1959 年 79 巻 10 号 p. 1260-1267
In order to elucidate the structure of O-methyl thalicberine, cleavage reaction of it (I) with metallic sodium in liquid ammonia was carried out. It was thereby found that (I) is bisected almost quantitatively into d-O, O, N-trimethylcoclaurine (II) and d-N-methylisococlaurine (V). The same reaction of O-ethylthalicberine (VII) was also found to effect almost quantitative cleavage into d-N-methylisococlaurine (V) and d-O-ethylarmepavine (VIII). These experiments have proved that the one phenolic hydroxyl in thalicberine is present in the position ortho to the ethertype oxygen binding the benzyl groups (formula (VI)). Of the two phenolic hydroxyls in the bisected phenolic base, d-N-methylisococlaurine (V), one in the benzyl portion was naturally formed by cleavage of the ether linkage forming the diphenyl ether structure and the other hydroxyl in 6-position of the isoquinoline ring must also have been formed by cleavage of oxygen bridge forming the diphenyl ether since O-methylthalicberine (I) possesses four methoxyls. The other position at which this ether linkage is bonded was assumed to be 8-position in the isoquinoline ring considering biogenesis of the natural bases of this type and from all other bases of the oxyacanthine-berbamine series.
Based on these and other experimental results, the formula (XVIII) is forwarded for thalicberine and formula (XIX) for O-methylthalicberine. It was later proved that the spatial arrangement (optical direction) of the two asymmetric centers in (XVIII) and (XIX) is (+, +) in both.