THE THEBAINONES AND THEIR DERIVATIVES

Thebainone-A [v] results from thebaine or codeinone when these bases are reduced with stannous chloride and concentrated hydrochloric acid under conditions different from those required for the preparation of metathebainone, which nevertheless is formed at the same time in small amount [1]. (A small amount of a by-product m.p. 156-158° C. was also obtained during one reduction of thebaine [1].) Thebaine hydrochloride and stannous chloride in acetic acid at 160° C. yield methebenine [1] (see Chap. XXV). 

Thebainone-A can also be prepared by the catalytic rearrangement of codeine [vi] under the influence of palladized charcoal at 80° C. [2] by the hydrolysis of thebainone-A enol methyl ether [vn] (prepared by the rearrangement of codeine methyl ether on heating with sodium ethoxide) [3] by the hydrolysis of /j-ethylthiocodide [vm] (obtained by the action of sodium ethoxide on bromo- or /3-chlorocodide) [4-8] (see Chap. XVII) and, in small amount, by the hydrolysis of dihydrothe-baine- [iv] [3]. 

Catalytic reduction of thobainono-A proceeds readily with formation of dihydrothoboinono [ix], which is formed in oonsidorable quantity in 

Thebainone-A enol methyl ether [vn] is described in Chapter XIV. It is the enol ether directly related to thebainone-A, which it yields so readily on hydrolysis that no salts of the enol ether can be prepared even in anhydrous media [3]. 

O-desmethylthebainone-A [xi], the morphine analogue of thebainone-A, results from the catalytic rearrangement of morphine in the presence of palladized charcoal at 80° C. [2] it is doubtless identical with the ketone obtained by the hydrolysis of /3-ethylthiomorphide [14-15], Although it cannot be methylated to thebainone-A, on reduction it yields O-desmethyldihydrothebainone [xn], which gives dihydrothe-bajnone on treatment with diazomethane [2]. 

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The thebainones and their derivatives are phenols and can be oxidized to dimolecular substances by gold or silver salts or potassium ferricyanide (compare the oxidation of morphine to pseudomorphine, Chap. III). 

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