| 摘要 |
1375770 Prednisolone derivatives SDC STEROIDI DEVELOPMENT CO ESTABLISHMENT 27 Sept 1972 [7 July 1972] 44616/72 Heading C2U The invention comprises a process for preparing compounds of formula (wherein Y and Z are each hydrogen or a substituent) from compounds of formula (wherein X is hydrogen or acyl) by the successive steps of (i) exhaustive acylation to form the corresponding 11,17,21-triacylate; (ii) elimination of HOAc (e.g. by heating with an anhydrous alkali metal acetate) to form the corresponding #<SP>16</SP>-11,21-diacylate; (iii) oxidation (e.g. with OsO 4 , or with KMnO 4 in a continuous flow reactor with a reaction time of 3-seconds) to form the corresponding 16α,17α,diol-11,21-diacylate; (iv) ketalization with acetone to form the corresponding 16,17-acetonide-11,21-diacylate; and (v) basic hydrolysis to give a compound I. As an optional further step, a compound I may be acid hydrolysed to give the corresponding 11,16,17,21-tetrol. Exemplified compounds I are triamcinolone acetonide and fluocinolone acetonide. |
