Acetic Acid → HCID 22798537, compound

Participants

Reaction Steps

A mixture of the 17α-hydroxy-21-acetoxy-11β-trimethylsiloxy-9α-fluoro-pregn-1,4-diene-3,20-dione from Example 26 (20.6 g) dichloromethane (50 ml) and acetic acid (20 ml) was treated with trifluoro-acetic anhydride (20 ml) for a period of 5 hours at 25°. The reaction mixture was diluted with methyl-isobutylketone (200 ml) and extracted with sodium bicarbonate solution (500 ml) and then with water (200 ml). The organic layer was dried over sodium sulfate, and evaporated to dryness under reduced pressure. The residue was amorphous, homogenous in TLC (BPB, silica plates No. 254). Crystalline 17α,21-diacetoxy-11β-trimethylsiloxy-9α-fluoropregna-1,4-diene-3,20 -dione (compound 53) was obtained directly from the residue by trituration with methanol.

Provenance & Evidence