Synthesis and study of equilenin derivatives and modified analogs

Article abstract of DOI:10.1023/B:RUJO.0000036071.26335.eb

Modified equilenin analogs were synthesized with a view to examine the relation between the structure and biological properties of steroid estrogens. The ¹H and ¹³C NMR signals of six estra-1,3,5,7,9- pentaenes were completely assigned using homo- and heteronuclear correlation NMR spectroscopy. The structure of equilenin methyl ester was determined by X-ray analysis. Among the synthesized steroids, compounds were found which exhibit hypocholesterinemic activity with no uterotropic and hypertriglyceridemic effects.

Full text of DOI:10.1023/B:RUJO.0000036071.26335.eb

Russian Journal of Organic Chemistry, Vol. 40, No. 4, 2004, pp. 506–512. Translated from Zhurnal Organicheskoi Khimii, Vol. 40, No. 4, 2004,
pp. 537–543.
Original Russian Text Copyright © 2004 by Urusova, Gluzdikov, Selivanov, Starova, Nikolaev, Shavva.
Synthesis and Study of Equilenin Derivatives
and Modified Analogs
E. A. Urusova, I. A. Gluzdikov, S. I. Selivanov, G. L. Starova,
S. V. Nikolaev, and A. G. Shavva
St. Petersburg State University, Universitetskii pr. 26, St. Petersburg, 198504 Russia
Received July 17, 2003
Abstract—Modified equilenin analogs were synthesized with a view to examine the relation between the
1
structure and biological properties of steroid estrogens. The H and 13C NMR signals of six estra-1,3,5,7,9-
pentaenes were completely assigned using homo- and heteronuclear correlation NMR spectroscopy. The
structure of equilenin methyl ester was determined by X-ray analysis. Among the synthesized steroids,
compounds were found which exhibit hypocholesterinemic activity with no uterotropic and hypertri-
glyceridemic effects.
Analogs of steroid estrogens possessing hypo-
cholesterinemic activity attract interest from the view-
point of developing on their base of preparations for
treatment and prophylactics of cardiovascular diseases
[1]. A necessary conditions for preliminary selection
of new compounds for detailed biological studies is
the lack of both uterotropic effect (which is considered
to be a factor favoring carcinogenesis [2]) and the
ability to increase the concentration of triglycerides
in blood [3–6].
As model compounds for study of the relations
between the structure and biological properties of
steroid estrogens we selected analogs of equilenin,
taking into account that the latter exhibits no carcino-
genic properties [7]. Moreover, equilenin has been
proposed to use for prophylactics of mammary gland
carcinoma [8]. We have synthesized racemic steroids,
keeping in mind that modified estrogens of the L-series
are specific estrogen receptor modulators [9–11] and
that they may attract a stronger interest from the
viewpoint of medicine.
The simplest route to modified equilenin analogs
consists of reduction with Raney nickel of estrapenta-
enes prepared according to Torgov–Ananchenko
[12, 13]. The choice of modification, i.e., introduction
of substituents into positions 2 and 4 and/or ring D
expansion, was dictated by the fact that just in these
cases we can expect reduced hormonal action of
steroids having a topology related to the natural
hormone estradiol [14, 15]. Scheme 1 illustrates the
synthesis of model compounds.
Using homo- and heteronuclear correlation tech-
niques (DQF-COSY [16], HSQC [17], COLOC [18],
and NOESY [19]), we performed a detailed analysis
of scalar and direct (through space) dipole–dipole
1
interactions in the H and 13C NMR spectra of six
equilenin analogs. No extensive studies in this line
were performed previously (as far as we know, com-
plete assignment of the 13C NMR signals of two
equilenin derivatives has been reported only in
a single publication [20]). The results of signal assign-
ment are given in Tables 1 and 2.
Also, we have found no published data on X-ray
diffraction studies of equilenin derivatives. Therefore,
we tried to fill this gap by examining the crystalline
structure of racemic equilenin methyl ester X. The
structure was solved by the direct method and was
refined with account taken of anisotropy of thermal
vibrations of non-hydrogen atoms. The positions of
hydrogen atoms were calculated from the geometry
considerations. No absorption by the sample was taken
into account. The calculations were performed using
CSD [21] and SHELXL 97 software packages [22].
Table 3 contains the coordinates and thermal
parameters of the basis atoms in molecule X. The A
and B rings are planar. The methoxy carbon atom is
located trans with respect to the C2–C3 bond. The
oxygen atom at C3 lies almost in the A ring plane, and
the methyl carbon atom deviates from that plane by
only –0.18 Å. The angle between the A and B ring
planes is 2.0°. The C ring is a regular 13β-half-chair
where the angle between the planes formed by the
1070-4280/04/4004-0506 © 2004 MAIK “Nauka/Interperiodica”

SYNTHESIS AND STUDY OF EQUILENIN DERIVATIVES
507
Scheme 1.
OAc
OAc
( )n
( )n
Raney Ni, dioxane
H
MeO
MeO
Ia, Ib
IIa, IIb
OAc
( )n
OAc
( )n
(1) NaBH4
(2) Ac2O, pyridine
Cl2CHOMe, AlCl3
H
H
MeO
MeO
CHO
IIIa, IIIb
CH2OAc
IVa, IVb
O
OAc
( )n
(1) NaBH4
(2) Ac2O, pyridine
( )n
R
R
MeO
MeO
R'
R'
Va–Vc
VIa–VIc
OAc
( )n
O
(1) NaOH, MeOH
(2) CrO3, pyridine
( )n
Raney Ni, dioxane
R
R
H
H
MeO
MeO
R'
R'
VIIa–VIIc
VIIIa–VIIIc
O
O
(1) AcOH/HBr
(2) Ac2O, pyridine
Me
H
H
AcO
MeO
IX
X
I–IV: n = 1 (a), 2 (b); V–VIII: R = Me, R' = H, n = 1 (a); R = Me, R' = H, n = 2 (b); R = H, R' = Me, n = 1 (c).
C8C9C11C12C14 atoms (chair-bottom) and C12C13C14
(chair hack) is 127.5°. The D ring is an almost regular
14α-envelope where the angle between the
C13C15C16C17 (base) and C13C14C15 (flap) planes is
138.7°. On the whole, the molecule is essentially
planar: the aromatic ring with the chair-bottom plane
in the C ring forms an angle of 4.3°, and with the
envelope base plane in the D ring, 9.0°. The distance
between the oxygen atoms at C3 and C17 (which is
important for binding with estrogen receptors) is
10.802(5) Å. The corresponding distance in the mole-
cule of estradiol, which is the most active natural
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 40 No. 4 2004

URUSOVA et al.
508
Table 1. Carbon chemical shifts (δC, ppm) in the 13C NMR
spectra of modified equilenin analogs IIa, IIb, VIIa, VIIc,
VIIIb, and X
of potential estrone sulfatase inhibitors, for equilenin
analogs turned out to be strong inhibitors of that
enzyme [25].
Carbon
atom
IIa
IIb
VIIa VIIc VIIIb
X
EXPERIMENTAL
1
2
3
4
5
6
7
8
9
124.7 125.6 124.3 122.1 124.2 125.4
118.2 118.2 128.0 113.3 128.1 118.6
156.6 156.6 155.8 153.4 156.1 156.8
106.4 106.1 105.0 119.6 104.6 106.6
133.2 132.8 131.8 132.2 131.7 131.1
125.0 124.5 124.0 121.5 124.8 125.4
125.0 124.5 124.7 124.7 124.3 124.3
133.1 132.5 133.7 132.7 131.4 133.5
130.3 130.3 129.5 130.4 129.2 130.8
All the prepared compounds were racemic. Their
purity was checked by high-performance liquid
chromatography (HPLC) on an Altex chromatograph;
gradient elution with acetonitrile–water (80 to 95%),
15 min; columns: A (Lichrosorb RP-18, 5 µm, Merck),
B (Ultrasphere ODS, 5 µm, Beckman), and C (ISCO
C-8/6.5 µm, 4.6×250 mm).
The mass spectra were recorded on an MKh-1321
spectrometer (ion source temperature 200–210°C). The
NMR spectra were obtained at 295 K on a Bruker
DPX-300 instrument at 300.130 and 75.468 MHz for
10
127.2 127.3 127.0 127.3 126.9 127.3
024.1 022.7 024.2 024.2 022.8 023.8
034.0 033.3 033.9 034.0 029.0 029.0
042.4 036.8 042.8 042.3 046.9 047.4
046.1 045.0 046.3 046.0 045.4 046.7
023.5 024.7 023.4 023.4 023.6 021.8
028.2 023.8 031.2 028.2 025.5 036.5
081.7 026.2 080.9 081.7 036.8 219.8
1
11
1H and 13C, respectively. The H NMR spectra were
measured from solutions of 5–7 mg of a substance in
0.6 ml of CDCl3, and the 13C NMR spectra were
obtained from solutions containing 30–50 mg of
a substance in the same volume of a solvent. The
chemical shifts were measured relative to TMS using
the solvent signals as internal reference (CDCl3–
CHCl3, 99.9:0.1; δ 7.26 ppm, δC 76.90 ppm; accuracy
±0.01 ppm). The homonuclear coupling constants
were determined with an accuracy of ±0.02 Hz from
12
13
14
15
16
17
17a
18
–
080.2
–
–
215.5
–
011.1 010.4 010.1 011.1 015.6 013.0
1
the H NMR spectra processed by the Lorentz–Gauss
2-CH3
4-CH3
CH3O
–
–
–
–
017.1
–
–
–
transformation.
010.6
17β-Acetoxy-3-methoxyestra-1,3,5,7,9-pentaene
(IIa). To a solution of 2 g of compound Ia [26] in
50 ml of dioxane we added 10 g of Raney nickel pre-
pared at 60°C and thoroughly washed from isopropyl
alcohol (under a layer of which it was stored). The
mixture was stirred for 8 h at 70°C, the catalyst was
filtered off, and the filtrate was evaporated on a rotary
evaporator. The product was purified by recrystal-
lization from chloroform–ethanol (1:5). Yield 1.1 g
(55%), mp 201–203°C. Retention time 8.7 min
(column A), purity > 99.5%. Found, %: C 77.97;
H 7.46. C21H24O3. Calculated, %: C 77.75; H 7.46.
055.1 055.1 055.1 056.5 055.0 055.2
CH3CO 021.0 021.1
CH3CO 171.1 170.9
–
–
021.0
171.1
–
–
–
–
estrogen, is 10.93 Å [23]. The structure of molecule X
is shown in figure. The obtained X-ray diffraction data
can be used for simulation of structures of equilenin
complexes with various receptors and enzymes
responsible for metabolism of steroids.
Oral administration of compounds IIb and VIIa in
peach oil to ovariectomated rats at a dose of 5 mg/kg
per day over a period of 35 days normalizes the
concentration of cholesterol in blood serum. Neither
IIb nor VIIa showed uterotropic or hypertriglyceri-
demic activity. Thus equilenin analogs IIb and VIIa
exhibit better biological properties than most known
compounds of this series [24]. Steroids IIIa, IIIb, IVa,
IVb, and VIIb having a substituent in position 4
showed no biological activity. Nevertheless, they may
be of interest as starting materials for the synthesis
17aβ-Acetoxy-3-methoxy-D-homoestra-1,3,5,7,9-
pentaene (IIb) was synthesized from 3.53 g of com-
pound Ib [27] as described above for steroid IIa. Yield
2.74 g (77%), mp 198–199°C. Retention time 6.7 min
(column A), purity >99.5%. Mass spectrum, m/z
(Irel, %): 338 (100) [M]+, 278 (5), 277 (4.5), 263 (12),
249 (2.5), 223 (9.5), 211 (19,5), 197 (5), 171 (9).
Found, %: C 78.09; H 7.75. C22N26O3. Calculated, %:
C 78.07; H 7.74.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 40 No. 4 2004

SYNTHESIS AND STUDY OF EQUILENIN DERIVATIVES
509
1
Table 2. Proton chemical shifts in the H NMR spectra of
estra-1,3,5,7,9-pentaenes IIa, IIb, VIIa, VIIb, VIIIa, and X
17β-Acetoxy-4-formyl-3-methoxyestra-1,3,5,7,9-
pentaene (IIIa). To a solution of 0.85 g of compound
IIa and 1.5 g of aluminum chloride in 30 ml of
nitrobenzene we added 1.3 ml of α,α-dichlorodimethyl
ether in 10 ml of nitrobenzene, and the mixture was
left to stand for 12 h in a flask capped with a drying
tube. Water, 150 ml, was added, the aqueous phase was
separated, and nitrobenzene was removed by steam
distillation. After appropriate treatment, compound
IIIa was purified by double recrystallization from
chloroform–methanol. Yield 0.45 g (49%), mp 225–
230°C. Retention time 8.4 min (column C), purity
Hydrogen
atom
IIa
IIb
VIIa VIIb VIIIa
IX
1
2
4
6
7
7.87 7.91 7.71
7.85
7.28
–
7.75
–
7.87
7.18
7.13
7.64
7.27
7.18 7.18
7.13 7.11
–
7.06
7.06
7.60
7.37
7.59 7.58 7.56
7.17 7.40 7.11
7.83
7.23
11α
11β
3.27 3.20 3.29
3.20 3.08 3.22
3.32
3.22
3.27
3.12
3.33
3.33
1
12α
1.81 1.67 1.70
2.22 2.03 2.20
1.79
2.13
1.83
2.37
1.91
2.21
>99.5%. H NMR spectrum, δ, ppm: 0.74 s (3H),
12β
2.11 s (3H), 4.04 s (3H), 4.89 m (1H), 7.28 m (2H),
8.20 d (1H), 9.12 d (1H), 10.85 s (1H). 13C NMR
spectrum, δC, ppm: 11.1, 21.0, 23.3, 24.2, 28.2, 34.0,
42.3, 46.1, 56.4, 81.5, 112.2, 116.9, 122.9, 126.9,
128.4, 130.2, 130.4, 132.4, 134.4, 170.0. Mass
spectrum, m/z (Irel, %): 352 (100), 309 (2.5), 291 (11),
277 (15), 266 (3.5), 251 (17), 199 (14), 165 (9). Found,
%: C 74.89; H 6.96. C22H24O4. Calculated, %: C 74.98;
H 6.86.
14α
2.88 2.69 2.81
2.91
2.94
3.17
15α
2.16 2.55 2.17
1.79 1.38 1.78
2.25
1.78
2.51
1.89
2.55
2.05
15β
16α
16β
2.46 1.64 2.36
1.83 2.08 1.68
2.48
1.80
1.90
2.33
2.34
2.70
17α
4.92 1.87 4.95
1.70
4.91
2.80
2.38
17β
17aα
4.75
0.77 0.87 0.71
2.41
4.74
1.05
2.44
13-CH3
2-CH3
4-CH3
CH3O
CH3CO
0.76
0.81
3.92
17aβ-Acetoxy-4-formyl-3-methoxy-D-homo-
estra-1,3,5,7,9-pentaene (IIIb) was synthesized from
1.6 g of compound IIb as described above for IIIa.
The product was purified by double recrystallization
from chloroform–methanol (5:1). Yield 1.1 g (63.5%),
2.56
3.95
2.11
3.92
2.11
3.92 3.94
2.12 2.11
3.95
1
mp 241–246°C. H NMR spectrum, δ, ppm: 0.83 s
(3H), 2.09 s (3H), 4.05 s (3H), 4.75 m (1H), 7.29 d
(1H), 7.55 d (1H), 8.27 d (1H), 9.10 d (1H), 10.86 s
(1H). 13C NMR spectrum, δC, ppm: 10.4, 21.1, 22.9,
23.6, 23.7, 26.2, 33.3, 36.6, 44.9, 56.3, 80.1, 112.1,
116.7, 122.8, 127.0, 128.0, 130.0, 130.4, 132.3, 133.7,
162.9, 170.8, 191.9. Mass spectrum, m/z (Irel, %): 366
(100), 322 (3.5), 304 (5.5), 291 (11), 277 (3.5), 251
(8.5), 239 (18), 225 (4), 199 (7), 165 (8). Found, %:
C 75.49; H 7.01. C23H26O4. Calculated, %: C 75.38;
H 7.15.
Found, %: C 72.63; H 7.26. C24H28O5. Calculated, %:
C 72.66; H 7.17.
17aβ-Acetoxy-4-acetoxymethyl-3-methoxy-D-
homoestra-1,3,5,7,9-pentaene (IVb) was synthesized
from 0.5 g of steroid IIIb as described above for IVa.
Yield 0.37 g (66%), mp 147.5–149.5°C. Retention
1
time 7.3 min (column A), purity 99%. H NMR
C12
C13
O2
17β-Acetoxy-4-acetoxymethyl-3-methoxyestra-
1,3,5,7,9-pentaene (IVa). To a solution of 0.15 g of
compound IIIa in 10 ml of a 10:1 dioxane–water
mixture we added 0.08 g of sodium tetrahydridoborate,
the mixture was stirred for 30 min, and excess
reducing agent was decomposed with acetic acid. The
mixture was diluted with 100 ml of water, and 100 ml
of diethyl ether was added. The subsequent treatment
of the mixture and acetylation of the product were
performed according to standard procedures. Recrys-
tallization from chloroform–ethanol gave 0.075 g
(44%) of compound IVa with mp 169.5–171.5°C.
C2
C1
C10
C11
C9
C17
C18
C8
O1
C3
C16
C5
C6
C14
C4
C15
C7
C3A
Structure of the molecule of equilenin methyl ether (X) in
crystal according to the X-ray diffraction data.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 40 No. 4 2004

URUSOVA et al.
510
Table 3. Coordinates (× 104) and thermal parameters
(Å2×103) of basis atoms in molecule X (Ueq is equal to 1/3
of the sum of the projections of the Uij tensor onto the
orthogonal axes)
spectrum, δ, ppm: 1.00 s (3H, C18H3), 2.12 s (3H,
CH3CO), 2.22 s (3H, 2-CH3), 3.85 s (3H, CH3O),
5.05 d.d (1H, 17-H, J1 = J2 = 8.4 Hz), 5.49 br.s (1H,
15-H), 6.66 s and 7.10 s (1H each, 2-H, 1-H). Found,
%: C 78.01; H 7.75. C22H26O3. Calculated, %: C 78.07;
H 7.74.
Atom
x
y
z
Ueq
O1
O2
C1
C2
C3
–3982(2)
–3810(2)
–4837(3)
–4819(3)
–3880(3)
–3103(1)
919(1)
–3625(1)
–7506(1)
–5025(1)
–4550(1)
–4069(1)
65(1)
91(1)
46(1)
50(1)
46(1)
17β-Acetoxy-3-methoxy-2-methylestra-1,3,5,7,9-
pentaene (VIIa). To a solution of 2 g of compound
VIa in 50 ml of dioxane we added 10 g of Raney
nickel, and the mixture was stirred for 8 h at 70°C.
After appropriate treatment, the product was recrystal-
lized from chloroform–ethanol (1:5). Yield 0.90 g,
mp 172–182°C. Retention time 11.0 min (column A),
purity 99.6%. Mass spectrum, m/z (Irel, %): 338 (100)
[M]+, 295 (4), 277 (5), 263 (19.5), 247 (4.5), 237 (14),
225 (7.5), 185 (15.5), 165 (5), 152 (2). Found, %:
C 78.01; H 7.87. C22H26O3. Calculated, %: C 78.07;
H 7.74.
–2173(2)
–2713(2)
–2493(2)
C3A
C4
C5
C6
C7
–3257(3)
–3001(3)
–3003(3)
–2144(3)
–2168(2)
–2863(2)
–1740(2)
–1161(2)
–362(2)
191(1)
–3095(1)
–4070(1)
–4560(1)
–4564(1)
–5035(1)
84(1)
45(1)
38(1)
47(1)
44(1)
C8
–3043(3)
–3914(2)
–3917(3)
–4822(3)
–4811(3)
–29(2)
–811(2)
–5530(1)
–5548(1)
–5055(1)
–6083(1)
–6592(1)
39(1)
38(1)
38(1)
49(1)
53(1)
C9
17aβ-Acetoxy-3-methoxy-2-methyl-D-homo-
estra-1,3,5(10),8,14-pentaene (VIb) was synthesized
from 4.32 g of estrapentaene Vb (prepared accord-
ing to Torgov–Ananchenko [29]) by reduction with
sodium tetrahydridoborate in dioxane–water (10:1)
and subsequent acetylation with acetic anhydride in
pyridine under the conditions recommended in [30].
Recrystallization from chloroform–ethanol (1:4) gave
2.9 g (59%) of compound VIb with mp 187–191°C.
1H NMR spectrum, δ, ppm: 1.08 s (3H, C18H3), 2.11 s
(3H, CH3CO), 2.22 s (3H, 2-H), 3.87 s (3H), 4.85 m
(1H, 17-H), 5.78 (1H, 15-H, J = 3.9 Hz), 6.69 s (1H,
4-H), 7.16 s (1H, 1-H). Found, %: C 78.58; H 7.95.
C23H28O3. Calculated, %: C 78.38; H 8.01.
C10
C11
C12
–1381(2)
–1086(1)
–420(2)
C13
C14
C15
C16
C17
C18
–3301(3)
–3123(3)
–1859(3)
–2238(3)
–3211(3)
–1878(3)
106(2)
601(1)
–6608(1)
–6034(1)
–6144(1)
–6757(1)
–7032(1)
–6743(1)
45(1)
43(1)
58(1)
63(1)
59(1)
61(1)
1301(2)
1622(2)
884(2)
–497(2)
spectrum, δ, ppm: 0.90 s (3H), 2.08 s (3H), 2.13 s
(3H), 3.96 s (3H), 4.75 m (1H), 5.67 s (2H); in
addition, signals from four protons were present in the
aromatic region. 13C NMR spectrum, δC, ppm: 10.4,
20.9, 21.1, 22.8, 23.6, 23.7, 26.2, 33.3, 45.0, 56.6,
57.2, 80.1, 112.8, 116.1, 121.1, 125.4, 126.0, 127.4,
130.7, 131.7, 132.6, 155.3, 170.8, 171.3. Mass
spectrum, m/z (Irel, %): 410 (100), 367 (5), 351 (33),
335 (2), 307 (10), 296 (4), 283 (4), 275 (2), 237 (4),
207 (3.5), 191 (3.5), 178 (4), 165 (4), 153 (5.5). Found,
%: C 73.01; H 7.47. C25H30O5. Calculated, %: C 73.15;
H 7.37.
17aβ-Acetoxy-3-methoxy-2-methyl-D-homo-
estra-1,3,5,7,9-pentaene (VIIb). Estrapentaene VIb,
1.75 g, was converted into steroid VIIb as described
above for compound Va. Recrystallization from
chloroform–ethanol (1:5) gave 1.26 g (72%) of com-
pound VIIb with mp 191.5–194°C. Mass spectrum,
m/z (Irel, %): 352 (100) [M]+, 309 (1.5), 292 (6), 277
(13), 238 (8), 237 (8), 223 (5.5), 185 (18). Found, %:
C 78.22; H 8.19. C23H28O3. Calculated, %: C 78.38;
H 8.01.
17β-Acetoxy-3-methoxy-2-methylestra-1,3,-
5(10),8,14-pentaene (VIa). A 3-g portion of 3-meth-
oxy-2-methylestra-1,3,5(10),8,14-pentaene (Va),
synthesized according to Torgov–Ananchenko [28],
was reduced with sodium tetrahydridoborate, followed
by acetylation with acetic anhydride in pyridine.
Recrystallization from methanol gave 2.65 g (76.8%)
17β-Acetoxy-3-methoxy-4-methyl-1,3,5,7,9-estra-
pentaene (VIIc). Compound Vc [31], 1.4 g, was
reduced with sodium tetrahydridoborate, followed by
acetylation with acetic anhydride in pyridine. Acetate
VIc thus obtained [31] was recrystallized from
methanol and treated with Raney nickel as described
above for the synthesis of steroid IIa. Recrystallization
from chloroform–methanol gave 0.90 g (60%) of com-
1
of compound VIa with mp 123.5–124.5°C. H NMR
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 40 No. 4 2004

SYNTHESIS AND STUDY OF EQUILENIN DERIVATIVES
511
pound VIIc with mp 185–192°C. Mass spectrum, m/z
(Irel, %): 338 (100), 323 (2), 295 (3), 277 (5), 263 (12),
247 (3), 237 (8), 225 (5), 185 (9). Found, %: C 77.93;
H 7.88. C22H26O3. Calculated, %: C 78.07; H 7.74.
steroid IX with mp 191–194°C (decomp). Retention
time 4.6 min (column A), purity 98.7%. Mass spec-
trum, m/z (Irel, %): 322 (26), 280 (100), 265 (9), 252
(10), 237 (20), 224 (15), 223 (14), 211 (15), 195 (6),
1
178 (6), 165 (8), 152 (5). H NMR spectrum, δ, ppm:
2-Methylequilenin methyl ester (VIIIa). To a so-
lution of 10 g of acetoxy derivative VIIa in 40 ml of
benzene we added a solution of 25 g of sodium
hydroxide in 350 ml of methanol, and the mixture was
heated for 2.5 h under reflux and was poured into
water. The oily material was treated with ethyl acetate,
and the organic phase was washed with water until
neutral reaction and dried over sodium sulfate. The
hydrolysis product was dissolved in 50 ml of pyridine,
and the Sarett reagent prepared from 5.5 g of
chromium(VI) oxide and 100 ml of pyridine was
slowly added under vigorous stirring. The mixture was
left to stand for 12 h, and excess oxidant was
decomposed with methanol. After appropriate treat-
ment [29], the product was recrystallized from
chloroform–methanol. Yield 5.9 g (68%), mp 205–
210°C. Retention time 7.1 min (column A), 9.31 min
(C), purity >99.5%. Mass spectrum, m/z (Irel, %): 294
(100), 279 (13), 266 (13), 251 (35), 238 (24), 225 (22),
0.92 s (3H), 2.35 s (6H), 7.25 d (1H), 7.57 s (1H),
13
7.62 d (1H), 7.81 s (1H). C NMR spectrum, δ, ppm:
13.0, 17.0, 20.7, 21.7, 23.9, 28.9, 36.4, 46.7, 47.3,
119.5, 123.6, 125.0, 125.9, 130.1, 130.3, 131.5, 134.1,
169.3, 219.5. Found, %: C 78.17; H 7.05. C21H22O3.
Calculated, %: C 78.23; H 6.88.
Equilenin methyl ether (X) was synthesized from
1.4 g of acetate IIa by alkaline hydrolysis and sub-
sequent oxidation with the Sarett reagent under
standard conditions [30]. Yield 0.84 g (69%), mp 202–
205°C; published data: mp 185°C [32], 187°C [33].
Crystals of X suitable for X-ray analysis were
obtained from a solution in hexane. Orthorhombic
system, space group Pbca; unit cell parameters: a =
8.5150(12), b = 14.949(2), c = 23.120(3) Å; α = β =
γ = 90°; dcalc = 1.270 g/cm3. The structure was solved
by the direct method and was refined in anisotropic
approximation for non-hydrogen atoms to R = 0.0438
from reflection intensities measured on a SMART
automatic diffractometer [3553 non-zero independent
reflections with I ≥ 2σ(I)].
1
210 (6), 195 (5), 178 (7), 165 (9), 152 (5). H NMR
spectrum, δ, ppm: 0.80 s (3H), 2.43 s (3H), 3.92 s
(3H); signals from four protons were observed in the
aromatic region. 13C NMR spectrum, δC, ppm: 12.9,
17.2, 21.7, 23.8, 29.0, 36.4, 46.6, 47.4, 55.1, 105.0,
123.1, 124.2, 124.9, 127.0, 128.4, 129.9, 131.9, 132.2,
156.0, 219.9. Found, %: C 81.44; H 7.72. C20H22O2.
Calculated, %: C 81.60; H 7.53.
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