| 摘要 |
A process for the preparation of corticosteriod esters of the formula <IMAGE> (I) in which ---- signifies that a double bond can be present; X is hydrogen, chlorine or fluorine; R1 is hydrogen, fluorine, chlorine or methyl, which may be either alpha or beta ; R2 is halogen, oxo or hydroxyl; or R3 is hydrogen, alpha -methyl or beta -methyl; or R2 and X jointly form an epoxide group; R4 is an acyl group of the formula RCO, in which R is one of the following (i) an alkyl group containing 1 to 16 carbon atoms, whether straight-chained, branched or cyclic; (ii) an aralkyl group of 7 to 8 carbon atoms; (iii) a phenyl group; R5 is hydroxyl or R6; where R6 is hydrogen, one or two halogen atom substituents or OR7, where R7 is an acyl group of the formula R'CO in which R', which can be identical or different to R in the same molecule, is one of the following: (i) an alkyl group of 1 to 16 carbon atoms, whether straight-chained, branched or cyclic; (ii) an aralkyl group of 7 to 8 carbon atoms; or (iii) a phenyl group. which comprises esterifying a compound of the formula <IMAGE> (III) wherein X, R1, R3 and R5 are as defined above, and R8 is trihaloacetate, halogen or oxo, or jointly forms an epoxide group with X; at the 17-position only, or at the 17- and 21-positions when R5 in formula III is hydroxyl, the said esterification being carried out with the anhydride of the acid containing the group desired. |
