Patent GB-843213-A (GB)
Title: Process for the production of pregnadienes
IPC: C07J5/00
Filed: 1955-08-03
Abstract: Cyclopentanophenanthrene compounds of the general formula: <FORM:0843213/IV(b)/1> wherein R represents hydrogen or an acyl group and X represents <FORM:0843213/IV(b)/2> are prepared by di-dehydrohalogenating a normal or allo-pregnane-2,4-dibromo-11X-17 a -ol 21-OR-3,20-dione, wherein R and X have the above significance, with a dehydrobrominating agent.  The above process may be modified in that the 2,4-dibromo reactant is prepared by brominating a normal or allo-pregnane of the formula:  <FORM:0843213/IV(b)/3> wherein R and X have the above significance.  The acyl group is preferably the formyl group or an alkanoyl group having not more than 8 carbon atoms such as the acetyl, propionyl, butyryl or valeryl groups.  The 21-ester group in the resulting 1,4-pregnadiene may be hydrolysed to form the corresponding free 21-hydroxy compound with an acid or base. The di-dehydrohalogenation step may be carried out by refluxing with collidine, quinaldine or dimethylaniline.  The 21-esters of 11 a -hydroxy-pregnadienes of the above general formula may be prepared in a similar manner and then the 11 a - or 11BETA-hydroxy 1,4-pregnadienes may be oxidised to the corresponding 11-keto-1,4-pregnadienes, and, if required, hydrolysed to the corresponding 21-hydroxy compounds.  The hydrolysis of the 21-ester group may be carried out before the oxidation of the 11 a - or 11b -hydroxy group.  The bromination is preferably carried out in acetic acid or other inert organic solvent.  The hydrolysis of the 21-ester group may be hydrolysed with an alkali metal base such as a carbonate, bicarbonate or hydroxide, in a solvent such as methyl or ethyl alcohol.  In the examples:-(1) allopregnane-and pregnane-17 a ,21-diol-3,11,20-trione 21-acetate are brominated to form the corresponding 2,4-dibromo compounds and are didehydrobrominated to form 1,4-pregnadiene-17 a , 21-diol-3,11,20-trione 21-acetate; the 21-acetate is then hydrolysed to the corresponding 21-hydroxy compound; (2) allopregnane- and pregnane-11b ,17 a ,21-triol-3,20-dione 21-acetate are brominated to form the corresponding 2,4-dibromo compounds and are then di-dehydrobrominated to form 1,4-pregnadiene-11b ,17 a ,21-triol-3,20-dione 21-acetate; the 21-acetate is then hydrolysed to the corresponding 21-hydroxy compound; (3) pregnane-11 a ,-17 a ,21,triol-3,20-dione 21-acetate is brominated to form 2,4-dibromopregnane-11 a , 17 a ,21-triol-3,20-dione 21-acetate, the 2,4-dibromo compound is di-dehydrobrominated to form 1,4-pregnadiene-11 a ,-17 a ,21-triol-3,20-dione 21-acetate and hydrolysed to the corresponding 21-hydroxy compound, and the 21-hydroxy and the 21-acetate compound are then oxidised with chromium trioxide, N-bromacetamide or N-bromo-succinimide to form 1,4-pregnadiene-17 a ,21-diol-3,11,20-trione and the 21-acetate thereof respectively; (4) pregnane-17 a ,21-diol-3,11,20-trione 21-(21,41-dichlorophenoxy-acetate) is brominated to form the corresponding 2,4-dibromo-compound and is then di-dehydrobrominated to form 1,4-pregnadiene-17 a ,21-diol-3,11,20-trione 21-(21,41-dichlorophenoxyacetate); (5) allopregnane and pregnane-11b ,17 a ,21-triol-3,20-dione 21-(41-chlorophenoxyacetate) are brominated to form the corresponding 2,4-dibromo-compounds and are then dehydrobrominated to form 1,4-pregnadiene-11b ,17 a ,21-triol-3,20-dione 21-(41-chlorophenoxyacetate).  Allopregnane - 17 a ,21 - diol - 3,11,20 - trione 21-acetate and allopregnane-11b ,17 a ,21-triol-3,-20-dione 21-acetate are prepared by hydrogenating the corresponding 4-pregnene compounds in the presence of palladium or charcoal.  Pregnane - 17 a ,21 - diol - 3,11,20 - trione 21 - (21,41-dichlorophenoxyacetate) is prepared by brominating pregnane-3 a -17 a ,diol-11,20-dione, treating the resulting 21-bromo compound with potassium 2,4-dichlorophenoxyacetate to form pregnane - 3 a ,17 a ,21 - triol - 11,20 - dione 21-(21,41-dichlorophenoxyacetate) and oxidising the last mentioned compound with N-bromosuccinimide. Allopregnane- and pregnane- 11b ,17 a ,21-triol-3,20-dione 21-(41-chlorophenoxyacetate) are prepared by treating allopregnane- and pregnane-11b , 17 a ,21-triol-3,20-dione with 4-chlorophenoxyacetyl chloride in the presence of pyridine. Specifications 735,429, 742,888 and 761,351 also are referred to.