Abstract
The structure of the estrone-related steroid, Equilenin, C18H18O2 (systematic name 3-hy-droxy-13-methyl-11,12,13,14,15,16-hexa-hydro-cyclo-penta-[a]phen-anthren-17-one), has been determined at 100 K. The crystals are ortho-rhom-bic, P212121, and the absolute structure of the mol-ecule in the crystal has been determined by resonant scattering [Flack parameter = -0.05 (4)]. The C atoms of the A and B rings are almost coplanar, with an r.m.s. deviation from planarity of 0.0104 Å. The C ring has a sofa conformation, while the D ring has an envelope conformation with the methine C atom as the flap. The keto O atom and the methyl group are translated 0.78 and 0.79 Å, respectively, from the equivalent positions on 17β-estrone. In the crystal, mol-ecules are linked by O-H⋯O hydrogen bonds, forming chains parallel to the c-axis direction.
Highlights
The structure of the estrone-related steroid, Equilenin, C18H18O2, has been determined at 100 K
The title compound, Equilenin 1, is one member of a series of three estrogenic steroids, the other members being Equilin 2 and 17-estrone 3, that are components of the hormone replacement therapy medication, ‘Premarin’, a mixture of natural estrogens isolated from the urine of pregnant equine mares
It can be seen from the scheme that on going from 17estrone 3 through to the title compound Equilenin 1, there is a progressive aromatization of the B ring of the steroid framework where in 1 rings A and B comprise a fully aromatic naphthalene core
Summary
The title compound, Equilenin 1, is one member of a series of three estrogenic steroids, the other members being Equilin 2 and 17-estrone 3, that are components of the hormone replacement therapy medication, ‘Premarin’, a mixture of natural estrogens isolated from the urine of pregnant equine mares. It can be seen from the scheme that on going from 17estrone 3 through to the title compound Equilenin 1, there is a progressive aromatization of the B ring of the steroid framework where in 1 rings A and B comprise a fully aromatic naphthalene core.
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