Paramethasone, is a fluorinated glucocorticoid, having anti-inflammatory and immunosuppressant properties.
A solution of 0.144 g of the 3-ethylene glycol ketal of 5α,11β,17α,21 tetrahydroxy-6β-fluoro-16α-methylallopregnane-3,20-dione-21 acetate in 12 ml of chloroform and 0.1 ml of absolute alcohol was cooled to -10°C in an icesalt bath and a stream of anhydrous hydrochloric acid was gently bubbled through the solution for 2.5 hours while the temperature was maintained between -5°C and -15°C. The solution was then diluted with 25 ml of chloroform, washed with dilute sodium bicarbonate and water, dried over anhydrous sodium sulfate, and evaporated to dryness under reduced pressure at 60°C or less to give 6α-fluoro-11β,17α,21-trihydroxy-16α-methyl-4-pregnene3,20-dione 21-acetate.
