Urea, (2,2-diethoxyethyl)- → 21-Chloro-16alpha-(2,2-diethoxyethoxy)-9-fluoro-11beta,17-dihydroxypregna-1,4-diene-3,20-dione

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Reaction Conditions

Reaction Steps

A solution of 2,2-diethoxy-1-diazoethane (prepared from 0.0935 mole of N-2,2-diethoxyethyl urea by the method of W. Kirmse and M. Buschhoff, Chem. Ber., 100, 1491 (1967)) in 300 ml of 3:2 ether-pentane is diluted with 100 ml of methanol and cooled to 0°C. A total of 2.5 g of 21-chloro-9-fluoro-11β,16α,17-trihydroxypregna-1,4-diene-3,20-dione, 16,17-cycloborate is added in portions until nitrogen evolution ceases. The solvent is removed in vacuo and the residue is dissolved in chloroform and chromatographed on an 80 g -- silica gel column. Elution with chloroform gives 2.16 g of TLC pure material that is recrystallized from acetone-hexane to give 1.75 g of 21-chloro-16α-(2,2-diethoxyethoxy)-9-fluoro-11β,17-dihydroxypregna-1,4-diene-3,20-dione, melting point 200°-202°C.

Provenance & Evidence