Abstract
The synthesis of 3β-hydroxy-5α-card-20 (22)-enolide (14-deoxy-14β-uzarigenin) (IX) was accomplished using 3β-acetoxy-5α, 14β, 17α-pregnan-20-one (I) derivable from △16-pregnenolone acetate as the starting material. The synthesis involved an inversion of the side chain at C17 (I→V) by Serini-Logemann reaction, Reformatsky condensation of V with ethyl bromoacetate, selenium dioxide oxidation to the butenolide (VIII) followed by saponification with acid. Isomerization of IX to 3β-hydroxy-5α, 17α-card-20 (22)-enolide (14-deoxy-14β, 17α-uzarigenin) (XI) was described, which was also prepared from I.
