GB852680A - 2-alpha-methyl-4-pregnenes and method of preparing the same - Google Patents

Abstract

The invention comprises 9a -halo-steroids of the general formula : <FORM:0852680/IV(b)/1> wherein R represents hydrogen or an alkanoyl radical having 2 to 6 carbon atoms, X represents >CHOH or >CO and Hal represents a halogen, and the preparation thereof when X is >CHOH by reacting the required 16a ,21-di-alkanoyloxy-17a -hydroxy-9b , 11b -oxido-2a -methyl-4-pregnene 3,20-dione with a hydrohalide e.g. hydrogen fluoride in a solvent to form a desired compound in which R is an alkanoyl radical, and if desired, either treating this compound with an alkali to obtain an 11b ,16a , 17a , 21-tetrahydroxy-9a -halo-2a methyl-4-pregnene-3,20-dione, or oxidising the said compound to form a compound of the above general formula in which X represents >CO and R is the alkanoyl radical. The invention also includes a process for the preparation of 16a , 21-di-alkanoyloxy-17a -hydroxy-9b ,11b -oxido -2a -methyl-4-pregnene-3,20-dione where the alkanoyl radicals contain 2 to 6 carbon atoms by reacting the required 16a , 21-di-alkanoyloxy-11b , 17a -dihydroxy-9a -bromo-2a -methyl-4-pregnene-3,20-dione with an alkali metal acetate e.g. potassium acetate. In the examples 16a ,21-diacetoxy-17#-hydroxy-9b , 11b -oxido-2a -methyl-4-pregnene-3,20-dione, 16a ,-21-diacetoxy-11b , 17a -dihydroxy-9a -fluoro-2a -methyl - 4-pregnene-3,20-dione,11b ,16a ,17a ,21-tetrahydroxy-9a -fluoro 2a -methyl-4-pregnene-3,20-dione and 16a ,21-diacetoxy-17a -hydroxy-2a -methyl-4-pregnene-3,11, 20-trione are prepared by methods referred to above. The 9a -bromo-steroids of the above general formula may also be prepared by a series of reactions illustrated in the following reaction scheme: <FORM:0852680/IV(b)/2> <FORM:0852680/IV(b)/3> <FORM:0852680/IV(b)/4> <FORM:0852680/IV(b)/5> <FORM:0852680/IV(b)/6> <FORM:0852680/IV(b)/7> <FORM:0852680/IV(b)/8> <FORM:0852680/IV(b)/9> <FORM:0852680/IV(b)/100> <FORM:0852680/IV(b)/111> wherein R has the above significance. The reaction scheme is exemplified in the examples wherein compound I is acetylated with acetic anhydride to form a compound II, compound II is dehydrated with phosphorus oxychloride to form a compound III, compound III is treated with acetic acid to form a compound IV, compound IV is treated with ethyl oxalate in the presence of sodium methoxide to form compound V, compound V is treated with methyl iodide to form compound VI, compound VI is treated with sodium methoxide to form compound VII, compound VII is treated with sulphuric acid to form compound VIII, compound VIII is acetylated to form compound IX, and compound IX is treated with N-bromoacetamide to form compound X.ALSO:A therapeutic composition suitable for use parenterally, orally or topically contains as the active ingredient a 9-halo-steroid of the general formula: <FORM:0852680/VI/1> wherein R represents hydrogen or an alkanoyl radical having 2 to 6 carbon atoms, X represents a drivalent radical of the formula-CHOH-or >C=O and Hal represents bromine, chlorine, iodine or fluorine. Thus the composition may be in the form of a tablet, capsule, suspension, solution, ointment or cream.