6036
A. Suksamrarn et al. / Tetrahedron 58 -2002) 6033±6037
11a-hydroxy ecdysteroids was dehydrated very readily
20 Hz, 1H, H-3), 3.90 0m, W1/210 Hz, 1H, H-2), b obscured
signal; 13C NMR 0100 MHz, C5D5N) d 19.1 0C-18), 19.2
0C-11), 21.2 0C-21), 21.6 0C-16), 26.6 0C-4), 27.5 0C-23),
27.7 0C-19), 30.0 0C-26), 30.2 0C-27), 31.7 0C-15), 34.4
0C-12), 39.7 0C-10), 40.4 0C-1), 41.6 0C-9), 41.8 0C-7),
42.6 0C-24), 43.6 0C-8), 48.0 0C-13), 50.3 0C-17), 51.7
0C-5), 67.5 0C-3), 69.6 0C-25), 70.5 0C-2), 76.9 0C-20),
77.6 0C-22), 83.9 0C-14), 212.4 0C-6); 13C NMR 0100
MHz, CD3OD) d 19.1 0C-18), 19.7 0C-11), 20.5 0C-21),
21.5 0C-16), 26.5 0C-4), 27.3 0C-23), 27.7 0C-19), 28.9
0C-26), 29.6 0C-27), 31.8 0C-15), 34.8 0C-12), 40.2
0C-10), 40.7 0C-1), 41.7 0C-9), 42.1 0C-7), 42.4 0C-24),
43.9 0C-8), 48.5 0C-13), 50.6 0C-17), 52.3 0C-5), 68.2
0C-3), 70.8 0C-2), 71.3 0C-25), 78.0 0C-20), 78.5 0C-22),
85.5 0C-14), 215.1 0C-6); HMBC correlations 0C5D5N):
H-2 0C-3, C-4, C-10), H-7b 0C-6, C-8, C-14), H-8 0C-6,
C-9, C-13), H-17 0C-12, C-13, C-14, C-16, C-18, C-21),
18-Me 0C-12, C-13, C-14, C-17), 19-Me 0C-5, C-9, C-10),
21-Me 0C-17, C-20), H-22 0C-20, C-21, C-23, C-24), 26-Me
0C-24, C-25, C-27), 27-Me 0C-24, C-25, C-26); HMBC
correlations 0CD3OD): H-1 0C-2), H-2 0C-3, C-10), H-4a
0C-3, C-6), H-4b 0C-2, C-6), H-5 0C-3, C-6, C-10), H-7a
0C-8, C-14), H-7b 0C-6, C-8, C-14), H-8 0C-6, C-9, C-13,
C-14), H-17 0C-13, C-14, C-16), 18-Me 0C-12, C-13, C-14,
C-17), 19-Me 0C-5, C-9, C-10), 21-Me 0C-17, C-20), H-22
0C-20, C-21, C-23), 26-Me 0C-24, C-25, C-27), 27-Me
0C-24, C-25, C-26); FABMS 0negative ion mode) m/z 481
[M2H]2.
under relatively mild conditions.22
The mechanistic implication of this reaction has not been
investigated. However, the results indicated that NaNO2 did
not just act as a retarder of hydrogenation reaction, since the
reaction products from both methods were different.
In conclusion, we have provided a method for stereo-
selective catalytic hydrogenation of ole®nic function in a
D7-6-keto system of 5b-steroids, the H-8 of which was in
the a-orientation and the H-5b con®guration was preserved.
The procedure was simple, convenient, high yielding and no
special precautions were required.
3. Experimental
3.1. General experimental procedures
Melting points were determined on an Electrothermal
melting point apparatus and were uncorrected. IR spectra
were recorded in KBr on a Perkin±Elmer FT-IR Spectrum
BX spectrophotometer. 1H and 13C NMR spectra were
recorded on a Bruker AVANCE 400 spectrometer. Mass
spectra were measured on a Finnigan MAT 90 instrument.
Column chromatography and TLC were carried out using
Merck's silica gel 60 0,0.063 mm) and precoated silica gel
60 F254 plates, respectively. Spots on TLC were visualized
under UV light and by spraying with anisaldehyde±H2SO4
reagent followed by heating.
3.2. Catalytic hydrogenation of compounds 2, 7 and 9
Compounds 2, 7 and 9 were separately subjected to catalytic
hydrogenation in similar manner to that of compound 1,
using conditions indicated in entries 2±4 to give, respec-
tively, compounds 6, 8 and 10.
3.1.1. Catalytic hydrogenation of compound 1. To a solu-
tion of compound 1 0150 mg, 0.312 mmol) in EtOH 05 mL)
was added 10% Pd±C 0450 mg, 0.422 mmol) and 25% aq
NaNO2 solution 01.8 mL, 6.521 mmol) and the mixture
hydrogenated at atmospheric pressure for 3 h, using a
hydrogen balloon. The mixture was ®ltered through a
short acidic alumina column; the residue was washed with
EtOH and the solvent evaporated. The crude product was
puri®ed by short silica column chromatography to afford
7,8-dihydro-20-hydroxyecdysone 03) 0145 mg, 0.300 mmol
or 96%), colourless needles 0from MeOH), mp 153±1558C;
0Found: C, 62.32; H, 9.91. C27H46O7´2H2O requires C,
62.52; H, 9.72%); IR nmax 3429, 2963, 1699, 1382, 1323,
3.2.1. 7,8-Dihydroponasterone A .6). 14 mg 00.030 mmol,
93%) from 15 mg 00.032 mmol) of 2. Colourless needles
0from acetone), mp 201±2038C; IR nmax 3438, 2953,
1
1701, 1383, 1064 cm21; H NMR 0400 MHz, C5D5N) d
0.79 0d, J6.5 Hz, 3H, 26-Me), 0.81 0d, J6.5 Hz, 3H,
27-Me), 1.54 0s, 2£3H, 18-Me and 21-Me), 1.67 0s, 3H,
19-Me), 2.55 0dd, J14.6, 4.5 Hz, 1H, H-7a), 2.73 0dt,
J14.6, 4.5 Hz, 1H, H-8), 2.90 0t, J9.1 Hz, H-17), 2.93
0t, J14.6 Hz, H-7b), 3.79 0br d, J9.7 Hz, 1H, H-22), 4.27
0m, W1/29 Hz, 1H, H-2), 4.33 0m, W1/220 Hz, 1H, H-3);
HRFABMS 0negative ion mode) m/z 465.3217 [M2H]2
0calcd for C27H46O62H, 465.3216).
1
1273, 1225, 1152, 1128, 1064, 950 cm21; H NMR 0400
MHz, C5D5N) d 1.35 0s, 2£3H, 26-Me and 27-Me), 1.53
0s, 3H, 18-Me), 1.54 0s, 3H, 21-Me), 1.56 01H, H-15a),a 1.68
0s, 3H, 19-Me), 1.70 01H, H-1b),a 1.85 01H, H-1a),a 2.08
01H, H-16a),a 2.10 01H, H-15b),a 2.20 01H, H-4b),a 2.46
01H, H-16b),a 2.53 01H, H-9),a 2.54 0dd, J14.6, 4.5 Hz,
1H, H-7a), 2.56 02H, H-4a and H-5),a 2.72 0dt, J14.6,
4.5 Hz, 1H, H-8), 2.92 0t, J14.6 Hz, 1H, H-7b), 2.96
0dd, J9.4, 8.5 Hz, 1H, H-17), 3.86 0br d, J9.4 Hz, 1H,
H-22), 4.27 0m, W1/29 Hz, 1H, H-2), 4.32 0m, W1/2
3.2.2. 7,8-Dihydropterosterone .8). 11.5 mg 00.023 mmol,
88%) from 13 mg 00.027 mmol) of 7. Amorphous; IR nmax
3418, 2925, 1697, 1465, 1383, 1064 cm21 1H NMR
;
0400 MHz, C5D5N) d 0.99 0d, J6.7 Hz, 3H, 26-Me), 1.00
0d, J6.7 Hz, 3H, 27-Me), 1.52 0s, 3H, 18-Me), 1.55 0s, 3H,
21-Me), 1.67 0s, 3H, 19-Me), 2.55 0dd, J14.5, 4.3 Hz, 1H,
H-7a), 2.73 0ddd, J14.5, 4.3, 4 Hz, 1H, H-8), 2.88 0t, J
8.9 Hz, H-17), 2.92 0t, J14.5 Hz, H-7b), 3.92 0m, W1/2
17 Hz, 1H, H-24), 4.12 0br d, J9.6 Hz, 1H, H-22), 4.28 0m,
W1/28 Hz, 1H, H-2), 4.32 0m, W1/220 Hz, 1H, H-3);
HRFABMS 0negative ion mode) m/z 481.3161 [M2H]2
0calcd for C27H46O72H, 481.3165).
a
1
20 Hz, 1H, H-3), obscured signal; H NMR 0400 MHz,
CD3OD) d 1.14 0s, 3H, 21-Me), 1.17 0s, 2£3H, 18-Me
and 26-Me), 1.18 0s, 3H, 27-Me), 1.37 0s, 3H, 19-Me),
1.45 01H, H-1b),b 1.65 01H, H-1a),b 1.77 01H, H-4b),b
1.78 01H, H-24a),b 2.00 01H, H-4a),b 2.24 0dd, J14.4,
4.4 Hz, 1H, H-7a), 2.30 0t, J9.3 Hz, 1H, H-17), 2.36 0dt,
J14.4, 4.4 Hz, 1H, H-8), 2.51 0br s, W1/210 Hz, 1H, H-5),
2.77 0t, J14.4 Hz, H-7b), 3.28 01H, H-22),b 3.75 0m, W1/2
3.2.3. 7,8-Dihydropoststerone .10). 9.5 mg 00.026 mmol,