Synthesis and investigation of the spatial arrangement of the 17β-acetoxy-7α,18-dimethyl-3-methoxy-6-oxaestra-1,3,5(10),8(9)-tetraene

A synthesis was developed of 17β-acetoxy-7α,18-dimethyl-3-methoxy-6-oxaestra-1,3,5(10),8(9)-tetraene. The spatial arrangement of the compound in a crystal and in solution was investigated by means of X-ray diffraction analysis and NMR spectroscopy. The conformation prevailing in solution with the 7α-methyl group in a quasiaxial position corresponds to the structure of the compound in the crystalline state. The presence of a methyl in the 7α position is an important factor governing the osteoprotecting activity of steroids with the similar structure.