Patent ID: 7098328

Claim:
A method of preparing a 6α-fluorinated corticosteroid, comprising the steps of: (a) reacting a 21-ester, 17-hydroxy epoxide of Formula XXV with a stereo selective fluorinating agent to stereo selectively form a 21-ester, 17-hydroxy, 6α-fluorinated compound of Formula XXVI; (b) reacting the 21-ester, 17-hydroxy, 6α-fluorinated compound of Formula XXVI with hydrofluoric acid to form a 21-ester, 11,17-dihydroxy, 6α,9α-difluorinated compound of Formula XXVII; and (c) reacting the 21-ester, 11,17-dihydroxy, 6α,9α-difluorinated compound of Formula XXVII with a weak base to form a 11,17,21-trihydroxy, 6α,9α-difluorinated compound of Formula XXVIII, wherein n=1 or 2, and the stereoselective fluorinating agent is selected from the group consisting of 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate), 1-fluoropyridinium triflate, 1-fluoropyridinium tetrafluoroborate, and 1-fluoropyridinium pyridine heptafluorodiborate.