| 摘要 |
<p>6 alpha -fluorpregnanes (I), where the dotted line between positions 1 and 2 represents a single or double bond; R1 is OH, OCOR2, X, SO3R3, or an (R7)(R8)(R9)SiO- group, where X is halogen, R2 and R3 are C1-6 alkyl or phenyl optionally substituted by C1-4 alkyl, and R7, R8 and R9, equal or different, are C1-6 alkyl or phenyl optionally substituted by C1-4 alkyl, can be obtained by means of a high stereoselectivity process comprising reacting a 3-(trisubstituted)silyloxy-pregna-3,5-diene (IV) with a fluorinating agent selected among N-fluorosulfonimides and N-fluorosulfonamides. The 6 alpha -fluorpregnanes (I) are intermediates for the synthesis of steroids useful as anti-inflammatory and anti-asthmatic agents. <CHEM></p> |
