Improved synthesis of a protected 11-oxoestrone
Résumé
An improved synthesis of 11-oxoestrone-3-acetate-17-ethyleneketal is reported. Adjustments are proposed for the oxidation of estrone by 2,3-dichloro-5,6-dicyano-1,4-benzoquinone into 9(11)-dehydroestrone. A complete hydroboration-oxidation of the resulting ketal, by means of borane-methylsulfide complex, gives the corresponding 11-hydroxy derivative. This latter compound is then acetylated for successful oxidation with pyridinium chlorochromate on alumina. The overall yield is 30%. © 1995.