GB522870A - Improvements in and relating to acids of the etiocholane series - Google Patents

Abstract

522,870. Cyclopentanophenanthrene carboxylic acids. NAAMLOOZE VENNOOTSCHAP ORGANON. Jan. 12, 1939, No. 1100. Convention date, Jan. 13, 1938. [Class 2 (iii)] Cyclopentanopolyhydrophenanthrene carboxylic acids-17 are prepared from compounds of this series which contain in the 17-position an unsaturated lactone ring by treatment with an oxidizing agent in an organic solvent which is resistant to the action of the oxidant. Parent material specified by way of example is digoxygenin. Oxidizing agents which may be used include potassium permanganate and chromium trioxide. A suitable solvent is' acetone. Nuclear double bonds in the parent material are preferably protected during the oxidation by methods such as halogen followed by regeneration afterwards by zinc dust. Free hydroxyl groups may also be protected by esterification or etherification. The acids obtained by the process of this invention may be subjected to further treatment such as the splitting off of water from tertiary hydroxyl groups, and the hydrogenation of double bonds. The acids may be esterified in the carboxyl group and in the hydroxyl groups, free secondary alcohol groups may be oxidized to keto groups, and new double bonds may be formed by halogenation and splitting off of halogen hydride. In an example, digoxigenin is converted into its diacetate and oxidized with potassium permanganate in acetone solution. The neutral fraction consisting of uncharged starting material is separated and re-oxidized. An acid product was isolated and purified by recrystallization. The diacetoxy acid thus produced is substantially saponified with methyl alcoholic potash to give a trioxy-acid of the constitution. The methyl ester of this acid may be prepared by treatment with diazo-methane. Oxidation of the acid by chromic anhydride results in the formation of the corresponding 3:11-diketo acid. Treatment of the trioxy-acid with sulphuric acid in dioxane solution results in withdrawal of water from the tertiary hydroxyl group at position-14 to give dioxy-aetiocholenic acid. Specification 514,437 is referred to. The Specification as open to inspection under Sect. 91 describes also the conversion of dioxyaetiocholenic acid into its methyl ester by treatment with diazomethane and the hydrogenation of this ester in the presence of platinum. The saturated dioxy-aetiocholenic acid produced by saponification with potash was then oxidized to the corresponding diketo acid by treatment with chromium trioxide. From the 3:11- diketoaetiocholenic acid so produced there is also made the # <SP>4</SP>-3:11 diketo-aetiocholenic acid by the addition of bromine to its methyl ester form 3:11-diketo-4-bromo-aetiocholenic acid methyl ester followed by removal of hydrobromic acid by treatment with pyridin e, and saponification. This subject-matter does not appear in the Specification as accepted.