Method for the preparation of 6-alpha fluoro corticosteroids

摘要

A method for producing a 6alpha-fluorinated corticosteroid or derivative thereof by reacting a 17-hydroxy-21-ester epoxide of Formula II with a stereoselective fluorinating agent to stereoselectively form a 21-ester-17-hydroxy 6alpha-fluorinated compound of Formula VII R¹ can be OC(O)-R_d; R⁴ can be C(O)-R_d; R³ can be H or R_d. Each R_d may be the same or different and is independently selected from (C_1-4)alkyl, aryl and heteroaryl. The dashed line can be a single or a double bond. R⁴ may be, for example, acetyl; R³ may be, for example, alpha or beta methyl; R¹ may be, for example, acetate or propionate, The stereoselective fluorinating agent used in the reaction may be, for example, a fluoropyridinium or fluoroquinuclidium compound, for example, Selectfluor(R).