Patent GB-508576-A (GB)
Title: Process for the manufacture of compounds of the cyclopentanopolyhydrophenanthrene series
IPC: C07J5/00
Filed: 1937-09-29
Abstract: 508,576. Cyclopentanopolyhydrophenanthrene compounds. SCHERING AKT.- GES. Sept. 29, 1937, Nos. 26389, 26390, 26394, 26395, and 26398. Convention dates, Sept. 29, 1936, Jan. 13, 1937, March 1, 1937, March 3, 1937, and Sept. 4, 1937. Drawings to Specification. Samples furnished. [Class 2 (iii)] Cyclopentanopolyhydrophenanthrene compounds which contain an aromatic ring A are prepared from compounds of the above series in which ring A is not aromatic but Which contain one or two double bonds in ring A and in 3-position a keto group or an alcoholic hydroxy group, or a functional derivative of the hydroxyl group, or a derivative thereof which contains on the carbon atoms 1, 2, 4, and /or 5 a group capable of being split off with the formation of a double bond, by a thermal and/or a mineral acid treatment. The treatment effects the removal or displacement of the 10-methyl group and then follows the aromatization of ring A. In order that the 10-methyl group may be labile enough to be removed by a heat or mineral acid treatment it is necessary that the starting material should be in one of the forms set out above. When . the rendering aromatic takes place by thermal treatment, the. above starting materials are heated to a temperature of from 260-350‹ C. or above. The heating is advantageously carried out in the presence of high boiling solvents or inert gases. The exact temperature to be employed in each instance depends on the characteristics of the particular compound, and is determined by a preliminary experiment. In this the substance is heated in a closed apparatus, in the presence of carbon dioxide, and by a slow increase of temperature, there is ascertained that temperature at which in an attached glass burette over 50 per cent caustic potash lye methane gas collects. The end of the reaction is indicated by the ceasing of the evolution of methane. The temperature and duration of heating may vary considerably from one substance to another. In addition to the rendering aromatic by splitting off the 10-methyl group, the same effect may be obtained by treatment with a mineral acid whereby the 10-methyl group wanders to another carbon atom not connected with the rings. The mineral acid treatment may take place At normal or elevated temperatures, and if desired in the presence of a solvent. The wandering of the methyl group may also occur when a substituent is split off from carbonatom-1 with the formation of a double bond. The starting materials which are used according to the present invention are conveniently divided into groups as follows: (1) 3-ketones of steroids doubly unsaturated in ring A or . their enol derivatives; (2) 3-ketones of steroids singly unsaturated in ring A or their enol derivatives which in addition passes in ring A a group capable of being split off with formation of further' double bond ; (3) 3-ketones of steroids singly unsaturated in ring A between the carbon atoms 1 and 2, and their enol derivatives; (4) 3-hydroxy compounds of steroids doubly unsaturated in ring A and their derivatives; (6) 3-hydroxy compounds of steroids singly unsaturated in ring A or their derivatives which in addition possess in ring A a group capable of being split off with formation of a further double bond ; (6) 2 : 3-, or 3 : 4-diketones of steroids or their enol-derivatives; (7) saturated 3-ketones of steroids which possess on the 2-carbon atom a group capable of being split off with the formation of a double bond. In the above groups of compounds the ketones always react in the present invention in their enol form, and the term enol derivatives as used above denotes enol esters or ethers. Instead of the free ketones, their reaction products with the customary ketone reagents such as semicarbazide and phenylhydrazine may be used. The above groups of starting materials contain two constitutional features which are essential to all materials which form starting materials for the present invention, viz. : (1) two double bonds in ring A, and (2) an alcoholic or enolic hydroxy group in ring A or a group convertible thereinto. The starting materials may contain variations of the above two characteristics of which there are mentioned (1) the pre-aromatic stage contains in addition one or more double bonds in ring B; (2) the two double bonds in ring A may be produced by the enolization of two keto groups present in ring A ; (3) unsaturated diketones may be used which in the prearomatic stage are in addition unsaturated 'in ring B. As starting materials for group (1) there is mentioned #<1.2.4.5>-cholestadienone-3, and the organic. and inorganic esters of the enolic forms of this and similar ketones such as the acetate, benzoate, and halogen compounds. Also the enol ethers may be used. Such starting materials may be prepared by the process of Specification 500,353. Other compounds within this group are compounds which contain a cyclopentanopolyhydrophenanthrene ring system with a methyl group on carbon atom 10 and the structure of #<1.2.1.5-> cholestadionone-3 such as compounds of the androstane, and pregnane, series and the 3-oxo. cholanic acids. As starting materials for group 2 there. may be employed the intermediate products such as produced as intermediate products in the manufacture of the above doubly unsaturated ketones according to Specification 500,353 and having for example the structure The pyridinium group may be substituted. These starting materials need not be isolated, but their production may be combined with the process of rendering them aromatic. In this case it is preferable to complete the removal of the 10-methyl group by an additional heating of the crude product. Also -in cases of non- isolation of the starting material it is preferable to introduce into the reaction mixture a halogen hydride binding agent such as silver carbonate, silver oxide and calcium carbonate. As starting materials for group (3) there are mentioned #<1.2>-cholestenone-3 and #<1.2>-androstendione- 3 : 17. Starting materials of the groups 4 and 5 mentioned include #<1.2.4.5>-cholestadienol-3 and its esters and ethers. It is also possible to start from the 4-pyridinium compound of #<1.2>-cholestenol-3. Starting materials of group (6) include such 3.4-ketones of steroid compounds as are obtainable according to the process of Specification 500,353, by means of which also 2 : 3-ketones or their enol derivatives are obtainable by splitting off halogen hydride and replacing halogen by an acyl residue. In group (7) there may be employed not only 3-ketones of steroids singly unsaturated in ring A, but also those which possess on carbon atom-2 a group capable of being split off with the formation of a double bond. It is also possible to employ compounds prepared.. by first replacing halogen by an ester, ether, or hydroxyl group, and then removing these groups with the formation of a double bond. The rendering aromatic may take place without the intermediate isolation of the unsaturated compounds. If there are used as starting materials such sterol compounds. as possess on the carbon atom 17 a side chain, this may, if desired, be removed by oxidation. In this oxidation it is necessary to protect the nuclear double bonds by the addition of halogen or halogen hydride. The side chain of aromatic cholene carboxylic acids may be split off by degradation of their.esters, e.g. by way of the corresponding Grignard compounds. Moreover, it is possible to remove the 17 side chain by thermal treatment if desired in the presence of catalysts to form a double bond in the cyclopentano-ring, and to convert the unsaturated compound so produced by the processes described in Specifications 494,773 and 496,799 into a saturated ketone or a saturated alcohol. In examples : (1) the isovalerate of hydroxycholestenone-3 obtained according to example 2 of Specification 500,353 is heated in a stream of carbon dioxide for one hour at 330-340‹ C. The product is taken up with ether, washed with alkali and distilled under reduced pressure to give a light oil which is an aromatic product; (2) the 4-benzoate of #<1.2>-cholestenone-3-ol-4 is heated in a stream of carbon dioxide to 310- 320‹ C., and worked up as in example, (1) to give an aromatic product; (3) the crude #<1.2.4.5>- androstadiene - dione - 3 : 17 obtained according to example (6) of Specification 500,353 is heated in a stream of carbon dioxide for five minutes to 300-310‹ C. and the product worked up as in example (1) to give an aromatic product; (4) the same material is treated as in example (3.) and the aromatic product obtained is subjected to a further purification consisting in dissolving. the light aromatic oil in ether and crystallizing whereby a crystalline product melting at 245-250‹ C. is obtained. A further modification consists in treating the crude, still halogen containing #<1.2.4.5>-androstadiene-dione-3 : 17 in the presence of sodium acetate and worked up as before to give a weak. yellow crystalline powder melting at 235-245‹ C. which is isoequilin. Physiological tests of this material are given and its physical properties are compared with equilin with which it is not identical ; (5) the water soluble ketone containing pyridine and halogen which is isolated in example (6) of Specification 500,353 in addition to #<1.2.4.5>- androstadiene - dione is rendered aromatic directly by heating in carbon dioxide to 300‹ C. The now water-insoluble .product is purified as in example (4).to give an aromatic product. In a modification, the pyridine compound obtained in the pyridine treatment of the dibromoandrostandione is heated in the presence of sodium acetate in carbon dioxide to 300- 320‹ C. for ten minutes. The product is taken up in chloroform and the acid portion isolated. This is distilled in high vacuum to give an aromatic product which on treatment with ether does not separate any iso-equilin crystals ; (6) cholestadienone is heated in a stream of carbon