Thebainone dihydromethine

Hydrogenation of thebainone-B methine proceeds rapidly, with the absorption of two moles of hydrogen and production of /S-dihydro-thebainone dihydromethine [xvin] [20-21] this is the only case in morphine series in which reduction of an 8 14 double bond results in configuration of the asymmetric carbon atom C-14 in the abnormal manner. The possibility of thebainone-B methine having the isomeric structure [xix] is ruled out by the ultra-violet absorption spectrum, which is closely similar to that of /S-codeimethine [xx] and dissimilar from that of a-codeimethine [xxi] (Kg. 9) [21]. 

Thebainone-B dihydromethine [xxm] may be obtained by the hydrolysis of dihydrothebaine- dihydromethine [xxiv], which is formed from thobaino methiodido by reduction with sodium in liquid ammonia [23],... 

Thebainone-B dihydromethine [xxm] was expected to give 8 14-dehydrothebenone [lx] on degradation, but partial isomerism probably occurred in alkaline solution as the product was clearly a mixture, doubtless of [lx] and [lxi] [23]. 8 14 9 10-Tetradehydrothebenone [lxii] is produced by the hydrolysis of 6-methoxythebentriene [lxiii] [21] (see Chap. XIV). 

Thebainone-A may be oxidized to bis-1 l -thebainone-A by 10 per cent, gold chloride in 10 per cent, hydrochloric acid. This may be hydrogenated to bis-1 l -dihydrothebainone, which is also obtained by the oxidation of dihydrothebainone with silver nitrate [52], Bis-1 l -dihydrothebainone yields bis-1 l -dihydrothebainone methine and dihydromethine, (+) bis-1 l -(9 10-dehydrothebenone) and (+) bis-1 1 -thebenone, the antipodes of which may all be prepared from bis-1 l -desmethoxydihydrosinomenine [62], on degradation. 

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