PROCESS FOR THE PREPARATION OF 21-CHLORO-6,6,9D-TRIFLUORO-11B,16D,17D-TRIHYDROXY-1,4-PREGNADIEN-3,20-DIONE 16,17-KETALS AND SELECTED INTERMEDIATES

摘要

6,6-Difluoro-11 alpha ,16 alpha ,17 alpha -trihydroxy-4-pregnen-3,20-dione 16,17-ketal 17-ketal is prepared by a process involving the 11 alpha -microbiological hydroxylation of the corresponding 16 alpha ,17 alpha -dihydroxy steroid. The 11 alpha -hydroxyl is converted sequentially to the 9,11-double bond, 9,11-epoxy and 9 alpha -fluoro-11 beta -hydroxyl. Optionally the 1,2-position is dehydrogenated and a 21-hydrogen converted to a 21-hydroxy, acyloxy, bromine or chlorine. The latter steroid ketals are highly active anti-inflammatory and glucocortical agents.