Conformational studies. Part 12. The crystal and molecular structure of 17β-iodoacetoxy-4,4-dimethyl-19-nor-5α-androstan-3-one and of 17β-iodoacetoxy-4,4-dimethyl-5α-androstan-3-one

Abstract

The crystal and molecular structures of the title compounds have been determined by X-ray crystallography. The 19-nor-derivative (1), C₂₂H₃₃IO₃, crystallises in the orthorhombic system, space group P2₁2₁2₁ with four molecules in a unit cell of dimensions a= 11.358(5), b= 25.429(3), and c= 7.516(7)Å; the 19-methyl derivative (2), C₂₃H₃₅IO₃, crystallizes in the orthorhombic space group P2₁2₁2₁ with four molecules in a unit cell a= 14.917(3), b= 19.466(3), c= 7.490(3)Å. Both structures were solved by the heavy-atom method and refined by full-matrix least-squares calculations with three-dimensional diffractometer data, for (1)R= 0.046 for 1 110 reflections, for (2)R= 0.040 for 1 561 reflections. The conformation of ring A in both molecules exhibits a degree of flattening; ring D in (1) approximates to a C-13 envelope whilst the same ring in (2) has a conformation exactly intermediate between a C-13 and a C-14 envelope. Rings B and C in both molecules have normal chair conformations.