Mifepristone has been synthesis via selective protection of the 3-Keto of the 4,9-estradiene-3-17-dione, followed by epoxidation, Grignard reaction, and hydrolyses - dehydration, in 29.7 % yield. In the selective protection of the 3-Keto, the p-toulenesulfonic acid - collidine salt was used as catalyst. The crude yield of the epoxidation with 30% H2O2 and Hexafluoroacetone was 97% Fig 1 shows a probable schematic diagram for the syntheses of Mifepristone.

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