GB470247A - Process for the manufacture of pregnendiones - Google Patents

Abstract

Pregnendiones of the formula C21H30O2 are prepared from pregnanol-20-ones-3 by a process which comprises monohalogenation, oxidation, and the splitting off of hydrogen halide. The process may be modified in that esters of pregnanol - 20 - ones - 3 may be halogenated, hydrogen halide removed and the pregnenolone so formed subjected to oxidation to the corresponding pregnendione. The preferred oxidizing agent is chromium trioxide. In an example, monobromo-pregnanol-20-one-3 obtained by the action of bromine on pregnanol-20-one-3 in glacial acetic acid solution is oxidized with chromium trioxide and dehalogenated by boiling for 12 hours with pyridine. The product crystallizes in needles of m.p. 121 DEG C. which can on heating to the melting point be transformed into a polymorphous modification consisting of prisms of m.p. 128 DEG C. Samples have been furnished under Sect. 2 (5) of products made in accordance with the following schedules: (1) a solution of pregnenol-20-one-3 made according to sample 4 of Specification 467,482 in glacial acetic acid is oxidized with chromium trioxide in an ice chest. The product is neutralized and extracted with ether, m.p. 120--125 DEG C.; (2) pregnenol-20-one-3 (cf. example 1) is fused with copper oxide powder at 280--300 DEG C. to give the same diketone mixture as is obtained according to sample (1); (3) a dioxane solution of pregnenol-20-one-3 is made alkaline with caustic potash and treated with hydrogen peroxide. The product is extracted with ether; (4) the brominated pregnenol-20-one-3 produced in the example is dissolved in benzene and then oxidized by shaking with an acid aqueous solution of potassium permanganate. The product is then worked up as in the previous samples. Specification 464,397 also is referred to.