Crystal and molecular structures of (20R)-20-aminopregn-5-en-3β-ol and (20S)-20-aminopregn-5-en-3β-ol hydrochloride

Article abstract of DOI:10.1023/A:1009553022723

Two epimers of 20-aminopregn-5-en-3β-ol differing in configuration at C(20) have been synthesized and their structures have been determined by single crystal X-ray diffraction methods. The (20R)-epimer (1) crystallized in the orthorhombic system, space group P2₁2₁2₁, with a = 9.0432(5) A, b = 13.3446(7) A, c = 15.1086(8) A, and Z = 4. The (20S)-epimer hydrochloride hydrate (2 hydrate) crystallized in the monoclinic system, space group C2, with a = 31.0501(3) A, b = 11.8221(1) A, c = 11.9703(2) A, β = 98.5140(10)^o, and Z = 8. The absolute configurations at the C(20) chiral centers for the title compounds were unequivocally established for the first time. The asymmetric unit cell of 2 hydrate contained two steroid molecules, A and B, two hydrochloride molecules, and two molecules of water. The crystal packing for both diastereomers was strongly influenced by the presence of intermolecular hydrogen bonding. The molecules of 1 were linked in a head-to-tail fashion via hydrogen bonds between the hydroxyl group of the ring A and the amino group of the side chain of the ring D. The two molecules A and B of 2 hydrate were held together in head-to-head and head-to-tail fashions by a three-dimensional network of hydrogen bonds involving chlorine ions, disordered water molecules, and hydroxyl - amino groups interactions.

Full text of DOI:10.1023/A:1009553022723

Journal of Chemical Crystallography, Vol. 30, No. 5, 2000
Crystal and molecular structures of
(20R)-20-aminopregn-5-en-3 -ol and
(20S)-20-aminopregn-5-en-3 -ol hydrochloride
(1)
Ewa Gruszecka-Kowalik,
Donald G. VanDerveer,(1) and Leon H. Zalkow(1)*
Received May 4, 2000
Two epimers of 20-aminopregn-5-en-3 -ol differing in configuration at C(20) have been syn-
thesized and their structures have been determined by single crystal X-ray diffraction meth-
ods. The (20R)-epimer (1) crystallized in the orthorhombic system, space group P212121,
˚
˚
˚
with a = 9.0432(5) A, b = 13.3446(7) A, c = 15.1086(8) A, and Z = 4. The (20S)-epimer hy-
drochloride hydrate (2 hydrate) crystallized in the monoclinic system, space group C2, with
˚
˚
˚
a = 31.0501(3) A, b = 11.8221(1) A, c = 11.9703(2) A, = 98.5140(10) , and Z = 8. The ab-
solute configurations at the C(20) chiral centers for the title compounds were unequivocally
established for the first time. The asymmetric unit cell of 2 hydrate contained two steroid
molecules, A and B, two hydrochloride molecules, and two molecules of water. The crystal
packing for both diastereomers was strongly influenced by the presence of intermolecular
hydrogen bonding. The molecules of 1 were linked in a head-to-tail fashion via hydrogen
bonds between the hydroxyl group of the ring A and the amino group of the side chain of
the ring D. The two molecules A and B of 2 hydrate were held together in head-to-head and
head-to-tail fashions by a three-dimensional network of hydrogen bonds involving chlorine
ions, disordered water molecules, and hydroxyl–amino groups interactions.
KEY WORDS: Amino steroids; X-ray analysis; absolute configuration; epimers; hydrogen bonding.
Introduction
17 and 5 -reductase, could be effective in the treat-
ment of prostatic cancer by achieving total andro-
The title compounds, epimeric 20-amino preg-
gen blocade.5 The isomeric configurations of amino
steroids are important factors which influence the po-
tency of the inhibition. The presence of the amino
group in the steroidal skeletons creates the pos-
sibility for the introduction of cytotoxic alkylating
moieties into the lipophilic carrier with high selec-
tivity toward steroid receptors.6 In order to estab-
lish the configuration of a given carbon atom in the
steroidal side chain, the empirically derived differ-
ences in physical properties such as polarity, basicity,
1H and 13C NMR signals were used and generalized,
but only for a limited class of related compounds.7
The structures of the epimeric (20R)- and (20S)-20-
aminopregn-5-en-3 -ols were previously established
by chemical and spectroscopic investigations and are
nenes, represent a series of steroid analogs, each hav-
ing an amino group attached to a shortened side
chain. This class of amino steroids has been de-
scribed as inhibitors of cytochromic P-450scc, the
mixed function oxidase which catalyzes the side chain
cleavage of cholesterol.1,2 These compounds have
also been shown to inhibit human testicular 17 -
hydroxylase/C17,20-lyase (P450 17).3,4 The develop-
ment of new types of potent inhibitors of two impor-
tant enzymes in the biosynthesis of androgens, P450
(1) SchoolofChemistryandBiochemistry, GeorgiaInstituteofTech-
nology, Atlanta, Georgia 30332-0400, USA.
* To whom correspondence should be addressed.
291
C
1074-1542/00/0500-0291$18.00/0 2000 Plenum Publishing Corporation

292
Gruszecka-Kowalik, VanDerveer, and Zalkow
Table 1. Crystal Data and Structure Refinement for 1 and 2 Hydrate
Compound
1
2 H2O
CCDC deposit no.
Color/shape
CCDC-1003/5868
Colorless/needle
C21H35NO
317.50
173(2)
CCDC-1003/5869
Colorless/needle
C21H35NO HCl H2O
371.99
173(2)
0.71073
Empirical formula
Formula weight
Temperature, K
˚
Wavelength, A
0.71073
Crystal system
Space group
Orthorhombic
P212121
Monoclinic
C2
Unit cell dimensions
˚
a, A
9.0432(5)
13.3446(7)
15.1086(8)
31.0501(3)
11.8221(1)
11.9703(2)
˚
b, A
˚
c, A
,
98.5140(10)
4345.60(8) A , 8
1.113
0.187
3
3
˚
˚
Volume, Z
1823.3(2) A , 4
1.157
0.069
Density (calculated), mg/m3
Absorption coefficient, mg/m
Diffractometer/scan
F(000)
1
Siemens SMART/CCD area detector
1592
704
Crystal size, mm
range for data collection,
Limiting indices
0.459 0.068 0.068
2.04–25.00
0.70 0.17 0.07
1.33–25.00
10
h
11, 17
20
k
17,
36
h
36, 12
l 14
k
14,
11
9480
l
11
11554
Reflections collected
Independent reflections
Completeness to = 25.00
Max. and min. transmission
Refinement method
3206 (R = 0.0512)
6114 (R = 0.0422)
int
int
100%
99.6%
0.9953 and 9689
0.9874 and 0.8809
Full-matrix least-squares on F2
Data/restraints/parameters
Extinction coefficient
3192/0/238
0.0062(11)
3(3)
1.073
6114/0/509
0.0011(3)
0.12(8)
Absolute structure parameter
Goodness of fit on F2
1.014
Final R indices [I > 2 (I)]
R indices (all data)
Largest diff. peak and hole, eA
R1 = 0.0496, wR2 = 0.0936
R1 = 0.0789, wR2 = 0.1078
0.211 and 0.223
R1 = 0.0525, wR2 = 0.1307
R1 = 0.0767, wR2 = 0.1460
0.449 and 0.255
3
˚
now unequivocally confirmed by single crystal X-ray
analyses.(2)
Experimental
Synthesis
Scheme 1. Synthesis of (20R)- and (20S)-20-aminopregn-5-en-
The synthesis of the mixture of epimeric 20-
amines was performed by reductive amination of
the corresponding carbonyl compound, using sodium
cyanoborohydride as a reducing agent (Scheme 1).
The described preparation is unprecedented for both
3 -ols.
epimers, previously obtained by different pro-
cedures.8 12 The epimeric mixture was separated into
the pure epimers by column chromatography as de-
scribed earlier.11
A solution of 5-pregnen-3 -ol-20-one (1.90 g,
6.0 mmol), ammonium acetate (4.625 g, 60.0 mmol),
and sodium cyanoborohydride (0.264 g, 4.2 mmol) in
methanol (90 mL) was stirred at room temperature
over molecular sieves (4A). The reaction progress was
(2)It was pointed out to us by Professor W. D. Nes that the (20S)-
epimer of the 20-amino pregnene was particularly noncoopera-
tive in producing single crystals suitable for an X-ray analysis—
as the multiple efforts to establish its absolute configuration and
molecular structure by alternative methods presented in the lit-
erature seem to suggest.

Structures of (20R)- and (20S)-20-aminopregn-5-en-3 -ols
293
Table 2. Atomic Coordinates ( 104) and Equivalent Isotropic
2
103) for 1
˚
Displacement Parameters (A
a
x
y
z
Ueq
O
2692(3)
3128(3)
2869(3)
2940(3)
1804(3)
1966(3)
2022(3)
2139(3)
1883(3)
2647(3)
2046(3)
2654(3)
3217(3)
2347(3)
2465(3)
1828(3)
2319(3)
3013(3)
734(3)
3382(2)
6157(2)
5102(2)
4350(2)
4616(2)
5677(2)
5873(2)
6891(2)
7736(2)
7477(2)
6505(2)
8363(2)
9337(2)
9619(2)
8727(2)
9131(2)
10235(2)
10454(2)
9870(2)
6652(2)
11549(2)
12260(2)
11791(2)
2359(1)
2398(2)
2738(2)
1995(2)
1298(2)
961(2)
102(2)
303(2)
364(1)
1241(1)
1665(2)
1889(2)
1476(2)
645(2)
9(1)
860(2)
867(2)
50(2)
878(2)
2065(2)
337(2)
348(2)
1197(2)
59(1)
34(1)
38(1)
42(1)
39(1)
31(1)
32(1)
31(1)
27(1)
28(1)
28(1)
39(1)
38(1)
29(1)
28(1)
35(1)
39(1)
33(1)
41(1)
36(1)
42(1)
60(1)
73(1)
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)
C(7)
C(8)
C(9)
C(10)
C(11)
C(12)
C(13)
C(14)
C(15)
C(16)
C(17)
C(18)
C(19)
C(20)
C(21)
N
Fig. 1. Thermal ellipsoids diagram of the molecular structure of
the (20R)-epimer along with the atom-numbering scheme. Dis-
placement ellipsoids are drawn at the 30% probability level. All
hydrogen atoms have been omitted for clarity.
monitored by TLC. After 2 days, the molecular sieves
were removed by filtration and the solution was acid-
ified to pH < 2 with concentrated hydrochloric acid.
The solvent was removed under reduced pressure.
The residue was treated with ethyl ether. The insolu-
ble material was collected by filtration, washed with
an additional amount of ether, dried, and finally taken
up in water (20 mL). The aqueous solution was made
basic to pH > 10 with sodium hydroxide, saturated
with sodium chloride, and extracted several times
490(3)
2842(3)
3478(4)
3528(4)
aEquivalent isotropic
trace of the orthogonalized U tensor.
U is defined as one third of the
ij
with methylene chloride. The combined extracts were
dried (MgSO4) and evaporated under reduced pres-
sure to give the crude amine mixture. Stereoisomeric
amines were separated by column chromatography
on alumina grade II, using as eluent a mixture of
CH2Cl2/EtOH = 998:2 with gradient to obtain the
(20R)-amine (0.81 g), (20S)-amine (0.46 g), and a
mixture of both (0.16 g). Yield 75%, ratio of (20R)
to (20S) = 64:36. Their identity and purity was con-
1
firmed by TLC, H NMR and MS spectra. (20R)-
20-Aminopregn-5-en-3 -ol (1) had a mp 222–223 C
(ethyl acetate); TLC (silica gel, CH2Cl2/CH3OH =
1
5:3) R 0.23; H NMR (300 MHz, CDCl3, for se-
f
lected protons): 0.75 (s, 3H, C-18), 1.01 (s, 3H, C-19),
1.01 (d, J = 6.3 Hz, 3H, C-21), 2.90–2.81 (m, 1H,
C-20), 3.58–3.47 (m, 1H, C-3), 5.36–5.34 (m, 1H, C-
6); HRMS (m/z): M+ calcd for C21H35NO, 317.2719;
found, 317.2711. (20S)-20-Aminopregn-5-en-3 -ol
had a mp 177–178 C (methanol); TLC (silica gel,
CH2Cl2/CH3OH = 5:3) R 0.08; 1H NMR (300 MHz,
f
Fig. 2. Thermal ellipsoids diagram of the molecular structure of the
(20S)-epimer along with the atom-numbering scheme. Displace-
ment ellipsoids are drawn at the 30% probability level. All hydro-
gen atoms have been omitted for clarity.
CDCl3, for selected protons): 0.68 (s, 3H, C-18),
1.01 (s, 3H, C-19), 1.11 (d, J = 6.6 Hz, 3H, C-21),
2.85–2.75 (m, 1H, C-20), 3.57–3.49 (m, 1H, C-3),

Table 3. Atomic Coordinates ( 104) and Equivalent Isotropic Displacement Parameters
2
˚
(A
103) for 2 Hydrate
a
x
y
z
Ueq
Molecule A
O
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)
C(7)
444(1)
1534(1)
1045(1)
900(1)
8642(3)
9613(4)
9654(4)
8643(4)
8632(4)
8610(4)
7840(4)
7739(3)
8770(4)
9187(3)
9520(4)
10100(4)
9833(4)
9487(4)
8496(3)
7982(4)
8117(4)
8901(4)
10487(4)
10656(4)
9637(4)
10449(4)
8874(3)
8415(3)
9950(4)
9547(4)
8824(4)
7818(4)
8164(3)
7758(4)
8042(4)
8671(3)
9544(3)
9007(3)
10312(4)
10805(4)
9892(3)
9241(3)
8551(4)
9321(4)
10309(4)
9121(4)
8373(4)
10695(4)
11667(4)
11086(3)
36(1)
35(1)
36(1)
31(1)
34(1)
26(1)
29(1)
28(1)
24(1)
24(1)
26(1)
31(1)
29(1)
26(1)
25(1)
36(1)
39(1)
30(1)
35(1)
35(1)
30(1)
38(1)
36(1)
1145(1)
1633(1)
1878(1)
2359(1)
2569(1)
2291(1)
1822(1)
2528(1)
2997(1)
3269(1)
3022(1)
3351(1)
3789(2)
3711(1)
3334(2)
1813(1)
4110(1)
4075(1)
4490(1)
C(8)
C(9)
C(10)
C(11)
C(12)
C(13)
C(14)
C(15)
C(16)
C(17)
C(18)
C(19)
C(20)
C(21)
N
Molecule Bb
O0
1040(1)
2138(1)
1655(1)
1492(1)
1760(1)
2242(1)
2478(1)
2962(1)
3178(1)
2898(1)
2433(1)
3130(1)
3591(1)
3871(1)
3630(1)
3971(2)
4408(2)
4307(1)
3960(1)
2434(1)
4682(1)
4600(2)
5065(1)
4312(3)
5680(4)
5485(4)
4461(4)
3437(4)
3612(4)
2903(4)
2970(4)
3826(3)
4899(4)
4671(3)
5850(4)
6081(4)
5018(4)
4140(3)
3216(4)
3852(4)
5103(4)
4598(5)
4499(5)
5717(4)
6951(4)
5692(3)
5446(3)
5686(4)
5267(4)
5864(4)
5668(4)
6009(4)
6677(4)
7011(4)
6322(4)
6137(4)
5516(3)
5580(4)
6170(4)
6270(3)
6909(3)
7225(5)
7454(4)
7108(4)
5121(3)
4240(4)
6705(4)
6377(5)
7640(3)
40(1)
32(1)
37(1)
33(1)
35(1)
28(1)
32(1)
36(1)
25(1)
26(1)
25(1)
36(1)
38(1)
26(1)
26(1)
44(1)
41(1)
27(1)
40(1)
39(1)
32(1)
50(2)
31(1)
C(10)
C(20)
C(30)
C(40)
C(50)
C(60)
C(70)
C(80)
C(90)
C(100)
C(110)
C(120)
C(130)
C(140)
C(150)
C(160)
C(170)
C(180)
C(190)
C(200)
C(210)
N0
Hydrochloride
Cl(1)
Cl(2)
Cl(3)
0
0
1887(2)
7103(2)
2283
0
0
39(1)
45(1)
37(1)
803(1)
6982(1)
Occupancy
factors
0.80
Water
W(3)
W(4)
W(5)
W(6)
W(7)
265(1)
478(4)
266(8)
377(8)
265(9)
5057(4)
1579(4)
42(1)
119(4)
117(8)
81(7)
5440(11)
5660(20)
5290(20)
5690(30)
3824(11)
4430(20)
2460(20)
5440(30)
0.55
0.25
0.20
0.20
111(9)
aEquivalent isotropic U is defined as one third of the trace of the orthogonalized U tensor.
ij
bAdd mark “0” to atom-numbering in molecule A to generate labels for the corresponding
atoms in molecule B.

Structures of (20R)- and (20S)-20-aminopregn-5-en-3 -ols
295
5.37–5.35 (m, 1H, C-6). HRMS-FAB (m/z): [M + 1]+
calcd for C21H36NO, 318.2797; found, 318.2786. The
sample of (20S)-amine hydrochloride (2) was pre-
pared by dissolving pure (20S)-epimer in methanol,
bubbling in HCl gas and evaporating to dryness un-
der reduced pressure.
General. 5-Pregnen-3 -ol-20-one was purchased
from Fluka Chemical. Melting points were taken on
a Kofler hot stage apparatus and are uncorrected. 1H
NMR spectra were recorded on a Varian Gemini 300
(300 MHz) NMR spectrometer. Mass spectra were
measured on a VG 70-SE, 2 sector, forward geome-
try instrument. TLC chromatography was performed
with EM Science precoated silica gel 60F-254 plates.
Spots were detected with shortwave UV light. Col-
umn chromatography was carried out on neutral alu-
mina Woelm N, Act. I distributed by Universal Scien-
tific Inc. deactivated to activity II.
Results and discussion
The molecular structures of the (20R)-epimer
and the (20S)-epimer are shown in Figs. 1 and 2, re-
spectively.
The asymmetric unit of hydrochloride hydrate of
the (20S)-epimer (2 hydrate) contained two steroid
molecules, A and B, two hydrochloride molecules, and
two molecules of water. Atomic coordinates for the
crystal structures of 1 and 2 hydrate are presented in
Tables 2 and 3, respectively.
Table 4 contains the bond lengths and Table 5
contains bond angles for nonhydrogen atoms in both
epimers. The selected torsion angles are listed in
Table 6.
The bond length and valence angle data for
both epimers did not differ substantially from the
average values described for relevant 15-steroids.17,18
Analysis of endocyclic torsion angles and asymmetry
parameters showed that in all molecules, the A
X-ray analysis
˚
Table 4. Bond Lengths (A) for 1 and 2 hydrate
Suitable crystals of 1 were obtained by recrystal-
lization from ethyl acetate. A single crystal of 2 was
obtained from methanol solution by slow evapora-
tion of the solvent at room temperature. The crystals
were selected, mounted on a glass fiber with stopcock
grease and placed in the cold gas stream of the diffrac-
tometer. Crystal data, data collection parameters, and
details of structure refinements for both epimers are
given in Table 1. The structures were solved by direct
methods and refined by full-matrix least-squares tech-
niques performed with SHELXTL.13 Other programs
included SMART14 for data collection, SAINT15 for
data reduction, and PLATON16 for conformational
calculations.
All nonhydrogen atoms were refined to conver-
gence with anisotropic displacement coefficients. All
hydrogen atom positions for 1 and 2 hydrate were
calculated using the riding mode. Their temperature
factors were varied isotropically. Hydrogen atom
positions for the disordered solvent were not de-
termined. A number of peaks in the residual
electron density were located in a region about
0, 1/2, 1/2. These were assumed to be disordered
water molecules, oxygen 3–7, each was assigned a
partial occupancy. The absolute configuration for 2
hydrate was based on the calculation of the Flack
parameter for both possible epimers. The structure
presented is within 1.5 of 0; the opposite is 3
from 1.0.
2
H2O
Molecule
A
Molecule
Ba
1
0
0
----
0 ----
O
C(3)
----
----
----
----
----
----
----
----
----
----
----
----
----
----
----
----
----
----
----
----
----
----
----
1.422(3) 1.428(5)
1.517(3) 1.524(6)
1.548(3) 1.545(5)
1.507(3) 1.506(6)
1.513(4) 1.516(6)
1.513(3) 1.512(6)
1.324(3) 1.324(6)
1.536(3) 1.531(6)
1.493(3) 1.488(6)
1.530(3) 1.526(6)
1.521(3) 1.505(5)
1.534(3) 1.532(5)
1.535(3) 1.534(6)
1.545(3) 1.552(6)
O
C(3 ) 1.431(5)
0
----
----
----
----
----
----
----
----
----
----
----
----
----
----
----
----
C(1) C(2)
C(1) C(10)
C(2) C(3)
C(3) C(4)
C(4) C(5)
C(5) C(6)
C(5) C(10)
C(6) C(7)
C(7) C(8)
C(8) C(14)
C(8) C(9)
C(9) C(11)
C(9) C(10)
C(10) C(19)
C(11) C(12)
C(12) C(13)
C(13) C(14)
C(13) C(18)
C(13) C(17)
C(14) C(15)
C(15) C(16)
C(16) C(17)
C(17) C(20)
C(20)
C(10) C(2 )
1.526(6)
0
C(10) C(10 ) 1.535(6)
0
C(20) C(30)
1.530(6)
1.505(6)
1.508(6)
1.306(6)
C(30) C(40)
C(40) C(50)
C(50) C(6 )
0
C(50) C(10 ) 1.540(6)
0
C(60) C(70)
1.499(6)
1.521(6)
C(70) C(8 )
0
C(80) C(14 ) 1.520(6)
0
C(80) C(9 )
1.534(6)
0
C(90) C(110) 1.539(6)
C(90) C(100) 1.546(5)
1.544(3) 1.540(6) C(100) C(190) 1.541(5)
1.529(3) 1.521(6) C(110) C(120) 1.525(6)
1.529(3) 1.534(5) C(120) C(130) 1.522(6)
----
----
----
----
----
----
1.533(3) 1.547(6) C(130) C(140) 1.547(6)
1.537(4) 1.531(6) C(130) C(180) 1.525(6)
1.553(3) 1.551(6) C(130) C(170) 1.566(6)
1.532(3) 1.532(5) C(140) C(150) 1.530(6)
1.539(3) 1.536(6) C(150) C(160) 1.539(6)
1.549(4) 1.549(6) C(160) C(170) 1.556(6)
----
----
1.531(3) 1.529(6) C(170) C(20 ) 1.511(6)
0
----
N
1.475(4) 1.503(5) C(200)
N
1.506(5)
0
----
----
C(20) C(21)
1.518(4) 1.524(6) C(20 ) C(21 ) 1.523(7)
aAddmark“0”toatom-numberinginmoleculeAtogeneratelabels
for the corresponding atoms in molecule B.

296
Gruszecka-Kowalik, VanDerveer, and Zalkow
Table 5. Bond Angles ( ) for 1 and 2 Hydrate
H2O
2
1
Molecule A
Molecule Ba
0
0
----
----
0
----
----
C(3) C(2) C(1)
----
----
0 ----
0 ----
----
----
----
----
----
----
----
----
----
----
----
----
----
----
----
----
----
----
----
----
----
----
----
----
----
----
----
----
----
C(2) C(1) C(10)
115.0(2)
111.0(2)
108.1(2)
112.0(2)
109.5(2)
112.8(2)
121.2(2)
122.4(2)
116.4(2)
125.7(2)
113.0(2)
110.9(2)
110.2(2)
109.5(2)
112.3(2)
112.9(2)
112.5(2)
108.6(2)
109.4(2)
112.1(2)
108.0(2)
109.5(2)
109.0(2)
113.3(2)
111.9(2)
106.7(2)
110.7(2)
112.2(2)
116.9(2)
99.6(2)
115.3(3)
110.9(3)
113.3(3)
108.4(3)
108.6(4)
112.5(3)
121.2(4)
122.7(4)
116.1(3)
125.7(4)
112.9(3)
110.7(3)
110.1(3)
110.6(3)
111.5(3)
112.8(3)
114.0(3)
108.1(3)
109.8(3)
111.9(3)
108.9(3)
109.1(3)
108.9(3)
115.7(3)
112.1(3)
106.0(3)
111.0(3)
112.4(3)
116.4(3)
100.0(3)
110.5(3)
119.6(3)
115.3(3)
104.5(3)
103.8(3)
107.2(3)
111.1(4)
118.8(4)
104.7(3)
106.3(3)
108.4(3)
116.3(4)
C(20) C(10) C(10 )
114.5(4)
110.0(4)
108.0(3)
112.5(4)
109.6(3)
113.3(4)
121.5(4)
122.9(4)
115.6(4)
125.4(4)
113.3(4)
111.2(3)
109.2(3)
110.1(3)
112.1(3)
113.1(3)
112.4(3)
109.2(3)
110.0(3)
111.2(3)
108.1(3)
108.8(3)
109.5(3)
113.4(4)
112.0(4)
106.3(3)
112.1(4)
113.1(4)
115.2(4)
99.4(3)
0
---- ----
C(3) C(2)
C(3) C(4)
C(3 ) C(20) C(10)
----
----
----
----
----
O
O
O
C(30) C(20)
----
----
O
C(3 ) C(4 )
0
0
0
----
----
C(2) C(3) C(4)
C(20) C(30) C(40)
---- ----
----
----
----
----
----
----
----
----
C(5) C(4) C(3)
---- ----
C(50) C(40) C(30)
C(6) C(5) C(4)
---- ----
C(60) C(50) C(4 )
0
C(6) C(5) C(10)
---- ----
C(60) C(50) C(100)
C(4) C(5) C(10)
---- ----
C(40) C(50) C(10 )
0
C(5) C(6) C(7)
---- ----
C(50) C(60) C(70)
C(6) C(7) C(8)
---- ----
C(60) C(70) C(80)
C(14) C(8) C(7)
---- ----
C(140) C(80) C(70)
C(14) C(8) C(9)
---- ----
C(140) C(80) C(90)
----
----
----
C(7) C(8) C(9)
---- ----
C(70) C(80) C(9 )
0
C(8) C(9) C(11)
---- ----
C(80) C(90) C(110)
C(8) C(9) C(10)
---- ----
C(80) C(90) C(100)
----
----
C(11) C(9) C(10)
---- ----
C(110) C(9 ) C(10 )
0
0
C(5) C(10) C(19)
---- ----
C(50) C(100) C(19 )
0
----
----
----
----
----
----
----
----
----
----
----
----
----
----
----
----
C(5) C(10) C(9)
---- ----
C(50) C(100) C(90)
C(19) C(10) C(9)
---- ----
C(190) C(100) C(90)
C(5) C(10) C(1)
---- ----
C(50) C(100) C(10)
C(19) C(10) C(1)
---- ----
C(190) C(100) C(10)
C(9) C(10) C(1)
---- ----
C(90) C(100) C(10)
C(12) C(11) C(9)
---- ----
C(120) C(110) C(9 )
0
C(11) C(12) C(13)
---- ----
C(110) C(120) C(130)
C(12) C(13) C(14)
---- ----
C(120) C(130) C(140)
C(12) C(13) C(18)
---- ----
C(120) C(130) C(180)
C(14) C(13) C(18)
---- ----
C(140) C(130) C(180)
C(12) C(13) C(17)
---- ----
C(120) C(130) C(170)
C(14) C(13) C(17)
---- ----
C(140) C(130) C(170)
C(18) C(13) C(17)
---- ----
110.1(2)
118.6(2)
115.5(2)
103.8(2)
103.5(2)
107.0(2)
113.1(2)
118.8(2)
103.0(2)
107.7(3)
114.5(2)
111.4(2)
C(180) C(130) C(170)
110.1(3)
120.0(3)
114.6(3)
103.4(3)
104.8(4)
106.3(4)
114.0(4)
117.5(3)
103.3(3)
107.1(4)
108.3(3)
115.8(4)
C(8) C(14) C(15)
---- ----
C(80) C(140) C(150)
C(8) C(14) C(13)
---- ----
C(80) C(140) C(130)
----
----
----
----
C(15) C(14) C(13)
---- ----
C(150) C(140) C(130)
----
----
----
----
C(14) C(15) C(16)
---- ----
C(140) C(150) C(160)
C(15) C(16) C(17)
---- ----
C(150) C(160) C(170)
C(20) C(17) C(16)
---- ----
C(200) C(170) C(160)
----
C(20) C(17) C(13)
---- ----
C(200) C(170) C(130)
----
----
C(16) C(17) C(13)
C(16 ) C(170) C(130)
----
----
----
----
0 ----
----
N
N
C(20) C(21)
C(20) C(17)
N
C(200) C(210)
0 ----
----
N
C(200) C(170)
0
----
----
----
----
C(21) C(20) C(17)
C(21 ) C(20 ) C(17 )
aAdd mark “0” to atom-numbering in molecule A to generate labels for the corresponding atoms
in molecule B.
drate with 1CS3 = 2.66 and 1C22,3 = 4.37. The flexible
B rings adopted in all molecules half-chair forms. For
1 and the molecules A and B of 2 hydrate, the rota-
tional symmetry was dominant with 1C52,6 = 5.94,
4.51, 2.81 and 1C6S = 17.56, 17.60, 19.96, respec-
tively. The C rings in all molecules exhibited chair
conformations with mirror symmetry dominant for
rings had chair conformations with some degree of
flattening, which affected the region of junction of A
and B rings, especially in the molecule A of 2 hydrate.
Rotational symmetry was dominant for 1 with
1C22,3 = 2.42, 1C3S = 4.35 and for the molecule B
of 2 hydrate with 1C22,3 = 2.48, 1C2S = 3.21. Mirror
symmetry was dominant for the molecule A of 2 hy-

Structures of (20R)- and (20S)-20-aminopregn-5-en-3 -ols
297
Table 6. Selected Torsion Angles ( ) for 1 and 2 Hydrate
H2O
2
1
Molecule A
Molecule Ba
0
0
0
----
0
----
----
----
----
----
----
----
----
----
----
----
----
----
----
----
C(10) C(1) C(2) C(3)
57.3(3)
57.9(3)
55.0(3)
51.1(3)
45.4(3)
48.5(3)
1.1(4)
11.5(4)
40.8(3)
60.9(3)
47.4(3)
16.6(3)
48.4(3)
50.2(3)
55.4(3)
56.7(3)
58.7(3)
55.2(3)
47.8(2)
34.8(2)
7.9(3)
56.0(5)
59.0(5)
57.5(5)
52.1(5)
44.1(5)
46.2(5)
0.1(7)
C(100 ) C(1 ) C(2 ) C(3 )
58.2(5)
57.2(5)
54.7(5)
51.7(5)
47.4(5)
51.3(5)
3.5(7)
11.0(7)
40.7(5)
59.0(5)
44.1(5)
13.1(6)
50.2(5)
50.6(5)
55.1(5)
56.9(5)
60.6(4)
57.7(4)
47.1(4)
34.2(5)
7.2(5)
0
0
----
0
---- ---- ----
C(1) C(2) C(3) C(4)
---- ---- ----
C(10) C(20) C(30) C(40)
----
C(2) C(3) C(4) C(5)
---- ---- ----
C(20) C(30) C(40) C(5 )
0
----
----
C(3) C(4) C(5) C(10)
---- ---- ----
C(30) C(40) C(5 ) C(100)
0
C(4) C(5) C(10) C(1)
---- ---- ----
C(40) C(5 ) C(100) C(10)
0
----
C(5) C(10) C(1) C(2)
---- ---- ----
C(5 ) C(100) C(10) C(20)
0
---- ---- ----
C(10 ) C(5 ) C(6 ) C(7 )
C(10) C(5) C(6) C(7)
---- ---- ----
0
0
0
0
0
0
C(500) C(6 ) C(7 ) C(8 )
----
----
----
----
----
----
----
----
----
C(5) C(6) C(7) C(8)
---- ---- ----
12.3(6)
40.6(5)
59.2(4)
45.6(4)
16.4(5)
48.5(4)
47.7(5)
52.2(5)
54.4(4)
60.4(4)
58.3(4)
44.8(4)
34.9(4)
10.8(5)
16.9(5)
37.2(4)
60.3(4)
178.3(3)
----
----
----
----
----
----
C(6) C(7) C(8) C(9)
---- ---- ----
C(60) C(70) C(80) C(9 )
0
----
----
C(7) C(8) C(9) C(10)
---- ---- ----
C(70) C(80) C(9 ) C(100)
0
C(8) C(9) C(10) C(5)
---- ---- ----
C(80) C(9 ) C(100) C(50)
0
----
----
C(9) C(10) C(5) C(6)
---- ---- ----
C(9 ) C(100) C(50) C(6 )
0
0
C(14) C(8) C(9) C(11)
---- ---- ----
C(104 ) C(8 ) C(90) C(110)
0
----
----
0
----
C(8) C(9) C(11) C(12)
---- ---- ----
C(80) C(9 ) C(11 ) C(12 )
0
---- ----
C(9 ) C(11 ) C(12 ) C(13 )
0
0
C(9) C(11) C(12) C(13)
---- ---- ----
0
0
0
----
----
----
----
----
----
----
----
----
----
----
----
----
----
----
----
C(11) C(12) C(13) C(14)
---- ---- ----
C(110) C(120) C(130) C(14 )
0
----
C(12) C(13) C(14) C(8)
---- ---- ----
C(120) C(130) C(140 ) C(8 )
0
----
C(13) C(14) C(8) C(9)
---- ---- ----
C(130) C(140) C(8 ) C(9 )
0
0
----
----
----
----
----
----
----
C(17) C(13) C(14) C(15)
---- ---- ----
C(170) C(130) C(140) C(150)
C(13) C(14) C(15) C(16)
---- ---- ----
C(130) C(140) C(150) C(160)
C(14) C(15) C(16) C(17)
---- ---- ----
C(140) C(150) C(160) C(170)
C(15) C(16) C(17) C(13)
---- ---- ----
21.3(3)
41.8(2)
178.4(3)
60.7(4)
C(150) C(160) C(170) C(130)
22.0(5)
42.0(4)
58.8(5)
179.8(3)
C(16) C(17) C(13) C(14)
C(160) C(170) C(130) C(14 )
0
----
----
----
----
----
----
----
----
C(16) C(17) C(20)
N
N
C(160) C(170) C(200) N 0
---- ----
C(13) C(17) C(20)
C(13 ) C(17 ) C(20 ) N
aAdd mark “0” to atom-numbering in molecule A to generate labels for the corresponding atoms in molecule B.
1 (1C9S = 1.58, 1C28,9 = 4.23) and the molecule B of
rings in the (20R)-epimer and in the molecule B of
the (20S)-epimer hydrochloride hydrate showed in-
termediate II forms, midway between a 13 -envelope
and a 13 ,14 -half-chair with asymmetry parameters
2 hydrate (1C9S = 2.61, 1C92,11 = 3.49). Rotational
symmetry was dominant for the molecule A of 2
hydrate with 1C92,11 = 3.85 and 1C1S1 = 4.46. The D
----
----
Fig. 3. Partial packing diagram showing the NH2 HO hydrogen bonding and infinite chain for 1; the hydrogen bonds are shown by
dashed lines.

298
Gruszecka-Kowalik, VanDerveer, and Zalkow
Fig. 4. Partial packing diagram for 2 hydrate showing the hydrogen bonding detailed in Table 7 and inset diagram to further clarity hydrogen
bonding; the labels for the atoms in molecule B are generated by adding the mark “0” to the corresponding atom-numbering in molecule A;
the hydrogen bonds are shown by dashed lines.
1C1S3 = 10.48, 9.40, 1C1S4 = 25.65, 26.22, and
more twisted than the molecule A. The configurations
of the asymmetric carbon atoms of the main steroid
1C123,14 = 10.68, 11.81, respectively.19 In the molecule
skeletons followed known configurations in the
substrate used for the synthesis of the two epimers.
These X-ray analyses provide unequivocal proof
for the absolute configurations at the chiral C(20)
atoms in the steroidal moieties, which until now have
been tentatively assigned by other methods. The
amino group at C(20) position was synclinal to
A of the (20S)-epimer hydrochloride hydrate, ring
D exhibited a 13 ,14 -half-chair conformation with
1C123,14 = 4.62, 1CS13 = 13.80 and 1C1S4 = 19.94.
The A/B junction observed was quasi-trans and the
B/C and C/D junctions were both trans for 1 and 2
hydrate.20 The conformational analysis presented
here showed subtle differences in the two molecules,
A and B, of the (20S)-epimer hydrochloride hydrate.
The conformation of the molecule B of 2 hydrate
had greater similarity to the conformation of the
(20R)-epimer. No close intramolecular contacts
were indicated in all molecules. The twist of the
steroid nucleus about a line joining C(10) and C(13)
----
the C(13) C(17) bond in 1 and antiperiplanar in
both molecules of 2 hydrate. The crystal packing for
both diastereomers was strongly influenced by the
presence of intermolecular hydrogen bonding (Figs. 3
and 4).
The molecules of the (20R)-epimer were linked
head-to-tailviahydrogenbondsbetweenthehydroxyl
group of the ring A and the amino group of the side
chain of the ring D. They were packed in a par-
allel manner, forming an infinite chain along the b
----
----
----
was described by the C(19) C(10) C(13) C(18)
pseudo-torsional angle of 10.9(1) , 12.8(2) , and
15.5(2) , respectively, for 1 and the molecules A and
B of 2 hydrate, indicating that the molecule B of the
(20S)-epimer hydrochloride hydrate was slightly
˚
axis, having an O N distance of 2.857(4) A. The

Structures of (20R)- and (20S)-20-aminopregn-5-en-3 -ols
299
˚
Table 7. Hydrogen Bonds Geometry (A and ) for 2 Hydrate
----
----
d(D H) d(H A) d(D A) <(DHA)
D
H
A
----
----
----
0 ----
0 ----
0 ----
0 ----
0 ----
0 ----
O
N
N
N
N
N
O
O
O
H(0) Cl (2)a
H(0B) Cl (1)b
H(0C) W(3)b
0.93
0.88
0.88
0.88
0.88
0.88
2.17
2.46
1.90
2.28
1.94
2.34
3.096(3)
3.214(4)
2.772(5)
3.152(3)
2.792(5)
3.192(4)
2.755(4)
2.906(4)
2.988(4)
3.105(4)
175.2
143.8
172.3
171.8
163.7
164.1
0
H(00B) Cl (3)c
H(00A) Od
H(0 C) Cl (1)b
H(0) W(4)
H(0) W(7)
H(0) W(5)
Cl (2) W(3)
Note. Symmetry transformations used to generate equivalent atoms: a x, y, z 1;
bx 1/2, y 1, z 1; c3 x 1/2, y 1/2, z; d
x
1/2, y + 1/2, z.
4. Njar, V.C.O.; Hector, M.; Hartmann, R.W. Bioorg. Med. Chem.
1996, 4, 1447.
5. Ling, Y.; Li, J.; Kato, K.; Liu, Y.; Wang, X.; Klus, G.T.; Marat,
K.; Nnane, I.P.; Brodie, A.M.H. Bioorg. Med. Chem. 1998, 6,
1683.
6. Chavis, C.; de Gourcy, C.; Borgna, J.-L.; Imbach, J.-L. Steroids
1982, 39, 129.
7. Biesemans, M.; Van de Woude, G.; Van Hove, L. Bull. Soc.
Chim. Belg. 1985, 94, 59.
8. Lucas, R.A.; Dickel, D.F.; Dziemian, R.L.; Ceglowski, M.J.;
Hensle, B.L.; MacPhillamy, H.B. J. Am. Chem. Soc. 1960, 82,
5688.
9. Van de Woude, G.; Van Hove, L. Bull. Soc. Chim. Belg. 1967,
76, 566.
10. Lu, M.C.; Afiatpour, P.; Sullivan, C.B.; Counsell, R.E. J. Med.
Chem. 1972, 15, 1284.
11. Goutarel, R.; Mahler, H.R.; Green, G.; Khuong-Huu, Q.; Cave´,
A.; Conreur, C.; Jarreau, F.-X.; Hannart, J. Bull. Soc. Chim. Fr.
1967, 12, 4575.
packing for the (20S)-epimer hydrochloride hydrate
was much more complex. The steroid molecules, A
and B, were linked together in head-to-tail and head-
to-head fashions by a number of different, intricate
hydrogen bonds. A three-dimensional network of
hydrogen bonds was observed for the steroidal hy-
droxyl and protonated amino groups, chlor+ine ions
----
----
and w+ater. These wer+e OH Cl , NH3 Cl ,
----
----
NH3 H2O, NH3
---- ----
HO
H2O. The geometry of these hydrogen bonds is
, OH H2O, Cl
detailed in Table 7 (identical, symmetry-related
hydrogen bonds are omitted). Disordered water
molecules assisted in holding steroidal molecules to-
gether along the a axis.
12. Szendi, Z.; Dombi, G.; Vincze, I. Monatsh. Chem. 1996, 127,
1189.
13. Sheldrick, G.M. SHELXTL, Version 5.10; Bruker AXS Inc.:
Madison, WI, USA, 1998.
Acknowledgments
14. SMART, Version 5.054; Bruker AXS Inc.: Madison, WI, USA,
1998.
15. SAINT, Version 6.01; Bruker AXS Inc.: Madison, WI, USA,
1999.
16. Spek, A.L. PLATON; Utrecht University, The Netherlands,
Windows Version by Farrugia, L.J., University of Glasgow,
United Kingdom, 1999.
We gratefully acknowledge support of this re-
search by the National Cancer Institute, National In-
stitutes of Health (Grant 5U19 CA52995).
17. Duax, W.L.; Norton, D.A. Atlas of Steroid Structure; Plenum:
New York, 1975; Vol. 1.
18. Griffin, J.F.;Duax, W.L.;Weeks, C.M. AtlasofSteroidStructure;
Plenum: New York, 1984; Vol. 2.
References
1. Sheets, J.J.; Vickery, L.E. J. Biol. Chem. 1983, 258, 11446.
2. Kellis, J.T., Jr.; Sheets, J.J.; Vickery, L.E. J. Steroid Biochem.
1984, 20, 671.
3. Li, J.; Li, Y.; Son, C.; Brodie. A.M.H. J. Med. Chem. 1996, 39,
4335.
19. Thomas, S.A. J. Crystallogr. Spectrosc. Res. 1982, 12,
171.
20. Bucourt, R. Topics in Stereochemistry; Eliel, E.L.;
Allinger, N.L., Eds., Interscience: New York, 1974; Vol. 8,
p. 159.