Betamethasone → 9-Fluoro-11beta-hydroxy-16beta-methylandrosta-1,4-diene-3,17-dione

Beteiligte Stoffe

Reaktionsschritte

A solution of 4.7 g (12.0 mmole) of 9-fluoro-16β-methyl-11β,17,21-trihydroxypregna-1,4-diene-3,20-dione in 50% acetic acid (600 ml) was stirred with 18 g of sodium bismuthate at room temperature for 2 hours. The brown suspension was filtered through a bed of deactivated silica powder and washed with 100 ml of 50% acetic acid. The filtrate was concentrated in vacuo to 100 ml, diluted with 100 ml of 20% hydrochloric acid and extracted with chloroform. The chloroform solution was washed with 20% hydrochloric acid and water, dried over anhydrous Na2SO4 and evaporated in vacuo to give a solid. This was dissolved in chloroform and chromatographed on a 30 g silica gel column, eluting successively with chloroform and 1:4 ethyl acetate-chloroform to give 2.6 g of the title compound, melting point 281°-283° C., dec.

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