Neopine hydrobromide

An intractable phenolic substance is produced by the prolonged boiling of neopine hydrobromide with Raney nickel in alcohol [7], Lithium aluminium hydride reduction of p-toluenesulphonylneopine gives desoxyneopine (desoxycodeine-D) [vm] [8] (see Chap. IX). 

Treatment of neopine hydrobromide in aqueous formic acid with hydrogen peroxide affords 1-bromoneopino, which can be degraded to 1-bromo / . oodeimethine [2],... 

Thebainone-B [xm] is best prepared as its hydrobromide by the hydrolysis of dihydrothebaine- [iv] with alcoholic hydrobromic acid [13], but it is also formed by the hydrolysis of the same base with mineral acid in aqueous solution [13], a reaction first reported to give an ill-defined substance, isocodeine [18], and later said to give a coloured, varnish-like substance [3]. Thebainone-B appears to be stable only as its salts in the dry state, the damp salts and free base readily degenerating to brown tars [13]. The ultra-violet spectra of thebainone-A, /3-thebainone-A, and thebainone-B closely resemble those of dihydrothebaine- and codeine, whilst that of thebainone-C is widely different (Fig. 8) and the frequencies of the carbonyl-absorption in the infra-red indicate that whereas thebainone-A and /3-thebainone-A are a /3-unsaturated ketones, the unsaturation is /3 y- in thebainone-B and thebainone-C [13]. On this evidence thebainone-B is allotted the structure [xm]. It can be catalytically reduced to dihydrothebainone [ix], in which the configuration at C-14 is the same as in codeine [13] (cf. the production of dihydrocodeine on reduction of neopine [xiv] [19]). 

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