Papers
Experimental
(22R)- and (22S)-6␣,9␣-Difluoro-11,21-dihydroxy-
6␣,17␣-propylmethylenedioxypregn-4-ene-3,20-
dione (3a and 3b)
1
Compounds 5 (6␣,9␣-difluoro-11,21-dihydroxy-16␣,17␣-isopropyl-
idenedioxypregna-1,4-diene-3,20-dione) and 6 (6␣-fluoro-11,21-
dihydroxy-16␣,17␣-isopropylidenedioxypregna-1,4-diene-3, 20-
dione) were purchased from SICOR S.p.A. (Milan, Italy). Dexa-
methasone and [6,7- H]-dexamethasone were purchased from
Sigma Chemical Company (Sweden) and New England Nuclear
6␣,9␣-Difluoro-11,16␣,17␣,21-tetrahydroxypregn-4-ene-3,20-dione
(2; 1.8 g) was added in small portions to a solution of freshly
3
distilled butanal (470 mg) and perchloric acid (70%; 0.4 mL) in
5
purified and dried dioxane (100 mL) with stirring over 30 min.
Corporation (Boston, Massachusetts, USA), respectively.
1
The reaction mixture was left at ambient temperature with con-
tinued stirring for another 5 h. Methylene chloride (600 mL) was
added, the solution was washed with aqueous potassium carbonate
H-NMR spectra were recorded as solutions in CDCl at am-
3
bient temperature on a Varian VXR-300 spectrometer at 300 MHz.
The chemical shifts are given in ␦ units (ppm) relative to the
internal standard tetramethylsilane; d ϭ doublet, dd ϭ doublet of
doublets, m ϭ multiplet, q ϭ quartet, dq ϭ doublet of quartets, s ϭ
singlet, and t ϭ triplet.
Mass spectra were recorded on a Finnigan 4510 spectrometer
with desorption chemical ionization (DCI) using methane as the
reagent gas (direct inlet; filament current was increased at a rate of
(10%) and water, and dried over anhydrous sodium sulfate. The
crude product obtained after evaporation was purified on a Sep-
hadex LH-20 column (71 ϫ 6.3 cm I.D.), using chloroform as the
mobile phase. The fraction 3015–3705 mL was collected and
evaporated. The residue (epimeric mixture 3) was resolved into its
C-22-epimers on a Sephadex LH-20 column (76 ϫ 6.3 cm I.D.),
using a heptane/chloroform/ethanol mixture (20:20:1 v/v) as the
mobile phase. The fractions 8845-9565 mL (A) and 9745-10600
mL (B) were collected and evaporated. The residues were dis-
solved in methylene chloride and precipitated with petroleum ether
(b.p. 40–60°C).
1
0 mA/s). Alternatively, the mass spectra were obtained with
liquid chromatography thermospray mass spectrometry (TSP-MS)
on the same type of spectrometer equipped with a Finnigan ther-
mospray interface. Mobile phase: 0.1 M ammonium acetate buffer,
pH 5, containing 70% methanol. Temperatures: Ion source 222°C
and vaporizer 103°C. Repeller voltage: 90 V.
Preparative column chromatography was performed on a
Quickfit glass column equipped with adjustable Teflon end pieces.
A LKB Uvicord I flow analyzer, working at 254 nm, served as the
detection system. The effluent fractions were collected on a LKB
Fraction A gave 337 mg (17%) of the 22S-epimer 3b. The
purity determined by HPLC analysis (acetonitrile/water, 35:65 v/v)
25
was 95.7%; m.p. 231–234°C; [␣]D ϭ ϩ84° (c ϭ 0.096; CH Cl ).
2
ϩ
2
ϩ
MS: m/z (relative intensity) 469 (MH ; 100), 397 (MH
Ϫ
ϩ
CH CH CH CHO; 3.6), 379 (MH Ϫ CH CH CH CHO Ϫ H O;
3
2
2
3
2
2
2
7
3
000 Ultro Rac automatic fraction collector equipped with a LKB
404 B siphon stand, using a 15 mL siphon. Sephadex LH-20,
1
1
2.7). H-NMR (300 MHz; CDCl ): ␦ ppm 0.93 (t, 3H, H-25);
3
0
.96 (s, 3H, H-18); 1.51 (s, 3H, H-19); 4.23 and 4.64 (two q, 2H,
particle size 25–100 m (Pharmacia Fine Chemicals, Uppsala,
Sweden), was used as the stationary phase. All solvents used as the
mobile phase were of puriss grade and glass distilled. The ethanol
used in the mixed solvent system was 99.5% pure.
Preparative HPLC was performed on a liquid chromatograph
from Waters Associates with a type 590 Programmable HPLC
Pump, a type 170 Sample Loader, and a type 484 Tunable Absor-
bance Detector working at 280 nm. A column (250 ϫ 22.5 mm
I.D.), prepacked with Apex Prepsil ODS, 8 m, (Jones Chroma-
tography Ltd) was used as the stationary phase.
H-21); 4.39 (broad m, 1H, H-11); 5.20 (d, 1H, H-16); 5.25 (t, 1H,
H-22); 5.14–5.38 (two m, 1H, H-6); 6.14 (s, 1H, H-4).
Fraction B gave 923 mg (45%) of the 22R-epimer 3a. The
purity determined by HPLC analysis (cf. fraction A above) was
2
5
9
8.8%; m.p. 150–156°C; [␣] ϭ ϩ120° (c ϭ 0.190; CH Cl ).
D 2 2
ϩ ϩ
MS: m/z (relative intensity) 469 (MH ; 100), 397 (MH
CH CH CH CHO; 12.3), 379 (MH Ϫ CH CH CH CHO Ϫ
H O; 25.0). H-NMR (300 MHz; CDCl ); ␦ ppm 0.89 (s, 3H,
Ϫ
ϩ
3
2
2
3
2
2
1
2
3
H-18); 0.94 (t, 3H, H-25); 1.52 (s, 3H, H-19); 4.26 and 4.53 (two
q, 2H, H-21); 4.40 (broad m, 1H, H-11); 4.61 (t, 1H, H-22); 4.92
(d, 1H, H-16); 5.13–5.38 (two m, 1H, H-6); 6.14 (s, 1H, H-4).
The HPLC analyses were performed on a liquid chromatograph
from Waters Associates involving a M 6000A pump, an U6K
injector system, and a M 400 UV detector (240 nm). A column
(
(
150 ϫ 4.6 mm I.D.), prepacked with 3 m Apex octadecylsilane
Jones Chromatography Ltd), was used as the stationary phase.
Melting points were determined on a Leitz, Wetzlar, hot stage
(
22R)-6␣,9␣-Difluoro-11,21-dihydroxy-16␣,17␣-
microscope. Optical rotations were measured with a Perkin Elmer
model 241 polarimeter.
propylmethylenedioxypregna-1,4-diene-3,20-
dione (4)
A. Compound 4 was prepared in heptane from 6␣,9␣-difluoro-
11,21-dihydroxy-16␣,17␣-isopropylidenedioxypregna-1,4-diene-
6
␣,9␣-Difluoro-11,16␣,17␣,21-tetrahydroxypregn-
-ene-3,20-dione (2)
3
,20-dione (5) and butanal. The reaction was catalyzed by per-
4
6
chloric acid in the presence of fine sand, as previously described.
The purity determined by HPLC analysis (acetonitrile/water, 35:65
v/v) was 98.7%. M.p. 169–172°C; [␣]D ϭ ϩ94.5° (c ϭ 0.170;
A solution of tris(triphenylphosphine)rhodium chloride (1.13 g) in
toluene (400 mL) was hydrogenated at atmospheric pressure for
25
2
0
min.
tetrahydroxypregna-1,4-diene-3,20-dione (1; 1.0 g) in ethanol
250 mL) was added. The reaction mixture was hydrogenated for
4 h at room temperature and atmospheric pressure. After evap-
A
suspension of 6␣,9␣-difluoro-11,16␣,17␣,21-
ϩ
1
CH Cl ). MS: mz (relative intensity) 467 (MH ; 100). H-NMR
4
2
2
(
300 MHz; CDCl ): ␦ ppm 0.91 (s, 3H, H-18); 0.91 (t, 3H, H-25);
3
(
2
1
.53 (s, 3H, H-19); 4.26 and 4.53 (two q, 2H, H-21); 4.42 (m, 1H,
H-11); 4.59 (t, 1H, H-22); 4.92 (d, 1H, H-16); 5.26–5.52 (two m,
H, H-6); 6.37 and 6.40 (two d, 1H, H-2); 6.44 (d, 1H, H-4); 7.10
oration, the residue was suspended in chloroform (10 mL) and
filtered. The solid product was washed with several small portions
of chloroform yielding 0.83 g (83%) of 2. The purity determined
1
and 7.14 (two d, 1H, H-1).
B. Compound 4 was prepared in heptane from 6␣,9␣-difluoro-
by HPLC analysis (acetonitrile/water, 17:83 v/v) was 95.7%. M.p.
ϩ
1
1,16␣,17␣,21-tetrahydroxypregna-1,4-diene-3,20-dione (1) and
2
44–254°C. MS: m/z (relative intensity) 415 (MH ; 14), 397
ϩ ϩ 1
(MH Ϫ H O; 12), 395 (MH Ϫ HF; 17). H-NMR (300 MHz):
butanal. The reaction was catalyzed by perchloric acid in the
2
6
␦
ppm (CD OD) 0.99 (s, 3H, H-18), 1.60 (s, 3H, H-19), 4.32 and
presence of fine sand, as previously described. The purity deter-
3
4
.69 (dd, 2H, H-21), 4.29 (m, 1H, H-11), 4.97 and 5.00 (dd, 1H,
mined by HPLC analysis (acetonitrile/water, 35:65 v/v) was
98.9%. MS: m/z (relative intensity) 467 (MH ; 100).
ϩ
H-16), 5.36 and 5.52 (two m, 1H, H-6), and 6.03 (s, 1H, H-4).
3
8
Steroids, 1998, vol. 63, January