Alkaloids Containing Two Diphenyl Ether Linkages

Two additional sources for oxyacanthine (LXXII) have been found the alkaloid was isolated from Berberis tschonoskyana Regel (44) and from Magnolia compressa Maxim. (Michelia compressa Maxim.) (45). 

Oxyacanthine (LXXII) was assigned the SR-configuration by means of available data on the reductive cleavage of 0-methyloxyacanthine (LXXIII) (Section I) (9). 

Obaberine (SR-LXXIII) (mp 139°-140°) was isolated together with obamegine and oxyacanthine from Berberis tschonoskyana (44). 

Various reactions of obaberine, such as the Hofmann degradation and reductive cleavage, suggested that it is identical with 0-methyloxy-acanthine (LXXIII) (46). The identity was confirmed when, in the course of this work, 0-methyloxyacanthine was obtained for the first time in crystalline form and the melting point of a mixture of the two specimens was determined. 

The conversion of the three alkaloids to 0-methyloxyacanthine (LXXIII) (1) showed that they have the SR-configuration (9). 

This group of alkaloids is formed in the plant (Faltis theory) by a double enzymatic dehydrogenation of two molecules of norcoclaurine (II). It is necessary to perform this bimolecular dehydrogenation in three different ways in order to provide correct skeletal structures for the known bis-benzylisoquinoline alkaloids of this group. First, the two diphenyl ether linkages may be formed by the dehydrogenation occurring between the 

Secondly, the bimolecular dehydrogenation of norcoclaurine (II) can take place between the 12-hydroxyl groups and the 8-hydrogens to form the symmetrical structure XXIII. The alkaloids isochondodendrine, 

Thirdly, if the bimolecular dehydrogenation of II takes place between the 12-hydroxyl and 8 -hydrogen on the one hand and between the 7-hydroxyl and the ll -hydrogen on the other the structure XXIV is formed. To this class belong the alkaloids bebeerine, chondrofoline, curine, tubo-curarine chloride, and chondocurine. 

Tomita and coworkers (126) were able to prove (p. 215) that berbamine, which is the structural isomer of oxyacanthine, is represented by the formula XXXI. Therfore the structure of oxyacanthine must be XXVI. 

Oxyacanthine is reported to have some sympathicolytic action (19). In dogs, after chloralose anesthesia, double vagatomy in the neck, and artificial respiration, this alkaloid counteracts the action of adrenaline on the blood pressure and renal constriction. When oxyacanthine hydro- 

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The alkaloid was found to contain two methylimino groups, seven methoxyl groups, and one diphenyl ether linkage. Oxidation of fetidine with permanganate gave l-oxo-2-methyl-6,7-dimethoxy-l,2,3,4-tetra-hydroisoquinoline. Reduction with sodium in liquid ammonia furnished (+ )-laudanosine (XLI) and (-I- )-laudanidine (XXXII). Thus it was concluded that the alkaloid is represented by formula LII, or a variation of this formula having the ether linkage attached to C-10 or C-14. 

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