Steroids derived from fusidic acid. Part 3. Formation of a 9β-steroid from a Δ9,111-steroid precursor. X-Ray crystal structure of 3α-acetoxy-4α,8α,14β-trimethyl-18-nor-5α,9β,13β-androstan-17-one

Abstract

The crystal and molecular structure of the title compound (1) has been determined by X-ray crystallography. Crystals are orthorhombic, space group P2₁2₁2₁ with Z= 4, in a unit cell of dimensions a= 7.274(l), b= 10.041(1), c= 28.263(4)Å. The structure was solved by direct methods and refined by full-matrix least-squares caldulations to R 0.043 for 1 761 observed reflections. The C(9)β-configuration for the steroid is established unequivocally; rings A and C have chair conformations, ring B a twisted boat, and ring D a half-chair conformation. It is concluded that compound (1) is, unexpectedly, more stable than its C(9)α-epimer.