N-Hexyl-3-(4-hy-droxy-3,5-dimeth-oxy-phen-yl)propanamide.

In the title compound, C(17)H(27)NO(4), which is an hydro-sinapic acid derivative with increased lipophilicity conferred by an additional alkyl chain, the central and the hexyl linear chains contain slightly shorter bond lengths [C-N = 1.316 (2) Å; average linear chain C-C = 1.487 (6) Å] than reported average values [Csp(2)-N = 1.334, C-C for CH(2)-CH(2) = 1.524 and 1.513 Šfor CH(2)-CH(3)]. The 4-hy-droxy-3,5-dimeth-oxy-phenyl plane [r.m.s. deviation 0.055 (12) Å] makes an angle of 59.89 (5)° with the central plane of the mol-ecule (composed of the N atom, the carbonyl group and the two methyl-ene C atoms linking the carbonyl group and the ring, [r.m.s. deviation 0.0026 (10) Å], which, in turn, makes an angle of 64.24 (13)° with the essentially planar hexyl chain [r.m.s. deviation 0.035 (18) Å]. The N-H group of the amide group is involved in a bifurcated hydrogen bond towards the hy-droxy and one of the meth-oxy O atoms of the 4-hy-droxy-3,5-dimeth-oxy-phenyl substituent of a neighbouring mol-ecule, forming a two-dimensional network in the (100) plane. In addition, the same hy-droxy group acts as a donor towards the carbonyl O atom of another neighbouring mol-ecule, forming chains running along the b axis.

6-Methyl-ideneandrost-4-ene-3,17-dione.

In the title compound, C(20)H(26)O(2), which is the 6-methyl-ene derivative of androstenedione and a synthetic percursor of exemestane, the steroid A ring approximates to a sofa (or envelope) conformation, with the methyl-ene group adjacent to the link to the B ring lying out of the plane of the other atoms. The B and C rings have slightly flattened chair conformations and the D ring is an envelope, with the CH group forming the flap. In the crystal, mol-ecules are linked by two distinct C-H⋯O hydrogen bonds, involving acidic H atoms close to C=C and C=O double bonds.

5α,6α-Ep-oxy-7-norcholestan-3ß-yl acetate.

The title cholestan, C(28)H(46)O(3), was prepared by epoxidation of 7-norcholest-5-en-3ß-yl acetate and crystallized by slow evaporation from an ethano-lic solution. All rings are trans fused. The 3ß-acetate and the 17ß-cholestane side chain are in equatorial positions. The mol-ecule is highly twisted due to its B-nor characteristic. A quantum chemical ab-initio Roothaan Hartree-Fock calculation of the equilibrium geometry of the isolated mol-ecule gives values for bond lengths and valency angles in close agreement with the experimental ones.

Androstane-3ß,5α,6ß,17ß-tetrol tri-hydrate.

The title hydrated tetrol, C(19)H(32)O(4)·3H(2)O, was synthesized by stereoselective reduction of the compound 3ß,5α,6ß-trihy-droxy-androstan-17-one. All rings are fused trans. The organic mol-ecules are connected head-to-tail along the c axis via O-H⋯O hydrogen bonds. Layers of water mol-ecules in the ab plane inter-connect these chains. A quantum chemical ab initio Roothan Hartree-Fock calculation of the isolated mol-ecule gives values for the mol-ecular geometry close to experimentally determined ones, apart from the C-O bond lengths, whose calculated values are significantly smaller than the measured ones, probably a consequence of the involvement of the C-OH groups in the hydrogen-bonding network.

3ß,5α,6ß-Trihy-droxy-androstan-17-one.

The title compound, C(19)H(30)O(4), is an androstan-17-one derivative synthesized from the dehydro-epiandrosterone through a sequential addition of an oxidant, followed by a trans-diaxial opening of the epoxide generated, with Bi(OTf)(3) (OTf is trifluoro-methane-sulfonate). The six-membered rings have a slightly flattened chair conformation, while the five-membered ring adopts a 14-α envelope conformation. All rings are trans fused. In the crystal, the mol-ecules are connected by O-H⋯O hydrogen bonds involving the hydroxyl and carbonyl groups, forming a three-dimensional network. A quantum mechanical ab initio Roothan Hartree-Fock calculation of the free mol-ecule gives bond lengths, valency angles and ring torsion angles of the free molecule at equilibrium geometry (energy minimum) close to the experimental values.

6-[(4-Fluorophenyl)(1H-imidazol-1-yl)methyl]-1,3-benzodioxol-5-ol and 6-[(4-methoxyphenyl)(1H-imidazol-1-yl)methyl]-1,3-benzodioxol-5-ol.

The title compounds, C(17)H(13)FN(2)O(3) and C(18)H(16)N(2)O(4), are new potent aromatase inhibitors combining the common features of second- and third-generation nonsteroid anti-aromatase compounds. The molecules have a propeller shape, with dihedral angles between adjacent planes in the range 49-86°. A quantum mechanical ab initio Roothaan-Hartree-Fock calculation for the isolated molecules shows values for these angles close to the ideal value of 90°. Docking studies of the molecules in the aromatase substrate show that their strong inhibitor potency can be attributed to molecular flexibility, hydrophobic interactions, heme Fe coordination and hydrogen bonding.

6beta-Methyl-B-norandrostenedione.

The title compound, C(19)H(26)O(2), a B-norandrogen with a 6beta-methyl group, is a recently identified and experimentally tested potent new aromatase inhibitor. It shares structural and physicochemical similarities both with the natural substrate of the enzyme, androstenedione, and with exemestane, another potent aromatase inhibitor having a 6-methylidene group. X-ray diffraction results indicate that the B-nor molecule and exemestane have nearly the same oxygen-oxygen and methyl-methyl separations, though they have distinct configurations of the hydrophobic groups at the 6-position. These structural comparisons allow correlations to be inferred between the active site geometry of the molecules and the aromatase inhibition power of the studied compound.

5α-Androst-3-en-17ß-yl acetate.

In the crystal structure of the title compound, C(21)H(32)O(2), ring A is highly distorted, with a conformation inter-mediate between 10ß-sofa and 1α,10ß-half chair; rings B and C have slightly flattened chair conformations. Ring D assumes an unusual 13ß-envelope conformation, probably induced by the acet-oxy substituent. Cohesion of the crystal structure is due only to weak van der Waals inter-actions.

3α,4α-Ep-oxy-5α-androstan-17ß-yl acetate.

The title compound, C(21)H(32)O(3), results from modifications of the A and D rings of the aromatase substrate androstenedione. Ring A adopts a conformation between 10ß-sofa and 1α,10ß half-chair. Rings B and C are in slightly flattened chair conformations. Ring D approaches a 13ß-envelope conformation, probably due to the acet-oxy substituent, and shows a very short Csp(3)-Csp(3) bond next to the epoxide ring, which is characteristic of 3-4 epoxides. .

5alpha-Androst-3-en-17-one oxime.

The title compound, C(19)H(29)NO, is a C17-oxime derivative of a potent aromatase inhibitor, which surprisingly has been found to have no inhibitory power. It crystallizes with two independent molecules in the asymmetric unit. C=N-O-H...N hydrogen bonds link pairs of molecules to form dimers almost parallel to the bc plane. Cohesion of the structure is also due to another three C-H...O hydrogen bonds directed along the a axis. This hydrogen-bonding scheme can be correlated to the almost complete loss of inhibitory power of the title compound.

3,17-Dioxoandrost-4-en-4-yl acetate.

The title compound, C(21)H(28)O(4), has a 4-acetoxy substituent positioned on the steroid alpha face. The six-membered ring A assumes a conformation intermediate between 1alpha,2beta-half chair and 1alpha-sofa. A long Csp(3)-Csp(3) bond is observed in ring B and reproduced in quantum-mechanical ab initio calculations of the isolated molecule using a molecular-orbital Hartree-Fock method. Cohesion of the crystal can be attributed to van der Waals interactions and weak C-H...O hydrogen bonds.

2,2,4,4-Tetra-tert-butyl-1,3,5,2,4-benzotrioxadisilepine-7-carbaldehyde.

The molecule of the title compound, C23H40O4Si2, features an approximate non-crystallographic C2 symmetry axis. The aldehyde group is disordered over two positions with similar occupancies. The geometry of the isolated molecule was studied by ab initio quantum mechanical calculations employing a molecular orbital Hartree-Fock method. The calculations reproduce well the equilibrium geometry but slightly overestimate the value of the Si-O bond lengths of the trioxadisilepine ring.

17-Oxo-5alpha-androstane-3alpha,4beta-diyl diacetate and 17-oxo-5beta-androstane-3alpha,4beta-diyl diacetate.

The title compounds, both C23H34O5, are the 5alpha and 5beta configurations of two diacetate epimers. The 5beta-diacetate crystallizes in an hexagonal structure, unusual for steroid molecules. The unit cell has an accessible solvent volume of 358 A(3), responsible for clathrate behaviour. The 5beta-epimer also features some shorter than average bond lengths in the 3alpha,4beta-acetoxy groups. The conformations of the molecules of both epimers are compared with those obtained through ab initio quantum chemistry calculations. Cohesion of the crystals can be attributed to van der Waals and weak molecular C-H...O interactions.

3 beta,7 alpha,12 alpha-triformyloxy-24-nor-5 beta-chol-22-ene.

The title compound, alternatively called 24-nor-5 beta-chol-22-ene-3 beta,7 alpha,12 alpha-triyl triformate, C(26)H(38)O(6), has a cis junction between two of the six-membered rings. All three of the six-membered rings have chair conformations that are slightly flattened and the five-membered ring has a 13 beta,14 alpha-half-chair conformation. The 3 beta, 7 alpha and 12 alpha ring substituents are axial and the 17 beta group is equatorial. The 3 beta-formyloxy group is involved in one weak intermolecular C-H...O bond, which links the molecules into dimers in a head-to-head fashion.