A synthesis of thebaine and northebaine has been developed from codeinone dimethyl ketal and norcodeinone dimethyl ketal. Attempts to prepare the ketal by the action of trimethyl orthoformate on codeinone led only to 8-methoxyd6-dihydrothebaine. However, addition of methyl hypobromite to A6-dihydrothebaine gave 7-bromodihydrocodeinone dimethyl ketal, and dehydrobromination of the latter gave codeinone dimethyl ketal. Acid-catalyzed elimination of methanol resulted in thebaine, but this reaction was erratic and codeinone was an accompanying by-product. Good yields of thebaine from codeinone dimethyl ketal were achieved by using phosphorus oxychloride. Northebaine was obtained in the same way from norcodeinone dimethyl ketal, the latter being prepared by the action of cyanogen bromide on codeinone dimethyl ketal followed by lithium aluminum hydride hydrogenolysis of the N-cyano derivative to the nor compound. A method for separating ketonic, a,/$ unsaturated ketonic, and nonketonic alkaloidal material based on formation of the bisulfite addition compounds is described.hebaine is prodigious among the morphine alka-
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