmol) followed by stirring
for 12 h at rt. The reaction mixture was then poured to a mixture
of ice-water (200 mL) and the resulting white precipitate was fil-
tered, washed with water and dried under suction to afford pure
compound (2.78 g, 97%) of 14: mp 114–115 °C (lit. [20] 111–
113 °C); Rf = 0.6 (3.8% EtOH in MDC); IR (neat) 1729, 1240, and
1028; 1H NMR (500 MHz, CDCl3) d 0.851 (s, 3H, 18-CH3), 0.857
[a]
29 + 4.2 [1% in CHCl3].
D
2.5. 3b-Hydroxy-5
(17)
a-androstan-17b-yl dimethyl-tert-butylsilyl ether
(s, 3H, 19-CH3), 2.02 (s, 3H, 3b-OAc), 4.68 (m, 1H, 3a
-H); 13C
To a solution of 3b-acetoxy-5a-androstan-17b-yl dimethyl-tert-
NMR (500 MHz, CDCl3) d 221.34 (C-17), 170.81 (COCH3), 73.66
(C-3), 54.49 (C-9), 51.53 (C-14), 47.94 (C-13), 44.82 (C-5), 36.88
(C-1), 36.01 (C-8), 35.81 (C-16), 35.20 (C-10), 34.12 (C-4), 31.70
(C-12), 30.97 (C-7), 28.44 (C-2), 27.58 (C-6), 21.94 (C-15), 21.61
(COCH3), 20.63 (C-11), 13.99 (C-18), 12.38 (C-19); [
[1% in CHCl3].
butylsilyl ether (16) (2.5 g, 5.58 mmol) in methanol (15 mL) was
added 10% methanolic-KOH solution (10 mL) and refluxed for
2 h. The reaction mixture was concentrated under reduced pres-
sure and the residue treated with water (150 mL). The resulting
precipitate was filtered and washed with water (until the washing
was neutral). Solids dried under suction to afford white product of
17 (2.23 g, 98%): mp 163–164 °C (lit.[21] 161–163 °C); Rf = 0.3 (2%
EtOH in MDC); IR (neat) 3353, 1471, 1248, 1094, 832 and 773; 1H
NMR (500 MHz, CDCl3) d 0.010 and 0.016 (s, 6H, Si(CH3)2), 0.701 (s,
3H, 18-CH3), 0.824 (s, 3H, 19-CH3), 0.887 (s, 9H, tert-C4H9), 3.54(m,
a]
29 + 66.8
D
2.3. 3b-Acetoxy-5
a
-androstan-17b-ol (15)
-androstan-3b-acetoxy-17-one (14)
To an ice cold solution of 5
a
1H, 17a-H), 3.59 (m, 1H, 3a
-H); 13C NMR (500 MHz, CDCl3) d 82.04
(2.5 g, 7.53 mmol) in methanol (25 mL) was added sodium borohy-
dride (0.23 g, 6.07 mmol) over a period of 30 min in three portions.
The reaction mixture was stirred for another hour, neutralized
with dil. HCl and concentrated under reduced pressure. The resi-
due was stirred with water, filtered, washed with water, dried un-
der suction and recrystallized from methanol to afford white
powder (2.48 g, 98.7%) of 15: mp 103–104 °C (lit.[20] 106–
107 °C); Rf = 0.51 (4% EtOH in MDC); IR (neat) 3316, 1730, 1237,
and 1021; 1H NMR (500 MHz, CDCl3) d 0.730 (s, 3H, 18-CH3),
(C-17), 71.51 (C-3), 54.87 (C-9), 50.90 (C-14), 45.16 (C-13), 43.52
(C-5), 38.42 (C-4), 37.41 (C-12), 37.26 (C-1), 35.80 (2Â, C-8 and
C10), 31.90 (C-7), 31.73 (C-16), 31.13 (C-2), 28.83 (C-6), 26.06
(3Â, CH3)3), 23.74 (C-15), 21.10 (C-11), 18.31 (C(CH3)3), 12.56 (C-
19), 11.60 (C-18), À4.29 and À4.60 (SiCH3); [
a]
28 + 92 [1% in
D
CHCl3].
2.6. 17b-[(tert-Butyldimethylsilyl)oxy]-5a-androstan-3-one (18)
0.833 (s, 3H, 19-CH3), 2.01 (s, 3H, 3b-OAc), 3.63 (m, 1H, 17
a-H),
4.68 (m, 1H, 3
a
-H); 13C NMR (500 MHz, CDCl3) d 170.97 (CO),
Tetrapropylammonium perruthenate (0.16 g, 0.458 mmol) was
added to solution of 3b-hydroxy-5 -androstan-17b-yl di-
82.03 (C-17), 73.99 (C-3), 54.55 (C-9), 51.14 (C-14), 44.90 (C-13),
43.17 (C-5), 36.97 (C-12), 36.90 (C-1), 35.70 (2Â, C-8 and C10),
34.18 (C-4), 31.71 (C-7), 30.61 (C-16), 28.63 (C-6), 27.63 (C-2),
23.56 (C-15), 21.64 (COCH3), 20.97 (C-11), 12.42 (C-19), 11.34 (C-
a
a
methyl-tert-butylsilyl ether (17) (2 g, 4.93 mmol), 4-methylmor-
pholine N-oxide (1.07 g, 9.16 mmol) and molecular sieves (0.3 g)
in MDC (40 mL). After stirring at rt. for 2 h, the reaction mixture
was concentrated under reduced pressure. Flash column chroma-
tography (FCC) over short silica column eluting with 1% ethanol
in MDC afford off white solid of 18 (1.86 g, 93.4%): mp 131–
133 °C; Rf = 0.65 (2% EtOH in MDC); IR (neat) 1717, 1250, 1092,
833 and 771; 1H NMR (500 MHz, CDCl3) d 0.015 and 0.021 (2s,
6H, Si(CH3)2), 0.731 (s, 3H, 18-CH3), 0.891 (s, 9H, tert-C4H9), 1.02
18); [a]
29 + 2.4 [1% in CHCl3].
D
2.4. 3b-Acetoxy-5a-androstan-17b-yl dimethyl-tert-butylsilyl ether
(16)
To a dry solution of dry DMF (15 mL) containing 3b-acetoxy-5
a-
androstan-17b-ol (15) (4.5 g, 13.5 mmol) and imidazole (1.37 g,
(s, 3H, 19-CH3), 3.54 (m, 1H, 17a
-H); 13C NMR (500 MHz, CDCl3)