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The title cholestan, C28H46O3, was prepared by epoxidation of 7-norcholest-5-en-3β-yl acetate and crystallized by slow evaporation from an ethanolic solution. All rings are trans fused. The 3β-acetate and the 17β-cholestane side chain are in equatorial positions. The molecule 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 molecule gives values for bond lengths and valency angles in close agreement with the experimental ones.

In the crystal structure of the title compound, C21H32O2, ring A is highly distorted, with a conformation intermediate between 10β-sofa and 1α,10β-half chair; rings B and C have slightly flattened chair conformations. Ring D assumes an unusual 13β-envelope conformation, probably induced by the acetoxy substituent. Cohesion of the crystal structure is due only to weak van der Waals interactions.

In the title compound, C17H27NO4, which is an hydrosinapic 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 [Csp2—N = 1.334, C—C for CH2—CH2 = 1.524 and 1.513 Å for CH2—CH3]. The 4-hydroxy-3,5-dimethoxyphenyl plane [r.m.s. deviation 0.055 (12) Å] makes an angle of 59.89 (5)° with the central plane of the molecule (composed of the N atom, the carbonyl group and the two methylene 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 hydroxy and one of the methoxy O atoms of the 4-hydroxy-3,5-dimethoxyphenyl substituent of a neighbouring molecule, forming a two-dimensional network in the (100) plane. In addition, the same hydroxy group acts as a donor towards the carbonyl O atom of another neighbouring molecule, forming chains running along the b axis.

In the title compound, C20H26O2, which is the 6-methylene derivative of androstenedione and a synthetic percursor of exemestane, the steroid A ring approximates to a sofa (or envelope) conformation, with the methylene 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, molecules are linked by two distinct C—H...O hydrogen bonds, involving acidic H atoms close to C=C and C=O double bonds.