反应详情

Hydrocortisone or prednisolone with 20-hydroxy and 20-carboxy groups are known, e.g., (III) methyl (20R)-11β,17, 20-trihydroxy-3-oxo-1,4-pregnadien-21-oate; and (III) is reacted with an alkyl acetylalkanoate or alkyl formylalkanoate in the presence of perchloric acid to produce the corresponding 17,20-carboxycyclic acetal pregnane derivatives, e.g., when methyl acetylbutyrate is used the product is (IV) methyl (20R)-11β-hydroxy-3-oxo-17,20-(methyl,methoxycarbonyl-n-propyl)methylenedioxy-1,4-pregnadien-21-oate; when methyl formylformate is used the product is (V) methyl (20R)-11β-hydroxy-3-oxo-17,20-(methoxycarbonyl)methylenedioxy-1,4-pregnadien-21-oate;