GB816909A - Improvements in or relating to steroids - Google Patents

Abstract

The invention comprises laevo rotatory cyclopentanophenanthrene compounds of the general formula <FORM:0816909/IV (b)/1> wherein R1 and R2 represent hydrogen or acyl radicals, R1 and R2 being the same or different, and the preparation thereof by dibrominating in the presence of dioxane a compound of the general formula <FORM:0816909/IV (b)/2> wherein R1 and R2 have the above significance, and by monobrominating in the presence of dioxane a compound of the general formula <FORM:0816909/IV (b)/3> wherein R1 and R2 have the above significance. The latter process may be modified in that the mono-bromo reactant is obtained from a compound of the general formula <FORM:0816909/IV (b)/4> wherein R1 and R2 have the above significance, by the process described and claimed in Specification 760,362. The invention further consists in a process for the preparation of a compound having the general formula <FORM:0816909/IV (b)/5> wherein R1 and R2 have the above significance, by didehydrobrominating a dibromo compound of the general formula above, e.g. by the action of an organic tertiary base such as a collidine, or by means of 2,4-dinitrophenylhydrazine, a 2,4-dinitrophenylhydrazone being formed as an intermediate compound. Preferably R1 and R2 represent acetyl radicals, or R1 represents hydrogen and R2 represents an acetyl radical. The dibromination step is preferably carried out with bromine or N-bromo-succinamide in acetic acid and in the presence of hydrobromic acid in acetic acid, and the monobromination step is preferably carried out with bromine dissolved in acetic acid. The dibromo compound of the above general formula may be precipitated from the reaction mixture by the addition of water, and the precipitate is purified by recrystallization from aqueous acetone. In the examples laevo rotatory 2,4-dibromo-17a -hydroxy-21-acetoxy - pregnane - 3,11,20 - trione is prepared from 4 - bromo - 17a - hydroxy - 21 - acetoxy - pregnane-3,11,20-trione and from 17a -hydroxy - 21 - acetoxy - pregnane - 3,11,20 - trione (the 4-bromo-17a -hydroxy-21-acetoxypregnane-3,11,20-trione is obtained by heating 3a ,17a - dihydroxy - 21 - acetoxy - pregnane - 11,20-dione with acetic acid, dioxane, N-bromosuccimide and water), and 1-dehydrocortisone acetate is prepared from laevo-rotatory 2,4-dibromo - 17a - hydroxy - 21 - acetoxy - pregnane - 3,11,20-trione.