Topicon,Pierrel,Italy,1983
100 ml of a 70% hydrofluoric acid aqueous solution were cooled to -10°C in a
polyethylene flask equipped with electromagnetic stirrer. 10 g of 2-bromo-6β-
fluoro-17α,21-dihydroxy-9β, 11β-oxido-pregna-1,4-diene-3,20-dione-17,21-
diacetate were added under stirring during 15 minutes. After 0.5 hour the
reaction mixture was precipitated in water and ammonia. The solid was
collected by filtration, washed with water and dried to a constant weight,
giving about 9.5 g of 2-bromo-6β,9α-difluoro-11β,17α,21 -trihydroxypregna-
1,4-diene-3,20-dione-17,21-diacetate.
