(4bR,6bS,9aR,12S)-4b, 12-Difluoro-6b-glycoloyl-5-hydroxy-4a,6a,8,8-tetramethyl-4a,4b,5,6,6a,6b,9a,10,10a,10b,11,12-dodecahydro-2H-naphtho[2',1':4,5]indeno[1,2-d][1,3]dioxol-2-one → Fluocinolone

(4bR,6bS,9aR,12S)-4b,12-Difluoro-6b-glycoloyl-5-hydroxy-4a,6a,8,8-tetramethyl-4a,4b,5,6,6a,6b,9a,10,10a,10b,11,12-dodecahydro-2H-naphtho[2′,1′:4,5]indeno[1,2-d][1,3]dioxol-2-one (10.3 g, 22.76 mmol—commercially available) was suspended in 48% aqueous hydrofluoroboric acid (100 mL) and the resulting suspension stirred at ambient temperature under an atmosphere of nitrogen for 7 hours. The suspension was then diluted with water (200 mL), filtered and the solid washed with water (500 mL). The solid cake was suspended in methanol (200 mL) and concentrated in vacuo. The resulting solid was suspended in tert-butyl-methyl ether (150 mL), filtered and washed with tert-butyl methyl ether (200 mL) to yield the title compound as a white solid, 95% yield, 8.9 g.