Stereoselective β-face catalytic hydrogenation of Δ4-9α-fluoro-11β-hydroxycorticosteroids: reappraisal

At variance with previous reports, palladium-catalysed reduction of 9α-fluorohydrocortisone 21-acetate (1a) and 1,2-didehydro-9α-fluoro-16α-methylhydrocortisone 21-acetate (2a) yields the 5β-configuration.