Manufacturing Process

The synthesis is long and complex. For brevity, only the last steps are given here. Refer to the patents cited below for full details. Preparation of 9α-Bromo-11β,17α,21-Trihydroxy-16β-Methyl-4-Pregnene-3,20- Dione 21-Acetate: To a mixture of 620 mg of 17α,21-dihydroxy-16β-methyl- 4,9(11)-pregnadiene-3,20-dione 21-acetate and 330 mg of Nbromosuccinimide in 10 ml of dioxane and 3.2 ml of water cooled to 10°C was added 1.8 ml of cold 1 M aqueous perchloric acid. The mixture was stirred at 15°C for 3 hours. Excess N-bromosuccinimide was destroyed by addition of aqueous sodium thiosulfate and most of the dioxane was removed in vacuo. About 30 ml of water was added and crystalline bromohydrin, 9α-bromo- 11β,17α,21-trihydroxy-16β-methyl-4-pregnene-3,20-dione 21-acetate, was filtered, washed with water, and dried in air. Preparation of 9β,11β-Epoxy-17α-21-Dihydroxy-16β-Methyl-4-Pregnene-3,20- Dione 21-Acetate: To a stirred solution of 100 mg of the 9α-bromo- 11β,17α,21-trihydroxy-16β-methyl-4-pregnene-3,20-dione 21-acetate in 3 ml of tetrahydrofuran and 1 ml of methanol under nitrogen was added 1.02 ml of 0.215N methanolic sodium methoxide. After 10 minutes at 25°C, 0.2 ml of acetic acid was added and the methanol removed in vacuo. The residue was acetylated with 1.00 ml of pyridine and 0.5 ml of acetic anhydride at 60°C for 70 minutes. The mixture was taken to dryness in vacuo, water added, and the product extracted into chloroform. The residue was crystallized from etheracetone to give pure 9β,11β-epoxy-17α,21-dihydroxy-16β-methyl-4-pregnene- 3,20-dione 21-acetate. Preparation of 9α-Fluoro-11β,17α,21-Trihydroxy-16β-Methyl-4-Pregnene-3,20- Dione 21-Acetate: To a solution of 200 mg of 9β,11β-epoxy-17α,21-dihydroxy- 16β-methyl-4-pregnene-3,20-dione 21-acetate in 2 ml of chloroform and 2 ml of tetrahydrofuran in a polyethylene bottle at -60°C was added 2 ml of a 2:1 (by weight) mixture of anhydrous hydrogen fluoride and tetrahydrofuran. After 4 hours at -10°C the mixture was cooled to -60°C and cautiously added to a stirred mixture of 30 ml or 25% aqueous potassium carbonate and 25 ml of chloroform kept at -5°C. The aqueous phase was further extracted with chloroform and the latter phase washed with water and dried over magnesium sulfate. The residue on crystallization from acetone-ether gave pure 9α-fluoro- 11β,17α,21-trihydroxy-16β-methyl-4-pregnene-3,20-dione 21-acetate. Preparation of 9α-Fluoro-11β,17α,21-Trihydroxy-16β-Methyl-4-Pregnadiene- 3,20-Dione 21-Acetate 100 mg of 9α-fluoro-11β,17α,21-trihydroxy-16β- methyl-4-pregnene-3,20-dione 21-acetate was treated with selenium dioxide to produce the corresponding 9α-fluoro-11β,17α,21-trihydroxy-16β-methyl-4- pregnadiene-3,20-dione 21-acetate. Alternately, Bacillus sphaericus may be utilized.