Estradiol derivatives bearing sulfur-containing substituents at the 11β or 7α positions: Versatile reagents for the preparation of estrogen conjugates

Article abstract of DOI:10.1016/j.bmc.2004.06.017

Estradiol derivatives bearing HS-, HSCH₂-, HSCH ₂CH₂-, MeS-, MeSCH₂-, MeSCH₂CH ₂-, or PhCH₂SCH₂CH₂-groups at the 11β position or an HS-group at the 7α position have been synthesized, and their binding affinity to the estrogen receptor (ER) determined. Nearly all of these substituted estrogens retain high binding affinity, and at the 11β position, the sulfur atom has an effect on ER binding that is similar to that of a carbon atom. These thiol derivatives are promising intermediates for the preparation of a variety of estradiol conjugates. The methyl sulfides, in particular, might potentially be developed as ¹¹C-labeled agents for imaging ER-positive tumors by positron emission tomography.

Full text of DOI:10.1016/j.bmc.2004.06.017

Bioorganic & Medicinal Chemistry 12 (2004) 4393–4401
Estradiol derivatives bearing sulfur-containing substituents
at the 11b or 7a positions: versatile reagents for
the preparation of estrogen conjugates
Daniela Spera,a Gustavo Cabrera,a Rita Fiaschi,a Kathryn E. Carlson,b
John A. Katzenellenbogenb and Elio Napolitanoa,c,
*
aDipartimento di Chimica Bioorganica e Biofarmacia, Via Bonanno 33, 56127 Pisa, Italy
bDepartment of Chemistry, University of Illinois, 600 South Mathews Avenue, Urbana, IL 61801, USA
cScuola Normale Superiore di Pisa, Piazza dei Cavalieri, 56126 Pisa, Italy
Received 7 April 2004; accepted 7 June 2004
Available online 7 July 2004
Abstract—Estradiol derivatives bearing HS-, HSCH2-, HSCH2CH2-, MeS-, MeSCH2-, MeSCH2CH2-, or PhCH2SCH2CH2-groups
at the 11b position or an HS-group at the 7a position have been synthesized, and their binding affinity to the estrogen receptor (ER)
determined. Nearly all of these substituted estrogens retain high binding affinity, and at the 11b position, the sulfur atom has an
effect on ER binding that is similar to that of a carbon atom. These thiol derivatives are promising intermediates for the preparation
of a variety of estradiol conjugates. The methyl sulfides, in particular, might potentially be developed as 11C-labeled agents for
imaging ER-positive tumors by positron emission tomography.
ꢀ 2004 Elsevier Ltd. All rights reserved.
1. Introduction
Nonsteroidal estrogens have been actively investigated,
particularly in the search for selective modulators of
estradiol receptors, because of the ease with which
nonsteroidal structures can be chemically manipulated
and altered to optimize their binding and activity
properties.5 In fact, several nonsteroidal estrogens,
including tamoxifen and raloxifene, are termed selective
estrogen receptor modulators or SERMs. Continued
investigation of nonsteroidal compounds is encouraged
by the estrogenic activity of phytoestrogens and other
nonsteroidal natural products, such as coumestrol,
genistein, and b-zearalenone, compounds of polyketide
or mixed biosynthetic origin. Despite the popularity of
nonsteroidal ER ligands, we thought that the search for
new SERMs and radiotracers or radiotherapeutic agents
might greatly benefit from the possibility of generating
easily a wide variety of steroidal derivatives, namely,
estrogens substituted at the 11b or 7a positions. These
positions, although more difficult to functionalize than
the 17a position––which has been the most extensively
adopted for belling the estradiol molecule––are more
tolerant of the presence of substituents, which can fre-
quently give rise to derivatives having high binding
affinity, as well as potent estrogenic or antiestrogenic
activity.6
There is great interest in the development of estrogens
having tissue-selective pharmacological profiles that are
optimal for hormone replacement therapy and breast
cancer prevention and treatment, in particular, ones that
would block the proliferative actions of estrogens in the
uterus and breast, but maintain beneficial estrogen
function in the bone, brain, and the cardiovascular
system.1–3 There is also interest in the development of
radioactive estradiol derivatives that can be used as
receptor-based agents for imaging or radiotherapy of
estrogen-responsive breast cancer.4 Both of these goals
have stimulated continued interest in the study of the
relationship between the structure of ligands for the
estrogen receptor (ER) and their estrogenic activity and
ER binding affinity.
Keywords: Estradiol; Estrogens; Sulfur; Mercaptans; Methyl sulfides.
* Corresponding author. Fax: +39-050-43321; e-mail: eliona@farm.
unipi.it
0968-0896/$ - see front matter ꢀ 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmc.2004.06.017

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D. Spera et al. / Bioorg. Med. Chem. 12 (2004) 4393–4401
In this report, we describe the synthesis of estradiol
compounds 1–4, steroids that are mercapto substituted
at the 11b or 7a positions. Because of the ease with
which carbon–sulfur bonds can be formed and the sta-
bility of this bond, these compounds are promising
intermediates for generating estradiol conjugates of
different types. For instance, alkylation of SH with long
chain substituents could lead to sulfur analogs of
important antiestrogens; alkylation with groups con-
taining a triple bond, a cyclopentadiene, or a macrocy-
clic ligand could give rise to compounds amenable for
conjugation with transition metals.7 Besides 11-substi-
tuted mercapto derivatives 1–3, we also report the syn-
thesis and ER binding properties of their respective
methyl sulfides 5–7. The ER binding data on these
compounds reveals the influence of the sulfur atom on
the binding properties of estradiol derivatives, and they
show that compounds 5–7, which could be readily
labeled with the positron-emitting radionuclide carbon-
11 by the reaction of suitably protected versions of the
corresponding thiol compounds 1–3 with C-11 methyl
iodide, are promising new candidates as receptor-based
agents for imaging ER-positive breast tumors using
positron emission tomography (PET). It is of note that
these compounds would have the radiolabel at a site
where it is easily introduced and well tolerated (if not
binding enhancing), and it would leave positions 15, 16,
and 17 free to allow for substitution to control metab-
olism and clearance as is needed to achieve effective
target to background contrast with an imaging radio-
pharmaceutical labeled with an isotope having a half life
of 20.3 min.
2. Results and discussion
2.1. Chemical synthesis
2.1.1. Synthesis of 11b-substituted estrogens. The estra-
diol derivatives with sulfur-containing substituents at
11b (1–3 and 5–7) were prepared as outlined in Scheme
1. The hydroxy derivative 8, a common reaction inter-
mediate, was obtained from commercially available
estrone through the following steps, as detailed else-
where:8 (a) dehydrogenation with dichlorodicyano-
quinone; (b) reduction with sodium borohydride; (c)
di-benzylation with benzylbromide and sodium hydride,
and (d) hydroboration followed by oxidation with
alkaline peroxide. To obtain compounds 1 and 5, in
OBn
OBn
OH
X
RS
BnS
BnO
BnO
HO
12
a
c
e
d
1
8
(X=HO)
10 (R=Bn)
11 (R=Me)
b
d
9 (X=OSO Me)
5
2
OBn
OBn
OBn
ref. 8
OH
O
MeSCH
MeSCH
2
2
BnO
13
BnO
14
BnO
15
g
f
d
6
OBn
OBn
OBn
ref. 8
X(CH )
RS(CH )
2 n
2 n
BnO
BnO
BnO
d
to 17: h, i, j
b
a
17 (n=1; X=OH)
18 (n= 2; X= OH)
21 (n=2; R=Me)
7
16
to 18: ref. 10
d
c
19 (n= 1; X= OSO Me)
22 (n=1; R=Bn)
23 (n=2; R=Bn)
2
20 (n= 2; X= OSO Me)
2
OH
BnS(CH )
2 n
HO
24 (n=1)
e
2
3
25 (n=2)
Scheme 1. Conditions: (a) MeSO3Cl, Py. (b) CH3SNa, DMF, 60 ꢁC. (c) PhCH2SNa, DMF, 60 ꢁC. (d) BBr3, CH2Cl2, )5 ꢁC. (e) Na/EtOH, D. (f)
CH3SCH2Li/TMEDA. (g) Et3SiH, BF3ÆOEt2, CH2Cl2. (h) OsO4, 4-methylmorpholine N-oxide, CH3COCH3. (i) NaIO4, SiO2, H2O/CH2Cl2. (j)
NaBH4/MeOH.

D. Spera et al. / Bioorg. Med. Chem. 12 (2004) 4393–4401
4395
which the sulfur atom is directly bound to the 11b-po-
sition, alcohol 8 was converted to the corresponding
methanesulfonate 9, which underwent clean displace-
ment by sodium benzylmercaptide to give the tribenzyl-
ated derivative 10. The O-benzyl groups were removed
with boron tribromide, and the resulting S-benzylated
derivative 12 was further deprotected by reaction with
excess of sodium in ethanol, thus yielding the parent
mercaptan 1. Methyl sulfide 5 was obtained from mes-
ylate 9 by reaction with sodium methylmercaptide
(prepared by reduction of dimethyl disulfide with so-
dium powder in tetrahydrofuran), followed by debenz-
ylation with boron tribromide of intermediate
dibenzylated derivative 11.
not result in a clean transformation, and the following
alternative route from the vinylestradiol 16 was pre-
ferred. Thus, the unsaturated derivative 16 was di-
hydroxylated with osmium tetroxide and morpholine
N-oxide; the crude diol was cleaved with sodium perio-
date, and the intermediate aldehyde, without purifica-
tion, was subjected to sodium borohydride reduction to
afford the hydroxymethyl derivative 17. This material
was converted to mercaptan 2 by the sequence involv-
ing: (a) formation of the mesylate 19; (b) mesylate dis-
placement by sodium benzylmercaptide to give 22; (c)
O-debenzylation with boron tribromide to give diol 24,
and finally (d) S-debenzylation. Treatment of mesylate
19 with sodium methylmercaptide gave a sulfide identi-
cal to compound 15 obtained from precursor 14, thus
confirming the 11b stereochemistry of 15.
The higher methyl sulfide 6 was obtained from ketone 13
by an extension of our recent approach to 11b carbon-
substituted estradiol derivatives.8 Thus, the lithium
derivative of dimethyl sulfide (obtained by hydrogen
metal exchange with butyllithium in the presence of
tetramethylethylenediamine)9 added to the carbonyl of
13 the aface, as is generally observed with other nucleo-
philes, to give the tertiary alcohol 14. This material
underwent ionic reduction with triethylsilane and boron
trifluoride etherate, leading, after O-debenzylation of
the intermediate ether 15, to the expected sulfide 6. The
11b stereochemistry of 6 was confirmed by an alterna-
tive synthesis from 16 in which the stereochemistry at 11
is known (vide infra).
For the synthesis of the highest mercaptan and methyl-
sulfides of the series, olefin 16 was converted to mesylate
20 through alcohol 18, as already reported.10 The reac-
tion of 20 with either sodium methylmercaptide or
benzylmercaptide gave sulfides 21 or 23, respectively.
Debenzylation with boron tribromide converted the
ethers 21 and 23 to the alcohols 7 and 25, respectively.
Further debenzylation with sodium in ethanol converted
25 to the mercapto diol 3.
2.1.2. Synthesis of 7a-substituted estrogen. The synthesis
of 7a-mercaptoestradiol 4 is outlined in Scheme 2.
Estradiol was protected as the dimethylether 26 and
hydroxylated at C-6 to give alcohol 27, according to our
previously reported procedure involving deprotonation
Attempts to generate mercaptan 2 from sulfide 6 by a
sequence involving oxidation to a sulfoxide and sub-
sequent Pummerer rearrangement of the sulfoxide did
OMe
a
OMe
OMe
b
MeO
MeO
MeO
OH
O
26
27
28
c
OMe
OMe
OMe
e
d
MeO
SBn
MeO
SBn
MeO
Br
O
O
31
30
29
f
OMe
g
4
MeO
SH
32
Scheme 2. (a) 1. LDA/t-BuOK; 2. B(OCH3)3; 3. H2O2. (b) PCC, CH2Cl2. (c) Br2, CH2Cl2. (d) Conditions A: BnSH/t-BuOK, D. Conditions B: BnSH/
NaOH. (e) Et3SiH, BF3ÆOEt2, CH2Cl2. (f) Na/EtOH. (g) AlBr3/EtSH.

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D. Spera et al. / Bioorg. Med. Chem. 12 (2004) 4393–4401
of the 5-H, quenching of the anion with trimethyl
borate, and oxidation of the intermediate boronoic acid
with hydrogen peroxide.11 An improved procedure for
the preparation of 27 is here reported (involving the use
of potassium tert-butoxide as the additive and butyl-
lithium with a catalytic amount of diisopropylamine
as the metalating agent), which leads to higher and
more consistent yields of product while saving lith-
ium reagents (see Experimental). The alcohol 27 was
oxidized to the ketone 28, which underwent clean
bromination to give 7a-bromoketone 29 as the sole
(probably kinetically and thermodynamically con-
trolled) product.12 Exposure of this bromoketone (29) to
the potassium salt (or sodium salt) of benzylmercaptan
gave the 7a sulfide 30 (retention of configuration) as the
thermodynamically controlled product, the result of
substitution and then epimerization, presumably via
enol formation.
improved binding properties compared to the parent
ligand. Since the 11b-hydroxy analog of 1 has a lower
RBA than estradiol,6a the closer resemblance of 1 to
11b-methylestradiol can be rationalized on the basis of
the relatively nonhydrophilic nature of the mercapto
group. A further improvement in binding affinity is
observed going to the higher homologues, 2 and 5, in
which the 11b substituent consists of the mercapto-
methyl or the methylmercapto group, respectively: the
higher affinity of these two isomers is the thioether (5). It
is worth noting that the affinities of analogs 2 and 5 are
somewhat less than those observed for the isosteric
estradiol derivatives bearing an 11b-chloromethyl (110/
1780 at 0/25 ꢁC), ethyl (133/1372 at 0/25 ꢁC lamb), or
vinyl group (117/1780 at 0/25 ꢁC lamb), but superior to
those of the oxygenated analog 11b methoxyestradiol
(8.5/86 at 0/25 ꢁC lamb).6a Higher homologues with a
sulfur containing three-atom substituent at 11b (3 and 6)
have significantly lower RBA than their parents: isomer
3, having a terminal mercaptan, has an RBA value that
is lower than that for estradiol, but the thioether isomer
6 has RBA values that are comparable to higher than
that of estradiol. Methylation of the SH group of 3
produces the compound (7) that has the lowest affinity
in the series. Curiously, however, benzylation produces
a derivative (25) having better binding properties than
the methyl analog 7. It is not clear why some com-
pounds (1, 2, 5, and 6) show a pronounced temperature
dependence in their ER binding affinity, whereas others
(3, 7, and 25) do not, although such observations have
been made by us and others previously.13–15 The intro-
duction of the mercapto group at the 7a position sub-
stantially depresses the binding affinity, as generally
observed with other groups larger than a methyl, and
the temperature dependence of the binding (lower at
higher temperature) is also different for what observed
for the introduction of the mercapto group at the 11b
position.
Ionic reduction of keto sulfide 30 gave the sulfide 31
stereospecifically and in high yield. Debenzylation of 31
(sodium in ethanol) followed by the demethylation
(AlBr3 in methylene chloride) of the intermediate thio-
ether 32 gave the 7a-mercaptoestradiol 4.
2.2. Binding affinity determination
The binding affinities of the sulfur-containing estrogen
analogs for the estrogen receptor were determined by a
competitive radiometric binding assay using lamb uter-
ine cytosol as a source of receptor (see Experimental).
Affinities are expressed relative to that of the tracer,
[3H]estradiol, as relative binding affinity (RBA) values,
where the RBA of estradiol is 100. RBA values are
measured at both 0 and 25 ꢁC. Receptor binding assays
are traditionally run at 0 ꢁC, but some compounds show
considerably higher binding affinities at 25 ꢁC for rea-
sons that are not well understood: this may have to do
with achieving full equilibration in the competitive
binding assay,13 or accentuating of the hydrophobic
component of the binding affinity.14 The values at 25 ꢁC
may be more relevant to the behavior of these com-
pounds as radiopharmaceuticals for in vivo imaging.15
3. Conclusion
In conclusion, sulfur-containing groups have been
introduced into positions 11b and 7a of estradiol. The
sulfur atom promotes high estrogen receptor binding
affinity when it is part of a small group at 11b, but the
mercapto group depresses the binding when present in
the 7a position. The mercapto derivatives should be
convenient, advanced intermediates for the preparation
of a various estradiol conjugates that could be used for
different purposes. The methylthio derivatives 5 and 6
are promising candidates as 11C labeled receptor-based
imaging agents for ER-positive breast cancer.
The RBA values of the new sulfur-containing estradiol
derivatives, described above, are shown in Table 1.
Introduction of an SH at the position 11b of estradiol
results in a derivative (1) that has comparable to
Table 1. Relative binding affinity of sulfur-containing estradiol
derivatives
Compd
Substituent
RBA (0 ꢁC)
RBA (25 ꢁC)
Estradiol
1
H-
HS-11b
MeS-11b
HSCH2-11b
MeSCH2-11b
HSCH2CH2-11b
MeSCH2CH2-11b
PhCH2SCH2CH2-11b 110 20
HS-7a 43
100
100
270 1
49
29
7
4
4. Experimental
5
290 15
550 20
140 30
57 20
2
57 22
6
65
40
31
4
1
7
Melting points were taken with a Kofler hot plate
apparatus and are uncorrected. For analytical TLC
Merck Silica Gel F-254 on aluminum plates were used;
for the visualization of spots, the plates were soaked
with an ethanol solution containing phosphomolybdic
3
7
19
100 20
2
25
4
0
5 1

D. Spera et al. / Bioorg. Med. Chem. 12 (2004) 4393–4401
4397
acid (5%) and sulfuric acid (5%), and heated with a heat
gun. For column chromatography, the technique de-
scribed by Still and Kahn,16 was adopted, using mixture
methylene chloride. After 45 min stirring at 0 ꢁC, the
mixture was partitioned between methanol and EtOAc.
The organic layer was washed with 10% aq sodium
bicarbonate and then with brine, dried, and evaporated
to leave a residue from which 12 (0.1 g, 63% yield) was
obtained by chromatography (2:1, hexane–EtOAc) as a
1
of hexane and EtOAc or CH2Cl2 as eluants. H NMR
(200 MHz) spectra were obtained using a Bruker AC 200
spectrometer for samples dissolved, unless otherwise
indicated, in CDCl3; chemical shifts (d) are in parts per
million downfield from tetramethylsilane as internal
standard. Elemental analyses were performed by
microanalytical laboratory of the Faculty of Pharmacy
of the University of Pisa. All the reactions involving
organometallic reagents were performed under nitro-
gen in solvents distilled from sodium benzophenone
ketyl. Unless otherwise stated, solutions were dried
with magnesium sulfate and evaporated in a rotary
evaporator under diminished pressure. Compounds 8,
13, 16, 18, and 20 were synthesized as previously
reported.8;10
1
glass. H NMR (CD3OD) d 1.03 (s, 3H, 18-H), 3.55 (s,
2H, PhCH2S), 6.4 (m, 3H, 1-H, 2-H, 4-H), 7.15 (m, 5H,
PhCH2S). EIMS m=z 394.1967 (calcd for C25H30O2S
394.1966).
4.4. 11b-Mercaptoestra-1,3,5(10)-triene-3,17b-diol (1)
Sodium (300 mg, 13 mmol) was added in small portions
to a refluxing solution of 12 (80 mg, 0.2 mmol) in EtOH
(50 mL); complete consumption of 12 was checked by
TLC. Diluted HCl was added under nitrogen, and the
excess of EtOH was evaporated. The residue was
partitioned between water and EtOAc. The organic
layer was dried and evaporated to give a residue from
which 1 (40 mg, 66% yield) was obtained by trituration
with ether as a crystalline solid. Mp 228–230 ꢁC. 1H
NMR (CD3OD) d 1.04 (s, 3H, 18-H), 3.64 (m, 1H,
17-H), 4.01 (m, 1H, 11-H), 6.50 (d, J ¼ 2:6 Hz, 1H, 4-
H), 6.60 (dd, J ¼ 2:6, 8.4 Hz, 1H, 2-H), 6.92 (d,
J ¼ 8:4 Hz, 1H, 1-H). EIMS m=z 304.1501 (calcd for
C18H24O2S 304.1497).
4.1. 3,17b-Bis(benzyloxy)-11a-methanesulfonylestra-
1,3,5(10)-triene (9)
To a solution of 8 (0.1 g, 0.21 mmol) in methylene
chloride (0.5 mL) were added pyridine (1 mL, 12 mmol)
and methanesulfonyl chloride (0.5 mL, 6 mmol), and the
mixture was stirred at room temperature for 18 h. Ice
was added, and reaction mixture was extracted with
CH2Cl2. The organic layer was washed with 5% aq HCl,
dried, and evaporated to give a residue from which 9
(0.1 g, 95% yield) was obtained by trituration with ether
as a crystalline solid. Mp 145–147 ꢁC. 1H NMR (CDCl3)
d 0.9 (s, 3 H, 18-H), 3.0 (s, 3 H, CH3–SO3), 3.55 (t,
J ¼ 8 Hz, 1H, 17-H), 4.52, 5.01 (2s, 2 · 2H, PhCH2),
5.38 (m, 1H, 11-H), 6.74 (d, J ¼ 2:6 Hz, 1H, 4-H), 6.86
(dd, J ¼ 2:6 and 8.5 Hz, 1H, 2-H). EIMS m=z 546.2442
(calcd for C33H38O5S 546.2440).
4.5. 3,17b-Bis(benzyloxy)-11b-methylthioestra-1,3,5(10)-
triene (11)
Sodium powder (50% dispersion in oil, 0.5 g, 10.8 mmol)
was washed free of oil and then suspended in dry
THF (15 mL). Dimethyl disulfide (0.6 mL, 6.6 mmol)
was added dropwise, and after 1 h the solvent was
evaporated. Compound 9 (0.2 g, 0.36 mmol) dissolved in
dry DMF (1 mL) was added to the residue, and the
reaction mixture was stirred at 60 ꢁC for 18 h. The
reaction was partitioned between water and Et2O, and
the organic layer was washed with water, dried, and
evaporated to give a residue from which 11 (0.1 g, 56%
yield) was obtained by chromatography (9.7:0.3, hex-
ane–EtOAc) as a glass. 1H NMR (CDCl3) d 1.25 (s, 3H,
18-H), 2.06 (s, 3H, CH3S), 3.48 (t, J ¼ 8 Hz, 1H, 17-H),
3.60 (m, 1H, 11-H), 4.55, 4.99 (2s, 2 · 2H, PhCH2), 6.7
(d, J ¼ 2:6 Hz, 1H, 4-H), 6.8 (dd, J ¼ 2:6 and 8.6 Hz,
1H, 2-H), 7.1 (d, J ¼ 8:6 Hz, 1H, 1-H), 7.34 (m, 10H,
PhCH2). EIMS m=z 498.2594 (calcd for C33H38O2S
498.2592).
4.2. 3,17b-Bis(benzyloxy)-11b-benzylthioestra-1,3,5(10)-
triene (10)
Benzyl mercaptan (1.4 mL, 12 mmol) was added drop-
wise to a suspension of NaH (50% dispersion in oil,
0.3 g, 6 mmol) in dry DMF (1 mL), followed by the
addition of 9 (840 mg, 1.53 mmol). The mixture was
stirred at 60 ꢁC for 18 h. The excess of NaH was de-
stroyed by addition of water, and then the mixture was
partitioned between water and Et2O. The organic layer
was washed with water, dried, and evaporated to leave a
residue from which 10 (640 mg, 73% yield) was obtained
by chromatography (9.5:0.5, hexane–EtOAc) as a glass.
1H NMR (CDCl3) d 1.25 (s, 3H, 18-H), 3.45 (m, 2H, 11-
H, 17H), 3.67 (s, 2H, PhCH2S), 4.52, 5.0 (2s, 2 · 2H,
PhCH2), 6.6 (m, 3H, 1-H, 2-H, 4-H), 7.3 (m, 15H,
PhCH2). EIMS m=z 574.2906 (calcd for C39H42O2S
574.2905).
4.6. 11b-Methylthioestra-1,3,5(10)-triene-3,17b-diol (5)
Debenzylation of 11 under the same conditions detailed
for the conversion of 10 into 12 gave 5 (63% yield) as a
1
glass. H NMR (CD3OD) d 1.11 (s, 3H, 18-H), 2.02 (s,
4.3. 11b-Benzylthioestra-1,3,5(10)-triene-3,17b-diol (12)
3H, CH3S), 3.64 (m, 2H, 11-H, 17-H), 6.44 (d,
J ¼ 2:6 Hz, 1H, 4-H), 6.55 (dd, J ¼ 2:6, 8.5 Hz, 1H, 2-
H), 7.04 (d, J ¼ 8:5 Hz, 1H, 1-H). EIMS m=z 318.1653
(calcd for C19H26O2S 318.1653).
BBr3 (2 mL, 1 M in CH2Cl2) was added dropwise to a
cooled ()5 ꢁC) solution of 10 (230 mg, 0.4 mmol) in

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D. Spera et al. / Bioorg. Med. Chem. 12 (2004) 4393–4401
4.7. 3,17b-Bis(benzyloxy)-11a-methylthiomethylestra-
1,3,5(10)-triene-11b-ol (14)
EtOAc and 10% aq sodium thiosulfate. The organic
layer was washed with brine, dried, and evaporated to
give a residue from which diol 3,17b-bis(benzyloxy)-11b-
(1,2-dihydroxyethyl)estra-1,3,5(10)-triene (0.4 g, 78%
yield) was obtained by chromatography (1:1, hexane–
Metalation of dimethylsulfide was accomplished as re-
ported.9 To a solution of n-BuLi (2.2 mL, 2.6 mmol,
1.18 M in hexane), cooled at )5 ꢁC, TMEDA (0.5 mL,
3.3 mmol), and dimethylsulfide (0.3 mL, 4 mmol) were
added, under nitrogen. The reaction mixture was stirred
at room temperature for 18 h, and then 13 (0.2 g,
0.4 mmol) was added. After 2 h the mixture was parti-
tioned between Et2O and 10% aq ammonium chloride.
The organic layer was dried, filtered, and evaporated to
give a residue from which 14 (180 mg, 85% yield) was
obtained by chromatography (9:1, hexane–EtOAc) as
1
EtOAc) as a glass. H NMR (CDCl3) d 1.11 (s, 3H, 18-
H), 4.58, 5.02 (2s, 2 · 2H, PhCH2), 6.67 (d, J ¼ 2:6 Hz,
1H, 4-H), 6.75 (dd, J ¼ 2:6, 8.5 Hz, 1H, 2-H), 7.08 (d,
J ¼ 8:5 Hz, 1H, 1-H), 7.34 (m, 10H, PhCH2). EIMS m=z
512.2929 (calcd for C34H40O4 512.2927).
The above diol was dissolved in methylene chloride and
added to a vigorously stirred suspension of silica gel
(1.5 g) in CH2Cl2. A aqueous solution of sodium
periodate (1.5 mL, 1.0 mmol, 0.65 M) was added drop-
wise, and after 30 min stirring at room temperature the
organic layer was evaporated.17 The residue was dis-
solved in methanol (20 mL) containing NaBH4 (110 mg,
3 mmol), and the reaction mixture was allowed to
equilibrate at room temperature for 5 h. A few drops of
10% aq HCl were added to destroy the excess of NaBH4
and most of solvent was evaporated. The residue was
partitioned between water and CH2Cl2. The organic
layer was washed with NaHCO3, dried, and evaporated
to give almost pure 17 (210 mg, 56% yield) as a glass. 1H
NMR (CDCl3) d 0.99 (s, 3H, 18-H), 3.44–3.78 (m, 4H,
CH2OH, 17-H), 4.58, 5.01 (2s, 2 · 2H, PhCH2), 6.68–
6.85 (m, 2H, 2-H, 4-H), 7.35 (m, 11H, 1-H, PhCH2).
EIMS m=z 482.2823 (calcd for C33H38O3 482.2821).
1
glass. H NMR (CDCl3) d 1.08 (s, 3H, 18-H), 2.19 (s,
3H, CH3S), 2.77–2.84, 3.22–3.28 (ABq, 2H, CH2S), 3.42
(t, J ¼ 8 Hz, 1H, 17-H), 4.52, 5.0 (2s, 2 · 2H, PhCH2),
6.74 (m, 2H, 2-H, 4-H), 7.32 (m, 10H, PhCH2), 7.7 (d,
J ¼ 8:5 Hz, 1H, 1-H). EIMS m=z 528.2700 (calcd for
C34H40O3S 528.2698).
4.8. 3,17b-Bis(benzyloxy)-11b-methylthiomethylestra-
1,3,5(10)-triene (15)
To a cooled (0 ꢁC) solution of 14 (180 mg, 0.34 mmol)
and borontrifluoride etherate (0.25 mL, 2 mmol) in
methylene chloride (10 mL), triethylsilane (1 mL,
7 mmol) was added dropwise and the mixture was stir-
red at 0 ꢁC for 1 h. The solution was partitioned between
CH2Cl2 and 10% aq sodium carbonate. The organic
layer was washed with ice/water, dried, and evaporated
to give a residue from which 15 (120 mg, 69% yield) was
obtained by chromatography (7:3, CH2Cl2–hexane) as a
crystalline solid. Mp 95–97 ꢁC. 1H NMR (CDCl3) d 1.04
(s, 3H, 18-H), 2.05 (s, 3H, CH3S), 3.5 (m, J ¼ 8 Hz, 1H,
17-H), 4.52, 4.58, 4.6, 4.66 (ABq, 2H, PhCH2), 5.02 (s,
2H, PhCH2), 6.69 (d, J ¼ 2:6 Hz, 1H, 4-H), 6.8 (dd,
J ¼ 2:6, 8.5 Hz, 1H, 2-H), 7.1 (d, J ¼ 8:5 Hz, 1H, 1-H),
7.36 (m, 10H, PhCH2). EIMS m=z 512.2749 (calcd for
C34H40O2S 512.2749).
4.11. 3,17b-Bis(benzyloxy)-11b-methanesulfonylmethyl-
estra-1,3,5(10)-triene (19)
The alcohol 17 was mesylated as detailed for the con-
version of 8 into 9 to give 19 (100% yield) as a glass. 1H
NMR (CDCl3) d 0.99 (s, 3H, 18-H), 2.82 (s, 3H, CH3–
SO3), 3.49 (q, J ¼ 8 Hz, 1H, 17-H), 4.57, 5.02 (2s,
2 · 2H, PhCH2), 4.09–4.27 (m, 2H, SO2–OCH2), 6.67 (d,
J ¼ 2:6 Hz, 1H, 4-H), 6.8 (dd, J ¼ 2:6, 8.5 Hz, 1H, 2-H),
7.17 (d, J ¼ 8:5 Hz, 1H, 1-H), 7.37 (m, 10H, PhCH2).
EIMS m=z 560.2598 (calcd for C34H40O5S 560.2596).
4.9. 11b-Methylthiomethylestra-1,3,5(10)-triene-3,17b-diol
(6)
4.12. 3,17b-Bis(benzyloxy)-11b-benzythiomethylestra-
1,3,5(10)-triene (22)
Debenzylation of 15 under the same conditions detailed
for the conversion of 10 into 12 gave 6 (62% yield) as a
glass. H NMR (CD3OD) d 0.92 (s, 3H, 18-H), 2.01 (s,
3H, CH3S), 3.64 (m, 1H, 17-H), 6.47 (d, J ¼ 2:5 Hz, 1H,
4-H), 6.57 (dd, J ¼ 2:5, 8.5 Hz, 1H, 2-H), 7.0 (d,
J ¼ 8:5 Hz, 1H, 1-H). EIMS m=z 332.1811 (calcd for
C20H28O2S 332.1810).
The mesylate 19 was converted to the sulfide 22 (71%
yield, glass) under the same conditions adopted for the
conversion of 9 into 10. 1H NMR (CDCl3) d 0.9 (s, 3H,
18-H), 3.43 (t, J ¼ 8 Hz, 1H, 17-H), 3.62 (s, 2H,
PhCH2S), 4.48, 4.54, 4.57, 4.63 (ABq, 2H, PhCH2), 4.98
(s, 2H, PhCH2), 6.64–6.8 (m, 3H, 1-H, 2-H, 4-H), 7.3
(m, 15H, PhCH2). EIMS m=z 588.3063 (calcd for
C40H44O2S 588.3062).
1
4.10. 3,17b-Bis(benzyloxy)-11b-hydroxymethylestra-
1,3,5(10)-triene (17)
4.13. 11b-Benzylthiomethylestra-1,3,5(10)-triene-3,17b-
diol (24)
A solution of 16 (0.5 g, 1 mmol), 4-methylmorpholine N-
oxide (160 mg, 1.36 mmol), and osmium tetroxide
(10 mg, 0.04 mmol) in acetone–water (4, 1 mL) was
allowed to react until 16 was consumed (about 18 h).
The reaction mixture was then partitioned between
Debenzylation of 22 under the same conditions detailed
for the conversion of 10 into 12 gave 24 (61% yield) as a
1
crystalline solid. Mp 98–100 ꢁC. H NMR (CD3OD) d

D. Spera et al. / Bioorg. Med. Chem. 12 (2004) 4393–4401
4399
0.81 (s, 3H, 18-H), 3.62–3.72, (m, 3H, 17-H, PhCH2S),
6.49 (m, 2H, 2-H, 4-H), 6.73 (d, J ¼ 9 Hz, 1H, 1-H).
EIMS m=z 422.2281 (calcd for C27H34O2S 422.2279).
1-H). EIMS m=z 422.2278 (calcd for C27H34O2S
422.2279).
4.19. 11b-Mercaptoethylestra-1,3,5(10)-triene-3,17b-diol
(3)
4.14. 11b-Mercaptomethylestra-1,3,5(10)-triene-3,17b-
diol (2)
S-Debenzylation of 25 under the same conditions de-
tailed for the conversion of 12 into 1 gave 3 (60% yield)
as a glass after chromatography (2:1, hexane–EtOAc).
1H NMR (CD3OD) d 0.87 (s, 3H, 18-H), 3.62, (m, 1H,
17-H), 6.46 (d, J ¼ 2:5 Hz, 1H, 4-H), 6.57 (dd, J ¼ 2:5,
8.4 Hz, 1H, 2-H), 6.98 (d, J ¼ 8:5 Hz, 1H, 1-H). EIMS
m=z 332.1811 (calcd for C20H28O2S 332.1810).
S-Debenzylation of 24 under the same conditions de-
tailed for the conversion of 12 into 1 gave 2 (52% yield)
as a glass after chromatography (2:1, hexane–EtOAc).
1H NMR (CD3OD) d 0.9 (s, 3H, 18-H), 3.65, (m, 1H,
17-H), 6.47 (d, J ¼ 2:6 Hz, 1H, 4-H), 6.58 (dd, J ¼ 2:6,
8.4 Hz, 1H, 2-H), 6.97 (d, J ¼ 8:5 Hz, 1H, 1-H). EIMS
m=z 318.1654 (calcd for C19H26O2S 318.1653).
4.20. 3,17b-Bis(methoxy)estra-1,3,5(10)-triene-6-ol (27)
4.15. 3,17b-Bis(benzyloxy)-11b-methylthioethylestra-
1,3,5(10)-triene (21)
To a cooled ()15 ꢁC) mixture of 26 (2.5 g, 8.3 mmol), t-
BuOK (1.87 g, 16.6 mmol), and diisopropylamine
(210 mg, 2.07 mmol, 0.29 mL) in dry THF (20 mL), n-
BuLi (9.34 mL, 1.6 M in hexane) were added over a 10-
min period, and the resulting dark-red solution further
stirred for 10 min. Trimethyl borate (2.06 g, 20 mmol,
2.2 mL) was added, and to the resulting milky solution
was finally added 35% aq H2O2 (10 mL). After 1 h stir-
ring at room temperature, the reaction mixture was
partitioned between toluene and diluted with 10% aq
HCl. The organic layer was washed with water, dried
with Na2CO3, and evaporated to give a residue from
which 27 (2.1 g, 80% yield) was obtained by chroma-
tography (2:1, hexane–EtOAc) as a single stereoisomer
as an oil, which solidified upon standing. Mp 92–95 ꢁC.
1H NMR (CDCl3) d 0.77 (s, 3H, 18-H), 3.36 (s, 3H, 17-
OCH3), 3.8 (s, 3H, 3-OCH3), 4.8 (m, 1H, 6-H), 6.7 (dd,
J ¼ 2:9, 8.8 Hz, 1H, 2-H), 7.1 (d, J ¼ 2:9 Hz, 1H, 4-H),
7.2 (d, J ¼ 8:8 Hz, 1H, 1-H). EIMS m=z 316.2040 (calcd
for C20H28O3 316.2038).
The mesylate 20 was converted to the sulfide 21 (60%
yield, glass) under the same conditions adopted for the
conversion of 9 into 11. 1H NMR (CDCl3) d 1.0 (s, 3H,
18H), 2.01 (s, 3H, CH3S), 3.46 (q, J ¼ 8 Hz, 1H, 17-H),
4.57, 5.01 (2s, 2 · 2H, PhCH2), 6.67 (d, J ¼ 2:6 Hz, 1H,
4-H), 6.77 (dd, J ¼ 2:6, 8.5 Hz, 1H, 2-H), 7.1 (d,
J ¼ 8:5 Hz, 1H, 1-H), 7.35 (m, 10H, PhCH2). EIMS m=z
574.2906 (calcd for C35H42O2S 574.2905).
4.16. 11b-Methylthioethylestra-1,3,5(10)-triene-3,17b-
diol (7)
Debenzylation of 21 under the same conditions detailed
for the conversion of 10 into 12 gave 7 (63% yield) as a
1
glass. H NMR (CD3OD) d 0.9 (s, 3H, 18-H), 1.97 (s,
3H, CH3S), 3.63, (m, 1H, 17-H), 6.48 (d, J ¼ 2:6 Hz, 1H,
4-H), 6.57 (dd, J ¼ 2:6, 8.4 Hz, 1H, 2-H), 7.01 (d,
J ¼ 8:4 Hz, 1H, 1-H). EIMS m=z 346.1968 (calcd for
C21H30O2S 346.1966).
4.21. 3,17b-Bis(methoxy)estra-1,3,5(10)-triene-6-one (28)
4.17. 3,17b-Bis(benzyloxy)-11b-benzylthioethylestra-
1,3,5(10)-triene (23)
The alcohol 27 (1 g, 3 mmol) was added to a suspension
of PCC (1.3 g, 6 mmol) in CH2Cl2 (10 mL). The mixture
was stirred at room temperature until starting material
was consumed (about 1 h, TLC monitoring). Ethyl ether
(30 mL) was added, the mixture was filtered through
Florisil, and the filtrate was evaporated to give a residue
from which pure 28 (1 g, 100% yield) was obtained as a
white solid after trituration with ether. Mp 133–135 ꢁC.
1H NMR (CDCl3) d 0.78 (s, 3H, 18-H), 2.7 (dd, J ¼ 3:4,
16.6 Hz, 1H, 8-H), 3.32 (t, J ¼ 8 Hz, 1H, 17-H), 3.36 (s,
3H, 17-OCH3), 3.83 (s, 3H, 3-OCH3), 7.08 (dd, J ¼ 2:9,
8.8 Hz, 1H, 2-H), 7.33 (d, J ¼ 8:8 Hz, 1H, 1-H), 7.5 (d,
J ¼ 2:9 Hz, 1H, 4-H). EIMS m=z 314.1885 (calcd for
C20H26O3 314.1882).
The mesylate 20 was converted to the sulfide 23 (71%
yield, glass) under the same conditions adopted for the
conversion of 9 into 10. 1H NMR (CDCl3) d 0.91 (s, 3H,
18-H), 3.45 (t, J ¼ 8 Hz, 1H, 17-H), 3.64 (s, 2H,
PhCH2S), 4.5, 4.56, 4.59, 4.65 (ABq, 2H, PhCH2), 5.0 (s,
2H, PhCH2), 6.7–7.0 (m, 3H, 1-H, 2-H, 4-H), 7.51 (m,
15H, PhCH2). EIMS m=z 602.3220 (calcd for C41H46O2S
602.3218).
4.18. 11b-Benzylthioethylestra-1,3,5(10)-triene-3,17b-diol
(25)
Debenzylation of 23 under the same conditions detailed
for the conversion of 10 into 12 gave 25 (70% yield) as a
glass. H NMR (CD3OD) d 0.8 (s, 3H, 18-H), 3.6–3.7,
4.22. 7a-Bromo-3,17b-bis(methoxy)estra-1,3,5(10)-triene-
6-one (29)
1
(m, 3H, 17-H, PhCH2S), 6.48 (d, J ¼ 2:4 Hz, 1H, 4-H),
To a cooled ()5ꢁC) solution of 28 (2 g, 6.3 mmol) in
CH2Cl2 (10 mL) bromine (900 mg, 5.6 mmol, 29 mL, 1 M
6.59 (dd, J ¼ 2:4, 8.4 Hz, 1H, 2-H), 6.97 (d, J ¼ 8:5, 1H,

4400
D. Spera et al. / Bioorg. Med. Chem. 12 (2004) 4393–4401
1
in CCl4) was added dropwise, and the mixture was
stirred until the starting material was consumed (TLC
monitoring). The reaction mixture was then partitioned
between water and 10% aq sodium bicarbonate. The
organic layer was washed with 10% aq sodium thiosul-
fate, dried, and evaporated to give a residue from which
pure 29 (2.5 g, 100% yield) was obtained as a crystalline
as a glass. H NMR (CDCl3) d 0.78 (s, 3H, 18-H), 3.36
(s, 3H, 17-OCH3), 3.76 (s, 3H, 3-OCH3), 6.58 (d,
J ¼ 2:4 Hz, 1H, 4-H), 6.73 (dd, J ¼ 2:4, 8.8 Hz, 1H, 2-
H), 7.22 (d, J ¼ 8:8 Hz, 1H, 1-H). EIMS m=z 332.1811
(calcd for C20H28O2S 332.1810).
1
solid after trituration with ether. Mp 147–148 ꢁC. H
4.26. 7a-Mercapto-3,17b-dihidroxyestra-1,3,5(10)-triene
(4)
NMR (CDCl3) d 0.79 (s, 3H, 18-H), 3.35 (s, 4H, 17-H,
17-OCH3), 3.82 (s, 3H, 3-OCH3), 4.48 (d, 1H, J ¼ 2 Hz,
7-H), 7.1 (dd, J ¼ 2:9, 8.8 Hz, 1H, 2-H), 7.33 (d,
J ¼ 8:8 Hz, 1H, 1-H), 7.5 (d, J ¼ 2:9 Hz, 1H, 4-H).
EIMS m=z 392.0988 (calcd for C20H25BrO3 392.0987).
Aluminum tribromide (160 mg, 0.6 mmol) was generated
as follows: bromine (1 mL, 1 mmol) was added dropwise
to a suspension of aluminum scales (18 mg, 0.6 mmol) in
CH2Cl2 (10 mL); the mixture was refluxed until the red
color was discharged and a white solid was formed. To
the above suspension, stirred at 0 ꢁC, a solution of 32
(50 mg, 0.12 mmol) and EtSH (2 mL) in CH2Cl2 (3 mL)
was added, and the reaction mixture was stirred at room
temperature for 6 h. The mixture was partitioned
between ice/water and EtOAc. The organic layer was
washed with brine, dried, and evaporated to give a res-
idue from which 4 (83% yield) was obtained as a crys-
talline solid after trituration with ether/CH2Cl2. Mp
4.23. 7a-Benzylthio-3,17b-bis(methoxy)estra-1,3,5(10)-
triene-6-one (30)
Conditions A. Compound 29 (100 mg, 0.25 mmol) was
added to a mixture of t-BuOK (42 mg, 0.37 mmol) and
benzyl mercaptan (0.06 mL, 0.5 mmol) in DMF (2 mL).
The mixture was heated at 50 ꢁC for 20 min and then
stirred at room temperature for 6 h. The reaction mix-
ture was partitioned between water and CH2Cl2, and the
organic layer was dried and evaporated to give a residue
from which pure 30 (96 mg, 90% yield) was obtained as a
crystalline solid after trituration with ether/hexane.
Conditions B. To a mixture of 29 (150 mg, 0.38 mmol),
20% aq NaOH (3.8 mL, 1.9 mmol), and tetrabutylam-
monium hydrogensulfate (260 mg, 0.76 mmol) in benz-
ene (4 mL) was added benzyl mercaptan (0.08 mL,
0.6 mmol). The mixture was stirred at room temperature
for 2 h. The reaction mixture was partitioned between
water and Et2O, and the organic layer was dried and
evaporated to give a residue from which pure 30
(150 mg, 90% yield) was obtained as a crystalline solid
after trituration with hexane. Mp 163–165 ꢁC. 1H NMR
(CDCl3) d 0.71 (s, 3H, 18-H), 3.24 (d, J ¼ 2:9 Hz, 1H, 7-
H), 3.32 (m, 4H, 17-H, 17-OCH3), 3.65–3.71, 3.73–3.8
(ABq, 2H, PhCH2S), 3.87 (s, 3H, 3-OCH3), 7.1 (dd,
J ¼ 2:4, 8.5 Hz, 1H, 2-H), 7.35 (m, 6H, 1-H, PhCH2S),
7.68 (d, J ¼ 2:4 Hz, 1H, 4-H). EIMS m=z 436.6074
(calcd for C27H32O3S 436.6072).
1
162–163 ꢁC. H NMR (CD3OD) d 0.66 (s, 3H, 18-H),
3.56 (t, 1H, 17-H), 6.35 (d, J ¼ 2:4 Hz, 1H, 4-H), 6.46
(dd, J ¼ 2:4, 8.8 Hz, 1H, 2-H), 6.99 (d, J ¼ 8:8 Hz, 1H,
1-H). EIMS m=z 304.1499 (calcd for C18H24O2S
304.1497).
4.27. Estrogen receptor binding affinity determination
Relative binding affinities were determined by competi-
tive radiometric binding assay using 10 nM [3H]estradiol
as tracer as previously described,18 using uterine cytosol
diluted to approximatively 1.5 nM of receptor. 18 incu-
bations were done at 0 and 25 ꢁC for 18–24 h.
References and notes
1. Effects of estrogen on reproductive system in female: (a)
Jennings, T. S.; Creasman, W. T. Estrogen Antiestrogen
1997, 223; (b) Prichard, K. I. Estrogen Antiestrogen 1997,
175; (c) Satyaswaroop, P. G. Estrogen Antiestrogen 1997,
211; Effects of estrogen on reproductive system in male: (d)
Hess, R. A.; Bunick, D.; Bahr, J. Sci. Med. 1998, 19, 253;
(e) Hess, R. A.; Bunick, D.; Bahr, J. Mol. Cell. Endocrinol.
2001, 178, 29; (f) Rochira, V.; Balestrieri, A.; Madeo, B.;
Baraldi, E.; Faustini-Faustini, M.; Granata, A. R. M.;
Carani, C. Mol. Cell. Endocrinol. 2001, 178, 107; Effects of
estrogen brain functions: (g) Birge, S. J. Neurology 1997,
48(Suppl. 7), S36; (h) Halbreich, U. Neurology 1997,
48(Suppl. 7), S16; (i) Henderson, D. Neurology 1997,
48(Suppl. 7), S27; (j) McEwen, B. S.; Alves, S. E.; Bulloch,
K.; Weiland, N. G. Neurology 1997, 48(Suppl. 7), S8; (k)
Giacobini, E. Exp. Gerontol. 1998, 33, 865; (l) Yaffe, K.;
Sawaya, G.; Lieberburg, I.; Grady, D. J. Am. Med. Assoc.
1998, 279, 688; (m) Maki, P.; Resnick, S. M. NeuroImage
2001, 14, 789; (n) de Novaes Soares, C.; Almeida, O. P.;
Joffe, H.; Cohen, L. S. Arch. Gen. Psychiatry 2001, 58, 529;
Effects of estrogen on pathophysiological processes: (o)
Dickson, R. B.; Lippman, M. E. Endocr. Rev. 1987, 8, 29;
(p) Lippman, M. E.; Dickson, R. B. Recent Prog. Horm.
4.24. 7a-Benzylthio-3,17b-bis(methoxy)estra-1,3,5(10)-
triene (31)
Deoxygenation of 30 under the same conditions detailed
for the conversion of 14 into 15 gave 31 (82% yield) as a
crystalline solid after trituration with ether. Mp 148–
1
152 ꢁC. H NMR (CDCl3) d 0.72 (s, 3H, 18-H), 2.95–
3.03, 3.13–3.18 (ABXq, 2H, 6-H), 3.35 (m, 4H, 17-H and
17-OCH3), 3.78 (s, 3H, 3-OCH3), 6.61 (d, J ¼ 2:4 Hz,
1H, 4-H), 6.73 (dd, J ¼ 2:4, 8.5 Hz, 1H, 2-H), 7.2 (m,
6H, 1-H, PhCH2S). EIMS m=z 422.2281 (calcd for
C27H34O2S 422.2279).
4.25. 7a-Mercapto-3,17b-bis(methoxy)estra-1,3,5(10)-tri-
ene (32)
S-Debenzylation of 31 under the same conditions de-
tailed for the conversion of 12 into 1 gave 32 (73% yield)

D. Spera et al. / Bioorg. Med. Chem. 12 (2004) 4393–4401
4401
Res. 1989, 45, 383; (q) Pike, M. C.; Peters, R. K.; Cozen,
W.; Probst-Hensch, N. M.; Felix, J. C.; Wan, P. C.; Mack,
T. M. J. Natl. Cancer Inst. 1997, 89, 1110; (r) Clinton, G.
M.; Hua, W. Crit. Rev. Oncol. Hematol. 1997, 25, 1;
Effects of estrogens on cardiovascular system: (s) Lobo, R.
A. Ann. N. Y. Acad. Sci. 1990, 592, 286; (t) Foegh, M. L.
Sex Steroids Cardiovascular Syst. 1992, 129; (u) Sarrel, P.
M. Endothelium 1992, 2, 203; (v) Thomas, G.; Ito, K.;
Zikic, E.; Bhatti, T.; Han, C.; Ramwell, P. W. J.
Pharmacol. Exper. Ther. 1995, 273, 1544; (w) Clarkson,
T. B.; Anthony, M. S. Estrogen Antiestrogen 1997, 89; (x)
Nathan, L.; Chaudhuri, G. Annu. Rev. Pharmacol. Tox-
icol. 1997, 37, 477; (y) Skafar, D. F.; Xu, R.; Morales, J.;
Ram, J.; Sowers, J. R. J. Clin. Endocrinol. Metabol. 1997,
82, 3913; (z) Hammond, C. Off. Cont. Med. Ed. 2000, 2.
Laios, I.; Leclercq, G.; Jaouen, G. J. Organomet. Chem.
2002, 643, 350.
6. (a) Anstead, G. M.; Carlson, K. E.; Katzenellenbogen, J.
A. Steroids 1997, 62, 268; (b) Katzenellenbogen, B. S.;
Korach, K. S. Endocrinology 1997, 138, 861; (c) Von
Angerer, E. Handb. Exp. Pharmacol. 1999, 135/I, 81; (d)
Tremblay, M. R.; Simard, J.; Poirier, D. Bio. Med. Chem.
Lett. 1999, 9, 2827; (e) Katzenellenbogen, B. S.; Choi, I.;
Delage-Mourroux, R.; Ediger, T. R.; Martini, P. G. V.;
Montano, M.; Sun, J.; Weis, K.; Katzenellenbogen, J. A.
J. Steroid Biochem. Mol. Biol. 2000, 74, 279; (f) Pike, A. C.
W.; Brzozowski, A. M.; Walton, J.; Hubbard, R. E.;
ꢀ
Thorsell, A.-G.; Li, Y.-L.; Gustafsson, J.-A.; Carlquist,
M. Structure 2001, 9, 145.
7. For sulfur-containing estrogens, see: (a) Miller, C. P.;
Jirkovsky, I.; Tran, B. D.; Harris, H. A.; Moran, R. A.;
Komm, B. S. Bioorg. Med. Chem. Lett. 2000, 10, 147; For
recent work on estradiol derivatives labelled with metal
complex, see: (b) Luyt, L. G.; Bigott, H. M.; Welch, M. J.;
Katzenellenbogen, J. A. Bioorg. Med. Chem. 2003, 11,
4977; (c) Mull, E. S.; Sattigeri, V. J.; Rodriguez, A. L.;
Katzenellenbogen, J. A. Bioorg. Med. Chem. 2002, 10,
1381; (d) Cassino, C.; Gabano, E.; Ravera, M.; Cravotto,
ꢀ
2. (a) Kuiper, G. G.; Gustafsson, J. A. FEBS Lett. 1997, 410,
87; (b) Diel, P. Toxicol. Lett. 2002, 127, 217; (c) Warner,
ꢀ
M.; Nilsson, S.; Gustafsson, J. A. Curr. Opin. Obstet.
ꢀ
Gynecol. 1999, 11, 249; (d) Gustafsson, J. A J. Endocrinol.
1999, 163, 379; (e) Jordan, V. C. Sci. Am. 1998, 279, 60; (f)
Kuiper, G. G.; Lemmen, J. G.; Carlsson, B.; Corton, J. C.;
Safe, S. H.; van der Saag, P. T.; van der Burg, B.;
Gustafsson, J. A. Endocrinology 1998, 139(10), 4252; (g)
Lotke, P. S. Obstet. Gynecol. 1998, 5, 290; (h) Balk, J.
Obstet. Gynecol. Fertil. 2001, 24, 53; (i) Ruggiero, R. J.;
Likis, F. E. J. Midwifery Women’s Health 2002, 47, 130; (j)
Harris, H. A.; Bapat, A. R.; Gonder, D. S.; Frail, D. E.
Steroids 2002, 67, 379.
ꢁ
G.; Palmisano, G.; Vessieres, A.; Jaouen, G.; Mundwiler,
S.; Alberto, R.; Osella, D. Inorg. Chim. Acta 2004, 357,
ꢂ
2157; (e) Lecomte, V.; Stephan, E.; Vaissermann, J.;
Jaouen, G. Steroids 2004, 69.
8. Tedesco, R.; Fiaschi, R.; Napolitano, E. J. Org. Chem.
1995, 60, 5316.
9. Peterson, D. J. J. Org. Chem. 1967, 32, 1717.
10. French, A. N.; Napolitano, E.; Vanbrocklin, H. F.;
Hanson, R. N.; Welch, M. J.; Katzenellenbogen, J. A.
Nucl. Med. Biol. 1993, 20, 31.
11. Tedesco, R.; Fiaschi, R.; Napolitano, E. Synthesis 1995,
1493.
12. Wintersteiner, O. P.; Moore, M.; Cohen, A. I. J. Org.
Chem. 1964, 29, 1325.
3. For a study on estrogen effect on bone tissue, see: (a)
Turner, R. T. Estrogen Antiestrogen 1997, 129; (b)
Rochira, V.; Balestrieri, A.; Faustini-Faustini, M.; Carani,
C. Mol. Cell. Endocrinol. 2001, 178, 215; For structure–
selective activity relationship, see: (c) Smith, R. A.; Chen,
J.; Mader, M. M.; Muegge, I.; Moehler, U.; Katti, S.;
Marrero, D.; Stirtan, W. G.; Weaver, D. R.; Xiao, H.;
Carley, W. Bioorg. Med. Chem. Lett. 2002, 12, 2875, and
references cited therein.
4. (a) Gantchev, T. G.; Ali, H.; van Lier, J. E. J. Med. Chem.
1994, 37, 4164; (b) Nachar, O.; Rousseau, J.; Ouellet, R.;
Rioux, A.; Lefebvre, B.; Ali, H.; van Lier, J. E. J. Nucl.
Med. 2000, 41, 1324; (c) Osella, D.; Cavigiolio, G.;
13. (a) Bouton, M. M.; Raynaud, J. P. J. Steroid Biochem.
1978, 9, 9; (b) Aranyi, P. Biochim. Biophys. Acta 1980, 628,
220; (c) Bindal, R. D.; Carlson, K. E.; Reiner, G. C.;
Katzenellenbogen, J. A. J. Steroid Biochem. 1987, 28, 36I.
14. (a) Sasson, S.; Notides, A. C. J. Biol. Chem. 1983, 258,
8113; (b) Notides, A. C.; Hamilton, D. E.; Auer, H. E. J.
Biol. Chem. 1975, 250, 3945.
ꢁ
Vincenti, M.; Vessieres, A.; Laios, I.; Leclercq, G.;
Napolitano, E.; Fiaschi, R.; Jaouen, G. J. Org. Chem.
€
2000, 242; (d) Skaddan, M. B.; Wust, F. R.; Jonson, S.;
Syhre, R.; Welch, M. J.; Spies, H.; Katzenellenbogen, J. A.
Nucl. Med. Biol. 2000, 27, 269; (e) Katzenellenbogen, J. A.
J. Flu. Chem. 2001, 109, 49; (f) Seimbille, Y.; Ali, H.; van
Lier, J. E. J. Chem. Soc., Perkin Trans. 1 2002, 657; (g) Ali,
H.; van Lier, J. E. Bioorg. Med. Chem. Lett. 2002, 12,
2847.
15. Katzenellenbogen, J. A.; Heiman, D. F.; Carlson, K. E.;
Lloyd, J. E. In Receptor Binding Radiotracers; Eckelman,
W. C., Ed.; CRC: Boca Raton, 1982; Vol. 1, Chapter 6, pp
93–126.
16. Still, W. C.; Kahn, M. J. Org. Chem. 1978, 43, 2923.
17. Daumas, S.; Vo-Quang, Y.; Vo-Quang, L.; Le Goffic, F.
Synth. Commun. 1989, 64.
ꢁ
5. (a) Top, S.; Kaloun, E. B.; Vessieres, A.; Laios, I.;
Leclercq, G.; Provot, C.; Jaouen, G. J. Organomet. Chem.
18. Katzenellenbogen, J. A.; Johnson, H. J., Jr.; Myers, H. N.
Biochemistry 1973, 12, 4085.
ꢁ
2001, 637, 500; (b) Top, S.; Vessieres, A.; Cabestaing, C.;