Sinomenol dimethyl

The distillation of sinomenol with zinc-dust affords phenanthrene, and the former was soon recognized as a dimethoxydihydroxy-deriva-tive of the latter [9]. Diacetyl- and dibenzoylsinomenol give the corresponding quinones, [m, R = Ac] and [m, R = CO] respectively, on oxidation with chromic acid, indicating that the 9 10-positions in sinomenol are substituent-free. Hydrolysis of these quinones yields sinomenolquinone [in, R = H], methylation and ethylation of which affords dimethyl- [m, R = Me] and diethylsinomenolquinone [m, R = Et] respectively [9, 12]. 

Following the establishment of positions of the groups in dimethyl-sinomenol the structures [ix] [17] and [x] [18] having an oxygen function at position 5 became untenable, and the structure [xi] was proposed [19-20], This was subsequently modified to the generally accepted structure [i] by Goto and Sudzuki [12], when it was discovered that sinomenine contains a hydrolysable enol ether group. 

Dimethoxy-4 6-dihydroxyphenanthrene (sinomenol) [xc] is obtained when sinomenine [lxxxix] [98-99], and when the three sinomenine methines, [xci], [xoii], and [xcm] [100], are boiled with 66 per cent, potassium hydroxide. It gives a dimethyl ether [dimethyl-sinomenol] [98], also accessible from sinomenine methyl ether [101], and a dibenzoyl-derivative [98], which also results when sinomenine or the achro-methine [xci] is heated with benzoic anhydride at 160° 0. [100-102]. 

A greatly improved conversion of (-)-sinomenine into (+)-morphine with an overall yield of 28% has been recorded. Reduction of sinomenine to sinomenol followed by treatment with polyphosphoric acid gives (+)-dihydrocodeinone, the dimethyl ketal of which suffers elimination of methanol to give dihydrothebaine, which can be converted by standard procedures into (+)-codeinone, and hence into (+)-codeine and (+)-morphine. 

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