An efficient approach to novel 17-5′-(1′,2′,4′)- oxadiazolyl androstenes via the cyclodehydration of cytotoxic O-steroidacylamidoximes, and an evaluation of their inhibitory action on 17α-hydroxylase/C17,20-lyase

Article abstract of DOI:10.1016/j.ejmech.2013.10.038

Novel 17-exo-oxadiazoles in the androst-5-ene series were efficiently synthesized in a two-step sequence via the corresponding O-acylamidoxime intermediates (obtained from steroidal 17-carboxylic acids and amidoximes in the presence of coupling reagent), which then underwent tetrabutylammonium fluoride-induced cyclocondensation under mild reaction conditions. The synthesized compounds were subjected to in vitro pharmacological studies to investigate their inhibitory effect on rat testicular C_17,20-lyase and their antiproliferative action on four malignant human adherent cell lines (HeLa, MCF7, A2780 and A431). One of the oxadiazolyl derivatives proved to exert significant enzyme-inhibitory action (IC₅₀ = 0.60 μM), while some of the isolated O-acylated amidoxime intermediates displayed high cytotoxic activities on all examined cell lines, with IC₅₀ values in the range 0.22-3.94 μM.

Full text of DOI:10.1016/j.ejmech.2013.10.038

Accepted Manuscript
An efficient approach to novel 17-5′-(1′,2′,4′)-oxadiazolyl androstenes via the
cyclodehydration of cytotoxic O-steroidacylamidoximes, and an evaluation of their
inhibitory action on 17α-hydroxylase/C
-lyase
17,20
Dóra Kovács, János Wölfling, Nikoletta Szabó, Mihály Szécsi, Ida Kovács, István
Zupkó, Éva Frank
PII:
S0223-5234(13)00679-X
10.1016/j.ejmech.2013.10.038
EJMECH 6501
DOI:
Reference:
To appear in: European Journal of Medicinal Chemistry
Received Date: 9 August 2013
Revised Date: 2 October 2013
Accepted Date: 12 October 2013
Please cite this article as: D. Kovács, J. Wölfling, N. Szabó, M. Szécsi, I. Kovács, I. Zupkó, É. Frank, An
efficient approach to novel 17-5′-(1′,2′,4′)-oxadiazolyl androstenes via the cyclodehydration of cytotoxic
O-steroidacylamidoximes, and an evaluation of their inhibitory action on 17α-hydroxylase/C
-lyase,
7,20
1
European Journal of Medicinal Chemistry (2013), doi: 10.1016/j.ejmech.2013.10.038.
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to
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ACCEPTED MANUSCRIPT
Graphical abstract
R3
N
O
O
NH2
R3
N
COOH
R1
N
OH
O
R3
R1
N
R1
NH2
R2
17
R2
H
R2
H
CDI
CH Cl2
TBAF
THF
R4O
H
H
H
H
2
H
AcO
1
2
R3 = CH3, Ph, 4-CH3-C6H4, 4-OMe-C6H4, 4-Br-C6H4
R4 = H, Ac
R
= R = H
1
2
R , R = double bond

ACCEPTED MANUSCRIPT
Highlights
Novel 17-exo-1,2,4-oxadiazolyl androstenes were synthetized in high yields
O-Acylation of different amidoximes with steroidal carboxylic acids were carried out
Cyclocondensations of O-acylamidoximes occurred under mild conditions
Enzyme-inhibitory and antiproliferative effects of the products were examined

ACCEPTED MANUSCRIPT
An efficient approach to novel 17-5′-(1′,2′,4′)-oxadiazolyl androstenes via the
cyclodehydration of cytotoxic O-steroidacylamidoximes, and an evaluation of their
inhibitory action on 17α-hydroxylase/C17,20-lyase
a
a
b
b
c
Dóra Kovács, János Wölfling, Nikoletta Szabó, Mihály Szécsi, Ida Kovács, István
c
,a
Zupkó, Éva Frank*
a
Department of Organic Chemistry, University of Szeged, Dóm tér 8, H-6720 Szeged,
Hungary
b
1
st Department of Medicine, University of Szeged, Korányi fasor 8-10, H-6720 Szeged,
Hungary
c
Department of Pharmacodynamics and Biopharmacy, University of Szeged, Eötvös u. 6, H-
6
720 Szeged, Hungary
*
Corresponding author. Tel.: +36 62 544275; fax: +36 62 544200.
E-mail address: frank@chem.u-szeged.hu (É. Frank).
1

ACCEPTED MANUSCRIPT
Abstract
Novel 17-exo-oxadiazoles in the androst-5-ene series were efficiently synthesized in a two-
step sequence via the corresponding O-acylamidoxime intermediates (obtained from steroidal
1
7-carboxylic acids and amidoximes in the presence of coupling reagent), which then
underwent tetrabutylammonium fluoride-induced cyclocondensation under mild reaction
conditions. The synthestized compounds were subjected to in vitro pharmacological studies to
investigate their inhibitory effect on rat testicular C17,20-lyase and their antiproliferative
action on four malignant human adherent cell lines (HeLa, MCF7, A2780 and A431). One of
the oxadiazolyl derivatives proved to exert significant enzyme-inhibitory action (IC50 = 0.60

M), while some of the isolated O-acylated amidoxime intermediates displayed high
cytotoxic activities on all examined cell lines, with IC50 values in the range 0.22 3 .94  M.
Keywords: steroids, O-acylamidoximes, antiproliferative activity, 1,2,4-oxadiazoles, P45017
inhibitor
2

ACCEPTED MANUSCRIPT
1
. Introduction
In consequence of the numerous synthetic possibilities available for the construction of
different heterorings on the sterane core, and also of the differences in the ability of these
derivatives to bind to their target receptors, leading to the manifestation of certain beneficial
biological effects, research into steroidal compounds has recently focused on the syntheses
and pharmacological investigations of heterocycle-containing compounds [1−3]. The most
frequent chemical modifications are introduced at position 17 on ring D, where transformation
of the extant functional group is facilitated. Cardiac glycosides, a large family of naturally
occurring steroidal 17-exo-heterocycles present in both plants and animals, contain a five- or
six-membered lactone ring at C-17 and a sugar moiety at C-3 of the sterane nucleus. The cis
conformations of the skeletal rings A/B and C/D, together with the connected sugar moiety,
are of significant pharmacological relevance as concerns their efficacy in the treatment of
congestive heart failure and as anti-arrhythmic agents [4, 5]. Less well known, however, is the
emerging role of this category of compounds for the prevention and/or treatment of cancer, as
a result of which the 17-exo-heterocyclic steroids are now at the focus of scientific interest
[
6]. Attempts to modify the original aglycone cores in order to broaden the narrow therapeutic
window typical for glycosides led to the conclusion that sex hormone-derived 17-exo-
heterocycles involving a trans C/D ring junction exert an inhibitory effect on 17α-
+
+
hydroxylase-C17,20-lyase (P45017α) rather than cardiotonic activity by blocking Na /K -
ATPase [7]. P45017α is a key regulatory enzyme in the androgen biosynthetic pathway and
inhibitors of this protein can block male sex hormone synthesis at an early stage leading to
their potential use in the medication of androgen-dependent diseases [8]. The first steroidal
inhibitor, abiraterone, which is based on the structure of pregnenolone, one of the natural
3

ACCEPTED MANUSCRIPT
substrates of P45017α, was approved in 2011 in the form of its 3β-acetate prodrug for the
treatment of prostate cancer (Figure 1). The features responsible for the observed activity of
abiraterone are the direct coordination of the lone pair of the nitrogen in the pyridyl ring at C-
1
7 with the heme Fe and the interaction of the 3β-OH with asparagine 202 in the F helix in
the active site of the enzyme [9]. The presence of the C16-17 double bond, however, also
appears to be of crucial importance in its irreversible inhibitory effect on human P45017α [8].
Besides abiraterone, a large number of 17-exo-heterocycles are known to induce efficient
P45017α inhibition: furanyl, thienyl [10, 11], oxazolyl, thiazolyl [12, 13], imidazolyl,
isoxazolyl, triazolyl, tetrazolyl, pyrazolyl [14, 15], pyrimidyl [16], and benzimidazolyl
derivatives [17] were synthesized earlier and demonstrated to be more or less effective.
Figure 1.
Some 17-exo-heterocyclic steroids have also been reported to be involved in complex cell-
signal transduction mechanisms in a hormone-receptor independent manner by the inhibition
of angiogenesis, tubulin polymerization and the regulation of apoptotic pathways, and
resulting in the selective control of human tumor but not normal cellular proliferation [18].
As such, they represent a promising form of targeted cancer chemotherapy.
As a continuation of our research on steroidal exo-heterocycles [19-24], our present goal
was to introduce an 1,2,4-oxadiazole moiety at C-17, since the effects of this structural
element on the biological activities of steroids have not yet been examined. 1,2,4-Oxadiazoles
have often been used as hydrolysis-resistant bioisosteres of esters and amides in a number of
biologically active synthetic compounds with widespread pharmacological effects [25],
including anti-cancer activity [26−28]. The most common route for the construction of 1,2,4-
4

ACCEPTED MANUSCRIPT
oxadiazoles is through the reaction of amidoximes with carboxylic acids in the presence of
coupling reagents, e.g. dicyclohexylcarbodiimide (DCC) or 1,1’-carbonyldiimidazole (CDI),
or with reactive acid chlorides, active carboxylic esters or anhydrides [29]. The O-acylation of
amidoximes with carboxylic acid derivatives occurs under mild conditions [30], but the
subsequent cyclodehydration of the intermediates to oxadiazoles generally requires long
reaction times (5-12 h) in the presence of a strong base (NaH or NaOEt) or elevated
temperatures (80-100 °C) for a weaker base (pyridine). The cyclization of O-acylamidoximes,
however, can be promoted by tetrabutylammonium fluoride (TBAF) under mild conditions,
since the fluoride ion acts as a strong base in a polar aprotic solvent, inducing both the ring-
closure and dehydration steps of the cyclocondensation reaction [31].
Different routes were designed for the synthesis of 17-5′-(1′,2′,4′)-oxadiazolylandrost-5-
enes structurally similar to abiraterone, so as to find reaction conditions ensuring high
productivity. Furthermore, all compounds, including the O-acylated amidoxime intermediates,
were screened in vitro by means of MTT assays for their antiproliferative activities against a
panel of four human adherent cancer cell lines (HeLa, MCF7, A2780 and A431). The
inhibitory effects of the heterocyclic products on rat testicular C17,20-lyase were also
determined by a radioligand incubation technique.
2
. Results and Discussion
2
.1.
Synthetic studies
Steroidal 17-carboxylic acids (3, 5) and their 3β-acetates (4, 6) were synthesized from
pregnenolone acetate (1) and pregnadienolone acetate (2) via the bromoform reaction and
subsequent acetylation, using well-known literature methods (Scheme 1) [12, 32]. In order to
investigate the reactivity of carboxylic esters against amidoximes, the previously reported
methyl ester derivative 7 [33] was also produced via an alternative route from 3 in the
5

ACCEPTED MANUSCRIPT
.
presence of BF OEt in MeOH. However, the similar esterification of 5 could not be carried
3
2
out, since C-16 is highly reactive in this case due to conjugation, and the addition of a methyl
group to this position may also be feasible.
Scheme 1.
Amidoximes (IIa−e) were prepared by reacting aromatic nitriles (Ia−d) or acetonitrile (Ie)
with hydroxylamine hydrochloride in basic media, using general synthetic prescriptions [27]
(Scheme 2). The conventional 2-7-h heating period in aqueous EtOH resulted in the desired
amidoximes (IIa−e) together with small amounts (10-15%) of amide (IIIa−e) impurity [34],
but these by-products were easily removed during the work-up procedure or by column
chromatography. Nevertheless, it is important to note that amide traces do not interfere in the
reactions of amidoximes with carboxylic acid derivatives; the contaminated amidoxime
merely has to be applied in excess. The substitution reactions were also carried out by using
microwave (MW) irradiation, which shortened the reaction time to 15-20 min, but left the
chemoselectivity unchanged.
Scheme 2.
Preliminary substitution experiments were carried out by reacting ester 7 with
2 3
benzamidoxime (IIa) in the presence of K CO [35]. No reaction was observed when the
components were refluxed for 12 h [36], and MW irradiation either in solution or under
solvent-free conditions [37] resulted in only low conversions. Apart from the moderate
16
productivity, oxadiazolyl- ∆ -androst-5-enes are otherwise not accessible by this method in
consequence of the unavailability of suitable carboxylic esters.
6

ACCEPTED MANUSCRIPT
The reactions of the more reactive acid chlorides (8, 9) of 4 and 6 with benzamidoxime
IIa) were next investigated (Scheme 2). The steroidal carboxylic acids (4, 6) were first
(
converted to the acid chlorides (8, 9) using oxalyl chloride and a catalytic amount of
dimethylformamide (DMF) in CH Cl [38]. After stirring at room temperature for 12 h, the
2
2
excess of oxalyl chloride was distilled off, and 3 equivalents of benzamidoxime (IIa) in
pyridine were added. It was necessary to heat the reaction mixtures for 7 h in order to achieve
sufficient conversions because of the presence of the weakly basic pyridine, but the
corresponding oxadiazoles (12a, 13a) were obtained in yields of only 35 and 38% after
purification by flash chromatography. The O-acylated amidoximes (10a, 11a) formed as
intermediates were converted to the corresponding heteroaromatic derivatives (12a, 13a)
under the conditions applied and therefore could not be isolated, although their formation was
detected by TLC. When the transformations were repeated under MW irradiation, the reaction
time was reduced to 30 min, but the yields of the products increased by only a few per cent.
The application of a longer reaction time or a reagent excess did not have any effect on the
conversions.
In the hope of using milder reaction conditions, but achieving better yields of the desired
products, our attention turned to the reactions of carboxylic acids (4, 6) and amidoximes
(IIa−e) with the use of a coupling reagent. As concerns the relative effectiveness of DCC and
CDI in DMF, better, but not complete conversion was observes on the TLC plates when
carboxylic acid 4 was reacted with CDI. An investigation of the effects of other solvents
(
THF and CH Cl ) revealed complete coupling with CDI in CH Cl at room temperature. A
2 2 2 2
similar solvent dependence was reported earlier for the reactions of CDI-activated carboxylic
acids with acylhydrazides [39]. Subsequently, 4 was reacted with CDI in CH Cl , and
benzamidoxime (IIa) was added to the mixture after completion of the coupling reaction
2
2
(Scheme 2). The substitution was performed at room temperature to afford the corresponding
7

ACCEPTED MANUSCRIPT
O-acylated derivative (10a) in a yield of 85% after purification. The application of
temperatures higher than 30 °C resulted in decomposition of the CDI-activated carboxylic
acid. The subsequent TBAF-induced cyclodehydration of 10a furnished oxadiazole 12a in an
excellent yield within 1 h under mild conditions. Once the parameters appropriate for the
efficient synthesis of 17-exo-oxadiazolyl androstenes had been found, similar reactions of 4
and 6 with different amidoximes (IIa−e) were carried out via the above-mentioned two-step
protocol: both the O-acylated intermediates (10a−e, 11a−e) and the heterocyclic derivatives
(12a−e, 13a−e) were obtained in excellent yields. For pharmacological studies, the 3β-OH
analogs (14a−e, 15a−e) of the cyclocondensation products (12a−e, 13a−e) were synthesized
by simple deacetylation.
1
13
The structures of all synthesized compounds were confirmed by H and C NMR
measurements. The presence of the phenyl or p-substituted phenyl ring derived from the
amidoximes (IIa−d) was demonstrated by the signals in the aromatic range of the ppm scale
1
in (10-15)a-d, while an additional methyl signal was detected at around 2.0 ppm in the H
NMR spectra of 10e−15e. The spectra of the O-acylamidoximes (10a−e, 11a−e) and the
related heterocyclic products (12a−e, 13a−e) proved to be quite similar. The broad singlet of
the amide protons at around 5.0 ppm was present in the spectra of the former compounds, but
not in those of the cyclized products 12a−e and 13a−e. The chemical shifts of the protons
close to the cyclocondensation reaction center differed somewhat in the related open-chain
(10a−e, 11a−e) and cyclic compounds (12a−e, 13a−e), which is explained by the decreased
shielding and therefore the downfield shift of these protons in the latter case, caused by the
aromatic character of the oxadiazole ring.
2
.2. Pharmacological studies
8

ACCEPTED MANUSCRIPT
In recent years, there has been considerable interest in steroidal 17-exo-heterocycles in view
of their potential use in the treatment of cancer either by blocking one of the key regulatory
enzymes of androgen biosynthesis or by exerting direct antiproliferative effects on tumor
cells. However, the 1,2,4-oxadiazole scaffold [40] and its saturated variants [41] have
received less attention from both synthetic and pharmacological aspects. As several different
compounds containing an 1,2,4-oxadiazole moiety have been reported to exert
antiproliferative activity [26−28, 42], and the synthesized derivatives are structurally related
to abiraterone, which is generally used as an effective P45017α inhibitor in the medication of
malignant prostate cancer, investigation of the synthesized compounds for cytotoxic efficacy
and P45017α enzyme inhibition appeared obvious. The inhibitory effects of 14a−e and 15a−e
on rat testicular C17,20-lyase were tested by means of a radiosubstrate incubation technique.
Among the oxadiazoles, only 14e and 15e (containing a methyl group at position 3 of the
heteroaromatic ring) exhibited noteworthy activity (Table 1). This is in good agreement with
previous observations that bulky substituents on the heterocyclic moiety are less favorable in
respect of P45017α inhibition [43, 44]. Compound 15e, with IC50 = 0.60 µM, inhibited the
enzyme action to an extent roughly comparable with that of ketoconazole, whereas its potency
lagged behind that of abiraterone. Oxadiazole 15a, the saturated counterpart of 14a, however,
proved to be a poorer enzyme inhibitor, which demonstrates the importance of the C16-17
double bond, as expected.
Table 1
The antiproliferative activities of all the synthesized compounds, including the O-
acylamidoximes, against the HeLa, MCF7, A2780 and A431 cell lines, were determined by
9

ACCEPTED MANUSCRIPT
the microplate-based MTT colorimetric assay [46], in comparison with cisplatin as reference
agent. The cell-proliferation inhibitory potencies of the investigated derivatives, expressed as
IC50 and/or growth inhibition values (Table 2), revealed that the O-acylamidoxime derivatives
(10a–e, 11a–e) exerted consistently higher activities than those of the corresponding
oxadiazoles (12a–e, 13a–e). Moreover, the presence of the C16-17 double bond in 11a−e
generally led to an increase in potency relative to the saturated analogs (10a−e). Among the
16
∆
derivatives, 17-acyl-p-methoxybenzamidoxime (11c) and 17-acylacetamidoxime (11e)
exhibited outstanding cytotoxicity against all four cell lines, with IC50 values (at least in most
cases) lower than those of cisplatin. The introduction of the various substituents R into the O-
acylamidoxime residue had a greater effect on the antiproliferative action in 11a−e than in
1
0a−e. As concerns the oxadiazoles, the 3β-acetoxy derivatives (12a−e, 13a−e) induced
negligible cell-growth inhibition, irrespectively of the structure of their sterane skeleton, while
their 3β-OH counterparts, especially those containing a saturated ring D (14a−e), proved to be
more potent.
Table 2
1
0

ACCEPTED MANUSCRIPT
3
. Conclusions
In summary, novel types of 1,2,4-oxadiazoles in the androst-5-ene series were prepared from
steroidal 17-carboxylic acids via a two-step pathway. After the determination of acceptable
parameters for efficient conversions, various amidoximes were O-acetylated with CDI-
activated carboxylic acids, and then subjected to TBAF-induced cyclodehydration. Both the
substitution and ring-closure reaction steps proceeded under mild reaction conditions, to
afford the O-acylamidoximes and then the 17-exo-heterocycles in good to excellent yields.
The synthesized derivatives may deserve attention from a pharmacological aspect, since one
of the heteroaromatic derivatives, 15e, displayed significant in vitro inhibition of C17,20-lyase.
In contrast with the expected results, not the oxadiazoles, but their open-chain precursors
(10a−e, 11a−e) exerted in vitro cytotoxic activity against all four examined malignant cell
lines which were higher than or comparable to that of the reference cisplatin. The nature of
the substituent R had only a limited impact on the anticancer action in both the open-chain
(10a−e, 11a−e) and the cyclized products (14a−e, 15a−e); the effects of differences in the
sterane structure, i. e. the saturation of ring D were more substantial.
1
1

ACCEPTED MANUSCRIPT
4
. Experimental
Melting points (mp) were determined on an SMS Optimelt digital apparatus. Elemental
analysis data were obtained with a Perkin Elmer CHN analyzer model 2400. The reactions
under MW irradiation were carried out with a CEM Corporation Focused Microwave System,
Model Discover SP. NMR spectra were recorded at room temperature with a Bruker DRX
5
00 instrument. Chemical shifts are reported in ppm (δ scale), and coupling constants (J) in
Hz. For the determination of multiplicities, the J-MOD pulse sequence was used. Automated
flow injection analyses were performed by using an HPLC/MSD system. The system
comprised an Agilent 1100 micro vacuum degasser, a quaternary pump, a micro-well plate
autoinjector and a 1946A MSD equipped with an electrospray ion (ESI) source operated in
positive ion mode. The ESI parameters were: nebulizing gas N
2 2
, at 35 psi; drying gas N , at
3
50 °C and 12 L/min; capillary voltage (VCap) 3000 V; and fragmentor voltage 70 V. The
MSD was operated in scan mode with the mass range m/z 60−620. Samples (0.2 ꢀL) were
injected with automated needle wash directly into the solvent flow (0.3 mL/min) of
2
MeCN/H O 70:30 (v/v) supplemented with 0.1% formic acid. The system was controlled by
Agilent LC/MSD Chemstation software. All solvents were distilled immediately prior to use.
Reagents and materials were obtained from commercial suppliers and were used without
purification. The reactions were monitored by TLC on Kieselgel-G (Merck Si 254 F) layers
(
0.25 mm thick); solvent systems (ss): (A) CH
2
Cl
2
, (B) EtOAc/CH
2
Cl
2
(2:98 v/v), (C)
Cl (40:60 v/v).
EtOAc/CH Cl (5:95 v/v), (D) EtOAc/CH Cl (10:90 v/v), (E) EtOAc/CH
2
2
2
2
2
2
1
2

ACCEPTED MANUSCRIPT
The spots were detected by spraying with 5% phosphomolybdic acid in 50% aqueous
phosphoric acid. The R values were determined for the spots observed by illumination at 254
f
and 365 nm. Flash chromatography: Merck silica gel 60, 40–63 ꢀm.
4
4
.1. Chemistry
.1.1. Synthesis of oxadiazoles 12a and 13a from steroidal carboxylic acids via acid chlorides
β-Acetoxyandrost-5-ene-17β-carboxylic acid (4, 288 mg, 0.80 mmol) or 3β-acetoxyandrost-
3
5
2 2
,16-diene-17-carboxylic acid (6, 287 mg, 0.80 mmol) was dissolved in dry CH Cl (10 mL),
and oxalyl chloride (0.5 mL, 5.82 mmol) was added dropwise at 0 °C with constant stirring.
After addition of a capillary drop of DMF, the mixture was stirred overnight at room
temperature. The excess of oxalyl chloride was distilled off following the addition of toluene
(2 × 10 mL) to the solution. The acid chloride (8 or 9) prepared in situ was dissolved in
pyridine (20 mL), and benzamidoxime (IIa, 327 mg, 3 equiv.) was then added. The solution
was refluxed for 7 h (method A) or irradiated with MW at 150 °C for 30 min (method B), then
poured into a mixture of ice and cc. H
The combined organic phase was dried over anhydrous Na
product was purified by flash chromatography with hexane/CH
furnish 12a (129 mg, 35% − method A; 155 mg, 42% − method B) or 13a (139 mg, 38%
method A; 161 mg, 44% − method B) as a white solid. The physical and spectral
characterization of 12a and 13a is to be found in Sections 4.1.3.1 and 4.1.3.6.
2
SO
4
(15 mL) and extracted with CH
SO , and evaporated. The crude
Cl = 20:80 as eluent to
2 2
Cl (3 × 10 mL).
2
4
2
2
−
4
.1.2. General procedure for the O-acylation of amidoximes (IIa−e)
1
3

ACCEPTED MANUSCRIPT
3β-Acetoxyandrost-5-ene-17 β-carboxylic acid (4, 288 mg, 0.80 mmol) or 3β-acetoxyandrost-
5
2 2
,16-diene-17-carboxylic acid (6, 287 mg, 0.80 mmol) was dissolved in dry CH Cl (10 mL)
and CDI (195 mg, 1.2 mmol) was added. The solution was stirred for 2 h at room temperature
until completion of the coupling reaction, and 3 equiv. of benzamidoxime (IIa), substituted
benzamidoxime (IIb−d) or acetamidoxime (IIe) was then added. After stirring for 2 h at room
temperature, the mixture was evaporated and subjected to flash chromatography.
4
.1.2.1. O-3β-Acetoxyandrost-5-ene-17β-acylbenzamidoxime (10a)
Compound 4 and benzamidoxime (IIa, 327 mg) were used in the procedure described in
section 4.1.2. After purification with EtOAc/CH Cl = 5:95 as eluent, 10a was obtained as a
2
2
1
white solid (325 mg, 85%), mp 177−179 °C, R
f 3
= 0.38 (ss C); H NMR (CDCl , 500 MHz):
δH 0.79 (s, 3H, 18-H ), 1.01 (m, 1H), 1.02 (s, 3H, 19-H ), 1.14 (m, 2H), 1.28−1.43
3
3
(overlapping m, 3H), 1.45−1.62 (overlapping m, 5H), 1.73 (m, 1H), 1.87 (m, 3H), 2.03 (s, 3H,
Ac-H ), 2.04 (m, 2H), 2.25 (m, 2H), 2.49 (t, 1H, J = 9.4 Hz, 17-H), 4.60 (m, 1H, 3-H), 5.06
3
2
(s, 2H, NH ), 5.38 (m, 1H, 6-H), 7.39 (m, 2H, 3′-H and 5′-H), 7.46 (m, 1H, 4′-H), 7.71 (d, 2H,
1
3
J = 8.1 Hz, 2′-H and 6′-H); C NMR (CDCl , 125 MHz): δC 13.4 (C-18), 19.3 (C-19), 20.9
3
(
CH
2
), 21.4 (Ac-CH
3
), 23.9 (CH
2
2 2 2
), 24.6 (CH ), 27.7 (CH ), 31.8 (CH ), 31.9 (CH), 36.6 (C-
1
0), 37.0 (CH ), 38.0 (CH ), 38.3 (CH ), 44.1 (C-13), 50.0 (CH), 54.3 (CH), 56.2 (CH), 73.8
2
2
2
(C-3), 122.3 (C-6), 126.7 (2C, C-2′ and C-6′), 128.6 (2C, C-3′ and C-5′), 130.9 (C-4′), 131.2
+
(
C-1′), 139.7 (C-5), 156.1 (C-21), 170.5 (Ac-CO), 170.7 (C-20); ESI-MS 480 [M+H] ; Anal.
38 2 4
Calcd. for C29H N O C 72.77; H 8.00. Found C 72.92; H 8.16.
4
.1.2.2. O-3
Compound 4 and p-toluamidoxime (IIb, 360 mg) were used in the procedure described in
section 4.1.2. After purification with EtOAc/CH Cl = 5:95 as eluent, 10b was obtained as a
β-Acetoxyandrost-5-ene-17β-acyl-p-toluamidoxime (10b)
2
2
1
4

ACCEPTED MANUSCRIPT
1
white solid (331 mg, 84%), mp 183−185 °C, R
f
= 0.40 (ss C); H NMR (CDCl
3
, 500 MHz):
δ
H
0.80 (s, 3H, 18-H
3
3
), 1.01 (m, 1H), 1.02 (s, 3H, 19-H ), 1.14 (m, 2H), 1.28−1.42
(
overlapping m, 3H), 1.45−1.62 (overlapping m, 5H), 1.73 (m, 1H), 1.88 (m, 3H), 2.03 (s, 3H,
Ac-H ), 2.05 (m, 2H), 2.26 (m, 2H), 2.37 (s, 3H, 4′-CH ), 2.49 (t, 1H, J = 9.4 Hz, 17-H), 4.60
m, 1H, 3-H), 5.01 (bs, 2H, NH ), 5.38 (m, 1H, 6-H), 7.20 (d, 2H, J = 8.0 Hz, 3′-H and 5′-H),
3
3
(
2
1
3
7
.60 (d, 2H, J = 8.0 Hz, 2′-H and 6′-H); C NMR (CDCl
3
, 125 MHz):
), 23.9 (CH ), 24.6 (CH
), 38.3 (CH ), 44.1 (C-13), 50.0 (CH),
δ
C
13.4 (C-18), 19.3
(C-19), 20.9 (CH
2
), 21.4 (2C, Ac-CH
3
and 4′-CH
3
2
2
), 27.7 (CH ), 31.8
2
(CH ), 32.0 (CH), 36.6 (C-10), 37.0 (CH
2
2
), 38.0 (CH
2
2
5
4.4 (CH), 56.2 (CH), 73.8 (C-3), 122.3 (C-6), 126.5 (2C, C-2′ and C-6′), 128.3 (C-1′), 129.3
(2C, C-3′ and C-5′), 139.7 (C-5), 141.1 (C-4′), 156.0 (C-21), 170.5 (Ac-CO), 170.7 (C-20);
+
ESI-MS 494 [M+H] ; Anal. Calcd. for C30
H
40
N
O
2 4
C 73.14; H 8.18. Found C 72.95; H 8.24.
4
.1.2.3. O-3β-Acetoxyandrost-5-ene-17β-acyl-p-methoxybenzamidoxime (10c)
Compound 4 and p-methoxybenzamidoxime (IIc, 399 mg) were used in the procedure
described in section 4.1.2. After purification with EtOAc/CH
Cl
2 2
= 5:95 as eluent, 10c was
1
obtained as a white solid (342 mg, 84%), mp 178−180 °C, R = 0.37 (ss C); H NMR (CDCl ,
f
3
5
1
2
4
3
00 MHz):
δ
H
0.79 (s, 3H, 18-H
3
), 1.01 (m, 1H), 1.02 (s, 3H, 19-H
3
), 1.14 (m, 2H),
.28−1.42 (overlapping m, 3H), 1.44−1.62 (overlapping m, 5H), 1.73 (m, 1H), 1.87 (m, 3H),
.02 (s, 3H, Ac-H ), 2.05 (m, 2H), 2.25 (m, 2H), 2.48 (t, 1H, J = 9.4 Hz, 17-H), 3.82 (s, 3H,
′-OMe), 4.60 (m, 1H, 3-H), 5.01 (bs, 2H, NH ), 5.37 (m, 1H, 6-H), 6.89 (d, 2H, J = 8.5 Hz,
C
′-H and 5′-H), 7.64 (d, 2H, J = 8.5 Hz, 2′-H and 6′-H); C NMR (CDCl , 125 MHz): δ 13.4
3
2
1
3
3
(
C-18), 19.3 (C-19), 20.9 (CH ), 21.4 (Ac-CH ), 23.9 (CH ), 24.6 (CH ), 27.7 (CH ), 31.8
2
3
2
2
2
(
CH
2
), 31.9 (CH), 36.6 (C-10), 37.0 (CH
2
), 38.0 (CH
2
2
), 38.3 (CH ), 44.1 (C-13), 50.0 (CH),
5
1
4.4 (CH), 55.3 (4′-OMe), 56.2 (CH), 73.8 (C-3), 113.9 (2C, C-3′ and C-5′), 122.3 (C-6),
23.4 (C-1′), 128.1 (2C, C-2′ and C-6′), 139.7 (C-5), 155.8 (C-21), 161.7 (C-4′), 170.5 (Ac-
1
5

ACCEPTED MANUSCRIPT
+
CO), 170.8 (C-20); ESI-MS 532 [M+Na] ; Anal. Calcd. for C H N O C 70.84; H 7.93.
3
0
40
2
5
Found C 71.01; H 8.09.
4
.1.2.4. O-3β-Acetoxyandrost-5-ene-17β -acyl-p-bromobenzamidoxime (10d)
Compound 4 and p-bromobenzamidoxime (IId, 516 mg) were used in the procedure
described in section 4.1.2. After purification with EtOAc/CH
2
Cl
2
= 2:98 as eluent, 10d was
1
obtained as a white solid (384 mg, 86%), mp 165−168 °C, R = 0.43 (ss C); H NMR (CDCl ,
f
3
5
1
2
3
00 MHz):
δ
H
0.79 (s, 3H, 18-H
3
), 1.01 (m, 1H), 1.02 (s, 3H, 19-H
3
), 1.14 (m, 2H),
.29−1.41 (overlapping m, 3H), 1.44−1.62 (overlapping m, 5H), 1.74 (m, 1H), 1.87 (m, 3H),
.03 (s, 3H, Ac-H ), 2.05 (m, 2H), 2.24 (m, 2H), 2.48 (t, 1H, J = 9.3 Hz, 17-H), 4.59 (m, 1H,
-H), 5.07 (bs, 2H, NH ), 5.37 (m, 1H, 6-H), 7.53 (d, 2H, J = 8.5 Hz) and 7.58 (d, 2H, J = 8.5
3
2
1
3
3 C
Hz): 3′-H, 5′-H and 2′-H and 6′-H; C NMR (CDCl , 125 MHz): δ 13.4 (C-18), 19.3 (C-19),
2
0.9 (CH ), 21.4 (Ac-CH ), 23.9 (CH ), 24.6 (CH ), 27.7 (CH ), 31.8 (CH ), 31.9 (CH), 36.6
2
3
2
2
2
2
(C-10), 37.0 (CH
2
), 38.0 (CH
2
2
), 38.3 (CH ), 44.2 (C-13), 50.0 (CH), 54.3 (CH), 56.2 (CH),
7
3.8 (C-3), 122.3 (C-6), 125.3 (C-4′), 128.2 (2C, C-2′ and C-6′), 130.1 (C-1′), 131.8 (2C, C-3′
+
and C-5′), 139.7 (C-5), 155.2 (C-21), 170.5 (Ac-CO), 170.7 (C-20); ESI-MS 559 [M+H] ;
2 4
Anal. Calcd. for C29H37BrN O C 62.48; H 6.69. Found C 62.62; H 6.58.
4
.1.2.5. O-3β-Acetoxyandrost-5-ene-17β-acylacetamidoxime (10e)
Compound 4 and acetamidoxime (IIe, 179 mg) were used in the procedure described in
section 4.1.2. After purification with EtOAc/CH
white solid (290 mg, 87%), mp 192−194 °C, R
.74 (s, 3H, 18-H ), 0.98 (m, 1H), 1.00 (s, 3H, 19-H
m, 3H), 1.41−1.58 (overlapping m, 5H), 1.70 (m, 1H), 1.83 (m, 4H), 1.95 (s, 3H, CH ), 1.97
Cl
2 2
= 20:80 as eluent, 10e was obtained as a
1
f
= 0.30 (ss E); H NMR (CDCl
3
, 500 MHz):
δ
H
0
3
3
), 1.11 (m, 2H), 1.25−1.34 (overlapping
3
1
6

ACCEPTED MANUSCRIPT
(
m, 2H), 2.01 (s, 3H, Ac-H ), 2.19 (m, 1H), 2.39 (t, 1H, J = 9.4 Hz, 17-H), 4.57 (m, 1H, 3-H),
3
1
3
4
.80 (bs, 2H, NH
2
), 5.36 (m, 1H, 6-H); C NMR (CDCl
3
, 125 MHz):
), 23.8 (CH ), 24.5 (CH
), 38.3 (CH ), 44.0 (C-13), 49.9 (CH),
δ
C
13.3 (C-18), 17.0
(CH
3
2
), 19.2 (C-19), 20.9 (CH
2
), 21.4 (Ac-CH
3
2
2
), 27.7 (CH ), 31.7
2
(CH
), 31.9 (CH), 36.6 (C-10), 36.9 (CH
2
), 38.0 (CH
2
2
5
1
6
4.2 (CH), 56.1 (CH), 73.8 (C-3), 122.2 (C-6), 139.7 (C-5), 154.8 (C-21), 170.5 (Ac-CO),
+
70.7 (C-20); ESI-MS 417 [M+H] ; Anal. Calcd. for C H N O C 69.20; H 8.71. Found C
24
36
2
4
9.38; H 8.59.
4
.1.2.6. O-3β-Acetoxyandrost-5,16-diene-17-acylbenzamidoxime (11a)
Compound 6 and benzamidoxime (IIa, 327 mg) were used in the procedure described in
section 4.1.2. After purification with EtOAc/CH Cl = 5:95 as eluent, 11a was obtained as a
2
2
1
white solid (351 mg, 92%), mp 190−193 °C, R
1.01 (s, 3H, 18-H ), 1.06 (s, 3H, 19-H
overlapping m, 8H), 1.86 (m, 2H), 2.02 (s, 3H, Ac-H ), 2.07 (m, 2H), 2.33 (m, 3H), 4.60 (m,
f
= 0.36 (ss C); H NMR (CDCl
3
, 500 MHz):
δ
Η
3
3
), 1.07 (m, 1H), 1.14 (m, 1H), 1.47−1.76
(
3
1
H, 3-H), 5.11 (s, 2H, NH ), 5.38 (m, 1H, 6-H), 6.84 (m, 1H, 16-H), 7.38 (m, 2H, 3′-H and 5′-
2
1
3
H), 7.45 (m, 1H, 4′-H), 7.71 (m, 2H, 2′-H and 6′-H); C NMR (CDCl
3
, 125 MHz):
), 30.2 (CH), 31.4 (CH
), 46.2 (C-13), 50.3 (CH), 56.4 (CH),
3.8 (C-3), 122.0 (C-6), 126.7 (2C, C-2′ and C-6′), 128.6 (2C, C-3′ and C-5′), 130.8 (C-4′),
δ
C
16.1
(
C-18), 19.2 (C-19), 20.7 (CH
2
), 21.4 (Ac-CH
3
), 27.7 (CH
2
2
), 32.1
(
CH ), 34.8 (CH ), 36.8 (C-10), 36.9 (CH
2
2
2
), 38.1 (CH
2
7
1
31.2 (C-1′), 140.1 (C-5), 143.4 (C-16), 145.6 (C-17), 156.5 (C-21), 162.1 (C-20), 170.5 (Ac-
+
CO); ESI-MS 478 [M+H] ; Anal. Calcd. for C29
H
36
N
2
O
4
C 73.08; H 7.61. Found C 73.19; H
7
.82.
4
.1.2.7. O-3β-Acetoxyandrost-5,16-diene-17-acyl-p-toluamidoxime (11b)
1
7

ACCEPTED MANUSCRIPT
Compound 6 and p-toluamidoxime (IIb, 360 mg) were used in the procedure described in
section 4.1.2. After purification with EtOAc/CH Cl = 2:98 as eluent, 11b was obtained as a
2
2
1
white solid (334 mg, 85%), mp 189−192 °C, R
1.02 (s, 3H, 18-H ), 1.07 (s, 3H, 19-H
overlapping m, 8H), 1.86 (m, 2H),2.03 (s, 3H, Ac-H ), 2.06 (m, 2H), 2.33 (m, 3H), 2.37 (s,
f
= 0.38 (ss C); H NMR (CDCl
3
, 500 MHz):
δ
H
3
3
), 1.08 (m, 1H), 1.14 (m, 1H), 1.47−1.76
(
3
3
7
H, 4′-CH ), 4.61 (m, 1H, 3-H), 5.04 (bs, 2H, NH ), 5.39 (m, 1H, 6-H), 6.84 (m, 1H, 16-H),
3 2
13
.20 (d, 2H, J = 8.1 Hz, 3′-H and 5′-H), 7.61 (d, 2H, J = 8.1 Hz, 2′-H and 6′-H); C NMR
(
CDCl , 125 MHz): δC 16.1 (C-18), 19.2 (C-19), 20.7 (CH ), 21.4 (Ac-CH ), 27.7 (4′-CH ),
3
2
3
3
3
1
1
1
0.2 (CH), 31.4 (CH
2
), 32.2 (CH
2
), 34.8 (CH
2
), 36.8 (C-10), 36.9 (CH
2
), 38.1 (CH
2
), 46.2 (C-
3), 50.4 (CH), 56.4 (CH), 62.1 (CH), 73.8 (C-3), 122.0 (C-6), 126.5 (2C, C-2′ and C-6′),
28.3 (C-1′), 129.3 (2C, C-3′ and C-5′), 140.2 (C-5), 141.1 (C-17), 143.3 (C-16), 145.7 (C-4′),
+
56.4 (C-21), 162.1 (C-20), 170.5 (Ac-CO); ESI-MS 492 [M+H] ; Anal. Calcd. for
30 38 2 4
C H N O C 73.44; H 7.81. Found C 72.31; H 7.87.
4
.1.2.8. O-3β-Acetoxyandrost-5,16-diene-17-acyl-p-methoxybenzamidoxime (11c)
Compound 6 and p-methoxybenzamidoxime (IIc, 399 mg) were used in the procedure
described in section 4.1.2. After purification with EtOAc/CH
2
Cl
2
= 5:95 as eluent, 11c was
1
obtained as a white solid (357 mg, 88%), mp 195−197 °C, R
f
= 0.32 (ss C); H NMR (CDCl
3
,
5
1
3
00 MHz):
.47−1.75 (overlapping m, 8H), 1.86 (m, 2H), 2.02 (s, 3H, Ac-H
H), 3.81 (s, 3H, 4′-OMe), 4.60 (m, 1H, 3-H), 5.05 (bs, 2H, NH
δ
H
1.01 (s, 3H, 18-H
3
), 1.06 (s, 3H, 19-H
3
), 1.08 (m, 1H), 1.13 (m, 1H),
), 2.05 (m, 2H), 2.33 (m,
), 5.38 (m, 1H, 6-H), 6.83
3
2
(bs, 1H, 16-H), 6.88 (d, 2H, J = 8.5 Hz, 3′-H and 5′-H), 7.66 (d, 2H, J = 8.5 Hz, 2′-H and 6′-
1
3
H); C NMR (CDCl
7.7 (CH ), 30.2 (CH), 31.4 (CH
CH ), 46.2 (C-13), 50.4 (CH), 55.3 (4′-OMe), 56.4 (CH), 73.8 (C-3), 113.9 (2C, C-3′ and C-
3
, 125 MHz):
δ
16.1 (C-18), 19.2 (C-19), 20.7 (CH
2
), 21.4 (Ac-CH
3
),
2
2
2
), 32.1 (CH
2
), 34.8 (CH ), 36.8 (C-10), 36.9 (CH
2
2
), 38.1
(
2
1
8

ACCEPTED MANUSCRIPT
5
1
′), 122.0 (C-6), 123.4 (C-1′), 128.1 (2C, C-2′ and C-6′), 140.1 (C-5), 143.3 (C-16), 145.7 (C-
+
7), 156.3 (C-21), 161.7 (C-4′), 162.2 (C-20), 170.5 (Ac-CO); ESI-MS 530 [M+Na] ; Anal.
38 2 5
Calcd. for C30H N O C 71.12; H 7.56. Found C 71.26; H 7.40.
4
.1.2.9. O-3β-Acetoxyandrost-5,16-diene-17-acyl-p-bromobenzamidoxime (11d)
Compound 6 and p-bromobenzamidoxime (IId, 516 mg) were used in the procedure
described in section 4.1.2. After purification with EtOAc/CH
obtained as a white solid (369 mg, 83%), mp 206−209 °C, R
2
Cl
2
= 5:95 as eluent, 11d was
1
f
= 0.47 (ss C); H NMR (CDCl
3
,
5
1
3
2
1
3
00 MHz):
.47−1.76 (overlapping m, 8H), 1.87 (m, 2H), 2.03 (s, 3H, Ac-H
H), 4.61 (m, 1H, 3-H), 5.08 (bs, 2H, NH ), 5.39 (m, 1H, 6-H), 6.85 (bs, 1H, 16-H), 7.53 (d,
H, J = 8.4 Hz) and 7.60 (d, 2H, J = 8.4 Hz): 2′-H, 6′-H and 3′-H, 5′-H); C NMR (CDCl
δ
H
1.02 (s, 3H, 18-H
3
), 1.07 (s, 3H, 19-H
3
), 1.08 (m, 1H), 1.15 (m, 1H),
3
), 2.06 (m, 2H), 2.33 (m,
2
1
3
3
,
25 MHz):
δ
C
16.1 (C-18), 19.2 (C-19), 20.7 (CH
2
), 21.4 (Ac-CH
3
), 27.7 (CH
2
), 30.2 (CH),
1.4 (CH ), 32.2 (CH
2
2
), 34.8 (CH ), 36.8 (C-10), 36.9 (CH
2
2
), 38.1 (CH
2
), 46.2 (C-13), 50.4
(CH), 56.4 (CH), 73.8 (C-3), 122.0 (C-6), 125.4 (C-4′), 128.2 (2C, C-2′ and C-6′), 130.1 (C-
1
′), 131.9 (2C, C-3′ and C-5′), 140.2 (C-5), 143.7 (C-16), 145.5 (C-17), 155.5 (C-21), 162.0
+
(
C-20), 170.5 (Ac-CO); ESI-MS 557 [M+H] ; Anal. Calcd. for C29
H
35BrN
2
O
4
C 62.70; H
6
.35. Found C 62.84; H 6.54.
4
.1.2.10. O-3β-Acetoxyandrost-5,16-diene-17-acylacetamidoxime (11e)
Compound 6 and acetamidoxime (IIe, 179 mg) were used in the procedure described in
section 4.1.2. After purification with EtOAc/CH Cl = 30:70 as eluent, 11e was obtained as a
2
2
1
white solid (292 mg, 88%), mp 205−208 °C, R
f
= 0.32 (ss E); H NMR (CDCl
3
, 500 MHz):
δ
H
0
.97 (s, 3H, 18-H ), 1.02 (m, 1H), 1.04 (s, 3H, 19-H ), 1.12 (m, 1H), 1.39−1.50 (overlapping
3 3
1
9

ACCEPTED MANUSCRIPT
3
m, 2H), 1.53−1.72 (overlapping m, 5H), 1.84 (m, 2H), 1.98 (s, 3H, CH ), 2.00 (m, 2H), 2.02
(
(
(
s, 3H, Ac-H
3
), 2.29 (m, 4H), 4.58 (m, 1H, 3-H), 4.81 (bs, 2H, NH
2
), 5.37 (m, 1H, 6-H), 6.78
1
3
m, 1H, 16-H); C NMR (CDCl , 125 MHz):
δ
16.1 (C-18), 17.0 (CH ), 19.2 (C-19), 20.6
3
3
CH
2
), 21.4 (Ac-CH
3
2 2 2 2
), 27.7 (CH ), 30.2 (CH), 31.4 (CH ), 32.1 (CH ), 34.8 (CH ), 36.7 (C-
1
1
4
0), 36.8 (CH ), 38.1 (CH ), 46.0 (C-13), 50.3 (CH), 56.4 (CH), 73.8 (C-3), 122.0 (C-6),
2
2
40.1 (C-17), 143.3 (C-16), 145.7 (C-5), 155.2 (C-21), 162.2 (C-20), 170.5 (Ac-CO); ESI-MS
+
15 [M+H] ; Anal. Calcd. for C24
H
34
N
2
O
4
C 69.54; H 8.27. Found C 69.66; H 8.47.
4
.1.3. General procedure for the cyclocondensation of O-acylamidoximes (10a−e, 11a−e)
O-Acylamidoxime (10a−e or 11a−e, 0.50 mmol) was dissolved in dry THF (5 mL) and TBAF
1M solution in THF, 0.05 mL) was added under a N atmosphere. The solution was stirred
for 1 h at room temperature, and then poured into water (10 mL) and extracted with CH Cl (2
10 mL). The combined organic phase was dried over anhydrous Na SO , and evaporated.
The crude product was purified by flash chromatography.
(
2
2
2
×
2
4
4
.1.3.1. 3β-Acetoxy-17β-(5′-[3′-phenyl]-1′,2′,4′-oxadiazolyl)androst-5-ene (12a)
1
0a (239 mg) was used for the reaction in the procedure described in section 4.1.3. After
purification with CH
Cl
2 2
as eluent, 12a was obtained as a white solid (214 mg, 93%), mp
1
1
3
31−134 °C, R
f
= 0.40 (ss A); H NMR (CDCl
3
, 500 MHz):
δ
H
0.65 (s, 3H, 18-H
3
), 1.03 (s,
H, 19-H
3
), 1.05 (m, 1H), 1.17 (m, 1H), 1.28 (m, 1H), 1.40−1.66 (overlapping m, 7H), 1.87
), 2.08 (m, 2H), 2.19 (m, 1H), 2.33 (m, 2H), 2.46 (m, 1H), 2.96 (t,
H, J = 9.5 Hz, 17-H), 4.61 (m, 1H, 3-H), 5.39 (m, 1H, 6-H), 7.47 (m, 3H, 3″-H, 4″-H and 5″-
(m, 3H), 2.03 (s, 3H, Ac-H
3
1
13
3 C
H), 8.09 (m, 2H, 2″-H and 6″-H), C NMR (CDCl , 125 MHz): δ 13.3 (C-18), 19.3 (C-19),
2
0

ACCEPTED MANUSCRIPT
2
0.8 (CH ), 21.4 (Ac-CH ), 24.7 (CH ), 25.3 (CH ), 27.7 (CH ), 31.8 (CH ), 32.1 (CH), 36.7
2
3
2
2
2
2
(
C-10), 37.0 (CH ), 37.6 (CH ), 38.1 (CH ), 45.3 (C-13), 48.5 (C-17), 49.9 (CH), 56.0 (CH),
2 2 2
7
1
3.8 (C-3), 122.2 (C-6), 127.2 (C-1″), 127.4 (2C, C-2″ and C-6″), 128.7 (2C, C-3″ and C-5″),
+
30.9 (C-4″), 139.8 (C-5), 167.9 (C-3′), 170.5 (Ac-CO), 180.9 (C-5′); ESI-MS 462 [M+H] ;
36 2 3
Anal. Calcd. for C29H N O C 75.62; H 7.88. Found C 75.78; H 8.02.
4
.1.3.2. 3β-Acetoxy-17β-(5′-[3′-4″-tolyl]-1′,2′,4′-oxadiazolyl)androst-5-ene (12b)
1
0b (246 mg) was used for the reaction in the procedure described in section 4.1.3. After
purification with CH
Cl
2 2
as eluent, 12b was obtained as a white solid (218 mg, 92%), mp
1
1
3
82−183 °C, R
f
= 0.41 (ss A); H NMR (CDCl
3
, 500 MHz):
δ
H
0.64 (s, 3H, 18-H
3
), 1.02 (s,
H, 19-H
3
), 1.05 (m, 1H), 1.16 (m, 1H), 1.27 (m, 1H), 1.40−1.66 (overlapping m, 7H), 1.87
), 2.08 (m, 2H), 2.18 (m, 1H), 2.33 (m, 2H), 2.40 (s, 3H, 4″-CH ),
.45 (m, 1H), 2.94 (t, 1H, J = 9.5 Hz, 17-H), 4.61 (m, 1H, 3-H), 5.39 (m, 1H, 6-H), 7.27 (d,
(m, 3H), 2.03 (s, 3H, Ac-H
3
3
2
2
1
1
3
3
H, J = 8.1 Hz, 3″-H and 5″-H), 7.97 (d, 2H, J = 8.1 Hz, 2″-H and 6″-H); C NMR (CDCl ,
25 MHz):
δ
C
13.3 (C-18), 19.3 (C-19), 20.8 (CH
2
), 21.4 (Ac-CH
3
), 21.5 (4″-CH
3
), 24.7
(
CH
2
), 25.3 (CH ), 27.7 (CH ), 31.8 (CH ), 32.1 (CH), 36.7 (C-10), 37.0 (CH
2
2
2
2 2
), 37.6 (CH ),
3
2
8.1 (CH ), 45.2 (C-13), 48.5 (C-17), 49.9 (CH), 56.0 (CH), 73.8 (C-3), 122.2 (C-6), 124.3
(C-1″), 127.3 (2C, C-2″ and C-6″), 129.4 (2C, C-3″ and C-5″), 139.8 (C-5), 141.2 (C-4″),
+
1
68.0 (C-3′), 170.5 (Ac-CO), 180.7 (C-5′); ESI-MS 498 [M+Na] ; Anal. Calcd. for
C H N O C 75.92; H 8.07. Found C 76.04; H 7.97.
30
38
2
3
4
.1.3.3. 3
β
-Acetoxy-17β-(5′-[3′-4″-methoxyphenyl]-1′,2′,4′-oxadiazolyl)androst-5-ene (12c)
1
0c (254 mg) was used for the reaction in the procedure described in section 4.1.3. After
purification with hexane/CH Cl = 20:80 as eluent, 12c was obtained as a white solid (231
2
2
1
f 3 H
mg, 94%), mp 193−196 °C, R = 0.43 (ss A); H NMR (CDCl , 500 MHz): δ 0.64 (s, 3H,
2
1

ACCEPTED MANUSCRIPT
1
8-H
3
), 1.02 (s, 3H, 19-H
3
), 1.05 (m, 1H), 1.17 (m, 1H), 1.26 (m, 1H), 1.39−1.67 (overlapping
3
m, 7H), 1.87 (m, 3H), 2.03 (s, 3H, Ac-H ), 2.08 (m, 2H), 2.17 (m, 1H), 2.33 (m, 2H), 2.44 (m,
1
H), 2.93 (t, 1H, J = 9.5 Hz, 17-H), 3.86 (s, 3H, 4″-OMe), 4.62 (m, 1H, 3-H), 5.39 (m, 1H, 6-
1
3
H), 6.97 (d, 2H, J = 8.5 Hz, 3″-H and 5″-H), 8.02 (d, 2H, J = 8.5 Hz, 2″-H and 6″-H); C
NMR (CDCl , 125 MHz): 13.2 (C-18), 19.3 (C-19), 20.8 (CH ), 21.4 (Ac-CH ), 24.6
CH ), 25.2 (CH ), 27.7 (CH ), 31.8 (CH ), 32.0 (CH), 36.7 (C-10), 37.0 (CH ), 37.6 (CH ),
3
δ
C
2
3
(
2
2
2
2
2
2
3
2
8.1 (CH ), 45.2 (C-13), 48.5 (C-17), 49.9 (CH), 55.3 (4″-OMe), 56.0 (CH), 73.8 (C-3), 114.1
(2C, C-3″ and C-5″), 119.7 (C-1″), 122.2 (C-6), 129.0 (2C, C-2″ and C-6″), 139.8 (C-5),
+
1
61.7 (C-4″), 167.6 (C-3′), 170.5 (Ac-CO), 180.6 (C-5′); ESI-MS 514 [M+Na] ; Anal. Calcd.
for C H N O C 73.44; H 7.81. Found C 73.62; H 7.96.
30
38
2
4
4
.1.3.4. 3β-Acetoxy-17β-(5′-[3′-4″-bromophenyl]-1′,2′,4′-oxadiazolyl)androst-5-ene (12d)
1
0d (279 mg) was used for the reaction in the procedure described in section 4.1.3. After
purification with hexane/CH
mg, 91%), mp 190−192 °C, R
8-H ), 1.02 (s, 3H, 19-H
m, 7H), 1.87 (m, 3H), 2.03 (s, 3H, Ac-H
H), 2.95 (t, 1H, J = 9.5 Hz, 17-H), 4.61 (m, 1H, 3-H), 5.39 (m, 1H, 6-H), 7.60 (d, 2H, J = 8.0
2
Cl
2
= 20:80 as eluent, 12d was obtained as a white solid (245
1
f
= 0.47 (ss A); H NMR (CDCl
3
, 500 MHz):
δ
H
0.64 (s, 3H,
1
3
3
), 1.06 (m, 1H), 1.17 (m, 1H), 1.27 (m, 1H), 1.39−1.66 (overlapping
), 2.07 (m, 2H), 2.18 (m, 1H), 2.33 (m, 2H), 2.44 (m,
3
1
1
3
Hz, 2″-H and 6″-H), 7.96 (d, 2H, J = 8.0 Hz, 3″-H and 5″-H); C NMR (CDCl , 125 MHz):
3
δ
3
1
C
13.3 (C-18), 19.3 (C-19), 20.8 (CH
1.8 (CH ), 32.1 (CH), 36.7 (C-10), 37.0 (CH
7), 49.9 (CH), 56.0 (CH), 73.8 (C-3), 122.1 (C-6), 124.4 and 126.1: C-1″ and C-4″, 128.9
2
), 21.4 (Ac-CH
3
), 24.7 (CH
2
), 25.3 (CH
2 2
), 27.7 (CH ),
2
2
), 37.6 (CH
2
), 38.1 (CH
2
), 45.3 (C-13), 48.5 (C-
(2C, C-2″ and C-6″), 132.0 (2C, C-3″ and C-5″), 139.8 (C-5), 167.2 (C-3′), 170.5 (Ac-CO),
+
1
6
81.2 (C-5′); ESI-MS 541 [M+H] ; Anal. Calcd. for C H BrN O C 64.56; H 6.54. Found C
2
9
35
2
3
4.74; H 6.71.
2
2

ACCEPTED MANUSCRIPT
4
.1.3.5. 3
β
-Acetoxy-17
β
-(5′-[3′-methyl]-1′,2′,4′-oxadiazolyl)androst-5-ene (12e)
1
0e (208 mg) was used for the reaction in the procedure described in section 4.1.3. After
purification with EtOAc/CH
2
Cl
2
= 2:98 as eluent, 12e was obtained as a white solid (185 mg,
1
9
1
7
3
3%), mp 163−166 °C, R
.01 (s, 3H, 19-H
H), 1.85 (m, 3H), 2.02 (s, 3H, Ac-H
′-CH ), 2.86 (t, 1H, J = 9.5 Hz, 17-H), 4.60 (m, 1H, 3-H), 5.38 (m, 1H, 6-H); C NMR
CDCl
f
= 0.43 (ss B); H NMR (CDCl
3
, 500 MHz):
δ
H
0.59 (s, 3H, 18-H
3
),
3
), 1.03 (m, 1H), 1.15 (m, 1H), 1.24 (m, 1H), 1.35−1.64 (overlapping m,
), 2.05 (m, 2H), 2.12 (m, 1H), 2.32 (m, 3H), 2.37 (s, 3H,
3
13
3
(
3
, 125 MHz):
δ
C
11.6 (3′-CH
3
), 13.2 (C-18), 19.3 (C-19), 20.7 (CH
2
3
), 21.4 (Ac-CH ),
2
4.6 (CH ), 25.2 (CH ), 27.7 (CH ), 31.8 (CH ), 32.1 (CH), 36.6 (C-10), 37.0 (CH ), 37.6
2
2
2
2
2
(
CH
2
), 38.1 (CH
2
), 45.1 (C-13), 48.4 (C-17), 49.9 (CH), 56.0 (CH), 73.8 (C-3), 122.1 (C-6),
+
1
39.8 (C-5), 166.6 (C-3′), 170.5 (Ac-CO), 180.6 (C-5′); ESI-MS 399 [M+H] ; Anal. Calcd.
34 2 3
for C24H N O C 72.33; H 8.60. Found C 72.51; H 8.54.
4
.1.3.6. 3β-Acetoxy-17-(5′-[3′-phenyl]-1′,2′,4′-oxadiazolyl)androst-5,16-diene (13a)
1
1a (238 mg) was used for the reaction in the procedure described in section 4.1.3. After
purification with hexane/CH
mg, 94%), mp 168−170 °C , R
and 1.10 (s, 3H): 18-H and 19-H
), 2.08 (m, 1H), 2.18 (m, 1H), 2.35 (m, 2H), 2.43 (m, 1H), 2.57 (m,
H), 4.62 (m, 1H, 3-H), 5.41 (m, 1H, 6-H), 6.98 (m, 1H, 16-H), 7.48 (m, 3H, 3″-H, 4″-H and
2
Cl
2
= 20:80 as eluent, 13a was obtained as a white solid (216
1
f
= 0.47 (ss A); H NMR (CDCl
3
, 500 MHz):
δ
H
1.08 (s, 3H)
3
3
, 1.15 (m, 2H), 1.51−1.81 (overlapping m, 7H), 1.89 (m,
2
1
5
1
3
6
H), 2.04 (s, 3H, Ac-H
3
1
3
3 C
″-H), 8.11 (m, 2H, 2″-H and 6″-H); C NMR (CDCl , 125 MHz): δ 16.0 (C-18), 19.2 (C-
9), 20.7 (CH ), 21.4 (Ac-CH ), 27.7 (CH ), 30.3 (CH), 31.5 (CH ), 32.6 (CH ), 34.7 (CH ),
2
3
2
2
2
2
6.8 (C-10), 36.9 (CH
2
2
), 38.1 (CH ), 46.8 (C-13), 50.3 (CH), 56.6 (CH), 73.8 (C-3), 122.0 (C-
), 127.1 (C-1″), 127.4 (2C, C-2″ and C-6″), 128.7 (2C, C-3″ and C-5″), 130.9 (C-4″), 139.8
2
3

ACCEPTED MANUSCRIPT
(C-5), 140.2 (C-17), 141.4 (C-16), 168.4 (C-3′), 170.5 (Ac-CO), 173.2 (C-5′); ESI-MS 481
+
[
M+Na] ; Anal. Calcd. for C H N O C 75.95; H 7.47. Found C 76.08; H 7.65.
2
9
34
2
3
4
.1.3.7. 3β-Acetoxy-17-(5′-[3′-4″-tolyl]-1′,2′,4′-oxadiazolyl)androst-5,16-diene (13b)
1
1b (245 mg) was used for the reaction in the procedure described in section 4.1.3. After
purification with EtOAc/CH
2
Cl
2
= 2:98 as eluent, 13b was obtained as a white solid (217 mg,
1
9
1
2
1
8
1
2%), mp 152−155 °C, R
.10 (s, 3H): 18-H and 19-H
.04 (s, 3H, Ac-H ), 2.08 (m, 1H), 2.16 (m, 1H), 2.35 (m, 2H), 2.41 (s, 3H, 4″-CH
H), 2.56 (m, 1H), 4.62 (m, 1H, 3-H), 5.41 (m, 1H, 6-H), 6.96 (m, 1H, 16-H), 7.27 (d, 2H, J =
f
= 0.47 (ss A); H NMR (CDCl
3
, 500 MHz):
δ
H
1.07 (s, 3H) and
3
3
, 1.17 (m, 2H), 1.51−1.79 (overlapping m, 7H), 1.88 (m, 2H),
), 2.43 (m,
3
3
1
3
.1 Hz, 3″-H and 5″-H), 7.99 (d, 2H, J = 8.1 Hz, 2″-H and 6″-H); C NMR (CDCl
25MHz): 16.0 (C-18), 19.2 (C-19), 20.7 (CH ), 21.4 (Ac-CH ), 21.5 (4″-CH ), 27.7
CH ), 30.3 (CH), 31.5 (CH ), 32.6 (CH ), 34.7 (CH ), 36.8 (C-10), 36.9 (CH ), 38.1 (CH ),
3
,
δ
C
2
3
3
(
2
2
2
2
2
2
4
6.8 (C-13), 50.3 (CH), 56.6 (CH), 73.8 (C-3), 122.0 (C-6), 124.4 (C-1″), 127.4 (2C, C-2″
and C-6″), 129.4 (2C, C-3″ and C-5″), 139.8 (C-5), 140.2 (C-17), 141.1 (C-4″), 141.2 (C-16),
+
1
68.4 (C-3′), 170.5 (Ac-CO), 173.0 (C-5′); ESI-MS 496 [M+Na] ; Anal. Calcd. for
C H N O C 76.24; H 7.68. Found C 76.39; H 7.65.
30
36
2
3
4
.1.3.8.
3β-Acetoxy-17-(5′-[3′-4″-methoxyphenyl]-1′,2′,4′-oxadiazolyl)androst-5,16-diene
(13c)
1
1c (253 mg) was used for the reaction in the procedure described in section 4.1.3. After
purification with CH Cl as eluent, 13c was obtained as a white solid (227 mg, 93%), mp
2
2
1
1
f 3 H
62−164 °C, R = 0.33 (ss A); H NMR (CDCl , 500 MHz): δ 1.07 (s, 3H) and 1.10 (s, 3H):
2
4

ACCEPTED MANUSCRIPT
1
8-H
3
and 19-H
3
, 1.16 (m, 2H), 1.53−1.78 (overlapping m, 7H), 1.87 (m, 2H), 2.04 (s, 3H,
Ac-H
3
), 2.06 (m, 1H), 2.17 (m, 1H), 2.35 (m, 2H), 2.40 (m, 1H), 2.54 (m, 1H), 3.86 (s, 3H,
4
2
2
″-OMe), 4.61 (m, 1H, 3-H), 5.41 (m, 1H, 6-H), 6.97 (m, 3H, 16-H, 3″-H and 5″-H), 8.04 (d,
1
3
H, J = 8.4 Hz, 2″-H and 6″-H); C NMR (CDCl
3 C
, 125 MHz): δ 16.0 (C-18), 19.2 (C-19),
0.7 (CH ), 21.4 (Ac-CH ), 27.7 (CH ), 30.3 (CH), 31.5 (CH ), 32.6 (CH ), 34.7 (CH ), 36.8
2
3
2
2
2
2
(
C-10), 36.9 (CH ), 38.1 (CH ), 46.8 (C-13), 50.3 (CH), 55.3 (4″-OMe), 56.6 (CH), 73.8 (C-
2 2
3
), 114.1 (2C, C-3″ and C-5″), 119.7 (C-1″), 122.0 (C-6), 129.0 (2C, C-2″ and C-6″), 139.8
(C-5), 140.2 (C-17), 141.2 (C-16), 161.7 (C-3′), 168.1 (C-4″) 170.5 (Ac-CO), 173.4 (C-5′);
+
ESI-MS 511 [M+Na] ; Anal. Calcd. for C30
H
36
N
2
O
4
C 73.74; H 7.43. Found C 73.56; H 7.61.
4
.1.3.9. 3β-Acetoxy-17-(5′-[3′-4″-bromophenyl]-1′,2′,4′-oxadiazolyl)androst-5,16-diene (13d)
1
1d (278 mg) was used for the reaction in the procedure described in section 4.1.3. After
purification with CH
Cl
2 2
as eluent, 13d was obtained as a white solid (255 mg, 95%), mp
1
1
1
79−181 °C, R
8-H and 19-H
), 2.08 (m, 1H), 2.17 (m, 1H), 2.35 (m, 2H), 2.42 (m, 1H), 2.54 (m, 1H), 4.62 (m, 1H,
-H), 5.41 (m, 1H, 6-H), 6.98 (m, 1H, 16-H), 7.61 (d, 2H, J = 8.4 Hz, 2″-H and 6″-H), 7.98
f
= 0.51 (ss A); H NMR (CDCl
3
, 500 MHz):
δ
H
1.07 (s, 3H) and 1.10 (s, 3H):
3
3
, 1.17 (m, 2H), 1.50−1.80 (overlapping m, 7H), 1.89 (m, 2H), 2.04 (s, 3H,
Ac-H
3
3
1
3
(
3 C
d, 2H, J = 8.4 Hz, 3″-H and 5″-H); C NMR (CDCl , 125 MHz): δ 16.0 (C-18), 19.2 (C-
1
3
6
1
5
9), 20.6 (CH ), 21.4 (Ac-CH ), 27.7 (CH ), 30.3 (CH), 31.5 (CH ), 32.7 (CH ), 34.6 (CH ),
2
3
2
2
2
2
6.8 (C-10), 36.9 (CH
2
2
), 38.1 (CH ), 46.8 (C-13), 50.3 (CH), 56.6 (CH), 73.8 (C-3), 122.0 (C-
), 125.5 and 126.2: C-1″ and C-4″, 129.0 (2C, C-2″ and C-6″), 132.0 (2C, C-3″ and C-5″),
39.6 (C-5), 140.2 (C-17), 141.8 (C-16), 167.7 (C-3′), 170.5 (Ac-CO), 173.4 (C-5′); ESI-MS
+
38 [M+H] ; Anal. Calcd. for C H BrN O C 64.80; H 6.19. Found C 64.98; H 6.31.
29
33
2
3
4
.1.3.10. 3β-Acetoxy-17-(5′-[3′-4″-methyl]-1′,2′,4′-oxadiazolyl)androst-5,16-diene (13e)
2
5

ACCEPTED MANUSCRIPT
1
1e (207 mg) was used for the reaction in the procedure described in section 4.1.3. After
purification with CH Cl as eluent, 13e was obtained as a white solid (180 mg, 91%), mp
2
2
1
9
1
2−94 °C, R
f
= 0.49 (ss B); H NMR (CDCl
3 H
, 500 MHz): δ 1.02 (s, 3H) and 1.07 (s, 3H):
8-H and 19-H
3
3
, 1.15 (m, 2H), 1.45−1.78 (overlapping m, 7H), 1.87 (m, 2H), 2.03 (s, 3H,
Ac-H ), 2.05 (m, 1H), 2.13 (m, 1H), 2.34 (m, 2H), 2.39 (s, 3H, 3′-CH ), 2.42 (m, 2H), 4.61
3
3
1
3
(
(
(
m, 1H, 3-H), 5.39 (m, 1H, 6-H), 6.88 (m, 1H, 16-H); C NMR (CDCl
3
, 125 MHz):
), 27.7 (CH ), 30.2 (CH), 31.4
), 46.7 (C-13), 50.3 (CH),
C
δ 11.7
3′-CH
3
), 16.0 (C-18), 19.2 (C-19), 20.6 (CH
2
), 21.4 (Ac-CH
3
2
CH ), 32.6 (CH
2
2
), 34.6 (CH ), 36.8 (C-10), 36.9 (CH
2
2
), 38.1 (CH
2
5
1
8
6.6 (CH), 73.8 (C-3), 122.0 (C-6), 139.7 (C-17), 140.2 (C-5), 141.2 (C-16), 167.1 (C-3′),
+
70.5 (Ac-CO), 173.0 (C-5′); ESI-MS 397 [M+H] ; Anal. Calcd. for C H N O C 72.70; H
24
32
2
3
.13. Found C 72.84; H 8.21.
4
.1.4. General procedure for the synthesis of oxadiazoles 14a−e and 15a−e
Compound 12a–e or 13a−e (0.30 mmol) was dissolved in MeOH (10 mL), and KOH (50 mg,
.89 mmol) was added. The solution was stirred at room temperature for 8 h, diluted with
0
water and neutralized with dilute HCl. The precipitate that formed was filtered off, washed
with water and dried.
4
.1.4.1. 3β-Hydroxy-17β-(5′-[3′-phenyl]-1′,2′,4′-oxadiazolyl)androst-5-ene (14a)
Substrate: 12a (138 mg). 14a was obtained as a white solid (116 mg, 92%), mp 184−186 °C,
1
R
f
= 0.34 (ss C); H NMR (CDCl
3
, 500 MHz):
δ
H
0.65 (s, 3H, 18-H
3
), 1.01 (s, 3H, 19-H
3
),
1
.03 (m, 1H), 1.12 (m, 1H), 1.27 (m, 1H), 1.40−1.70 (overlapping m, 7H), 1.85 (m, 3H), 2.08
(m, 2H), 2.13−2.33 (overlapping m, 3H), 2.46 (m, 1H), 2.95 (t, 1H, J = 9.5 Hz, 17-H), 3.53
(m, 1H, 3-H), 5.37 (m, 1H, 6-H), 7.47 (m, 3H, 3″-H, 4″-H and 5″-H), 8.09 (m, 2H, 2″-H and
1
3
6
″-H); C NMR (CDCl , 125 MHz): δC 13.3 (C-18), 19.4 (C-19), 20.8 (CH ), 24.7 (CH ),
3
2
2
2
6

ACCEPTED MANUSCRIPT
2
5.3 (CH ), 31.6 (CH ), 31.8 (CH ), 32.1 (CH), 36.6 (C-10), 37.3 (CH ), 37.7 (CH ), 42.2
2
2
2
2
2
(
CH ), 45.3 (C-13), 48.6 (C-17), 50.0 (CH), 56.1 (CH), 71.7 (C-3), 121.2 (C-6), 127.1 (C-1″),
2
1
3
27.4 (2C, C-2″ and C-6″), 128.7 (2C, C-3″ and C-5″), 130.9 (C-4″), 140.9 (C-5), 167.9 (C-
+
′), 180.9 (C-5′); ESI-MS 419 [M+H] ; Anal. Calcd. for C27
H
34
N
2
O
2
C 77.48; H 8.19. Found
C 77.60; H 8.25.
4
.1.4.2. 3β-Hydroxy-17β-(5′-[3′-4″-tolyl]-1′,2′,4′-oxadiazolyl)androst-5-ene (14b)
Substrate: 12b (142 mg). 14b was obtained as a white solid (121 mg, 93%), mp 162−164 °C,
1
R
f
= 0.33 (ss C); H NMR (CDCl
3
, 500 MHz):
δ
H
0.64 (s, 3H, 18-H
3
), 1.01 (s, 3H, 19-H
3
),
1
.03 (m, 1H), 1.11 (m, 1H), 1.27 (m, 1H), 1.39−1.69 (overlapping m, 7H), 1.85 (m, 3H), 2.08
m, 2H), 2.13−2.33 (overlapping m, 3H), 2.40 (s, 3H, 4″-CH ), 2.44 (m, 1H), 2.94 (t, 1H, J =
.5 Hz, 17-H), 3.53 (m, 1H, 3-H), 5.37 (m, 1H, 6-H), 7.27 (d, 2H, J = 8.1 Hz, 3″-H and 5″-H),
(
3
9
7
1
3
3 C
.97 (d, 2H, J = 8.1 Hz, 2″-H and 6″-H); C NMR (CDCl , 125 MHz): δ 13.3 (C-18), 19.4
(
C-19), 20.8 (CH ), 21.5 (4″-CH ), 24.7 (CH ), 25.3 (CH ), 31.6 (CH ), 31.8 (CH ), 32.1
2
3
2
2
2
2
(CH), 36.6 (C-10), 37.3 (CH
2
), 37.7 (CH
2
2
), 42.2 (CH ), 45.3 (C-13), 48.6 (C-17), 50.0 (CH),
5
6.1 (CH), 71.7 (C-3), 121.2 (C-6), 124.3 (C-1″), 127.3 (2C, C-2″ and C-6″), 129.4 (2C, C-3″
+
and C-5″), 140.9 and 141.2: C-5 and C-4″, 167.9 (C-3′), 180.7 (C-5′); ESI-MS 433 [M+H] ;
Anal. Calcd. for C H N O C 77.74; H 8.39. Found C 77.86; H 8.27.
2
8
36
2
2
4
.1.4.3. 3β-Hydroxy-17β-(5′-[3′-4″-methoxyphenyl]-1′,2′,4′-oxadiazolyl)androst-5-ene (14c)
Substrate: 12c (147 mg). 14c was obtained as a white solid (128 mg, 95%), mp 155−158 °C,
1
R
f
= 0.45 (ss C); H NMR (CDCl
3
, 500 MHz):
δ
H
0.64 (s, 3H, 18-H
3
), 1.00 (s, 3H, 19-H
3
),
1
2
3
.03 (m, 1H), 1.10 (m, 1H), 1.25 (m, 1H), 1.40−1.66 (overlapping m, 7H), 1.85 (m, 3H),
.03−2.45 (overlapping m, 6H), 2.92 (t, 1H, J = 9.5 Hz, 17-H), 3.53 (m, 1H, 3-H), 3.85 (s,
H, 4″-OMe), 5.36 (m, 1H, 6-H), 6.97 (d, 2H, J = 8.5 Hz, 3″-H and 5″-H), 8.02 (d, 2H, J =
2
7