(E)-(25S)-23-Acetyl-5β-furost-22-ene-3β,26-diol

The title steroid, C(29)H(46)O(4), is a furostene derivative with a C=C double-bond length of 1.353 (3) Å and an E configuration. The side chain is oriented toward the α face of the A-E steroidal nucleus and presents a disordered terminal CH(2)-OH group [occupancies for resolved sites are 0.591 (9) and 0.409 (9)]. The methyl group at C20 attached to ring E is also oriented toward the α face, avoiding steric hindrance with the carbonyl O atom of the acetyl group. The furostene and acetyl functionalities form an α,β-unsaturated ketone system, with an s-cis configuration. All hydr-oxy and carbonyl groups are involved in weak inter-molecular hydrogen bonds. The absolute configuration was assigned from the synthesis.