GB896596A - Steroids and their synthesis - Google Patents

Abstract

The invention comprises 11b , 12b -epoxy-pregnane-3a ,20(a or b )-diol and the 3-esters thereof derived from carboxylic acids preferably, having less than 10 carbon atoms, and a process for the preparation of a compound of the formula <FORM:0896596/IV (b)/1> by dehydrobrominating a compound of the formula <FORM:0896596/IV (b)/2> e.g. by means of a basic reagent or with a salt of a strong base and a weak acid such as potassium carbonate, and a process for the preparation of a compound of the general formula <FORM:0896596/IV (b)/3> wherein R represents hydrogen or an acyloxy group, by reducing a compound of the general formula <FORM:0896596/IV (b)/4> wherein R has the above significance, and dehydrobrominating the resulting corresponding 11b -hydroxy-20(a or b )-hydroxy compound. The latter process may be modified in the case where R represents hydrogen by first reducing the 11-keto-12a -bromo-reactant to form a corresponding 11-keto-12a -bromo-20(a or b )-hydroxy compound, and reducing further the latter compound to form an 11b -hydroxy-12a -bromo-20 (a or b )-hydroxy compound. The 11b , 12b -epoxy-pregnane-3a ,20-diol produced by the above processes may be oxidized to 11b , 12b -epoxy-pregnane-3,20-dione, this product may then be treated with hydrogen bromide and bromine to form 4b , 12a -dibromo-11b -ol-3,20-dione, and this product may then be treated with a lithium halide such as the bromide or chloride, in an organic solvent of high dielectric constant such as dimethyl formamide, to form a 12a -halo-11b -hydroxy-progesterone. The reducing agent used in the above processes may be a complex metal hydride-particularly lithium aluminium hydride for reducing both the 11- and 20-keto groups, and sodium borohydride at a low temperature for first reducing the 20-keto group followed by lithium aluminium hydride for the 11-keto group. Detailed examples are given. 12a -Bromopregnane-3a -ol-11,20-dione is prepared by treating the corresponding 3-acetate with perchloric acid in methanol. Specification 843,773 is referred to.