Manser, W. W. T. (1967)
Some biphenyls derived from thebaine.
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(+)-3,4-Dimethoxy-2-(5-methoxy-2-vinylphenyl)-stilbene has been prepared from thebaine. This is a biphenyl with a "buttressed" ortho-me thoxyl group, as well as being substituted in the 6,6-positions by vinyl groups. The rates of racemisation of this compound and of the dibenzyl, obtained by saturating the vinyl groups, give information about this "buttressing" effect. The ultraviolet spectra are also studied.Reaction of thebaine with anhydrous magnesium iodide and reduction of the product with lithium aluminium hydride is found to give (+)-dibenzasonine and not the N-demethylated compound, as had been thought at one time. A number of derivatives have been prepared and characterised. The H-methylazonine is a 2,2-bridged biphenyl with a nine-membered heterocyclic bridging ring, and its methyl ether has also a "buttressed" ortho-methoxyl group. For these reasons, the ultraviolet spectrum and the optical stability of this ether are of interest, Exhaustive methylation of the methyl ether methiodide gives (+)-2,3,31-trimethoxy-6,61-divinylbiphenyl, which polymerises too readily for investigations concerning its optical stability to be carried out. Measurements have been made, however, of the rates of racemisation of the diethylbiphenyl, obtained by hydrogenation of the vinyl groups. The results obtained from the racemisation experiments and the determinations of the ultraviolet spectra of the above compounds are compared with those for related compounds. The above stilbene, dibenzyl, and the diethylbiphenylare also amongst the very few known optically active biphenyls with ortho-alkyl groups, and would be very inaccessible by processes requiring optical resolution.
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Institution: University of London, Bedford College (United Kingdom).