Novel glucocorticoid antedrugs possessing a C16,17-fused γ-lactone ring

Article abstract of DOI:10.1039/a908358h

A series of novel γ-butyrolactones fused at the 16β,17β position of the 9α-fluoro-1 1β-hydroxy-3-oxoandrosta-1,4-diene nucleus and possessing oxygen substituents at 16α, 17α positions were prepared and tested as glucocorticoid agonists. The compounds were also tested for their lability in human plasma. Lactone 5 was found to be rapidly hydrolysed in plasma, whereas derivative 18? was found to be a potent glucocorticoid agonist, but was stable in plasma. The structure of the C21S diastereoisomer of compound 18 was confirmed by an X-ray diffraction study. The Royal Society of Chemistry 2000.

Full text of DOI:10.1039/a908358h

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Novel glucocorticoid antedrugs possessing a C16,17-fused
ꢀ-lactone ring
Keith Biggadike, Sean M. Lynn, Panayiotis A. Procopiou,* the late Rupert E. Shaw and
Christopher Williamson
1
Glaxo Wellcome Medicines Research Centre, Gunnels Wood Road, Stevenage, Hertfordshire,
UK SG1 2NY
Received (in Cambridge, UK) 19th October 1999, Accepted 21st December 1999
A series of novel γ-butyrolactones fused at the 16β,17β position of the 9α-fluoro-11β-hydroxy-3-oxoandrosta-1,4-
diene nucleus and possessing oxygen substituents at 16α,17α positions were prepared and tested as glucocorticoid
agonists. The compounds were also tested for their lability in human plasma. Lactone 5 was found to be rapidly
hydrolysed in plasma, whereas derivative 18† was found to be a potent glucocorticoid agonist, but was stable in
plasma. The structure of the C21S diastereoisomer of compound 18 was confirmed by an X-ray diffraction study.
Asthma is recognised as a chronic inflammatory disorder of the
airways and currently, it is treated most effectively with anti-
inflammatory glucocorticoids. However, long term treatment
with steroids can be associated with adverse systemic effects
such as growth retardation, osteoporosis, suppression of the
hypothalamic–pituitary–adrenal function and of the immune
system. The development of inhaled glucocorticoids which are
efficiently inactivated in the liver and which show low oral bio-
availability has led to a substantial reduction of the observed
systemic effects.1 Recently the terms ‘antedrug’2 or ‘soft drug’3
were introduced to describe drugs designed to act topically at
the site of application but that are transformed into inactive
metabolites upon entry into the systemic circulation. A number
of publications have appeared that describe the synthesis of
antiinflammatory glucocorticoid derivatives based on the ante-
drug concept.4–11 These have generally involved the introduc-
tion of carboxylic ester functionality in the expectation that this
will be hydrolysed by blood esterases to give inactive steroid
carboxylic acid metabolites.
γ-lactones was identified by our group as human serum
paraoxonase [EC.3.1.8.1], a known enzyme that is thought to
have a role in the metabolism of lipids and lipoproteins.13 As far
as we are aware, paraoxonase mediated hydrolysis of γ-lactones
has not been reported prior to our disclosure. However,
hydrolysis of simple γ-lactones by a mammalian enzyme
described as lactonase has been reported by Fishbein and
Bessman.14 We believe that Fishbein and Bessman’s lactonase
and paraoxonase are probably the same enzyme.
As part of our medicinal chemistry project we have investi-
gated the structural requirements for paraoxonase mediated
hydrolysis of a variety of glucocorticoid lactone derivatives.
In this paper we describe the synthesis and structure–activity
relationships of a series of glucocorticoids possessing a fused
γ-lactone at C16 and C17 of the steroidal nucleus. Gluco-
corticoids possessing a small 17β-carboxylic ester and a
17α-ester15 3 or 16,17-acetal/ketal16 4 are very potent anti-
In our search for even safer inhaled glucocorticoids we have
discovered that incorporation of a γ-lactone moiety provides
derivatives which are extremely rapidly inactivated in plasma,
but which show remarkable stability in lung S9 fraction. Thus,
the potent antiinflammatory glucocorticoid 1 is hydrolysed in
inflammatory agents. We envisaged preparing analogues where
the 17β-ester was locked in a rigid conformation in the form of
a C16,17-fused γ-lactone and having oxygen substituents at C16
and 17 such as the epoxide 5 or acetal 6. Metabolism of these
₁
human plasma (t < 2 min) to the inactive hydroxy carboxylic
₂

12
₁
acid 2, but is essentially stable in human lung S9 (t > 2 h).
₂

These ideal properties make such lactone derivatives excel-
lent lung selective antedrug candidates for use in asthma.
The enzyme responsible for the plasma hydrolysis of these
fused lactones would give 17β-carboxylic acid derivatives which
would be expected to show only weak glucocorticoid agonist
activity.17
† The numbering used in the discussion and NMR data is exemplified
in Scheme 4 for compound 18.
DOI 10.1039/a908358h
J. Chem. Soc., Perkin Trans. 1, 2000, 813–818
This journal is © The Royal Society of Chemistry 2000
813

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Our retro-synthesis of 5 involved a disconnection of the
lactone ring to the 17β-carboxylic acid and a hydroxymethyl or
bromomethyl group at 16β, which we expected to prepare from
the known 16-exo methylene derivative (Scheme 1). The syn-
Scheme 1
thesis of 5 in the forward sense started with the allylic alcohol 7
(Scheme 2), which was obtained by the method of Taub et al.18
Saponification of the acetate 7 with potassium carbonate
under nitrogen gave 9α-fluoro-16-methyleneprednisolone19 8,
which was then oxidised with periodic acid to the key inter-
mediate 9.15 An attempt to epoxidise 9 with m-chloroperoxy-
benzoic acid in chloroform for 4 days failed; only starting
material was recovered. However, treatment of 9 with 1,3-
dibromohydantoin in the presence of aqueous perchloric acid
gave the bromomethyl epoxide 10 via the initial formation of
the 16-exo bromonium ion, followed by internal trapping by
the 17α-hydroxy group. The synthesis of 5 was completed
by intramolecular displacement of the bromine in the 16β-
bromomethyl group by the 17β-carboxylate ion (potassium
carbonate in DMF) to give the required epoxy-γ-lactone in 57%
overall yield for the 4 steps. Hydrolysis of 5 with sodium
hydroxide gave the hydroxy acid 11, which was used as an
authentic sample for the plasma hydrolysis product of lactone
5. We were pleased to find that the lactone 5 was rapidly hydro-
Scheme 3 Reagents and conditions: i) EtCOCl, Et3N, CH2Cl2; ii)
Et2NH, acetone; iii) HBr, CH2Cl2; iv) K2CO3, DMF; v) KMnO4, H2O,
acetone, HCO2H.
acetonide 17 and butylidene 18 derivatives with the appropriate
carbonyl compound and acid catalysis (Scheme 4). The acetals
16 and 18 were obtained as diastereoisomeric mixtures at the
acetal asymmetric centre. The isomers of the latter compound
were separated by reversed phase HPLC and crystallisation,
and their configuration at C21 was established by NOE experi-
ments. Thus, for the C21R isomer 18R NOEs were observed
from 16Ј-H to 21-H and vice versa. For the C21S-isomer 18S
NOEs were observed from 21-H to 14-H, 22-H and 23-H, and
from 16Ј-H to 15-H and 18-H. The structure of the C21S
isomer (mp 317–319 ЊC) was confirmed by an X-ray diffraction
experiment (Fig. 1).
The glucocorticoid agonist activity of lactones 14, 15, 16, 17
and the individual isomers of 18 were tested by the method of
Stein and co-workers22 in the HeLa sPAP screen, a functional
in vitro assay. This test involves transfection of HeLa cells with
a detectable reporter gene (secreted placental alkaline phos-
phatase, sPAP) under the control of a glucocorticoid response
promoter (the LTR of the mouse mammary tumour virus,
MMTV). Various concentrations of dexamethasone (used as
standard) and the test compounds in Table 1 were incubated
with transfected HeLa cells for 72 h. At the end of the incu-
bation p-nitrophenyl acetate, used as substrate for sPAP, was
added and the product concentration measured spectrophoto-
metrically. Increased UV-absorbance reflected increased sPAP
transcription and concentration–response curves were plotted
so that ED50 values could be estimated. Dexamethasone exhib-
ited ED50 values in the range of 10–15 nmol dmϪ3. As it can be
seen from the data in Table 1 the most potent activity was seen
with the butylidene lactone 18 with the R-isomer being more
active as expected.23 The plasma stability of the compounds in
₁
lysed (t 15 min) by human plasma to 11. However, lactone 5
₂

was found to have no useful glucocorticoid agonist activity.
Nevertheless this result encouraged us to investigate the syn-
thesis of the lactones 6.
The synthesis of acetals 6 required the preparation of the
16α,17α-diol 15, and this was again derived from the key
intermediate 9 as shown in Scheme 3. Selective acylation of the
17α-hydroxy group without concomitant 11β-acylation was
achieved by reaction of 9 with excess propionyl chloride and
triethylamine, followed by aminolysis of the resulting mixed
anhydride with diethylamine.20 Treatment of 12 with hydrogen
bromide in dichloromethane furnished the allylic bromide 13
which was cyclised with potassium carbonate in DMF to the
αβ-unsaturated lactone 14 in 50% overall yield. cis-Hydroxyl-
ation of αβ-unsaturated lactone 14 using aqueous potassium
permanganate21 in acetone in the presence of formic acid
occurred exclusively from the less hindered α-face (81%). With
the cis-diol in hand we were in a position to form ethylidene 16,
Scheme 2 Reagents and conditions: i) K2CO3, MeOH, dioxane; ii) H5IO6, THF, H2O; iii) 1,3-dibromohydantoin, HClO4, THF; iv) K2CO3, DMF;
v) NaOH, H2O, MeOH.
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Fig. 1 X-Ray crystal structure of 18S.
Scheme 4 Reagents and conditions: i) MeCHO, HCl, DMF; ii) acetone, 2,2-dimethoxypropane, HCl; iii) butyraldehyde, HCl, DMF.
Table 1 In vitro glucocorticoid agonist activity and human plasma
It is possible that the severe congestion around the steroid
ring D, where three five-membered rings are fused together,
is the most likely explanation for their plasma stability.
In conclusion, novel glucocorticoids were prepared and
tested for glucocorticoid agonist activity. Butylidene lactone 18
was found to be a very potent glucocorticoid agonist. The com-
pounds were also tested for hydrolysis in plasma. Lactone 5 was
found to be rapidly hydrolysed in plasma but the 16,17-acetal
derivatives were found to be stable in plasma.
stability
Compound
number
HeLa/
Plasma
stability (%)
nmol dmϪ3
5
>10000
>10000
>10000
>10000
125
0
100
95
99
100
97
94
—
—
—
11
14
15
16
17
66
5
14
4
Experimental
18
18 (S)
Organic solutions were dried over MgSO4 and column chrom-
atography was performed on silica gel 60 (Merck, Art no. 9385).
Analytical HPLC was performed on a S5 ODS-2 column
(15 × 0.46 cm) using 35% MeCN–H2O for 25 min, increasing to
70% in 10 min and then holding at 70% for 20 min, flow rate
2 cm3 minϪ1 and detecting at 254 nm. Preparative HPLC was
conducted on a Prochrom ODS-2 column (38.5 × 5 cm) using
MeCN–H2O as eluent, flow rate 40 cm3 minϪ1 and detecting
18 (R)
Dexamethasone
10
Table 1 was estimated by HPLC after their incubation in human
plasma for 1 h at 37 ЊC. The results are expressed as % of com-
pound remaining after 1 h. Unfortunately all the compounds
in this series except the epoxy lactone 5 were stable in plasma.
J. Chem. Soc., Perkin Trans. 1, 2000, 813–818
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at 254 nm. IR spectra were recorded on a Nicolet 5SXC or a
Bio-Rad FTS-7 FT-IR spectrometer. NMR spectra of com-
pounds in DMSO-d6 solutions were recorded on a Bruker
AM500, AM250 or VarianVXR 400 spectrometer using
standard pulse sequences. Chemical shifts are expressed as
parts per million downfield from internal tetramethylsilane.
All J values are in Hz. Mass spectral abbreviations are
as follows: ESϩve electrospray positive, TSPϩve thermo-
spray positive or LSIMSϩve liquid secondary isotope mass
spectrometry.
16ꢁ,17ꢁ-Epoxy-9ꢁ-fluoro-11ꢂ-hydroxy-2Ј,3Ј,4Ј,5Ј-tetrahydro-
furo[3Ј,4Ј:16,17]androsta-1,4-diene-3,5Ј-dione 5
A solution of 10 (772 mg, 1.59 mmol) in DMF (23 cm3)
was treated with anhydrous potassium carbonate (330 mg,
2.39 mmol) and the mixture was stirred for 1.5 h, before it
was poured into dilute hydrochloric acid solution. The solid
was collected by filtration and washed with water. The solid was
crystallised from hot acetonitrile and the crystals were tritur-
ated in ethyl acetate to give 5 (411 mg, 69%): mp 315–320 ЊC;
νmax (Nujol)/cmϪ1 1775, 1660 and 1600; δH (250 MHz) 7.29
(1H, d, J 10, 1-H), 6.23 (1H, dd, J 10 and 2, 2-H), 6.02 (1H, s,
4-H), 5.62 (1H, m), 4.55 (1H, d, J 11, 16Ј-H), 4.46 (1H, d, J 11,
16Ј-H), 4.12 (1H, m, 11-H), 1.51 (3H, s, 19-H) and 1.27 (3H,
s, 18-H) (Found: C, 67.7; H, 6.2. C21H23FO5 requires C, 67.4;
H, 6.2%).
9ꢁ-Fluoro-11ꢂ,17ꢁ,21-trihydroxy-16-methylenepregna-1,4-
diene-3,20-dione 8
A
solution of 21-acetoxy-9α-fluoro-11β,17α-dihydroxy-16-
methylenepregna-1,4-diene-3,20-dione (7) (500 mg, 1.16 mmol)
in dioxane (10 cm3) and methanol (10 cm3) was deoxygenated
by bubbling nitrogen through the solution for 15 min. Potas-
sium carbonate (141 mg, 1.02 mmol) in water (1 cm3) was added
and the mixture was stirred under nitrogen for 1.5 h. Glacial
acetic acid was added and the solvents were removed under
reduced pressure. The residue was partitioned between ethyl
acetate and water, and the organic phase was separated. The
solution was washed with water, dried and evaporated to dry-
ness. The solid was triturated in diethyl ether and the product
collected by filtration to give 8 (423 mg, 93%) as a white solid:
δH (250 MHz) 7.29 (1H, d, J 10, 1-H), 6.23 (1H, dd, J 10 and 2,
2-H), 6.02 (1H, s, 4-H), 5.51 (1H, s, 17-OH), 5.31 (1H, m,
11-OH), 5.12 (1H, s, 16Ј-H), 4.88 (1H, s, 16Ј-H), 4.69 (1H, t, J 6,
21-OH), 4.52 (1H, dd, J 19 and 6, 21-H), 4.17 (1H, m, 11-H),
4.13 (1H, dd, J 19 and 6, 21-H), 1.50 (3H, s, 19-H) and 0.80
(3H, s, 18-H) (Found: C, 66.7; H, 7.2; F, 4.7. C22H27FO5ؒ
0.33H2O requires C, 66.65; H, 7.0; F, 4.8%).
16ꢁ,17ꢁ-Epoxy-9ꢁ-fluoro-11ꢂ-hydroxy-16ꢂ-hydroxymethyl-3-
oxoandrosta-1,4-diene-17ꢂ-carboxylic acid 11
A suspension of the lactone 5 (15 mg, 0.04 mmol) in methanol
(0.5 cm3) was treated with 0.1 mol dmϪ3 sodium hydroxide (0.42
cm3) and the mixture was stirred for 24 h. More sodium hydrox-
ide (0.1 cm3) and methanol (0.2 cm3) was added and the mixture
was stirred for a further 18 h. The reaction mixture was diluted
with ethyl acetate, acidified with dilute hydrochloric acid and
washed with brine. The organic solution was dried, concen-
trated and triturated in diethyl ether. The solid was dried in
vacuo for 18 h at 40 ЊC to give acid 11 (12 mg, 76%) as a white
solid: mp 163–164 ЊC; δH (400 MHz) 7.26 (1H, d, J 10, 1-H),
6.19 (1H, dd, J 10 and 2, 2-H), 5.99 (1H, s, 4-H), 5.38 (1H,
br s, 11-H), 4.08 (1H, m, 11-OH), 3.74 (1H, d, J 12, 16Ј-H),
3.65 (1H, d, J 12, 16Ј-H), 1.90 (1H, d, J 13), 1.49 (3H, s, 19-H)
and 1.22 (3H, s, 18-H); MS(FABϩve) m/z 393 (M ϩ H)ϩ.
Found: (LSIMSϩve) 393.1714 (M ϩ H)ϩ. C21H26FO6 requires
(M ϩ H) 393.1713.
9ꢁ-Fluoro-11ꢂ,17ꢁ-dihydroxy-16-methylene-3-oxoandrosta-1,4-
diene-17ꢂ-carboxylic acid 9
A suspension of 8 (500 mg, 1.28 mmol) in THF (5 cm3) was
treated with periodic acid (438 mg, 1.92 mmol) in water (1.5
cm3) and the mixture was stirred for 6 h. A further portion
of periodic acid (65 mg, 0.28 mmol) was added and the mix-
ture was stirred for 19 h. The solvent was removed under
reduced pressure and the residue was stirred in water for
2.5 h. The solid was collected by filtration, washed with water,
diethyl ether and dried in vacuo at 40 ЊC for 18 h to give 9
(431 mg, 89%) as a cream solid: δH (250 MHz) 12.3 (1H, br s,
CO2H), 7.29 (1H, d, J 10, 1-H), 6.23 (1H, dd, J 10 and 2, 2-H),
6.02 (1H, s, 4-H), 5.27 (1H, m), 5.21 (1H, s), 5.18 (1H, s), 5.12
(1H, s), 4.16 (1H, m, 11-H), 1.51 (3H, s, 19-H) and 0.93 (3H, s,
18-H) (Found: C, 64.0; H, 7.0; F, 4.8. C21H25FO5ؒH2O requires
C, 63.9; H, 6.9; F, 4.8%).
9ꢁ-Fluoro-11ꢂ-hydroxy-16-methylene-3-oxo-17ꢁ-propionyloxy-
androsta-1,4-diene-17ꢂ-carboxylic acid 12
A stirred suspension of 9 (1.38 g, 3.66 mmol) in dichloro-
methane (36 cm3) was cooled to 0 ЊC and treated with triethyl-
amine (1.7 cm3, 12.2 mmol). The clear solution was treated with
propionyl chloride (1.12 cm3, 12.9 mmol) and the mixture was
stirred for 1 h. The reaction mixture was diluted with dichloro-
methane and washed with sodium bicarbonate solution, dilute
hydrochloric acid and water, dried and evaporated to a white
foam. This was dissolved in acetone (55 cm3) and diethylamine
(1.33 cm3, 12.9 mmol) was added. The mixture was stirred for
1 h at 20 ЊC and the solid was collected by filtration. The solid
was dissolved in water, acidified with hydrochloric acid and
extracted with ethyl acetate. The organic extracts were dried,
and evaporated to dryness to give 12 (1.576 g, 99%). An
analytical sample was obtained by recrystallising a portion in
acetone–light petroleum: νmax (KBr)/cmϪ1 3500–2500, 1732,
1714, 1667 and 1651; δH (250 MHz) 7.29 (1H, d, J 10, 1-H), 6.24
(1H, dd, J 10 and 2, 2-H), 6.03 (1H, s, 4-H), 5.63 (1H, s,
11-OH), 5.45–5.33 (2H, s, 16Ј-H), 4.20 (1H, m, 11-H), 1.51 (3H,
s, 19-H), 0.98 (3H, s, 18-H) and 0.97 (3H, t, J 7, OCH2CH3);
MS(ESϩve) m/z 433 (M ϩ H)ϩ. Found: (ESϩve) (M ϩ H)ϩ,
433.2037. C24H30FO6 requires (M ϩ H), 433.2026.
16ꢂ-Bromomethyl-16ꢁ,17ꢁ-epoxy-9ꢁ-fluoro-11ꢂ-hydroxy-3-oxo-
androsta-1,4-diene-17ꢂ-carboxylic acid 10
A solution of 9 (600 mg, 1.59 mmol) in THF (30 cm3) was
cooled to 2 ЊC and treated with 3% aqueous perchloric acid (15
cm3), followed by 1,3-dibromo-5,5-dimethylhydantoin (331 mg,
1.16 mmol). The solution was allowed to warm to 20 ЊC over
1 h, and then NaHSO3 was added portionwise until a test with
KI–starch paper was negative. The mixture was poured into
water and extracted with ethyl acetate. The organic extracts
were washed with water, brine, dried and evaporated to dryness
to give 10 (724 mg, 100%). An analytical sample was obtained
after recrystallisation from methanol to give 10 as white
crystals: mp 197–199 ЊC (decomp.); δH (250 MHz) 7.28 (1H, d,
J 10, 1-H), 6.23 (1H, dd, J 10 and 2, 2-H), 6.02 (1H, s, 4-H),
5.48 (1H, s), 4.12 (1H, m, 11-H), 3.99 (1H, d, J 10, 16Ј-H), 3.90
(1H, d, J 10, 16Ј-H), 1.50 (3H, s, 19-H) and 1.29 (3H, s, 18-H)
(Found: C, 55.5; H, 5.4; Br, 17.3. C21H24BrFO5 requires C, 55.4;
H, 5.3; Br, 17.5%).
16-Bromomethyl-9ꢁ-fluoro-11ꢂ-hydroxy-3-oxoandrosta-1,4,16-
triene-17ꢂ-carboxylic acid 13
A solution of 12 (663 mg, 1.53 mmol) in dichloromethane (90
cm3) was treated with hydrogen bromide gas for 15 min and
then stirred at 20 ЊC for 21 h. The mixture was diluted with
dichloromethane and washed with water, dried and concen-
trated to a volume of about 10 cm3, whereupon crystallisation
occurred. The crystals were collected by filtration, washed with
dichloromethane and dried in vacuo for 20 h to give 13 (488 mg,
816
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73%) as a pale green solid: νmax (Nujol)/cmϪ1 3600–2100, 3344,
1679, 1659, 1615 and 1602; δH (400 MHz) 12.65 (1H, br s,
CO2H), 7.31 (1H, d, J 10, 1-H), 6.22 (1H, dd, J 10 and 2, 2-H),
6.02 (1H, br s, 4-H), 5.44 (1H, br s, 11-OH), 4.63 (1H, d, J 10,
16Ј-H), 4.47 (1H, d, J 10, 16Ј-H), 4.09 (1H, m, 11-H), 1.53 (3H,
s, 19-H) and 1.21 (3H, s, 18-H); δC (100 MHz) 185.0 (C3), 166.4
(C20), 165.4 (C5), 152.3 (C1), 149.8 (C16), 142.7 (C17), 128.9
(C2), 124.2 (C4), 101.4 (d, J 175, C9), 70.7 (d, J 37, C11), 47.9
(d, J 23, C10), 47.3 (C13), 46.5 (C14), 40.1 (C12), 34.9 (C16Ј),
32.4 (d, J 19, C8), 30.0 (C15), 29.0 (C6), 26.5 (C7), 22.5 (d, J 6,
C19) and 17.0 (C18); MS(FABϩve) m/z 439 and 441 (M ϩ H)ϩ;
LSIMS(Ϫve) m/z 437 and 439 (M Ϫ H)Ϫ. Found: (LSIMSϩve)
439.0917 (M ϩ H)ϩ. C21H25BrFO4 requires (M ϩ H) 439.0920.
The mixture was stirred at 20 ЊC for 1.5 h, diluted with ethyl
acetate and poured into aqueous sodium bicarbonate solution.
The aqueous phase was extracted with ethyl acetate and the
combined organic extracts were washed with aqueous NaHSO3
solution, water and brine, dried and concentrated. The residue
was chromatographed on silica gel eluting with diethyl ether.
Fractions containing the product were combined and evapor-
ated. The residue was triturated in ether, dried in vacuo to give 16
(21 mg, 39%) as a fawn solid. Analytical HPLC indicated two
diastereoisomers were present tr 42.6 min 66% and 44.3 min
34%; νmax (KBr)/cmϪ1 3450, 1775, 1664 and 1620; δH (500 MHz)
major isomer (66%) 7.27 (1H, d, J 10, 1-H), 6.23 (1H, dd, J 10
and 2, 2-H), 6.02 (1H, br s, 4-H), 5.52 (1H, m, 11-OH), 5.01
(1H, q, J 5, 21-H), 4.60 (1H, d, J 11, 16Ј-H), 4.51 (1H, d, J 11,
16Ј-H), 4.18 (1H, m, 11-H), 1.50 (3H, s, 19-H), 1.29 (3H, d, J 5,
22-H) and 1.08 (3H, s, 18-H); minor isomer (34%) 7.27 (1H, d,
J 10, 1-H), 6.23 (1H, dd, J 10 and 2, 2-H), 6.02 (1H, br s, 4-H),
5.55 (1H, m, 11-OH), 5.54 (1H, q, J 5, 21-H), 4.49 (1H, d, J 11,
16Ј-H), 4.47 (1H, d, J 11, 16Ј-H), 4.18 (1H, m, 11-H), 1.50
(3H, s, 19-H), 1.23 (3H, d, J 5, 22-H) and 1.11 (3H, s, 18-H);
LSIMS(ϩve) m/z 419 (M ϩ H)ϩ (Found: C, 65.7; H, 6.4.
C23H27FO6 requires C, 66.0; H, 6.5%).
9ꢁ-Fluoro-11ꢂ-hydroxy-2Ј,5Ј-dihydrofuro[3Ј,4Ј:16,17]-
androsta-1,4,16-triene-3,5Ј-dione 14
A solution of the bromide 13 (351 mg, 0.80 mmol) in DMF (10
cm3) was treated with solid anhydrous potassium carbonate
(122 mg, 0.88 mmol) and the mixture was stirred for 2 h at
20 ЊC. The mixture was diluted with ethyl acetate and washed
with water, brine, dried and concentrated to about 5 cm3 where-
upon crystallisation occurred. The crystals were collected by
filtration, washed with ethyl acetate, and dried in vacuo at 40 ЊC
for 18 h to give 14 (197 mg, 69%) as white crystals: νmax (Nujol)/
cmϪ1 3444, 1735, 1668 and 1629; δH (400 MHz) 7.32 (1H, d,
J 10, 1-H), 6.24 (1H, dd, J 10 and 2, 2-H), 6.05 (1H, br s, 4-H),
5.56 (1H, br d, J 4, 11-OH), 4.91 (1H, d, J 18, 16Ј-H), 4.82 (1H,
d, J 18, 16Ј-H), 4.12 (1H, m, 11-H), 1.54 (3H, s, 19-H), 1.22
(3H, s, 18-H); δC (100 MHz) 185.0 (C3), 173.6 (C20), 168.6
(C16), 166.2 (C5), 152.3 (C1), 143.8 (C17), 128.9 (C2), 124.3
(C4), 101.5 (d, J 175, C9), 70.4 (d, J 39, C11), 69.7 (C16Ј), 53.7
(C14), 47.9 (d, J 23, C10), 41.2 (C13), 38.9 (C12), 32.7 (d, J 20,
C8), 29.9 (C15), 28.8 (C6), 26.5 (C7), 22.5 (d, J 6, C19) and 18.2
(C18); MS(TSPϩve) m/z 359 (M ϩ H)ϩ (Found: C, 68.95; H,
6.6; F, 5.1. C21H23FO4ؒ0.4C4H8O2 requires C, 68.95; H, 6.7; F,
4.8%).
9ꢁ-Fluoro-11ꢂ-hydroxy-16ꢁ,17ꢁ-isopropylidenedioxy-
2Ј,3Ј,4Ј,5Ј-tetrahydrofuro[3Ј,4Ј:16,17]androsta-1,4-diene-
3,5Ј-dione 17
A solution of the dihydroxylactone 15 (310 mg, 0.79 mmol) in
DMF (6 cm3) was treated with acetone (20 cm3), 2,2-dimethoxy-
propane (20 cm3), and then hydrogen chloride gas was bubbled
through the solution for 4 min. The mixture was stirred at 20 ЊC
for 40 min and then was diluted with ethyl acetate and aqueous
sodium bicarbonate. The organic solution was washed with
water and brine, dried, and concentrated. The residue was
chromatographed on silica gel, eluting with ethyl acetate–
cyclohexane (1:1) to give a yellow solid. This was triturated in
diethyl ether (10 cm3), the solid was collected by filtration,
washed with more ether (5 × 2 cm3), and dried in vacuo at 60 ЊC
for 18 h to give 17 (195 mg, 57%) as a cream crystalline solid:
mp 319–321 ЊC; νmax (CHBr3)/cmϪ1 3593, 1777, 1664, 1626 and
1608; δH (250 MHz) 7.27 (1H, d, J 10, 1-H), 6.23 (1H, dd, J 10
and 2, 2-H), 6.02 (1H, s, 4-H), 5.52 (1H, br s, 11-OH), 4.59 (1H,
d, J 11, 16Ј-H), 4.49 (1H, d, J 11, 16Ј-H), 4.19 (1H, m, 11-H),
1.50, 1.36, 1.27, 1.06 (4s, 3H each); MS(TSPϩve) m/z 433
(M ϩ H)ϩ (Found: C, 66.5; H, 6.7; F, 4.5. C24H29FO6 requires
C, 66.65; H, 6.75; F, 4.4%).
9ꢁ-Fluoro-11ꢂ,16ꢁ,17ꢁ-trihydroxy-2Ј,3Ј,4Ј,5Ј-tetrahydrofuro-
[3Ј,4Ј:16,17]androsta-1,4-diene-3,5Ј-dione 15
A solution of the unsaturated lactone 14 (1.444 g, 4.03 mmol)
in acetone (235 cm3) and formic acid (0.71 cm3, 18.8 mmol) was
cooled to Ϫ7 ЊC and then treated dropwise with a chilled solu-
tion of potassium permanganate (670 mg, 4.24 mmol) in water
(7 cm3) and acetone (21 cm3). The solution was stirred at Ϫ6 ЊC
for 45 min, aqueous sodium metabisulfite solution (10%, 70
cm3) was added over 15 min, and then allowed to warm to
20 ЊC. The mixture was concentrated under reduced pressure
and the residue was triturated in water (100 cm3). The solid was
collected by filtration, washed with water, ethyl acetate and
dried at 60 ЊC in vacuo for 20 h over P2O5 to give 15 (1.285 g,
81%) as a cream coloured crystalline solid: mp >330 ЊC; νmax
(KBr)/cmϪ1 3430, 1754, 1664 and 1620; δH (400 MHz) 7.28 (1H,
d, J 10, 1-H), 6.22 (1H, dd, J 10 and 2, 2-H), 6.02 (1H, s, 4-H),
5.58 (1H, s, OH), 5.40–5.34 (2H, m), 4.34 (1H, d, J 11, 16Ј-H),
4.19 (1H, d, J 11, 16Ј-H), 4.16 (1H, m, 11-H), 1.50 (3H, s, 19-H)
and 1.03 (3H, s, 18-H); δC (100 MHz) 185.0 (C3), 166.5 (C20),
166.4 (C5), 152.4 (C1), 128.9 (C2), 124.1 (C4), 100.8 (d, J 175,
C9), 84.8 (C17-tentative), 81.4 (C16-tentative), 80.7 (C16Ј), 70.5
(d, J 37, C11), 47.8 (d, J 23, C10), 45.5 (C13), 44.7 (C14), 40.6
(C12), 35.4 (C15), 33.0 (d, J 20, C8), 30.0 (C6), 27.1 (C7), 22.8
(d, J 6, C19) and 15.6 (C18); MS(TSPϩve) m/z 393 (M ϩ H)ϩ
(Found: C, 63.9; H, 6.3. C21H25FO6 requires C, 64.25; H, 6.4%).
16ꢁ,17ꢁ-Butylidenedioxy-9ꢁ-fluoro-11ꢂ-hydroxy-2Ј,3Ј,4Ј,5Ј-
tetrahydrofuro[3Ј,4Ј:16,17]androsta-1,4-diene-3,5Ј-dione 18
A solution of the dihydroxylactone 15 (316 mg, 0.805 mmol)
in DMF (6.5 cm3) and butyraldehyde (20 cm3) was bubbled
through with hydrogen chloride gas for 5 min. The mixture was
stirred for 1 h and then was diluted with ethyl acetate and
poured into aqueous sodium bicarbonate solution. The organic
phase was washed with 10% aqueous sodium metabisulfite,
water and brine, dried and concentrated under reduced pres-
sure. The residue was chromatographed on silica gel eluting
with ethyl acetate–cyclohexane (1:1) to give a solid (293 mg).
This was triturated in diethyl ether (10 cm3) and the solid was
collected by filtration, washed with ether (3 × 5 cm3) and dried
in vacuo at 60 ЊC for 24 h to give 18 as a white solid (232
mg, 65%). Analytical HPLC indicated a mixture of the two
diastereoisomers: 19.70 min 49.0% and 21.76 min 49.2%; νmax
(KBr)/cmϪ1 3320, 1776, 1665 and 1620; δH (250 MHz) 7.28 (1H,
d, J 10, 1-H), 6.24 (1H, d, J 10, 2-H), 6.03 (1H, s, 4-H), 5.56
(1H, m), 5.43 (0.5H, t, J 4, 21-H), 4.92 (0.5H, t, J 4, 21-H), 4.62
and 4.50 (2d, 1H each, J 11, 16Ј-H), 4.48 (1H, s), 4.19 (1H, m,
11-H), 1.50 (3H, s, 19-H), 1.12 and 1.09 (3H, 2s, 18-H), 0.86
and 0.85 (3H, 2t, J 7, 24-H); MS(TSPϩve) m/z 447 (M ϩ H)ϩ
(Found: C, 67.05; H, 6.9; F, 4.3. C25H31FO6 requires C, 67.25;
16ꢁ,17ꢁ-Ethylidenedioxy-9ꢁ-fluoro-11ꢂ-hydroxy-2Ј,3Ј,4Ј,5Ј-
tetrahydrofuro[3Ј,4Ј:16,17]androsta-1,4-diene-3,5Ј-dione 16
A solution of the dihydroxylactone 15 (50 mg, 0.13 mmol) in
DMF (1 cm3) was treated with acetaldehyde (3 cm3) and hydro-
gen chloride gas was bubbled through the solution for 6 min.
J. Chem. Soc., Perkin Trans. 1, 2000, 813–818
817

View Article Online
3 N. Bodor, Trends Pharmacol. Sci., 1982, 3, 53.
H, 7.0; F, 4.25%). The two diastereoisomers were separated by
preparative HPLC: the more polar isomer (62 mg), which was
recrystallised from ethyl acetate, gave the C21 R-isomer as a
white solid: mp 273–277 ЊC; analytical HPLC tr 18.48 min
89.3% (contains 8.5% of S-isomer); δH (400 MHz) 7.27 (1H, d,
J 10, 1-H), 6.23 (1H, dd, J 10 and 2, 2-H), 6.02 (1H, br s, 4-H),
5.50 (1H, br d, J 4, 11-OH), 4.99 (1H, t, J 4, 21-H), 4.59 (1H, d,
J 11, 16Ј-H), 4.50 (1H, d, J 11, 16Ј-H), 4.19 (1H, m, 11-H), 1.50
(3H, s, 19-H), 1.08 (3H, s, 18-H) and 0.86 (3H, d, J 7, 24-H).
NOE’s were observed from 16Ј-H to 21-H and from 21-H to
16Ј-H. The second isomer (87 mg) was recrystallised from ethyl
acetate to give the C21 S-isomer as a crystalline solid: mp 317–
319 ЊC; analytical HPLC tr 20.42 min 97.2% (contains 2.8% of
the R-isomer); δH (400 MHz) 7.27 (1H, d, J 10, 1-H), 6.23 (1H,
dd, J 10 and 2, 2-H), 6.02 (1H, br s, 4-H), 5.53 (1H, dd, J 4 and
1, 11-OH), 5.41 (1H, t, J 4, 21-H), 4.47 (2H, s, 16Ј-H), 4.18 (1H,
m, 11-H), 1.50 (3H, s, 19-H), 1.13 (3H, s, 18-H) and 0.85 (3H, d,
J 7, 24-H). NOE’s were observed from 21-H to 14-H, 22-H and
23-H, and from 16Ј-H to 15-H and 18-H.
4 C. Milioni, L. Jung and B. Koch, Eur. J. Med. Chem., 1991, 26, 947.
5 H. Ueno, A. Maruyama, M. Miyake, E. Nakao, K. Nakao,
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8 K.-J. Yoon, M. A. Khalil, T. Kwon, S.-J. Choi and H. J. Lee,
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12 K. Biggadike, R. M. Angell, C. M. Burgess, R. M. Farrell,
A. P. Hancock, A. Harker, W. R. Irving, C. Ioannou, P. A.
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16 R. L. Brattsand and B. A. Thalen, Eur. Patent 143764 (1983), Chem.
Abstr., 1986, 104, 69061.
Crystal structure analysis of 18.‡ Crystal data for C25H31-
FO6: M = 446.5, monoclinic, a = 6.103(2), b = 13.105(2), c =
14.153(2) Å, β = 94.42(2)Њ, V = 1128.5(4) Å3, T = 160 K. Space
group P21 (No. 4), Z = 2, µ(Cu-Kα) = 0.813 mmϪ1, 3304 reflec-
tions were measured of which 3171 were unique, Rint = 0.0711.
The final wR(F2) was 0.1707 and Robs was 0.0730.
17 G. H. Phillipps, Mechanism of Topical Corticosteroid Activity,
ed. L. Wilson and R. Marks, Churchill Livingstone, New York,
1976.
18 D. Taub, R. D. Hoffsommer and N. L. Wendler, J. Org. Chem.,
1964, 29, 3486.
19 F. Werder, H. J. Mannhardt, K. H. Bork, H. Metz, K. Brückner and
K. Irmscher, Arzneim. Forsch., 1968, 18, 7.
20 G. H. Phillipps and B. M. Bain, Ger. Patent DE 2538595 (1974),
Chem. Abstr., 1976, 85, 63240.
21 L. Toscano, L. Barlotti, G. Fioriello, G. Grisanti, G. Bossoni,
L. M. Biraschi and M. Riva, Arzneim. Forsch., 1977, 27, 1628.
22 T. S. Berger, Z. Parandoosh, B. W. Perry and R. B. Stein, J. Steroid
Biochem. Mol. Biol., 1992, 41, 733.
23 E. Dahlberg, A. Thalen, R. Brattsand, J. A. Gustafsson,
U. Johansson, K. Roempke and T. Saartok, Swed. Mol. Pharmacol.,
1984, 25, 70.
Acknowledgements
We thank Mrs Y. E. Solanke and Mrs S. Walton for conducting
the biological assays.
‡ CCDC reference number 207/390. See http://www.rsc.org/suppdata/
p1/a9/a908358h for crystallographic files in .cif format.
References
1 P. J. Barnes, S. Pedersen and W. W. Busse, Am. J. Respir. Crit. Care
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2 H. J. Lee and M. R. I. Soliman, Science, 1982, 215, 989.
Paper a908358h
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J. Chem. Soc., Perkin Trans. 1, 2000, 813–818