Synthetic studies on antheridiol

Antheridiol (mixture of C22C23 epimers) has been obtained in 40% yield by aldol condensation of 3-tetrahydropyranyloxy-Δ5-7-oxo-bisnorcholenaldehyde and β-isopropylbut-2-enolide with subsequent removal of the tetrahydropyranyl protecting group.