Synthesis of 20α-Hydroxy-16-oxosteroids and the C-20 Configuration of Δ¹⁷⁽²⁰⁾-16-Ocosteroids

抄録

Treatment of 16β, 20α-dihydroxysteroids, Ia, Ib, and Ic, with Na₂Cr₂O₇-H₂SO₄ reagent in ether-benzene-tetrahydrofuran resulted in a selective oxidation of the 16-hydroxyl group to afford 20α-hydroxy-16-oxosteroids, IIIa, IIIb, and IIIc. IIIa, IIIb, and the 20-acetates, IVa and IVb, were treated with TsCl, KHCO₃, K₂CO₃ or alumina to afford a mixture of cis and trans 17(20)-16-oxosteroids (V and VI). The C-20 configuration of the isomers, V and VI, was established on the basis of the nuclear magnetic resonance spectra.