Synthesis and biological activity of some 17a-substituted homolactones of androst-5-ene derivatives

Article abstract of DOI:10.1135/cccc20051387

Some new 17a-homolactones were prepared from 3β-hydroxy-16- (hydroxyimino)androst-5-en-17-one (1) as a starting compound, which was transformed first to the corresponding 17α-phenyl and 17α-benzyl derivatives 2 and 3. The structure of compound 3 was confi

Full text of DOI:10.1135/cccc20051387

Homolactones of Androst-5-ene Derivatives
1387
SYNTHESIS AND BIOLOGICAL ACTIVITY OF SOME 17a-SUBSTITUTED
HOMOLACTONES OF ANDROST-5-ENE DERIVATIVES
a3
Katarina M. PENOV GAŠIa1,*, Srdjan Z. STOJANOVIĆa2, Marija N. SAKAČ
,
a6
Evgenija A. DJURENDIĆa4, János J. CSANÁDIa5, Dora MOLNAR-GABOR
,
b
c
Dušan LAZAR and Radmila M. KOVAČEVIĆ
a
Department of Chemistry, Faculty of Sciences, University of Novi Sad, Trg Dositeja Obradovića 3,
1
2
21000 Novi Sad, Serbia and Montenegro; e-mail: sazvon@eunet.yu, djena@ih.ns.ac.yu,
3 lmg@eunet.yu, 4 srks17@eunet.yu, 5 jcanadi@ih.ns.ac.yu, 6 dora.molnar-gabo@sanofi-synthelabo.com
Department of Physics, Faculty of Sciences, University of Novi Sad, Trg Dositeja Obradovića 4,
21000 Novi Sad, Serbia and Montenegro; e-mail: dlazar@im.ns.ac.yu
Department of Biology, Faculty of Sciences, University of Novi Sad, Trg Dositeja Obradovića 2,
21000 Novi Sad, Serbia and Montenegro; e-mail: radmilak@ib.ns.ac.yu
b
c
Received February 16, 2005
Accepted May 30, 2005
Som e n ew 17a-h om olacton es were prepared from 3β-h ydroxy-16-(h ydroxyim in o)an drost-
5-en -17-on e (1) as a startin g com poun d, wh ich was tran sform ed first to th e correspon din g
17α-ph en yl an d 17α-ben zyl derivatives 2 an d 3. Th e structure of com poun d 3 was con -
firm ed by X-ray structure an alysis. Beckm an n fragm en tation of com poun ds 2 an d 3 yielded
16,17-seco-cyan o keton es 4–7, wh ose reduction with NaBH4 gave 16,17-seco-cyan o alcoh ols
8–11, wh ereby th e structure of com poun d 7 was establish ed by X-ray structural an alysis.
Com poun ds 8–11 served as th e startin g com poun ds for obtain in g lacton es 12 an d 13 in a
reaction with potassium h ydroxide in eth ylen e glycol. On e-pot procedures were also devel-
oped for preparin g 17a-h om olacton es 12, 13 an d 16 from th e h ydroxyim in o alcoh ols 2, 3
an d 14. Com poun ds 12 an d 13 sh owed an in h ibitory activity again st th e en zym e arom atase
(63 an d 59%, respectively).
Keyw ord s: Steroids; D-h om oan drosten e derivatives; Steroidal lacton es; Arom atase in h ibitors;
X-ray an alysis; Oxim es; D-rin g cleavage.
Com poun ds th at in h ibit en zym e arom atase h ave poten tial application s in
th e treatm en t of advan ced estrogen -depen den t tum ors such as breast can -
cer, en dom etrial can cer, prostatic h yperplasia, an d prostate can cer1,2
.
Poten t arom atase in h ibitors are m ain ly A- an d B-m odified steroids. In our
previous papers3–5 we reported th e syn th esis of several groups of
D-m odified steroids as arom atase in h ibitors. Kin etic an alysis for an ti-
arom atase activity sh owed th at certain 16,17-seco keton es an d 17a-h om o-
lacton es expressed a h igh in h ibition (IC50 values were 0.42–16.84 µM for
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doi:10.1135/cccc20051387

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Penov Gaši et al.:
D-seco keton es an d 0.25–0.70 µM for D-h om olacton es). In h ibition poten cy
for 3β-h ydroxy-17aα-m eth yl-17-oxa-17a-h om oan drost-5-en -16-on e (IC50
0.25 µM) was th e h igh est com pared with th e oth er 17a-lacton es5, an d it was
twice lower in com parison with th e activity of am in ogluteth im ide5 (IC50
0.14 µM).
In view of th e previously establish ed fact th at th e presen ce of 17aα-
m eth yl group in th e 17a-h om olacton e system in th e an drosten e series h ad
a favorable effect on an ti-arom atase activity4, in th is work we syn th esized
th e correspon din g 17aα-ph en yl- an d 17aα-ben zyl-17a-h om olacton es of
an drost-5-en e with th e aim to exam in e th e effect of th e ph en yl an d ben zyl
groups on th e an ti-arom atase activity of th ese com poun ds.
EXPERIMENTAL
Meltin g poin ts were determ in ed usin g a Büch i SMP 20 apparatus an d are un corrected. IR
spectra (waven um bers in cm –1) were recorded in KBr pellets or as film on a NEXUS 670
SP–IR spectrom eter. NMR spectra were taken on a Bruker AC 250 spectrom eter operatin g at
250 (1H) an d 62.9 (13C) MHz with tetram eth ylsilan e as th e in tern al stan dard. Ch em ical
sh ifts are given in ppm (δ-scale); couplin g con stan ts (J) are given in Hz. All reagen ts used
were of an alytical grade. All solution s were dried with an h ydrous Na2SO4.
17-Ben zyl-3β-h ydroxy-17-oxo-16,17-secoan drost-5-en e-16-n itrile (6)
17α-Ben zyl-16-(h ydroxyim in o)an drost-5-en e-3β,17β-diol (3; 0.50 g, 1.22 m m ol) was dis-
solved in eth an ol (75 m l), a con cen trated HCl–eth an ol m ixture (1:1, 15 m l) was added, an d
th en an aqueous solution of titan ium (III) ch loride (15%; 4.5 m l, 4.8 m m ol). Th e reaction
m ixture was refluxed for 10 m in . Th en th e reaction m ixture was poured in to water (200 m l),
n eutralized with saturated solution of NaHCO3 an d extracted with dich lorom eth an e (4 ×
100 m l). Th e extract was dried an d th e solven t evaporated, an d crude product 6 (0.38 g) was
obtain ed. Ch rom atograph ic purification on a silica gel colum n (40 g, h exan e–EtOAc 9:1)
gave com poun d 6 (0.345 g, 72%) in th e form of ligh t-yellow oil.
Gen eral Procedure for Preparation of Diols 8–11 from 4–7
Com poun ds 4–7 (0.8 m m ol) were dissolved in m eth an ol (10 m l), sodium boroh ydride
(61 m g, 1.6 m m ol) was added, an d th e reaction m ixture was refluxed for 10 m in (com -
poun ds 4 an d 5), or 30 m in (com poun d 6), or for 45 m in (com poun d 7). After coolin g, th e
reaction m ixture was poured in to ice water (10 m l). Th e separated precipitates of crude 8–11
were collected an d dried. Th e crude products were purified by colum n ch rom atograph y on
silica gel (CH2Cl2–m eth an ol 100:1 for 8, 10 an d 11 an d CH2Cl2 for 9).
(17R)-3β,17-Dihydroxy-17-phenyl-16,17-secoandrost-5-ene-16-nitrile (8). Wh ite crystals (75%,
m .p. 187 °C after crystallization from MeOH). IR: 3700–3150, 2240, 1080, 1060, 1020, 710.
1H NMR (DMSO-d6): 0.76 s, 3 H (H-18); 0.89 s, 3 H (H-19); 3.26 m , 1 H (H-3); 4.55 d, 1 H,
J = 3.9 (H-17); 4.62 d, 1 H, J = 4.6 (OH-3); 5.30 m , 1 H (H-6); 5.34 d, 1 H, J = 3.9 (OH-17);
7.20–7.30 m , 5 H (Ph ). 13C NMR (DMSO-d6): 14.8, 17.0 (C-18); 19.0 (C-19); 19.2, 30.7, 31.3,
31.7, 32.4, 36.3, 36.5, 41.7, 41.8, 48.6, 69.9 (C-3); 76.8 (C-17); 119.8 (CN); 120.7, 126.6
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Homolactones of Androst-5-ene Derivatives
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(C-4′, Ph ); 127.0 an d 128.3 (C-2′, C-3′, C-5′, C-6′, Ph ); 140.9 (C-1′, Ph ); 142.4 (C-5). For
C
25H33NO2·0.5H2O (388.5) calculated: 77.28% C, 8.82% H; foun d: 77.47% C, 8.51% H.
(17R)-3β-Acetoxy-17-hydroxy-17-phenyl-16,17-secoandrost-5-ene-16-nitrile (9). Wh ite crystals
(82%, m .p. 204 °C after crystallization from MeOH). IR: 3700–3120, 2240, 1730, 1240, 1040,
700. 1H NMR (aceton e-d6): 0.93 s, 3 H (H-19); 1.02 s, 3 H (H-18); 2.04 s, 3 H (CH3, Ac);
4.39 d, 1 H, J = 3.6 (H-17); 4.51 m , 1 H (H-3); 4.72 d, 1 H, J = 3.6 (OH-17); 5.42 m , 1 H
(H-6); 7.23–7.40 m , 5 H (Ph ). 13C NMR (aceton e-d6): 16.8, 18.6, 19.5, 20.2 (CH3, Ac); 27.4,
31.2, 31.9, 32.5, 36.4, 36.6, 37.6, 40.6, 42.2, 49.0, 73.2 an d 78.2 (C-3, C-17); 119.8 (CN);
121.5, 126.8 (C-4′, Ph ); 127.1 (C-3′, C-5′, Ph ); 128.2 (C-2′, C-6′, Ph ); 139.5 (C-1′, Ph ); 142.1
(C-5); 169.4 (CO, Ac). For C27H35NO3·0.25H2O (426.1) calculated: 76.11% C, 8.40% H;
foun d: 76.02% C, 8.37% H.
(17S)-17-Benzyl-3β,17-dihydroxy-16,17-secoandrost-5-ene-16-nitrile (10). Colorless oil (83%).
IR: 3700–3150, 2250, 1070, 1040, 720. 1H NMR (CDCl3): 1.05 s, 3 H (H-19); 1.11 s, 3 H
(H-18); 2.50 dd, 1 H, Jgem = 12.5, J17,Ha = 9.0 (Ha, CH2Ph ); 2.91 d, 1 H, Jgem = 12.5 (Hb,
CH2Ph ); 3.54 m , 1 H (H-3); 3.59 d, 1 H, J17,Ha = 9.0 (H-17); 5.38 m , 1 H (H-6); 7.20–7.38 m ,
5 H (ArH). 13C NMR (DMSO-d6): 14.8, 17.5 (C-18); 19.2 (C-19); 20.1, 31.5, 32.0, 32.1, 33.2,
36.7, 36.9, 37.9, 40.1, 41.9, 42.7, 49.0, 71.6 (C-3); 78.0 (C-17); 119.8 (CN); 120.6, 126.8
(C-4′, Bn ); 128.9 (C-3′, C-5′, Bn ); 129.3 (C-2′, C-6′, Bn ); 139.1 (C-1′, Bn ); 140.4 (C-5).
(17S)-3β-Acetoxy-17-benzyl-17-hydroxy-16,17-secoandrost-5-ene-16-nitrile (11). Colorless oil
(90%). IR: 3600–3300, 2230, 1720, 1245, 1030, 730, 690. 1H NMR (CDCl3): 1.06 s, 3 H
(H-19); 1.11 s, 3 H (H-18); 2.04 s, 3 H (CH3, Ac); 2.50 dd, 1 H, Jgem = 12.5, J17,Ha = 9.0 (Ha,
CH2Ph ); 2.91 d, 1 H, Jgem = 12.5 (Hb, CH2Ph ); 3.59 d, 1 H, J17,Ha = 9.0 (H-17); 4.61 m , 1 H
(H-3); 5.39 m , 1 H (H-6); 7.20–7.39 m , 5 H (ArH). 13C NMR (DMSO-d6): 14.7, 17.5, 19.1,
20.0, 21.4, 27.6, 31.5, 31.8, 31.9, 36.6, 36.8, 37.9, 40.1, 42.6, 48.9, 73.7, 78.0, 119.8 (CN);
121.5, 126.8, 128.9, 129.3, 139.1, 170.5 (CO, Ac).
3β-Hydroxy-17aα-ph en yl-17-oxa-17a-h om oan drost-5-en -16-on e (12)
A) Com poun d 8 (0.05 g, 0.13 m m ol) was dissolved in eth ylen e glycol (3 m l) an d KOH
(0.295 g, 5.28 m m ol) was added. Th e reaction m ixture was refluxed for 4 h an d th en poured
in to water (6 m l), acidified with HCl (1:1) to pH 1 an d extracted with CH2Cl2 (5 × 20 m l).
Th e extract was dried an d th e solven t rem oved un der reduced pressure, wh ich resulted in
crude product 12 (0.075 g) as yellow oil. Th e product was ch rom atograph ed on a silica gel
colum n (8 g, CH2Cl2–MeOH 70:1) givin g com poun d 12 (0.043 g, 77%; m .p. 216 °C after
recrystallization from CH2Cl2–h exan e 2:1) as wh ite crystals.
B) By th e sam e procedure as in A), com poun d 9 (0.05 g, 0.11 m m ol) yielded th e crude
product 12 (0.062 g) in th e form of yellow oil. Colum n ch rom atograph y on silica gel (7 g,
ben zen e–EtOAc 5:1), afforded com poun d 12 (0.043 g, 91%) as wh ite crystals. IR: 3700–3100,
1730, 1230, 1190, 1030, 760, 700. 1H NMR (CDCl3): 0.97 s, 3 H (H-19); 1.24 s, 3 H (H-18);
3.44 m , 1 H (H-3); 5.14 s, 1 H (H-17); 5.30 m , 1 H (H-6); 7.04–7.38 m , 5 H (ArH). 13C NMR
(CDCl3): 18.2, 19.3, 19.5, 30.5, 31.3, 32.3, 33.0, 34.6, 35.4, 36.4, 36.6, 37.5, 41.9, 48.1, 71.5
(C-3); 91.5 (C-17); 120.4 (C-6); 127.4 an d 128.0 (C-2′, C-3′, C-5′, C-6′, Ph ); 128.1 (C-4′);
136.8 (C-1′, Ph ); 140.5 (C-5); 171.0 (C-16). For C25H32O3 (380.5) calculated: 78.91% C,
8.48% H; foun d: 79.23% C, 8.92% H.
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Penov Gaši et al.:
17aα-Ben zyl-3β-h ydroxy-17-oxa-17a-h om oan drost-5-en -16-on e (13)
A) In th e sam e way as described in A) for obtain in g com poun d 12, com poun d 10 (0.15 g,
0.38 m m ol), KOH (0.86 g, 15.23 m m ol) an d eth ylen e glycol (8 m l) gave a crude product 13
(0.16 g) as yellow oil. Th e product was ch rom atograph ed on a silica gel colum n (16 g,
CH2Cl2–MeOH 100:1), givin g com poun d 13 (0.12 g, 78%; m .p. 190 °C after recrystallization
from CH2Cl2–h exan e 1:1) as wh ite crystals.
B) In th e sam e way as described in A) for obtain in g com poun d 12, com poun d 11 (0.10 g,
0.23 m m ol), KOH (0.52 g, 9.20 m m ol) an d eth ylen e glycol (4 m l) gave a crude product 13
(0.14 g) as yellow oil. Th e product was ch rom atograph ed on a silica gel colum n (14 g,
CH2Cl2–MeOH 100:1), givin g com poun d 13 (0.08 g, 81%) as wh ite crystals. IR: 3440, 1710,
1240, 1200, 1060, 1010, 750, 700. 1H NMR (DMSO-d6): 0.95 s, 3 H (H-18); 0.98 s, 3 H
(H-19); 2.77 dd, 1 H, Jgem = 16.0, J17,Ha = 11.4 (Ha, CH2Ph ); 3.04 d, 1 H, Jgem = 16.0 (Hb,
CH2Ph ); 3.26 m , 1 H (H-3); 4.20 d, 1 H, J17,Ha = 11.4 (H-17); 4.64 d, 1 H, J = 4.3 (OH);
5.28 m , 1 H (H-6); 7.20–7.32 m , 5 H (ArH). 13C NMR (DMSO-d6): 17.2, 19.1, 19.5, 29.9, 31.3,
31.5, 32.5, 32.9, 34.6, 36.2, 36.3, 36.6, 38.3, 42.0, 48.3, 70.0 (C-3); 89.0 (C-17a); 120.0 (C-6);
126.0 (C-4′, Ph ); 128.1 (C-3′, C-5′, Ph ); 129.4 (C-2′, C-6′, Ph ); 138.7 (C-1′, Ph ); 140.9 (C-5);
170.2 (C-16). For C26H34O3·0.5H2O (403.6) calculated: 77.38% C, 8.74% H; foun d: 77.68% C,
8.28% H.
Gen eral Procedure for Preparation of 17a-Hom o Derivatives 12, 13 an d 16–19
from 2, 3, 14, an d 15
Oxim es 2, 3, 14, or 15 (1 m m ol) were dissolved in eth ylen e glycol (10 m l) an d KOH (35–
40 m m ol) was added. Th e reaction m ixture was vigorously stirred at reflux. Wh en th e reac-
tion was com pleted (3 h for 15, 4 h for 2 an d 3, 72 h for 14) th e m ixture was diluted with
water (200 m l), acidified with 2 M HCl to pH 1 an d extracted with CH2Cl2. Th e organ ic
ph ase was dried an d th e solven t was rem oved un der reduced pressure. Th e obtain ed m ixture
was separated by silica gel colum n (for 12 ben zen e–AcOEt 5:1; for 13, 16, 18, an d 19
CH2Cl2–MeOH 99:1; for 17 toluen e–AcOEt 2:1).
3β-Hydroxy-17aα-phenyl-17-oxa-17a-homoandrost-5-en-16-one (12). Wh ite crystals (68%,
m .p. 216 °C after recrystallization from CH2Cl2–h exan e 2:1).
17aα-Benzyl-3β-hydroxy-17-oxa-17a-homoandrost-5-en-16-one (13). Wh ite crystals (16.5%,
m .p. 190 °C after recrystallization from CH2Cl2–h exan e 1:1).
3β-Hydroxy-17aα-methyl-17-oxa-17a-homoandrost-5-en-16-one (16). Wh ite crystals (42%,
m .p. 169 °C after recrystallization from CH2Cl2–h exan e 2:1; lit.5 m .p. 169 °C).
3β-Hydroxy-17-oxa-17a-homoandrost-5-en-16-one (17). Wh ite crystals (62%, m .p. 206–207 °C
after recrystallization from CH2Cl2–h exan e 1:1; lit.6 m .p. 206–207 °C).
16-Amino-3β-hydroxy-17-phenyl-17a-homoandrosta-5,16-dien-17a-one (18). Wh ite crystals
(80%, m .p. 317–318 °C after recrystallization from MeOH; lit.4 m .p. 317–318 °C).
16-Amino-3β-hydroxy-17a-homoandrosta-5,16-dien-17a-one (19). Wh ite crystals (31%, m .p.
248–250 °C after recrystallization from MeOH; lit.4 m .p. 248–250 °C).
X-ray Crystal Studies of 3 an d 7
Diffraction data (Table I) for com poun ds 3 an d 7 were collected on an En raf–Non ius CAD-4
an d CCD Bruker Sm art Apex diffractom eter at 293 an d 110 K, respectively, usin g MoKα radi-
ation (λ = 0.71073 Å). Both structures were solved by direct m eth ods (SHELXS97 7) an d re-
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Homolactones of Androst-5-ene Derivatives
1391
fin ed by full-m atrix least-squares procedures (SHELXL97 7). Non -h ydrogen atom s were re-
fin ed an isotropically. Th e H atom s were gen erated an d refin ed as ridin g, with isotropic dis-
placem en t fixed at 1.2Ueq or 1.3Ueq of paren t atom s, or 1.5Ueq for th e m eth yl-H atom s.
Loren tz an d polarization correction s were applied to th e data. No absorption correction was
m ade.
CCDC 263771 (for 3) an d 263772 (for 7) con tain th e supplem en tary crystallograph ic data
for th is paper. Th ese data can be obtain ed free of ch arge via www.ccdc.cam .ac.uk/con ts/
retrievin g.h tm l (or from th e Cam bridge Crystallograph ic Data Cen tre, 12, Un ion Road,
Cam bridge, CB2 1EZ, UK; fax: +44 1223 336033; or deposit@ccdc.cam .ac.uk).
TABLE I
Crystallograph ic data, data collection an d structure refin em en t for com poun ds 3 an d 7
Param eter
Com poun d 3
Com poun d 7
Form ula
C
26H35NO3
C28H35NO3
433.6
Mw
409.5
Crystal size, m m 3
Crystal description
Crystal system , space group
a, Å; α, °
0.08 × 0.14 × 0.20
colorless prism
orth orh om bic, P212121
7.629(1); 90
12.854(1); 90
23.001(2); 90
2255.6(4); 4
1.206
0.07 × 0.18 × 0.22
colorless prism
m on oclin ic, P21
11.477(4); 90
5.916(2); 105.14(3)
17.783(9); 90
1165.5(8); 2
1.235
b, Å; β, °
c, Å; γ, °
V, Å3; Z
Dc, g cm –3
F(000); µ(MoKα), m m –1
θ ran ge, °; data com pleten ess, %
Ran ge of h,k,l
888; 0.078
1.81–25.23; 97.7
0/9, 0/15, 0/27
2289
468; 0.079
1.19–23.26; 99.9
–12/12, –6/6, –19/19
3350
No. of un ique diffraction s
No. of observed diffraction sa
No. of param eters
1665
2759
277
292
R, wR for observed diffraction s, % 3.83, 5.91
3.47, 7.32
R, wR for all data, %
GOF for all data
6.25, 6.19
1.203
4.83, 9.34
0.981
(∆/σ)m ax
0.000
0.000
Residual electron den sity, e Å–3
–0.127, 0.113
–0.154, 0.122
a
Diffraction s with Fo > 2σ(Fo).
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Penov Gaši et al.:
Biological Tests
Chemicals. An tiestradiol serum No. 244 was kin dly supplied by Dr. G. D. Niswen der
(Colorado State Un iversity (CO), U.S.A.), pregn an t m ares serum gon adotroph in (PMSG) was
obtain ed from th e Veterin ary In stitute Subotica (Serbia an d Mon ten egro), [1,2,6,7-3H(N)]-
estradiol from New En glan d Nuclear (Belgium ), NADPH from Sigm a (St. Louis (MO), U.S.A.).
Animals, treatments, and assays. Preparation of den ucleated ovarian fraction from PMSG
pretreated rats an d determ in ation of arom atase activity in ovarian h om ogen ate was carried
out as described previously3,4
.
For prelim in ary assessm en t of poten tial an tiarom atase activity, th e syn th esized com -
poun ds were added in two con cen tration s (1 an d 20 µM) to th e in cubation m ixture con tain -
in g 500 n M testosteron e as a substrate (saturated con cen tration ; th e estim ated Km for testos-
teron e was 49 n M an d Vm ax 5.76 pm ol/m in /m g protein ).
Purified den ucleated fraction of ovaries from PMSG pretreated fem ale rats (≈0.2 m g pro-
tein /tube) was in cubated at 37 °C for 15 m in in th e presen ce of saturated (500 n M) con cen -
tration of testosteron e an d NADPH (1 m M) in th e absen ce (con trol) or presen ce of th e two
con cen tration s (1 an d 20 µM) of com poun ds 12, 13, 16, 17. Each con cen tration was tested
in 5 replicates. Th e estradiol level was determ in ed by RIA.
RESULTS AND DISCUSSION
In our previous works3,4 we syn th esized 17α-ph en yl3 (2) an d 17α-ben zyl4 (3)
derivatives of an drost-5-en e by addin g ph en yl- or ben zyllith ium with th e
17-oxo group of 3β-h ydroxy-16-(h ydroxyim in o)an drost-5-en -17-on e (1)
(Sch em e 1).
Th e Beckm an n fragm en tation of com poun d 2 with titan ium (III) ch loride,
tosyl ch loride or acetic an h ydride yielded th e seco-cyan o keton es 4 an d
5
3,8, wh ile th e fragm en tation of th e h ydroxyim in o alcoh ol 3 with acetic
an h ydride in pyridin e gave product 7, wh ose h ydrolysis produced com -
poun d 6 in an overall yield of 62% 4. In th e presen t work we ach ieved a
better yield of com poun d 6 (72%) by m odifyin g th e fragm en tation proce-
dure usin g TiCl3 in eth an ol. Th e reaction was perform ed at th e boilin g tem -
perature of th e reaction m ixture for 10 m in , an d n ot at room tem perature,
wh en com poun d 6 was obtain ed in a yield of 23% 9.
X-ray structure an alysis con firm ed th e structure of com poun d 3 an d
α-orien tation of th e 17-ben zyl group (Fig. 1). Also, th e structure of th e
seco-cyan o keton e 7 was un am biguously proved by X-ray structure an alysis,
a perspective view of th e m olecule bein g presen ted. Th e equatorial orien ta-
tion of th e 13-ph en ylacetyl an d 14-cyan om eth yl groups, as well as th e axial
orien tation of th e 13-m eth yl group are obvious (Fig. 2).
Reduction of th e seco-cyan o keton es 4–7 with sodium boroh ydride in
MeOH yielded th e correspon din g 17-ph en yl an d 17-ben zyl seco-cyan o alco-
h ols 8–11.
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Homolactones of Androst-5-ene Derivatives
1393
Syn th esis of th e lacton es 12 an d 13 is presen ted in Sch em e 1. Com poun d
8 or its 3β-acetyl derivative 9 reacted with KOH in eth ylen e glycol an d acid-
ification of th e reaction m ixture yielded lacton e 12. In th e case of com -
poun d 9, a sim ultan eous h ydrolysis of th e 3β-acetoxy group took place.
Sim ilarly, lacton e 13 was obtain ed from th e cyan o alcoh ols 10 an d 11.
Con figuration at th e C-17 atom of lacton e 12 was establish ed by NOE ex-
perim en t, n am ely, by irradiatin g th e sign al of th e an gular C-18 m eth yl
group at 1.24 ppm . Th e NOE effect appeared on th e sin glet at 5.14 ppm , be-
lon gin g to th e H-17 atom , wh ich con firm ed th at th ey are on th e sam e side
(β-orien tation ) of th e m olecule. Sim ilarly, in th e case of lacton e 13, th e irra-
diation of th e proton of th e an gular C-18 m eth yl group at 0.95 ppm pro-
duced th e NOE effect of th e doublet at 4.20 ppm belon gin g to th e H-17
OH
O
R
NOH
NOH
(i) or (ii)
2, R=C6H5
HO
HO
1
3, R=CH2C6H5
(iii), (iv) or (v)
O
OH
H
R2
R2
CN
(vi)
CN
R1O
R1O
8, R1=H, R2=C6H5
9, R1=Ac, R2=C6H5
4, R1=H, R2=C6H5
5, R1=Ac, R2=C6H5
10, R1=H, R2=CH2C6H5
11, R1=Ac, R2=CH2C6H5
6, R1=H, R2=CH2C6H5
7, R1=Ac, R2=CH2C6H5
(vii)
H
R
O
O
HO
12, R=C6H5
13, R=CH2C6H5
(i) PhLi, ether, THF, –10 oC; (ii) BnLi, THF, –10 oC; (iii) TsCl, Py, r.t.; (iv) Ac2O, Py, reflux;
(v) TiCl3, HCl, H2O, EtOH, reflux; (vi) NaBH4, MeOH, reflux; (vii) KOH, HOCH2CH2OH, reflux
SCHEME 1
Collect. Czech. Chem. Commun. (Vol. 70) (2005)

1394
Penov Gaši et al.:
atom , wh ich con firm ed th eir β-orien tation . From th ese results it was possi-
ble to establish th e con figuration at C-17 in seco-cyan o alcoh ols 8–11, as R
for com poun ds 8 an d 9, an d S for com poun ds 10 an d 11 (Sch em e 1). Here
described stereoch em ical route of th e sodium boroh ydride reduction is in
agreem en t with our recen tly publish ed results related to reduction of a sim -
ilar 17-oxo com poun d in th e estron e series10.
In our previous work6 a procedure was developed for preparin g lacton e
17 directly from h ydroxyim in o alcoh ol 15 by h eatin g with KOH solution in
eth ylen e glycol (Sch em e 2). Applyin g th e sam e reaction con dition s, in th is
work we obtain ed lacton es 12, 13 an d 16 directly from com poun ds 2, 3 an d
14, wh ereby th e previously described preparation procedure was sh orten ed
FIG. 1
Perspective view of th e m olecular structure of com poun d 3
FIG. 2
Perspective view of th e m olecular structure of com poun d 7
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Homolactones of Androst-5-ene Derivatives
1395
by two steps. Lacton e 16 was obtain ed previously3,5 from com poun d 14 in
th ree reaction steps, in overall yield of 39%.
By an alyzin g th e reaction of th e h ydroxyim in o alcoh ols 2, 3, 14 an d 15
with KOH in eth ylen e glycol it can be seen th at in th e case of 17-ben zyl
an d 17-m eth yl derivatives of 3 an d 14, in addition to th e lacton es 13 an d 16,
4
4
16-am in o-17a-h om o derivatives 18 an d 19 are also obtain ed (Sch em e 2).
Th e sam e reaction carried out with 17α-ph en yl h ydroxyim in o alcoh ol 2 or
17α-un substituted alcoh ol 15 sh owed n o form ation of th e correspon din g
16-am in o-17a-h om o derivatives; in stead, D-lacton es 12 an d 17 were form ed.
H
O
OH
R
O
R
R
NOH
(i)
+
O
NH2
HO
HO
HO
12, 13, 16, 17
2, 3, 14, 15
18, 19
In formulae
2, 12, R = C6H5; 3, 13, 18, R = CH2C6H5; 14, 16, 19, R = CH3; 15, 17, R = H
(i) KOH, HOCH2CH2OH, reflux
SCHEME 2
Th e obtain ed results in dicate th at th e n ature of th e C-17 substituen t in
com poun ds 2, 3, 14 an d 15 govern s th e form ation of 16-am in o-17a-h om o
derivatives an d/or D-lacton es. If th e α-h ydrogen atom s are presen t in th e
C-17 substituen t (CH2C6H5, CH3), 16-am in o-17a-h om o derivatives are
form ed in a m ixture with D-lacton es, wh ich are solely form ed if th e m en -
tion ed h ydrogen atom s are n ot presen t. On th e oth er h an d, by ch oosin g
th e base, solven t an d reaction con dition s it is possible to favor th e form a-
tion of lacton es or 16-am in o-17a-h om o derivatives. Th ese results are in
agreem en t with th e m ech an ism of form ation of 16-am in o-17a-h om o deriv-
atives described in th e previous paper5 as well as with th e m ech an ism of
lacton ization of h ydroxyim in o alcoh ols of th e estran e series11.
Biological Properties
In th is study we tested lacton es 12 an d 13 for th e poten tial an ti-arom atase
activity in th e den ucleated ovarion fraction from PMSG-pretreated fem ale
rats. In order to exam in e th e effect of th e 17aα substituen ts in th is type of
17a-h om olacton es we com pared th e in h ibitory effects of th e lacton es 12,
13, 16, an d 17. Com poun ds were tested at differen t con cen tration as
sh own in Table II.
Collect. Czech. Chem. Commun. (Vol. 70) (2005)

1396
Penov Gaši et al.:
It can be con cluded th at ph en yl (in 12) an d ben zyl (in 13) groups at th e
17aα position in creased on ly a little th e in h ibitory activity (63 an d 59%, re-
spectively) again st arom atase com pared with th e 17aα-un substituted deriv-
ative 17 (49.2% of in h ibition ), observed at th e substrate con cen tration of
1 µM. However, th e m eth yl group (com poun d 16) in creased sign ifican tly
th e in h ibitory activity (89%).
TABLE II
In h ibitory effects of an drost-5-en e derivatives 12, 13, 16, an d 17 on th e arom atase activity
in th e den ucleated fraction of ovaries from PMSG pretreated rats
In h ibition , %
In h ibitor, con c.
µM
12
13
16
17
20
1
95.6 ± 4.4
62.8 ± 8.6
93.6 ± 4.5
95.9 ± 3.2
88.7 ± 3.9
99.0 ± 1.0
49.2 ± 4.2
58.7 ± 10.0
This research was supported by the Ministry of Science and Environmental Protection of the
Republic of Serbia (Grant No. 1896).
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