GB973147A - Process for the oxidation of 20-hydroxy-pregnanes - Google Patents

Abstract

18:11-lactones of saturated or unsaturated 11b -hydroxy-20-oxopregnane-18-acids are prepared by oxidation of the corresponding 20-hydroxy compounds with a compound of hexavalent chromium in acid solution, particularly chromium trioxide and sulphuric acid in acetone. The starting materials may be further substituted, e.g. by esterified hydroxyl groups, free or ketalized oxo groups, alkyl groups or halo atoms, in any of positions 1-10, 14-17 or 21, particular starting materials being of the general formula <FORM:0973147/C1/1> in which X represents hydrogen, fluorine, chlorine or bromine, which may be converted to the corresponding D 4-3-ketones during the process. Examples are given. The 18, 11-lactone of D 5-3-ethylenedioxy-9a -bromo-11b , 20b -dihydroxy-pregnene-18-acid is prepared by forming the 18,20-lactone of D 4-3-oxo-11a -tosyloxy-20b -hydroxy-pregnene-18- acid from the 11a -ol converting this to the 18, 20-lactone of D 4,9(11)-3-oxo-20b -hydroxy-pregnadiene-18-acid, treating this with N-bromo-succinimide to give the 18, 11-lactone of D 4-3-oxo-9a -bromo-11b , 20b -dihydroxy-pregnene-18-acid and ketalizing this. The 18, 11-lactone of D 5-3-ethylenedioxy- 9a - fluoro - 11b , 20b - dihydroxypregnene-18-acid is prepared by ketalization of the corresponding D 4-3-one, itself prepared from the 18, 20-lactone of D 5-3-ethylenedioxy-9, 11b -oxido-20b -hydroxy-pregnene-18-acid and hydrofluoric acid. The corresponding 9a -chloro compounds are prepared similarly. These processes are also described in more general terms, intermediates in the transbutonization process being 11-ones. Specifications 973,143, 973,144, 973,145 and 973,146 are referred to.