Pseudokobusine

Among the first hetisine alkaloids isolated were nominine (1) [2], kobusine (2) [3], pseudokobusine (3) [4], hetisine (4) [5], and ignavine (5) [6] in the 1940s and 1950s (Chart 1.2). Since these early isolations, over 100 distinct hetisine alkaloids have... 

Pseudokobusine Aconitum orientate Mill Acorientine Orientinine... 

By virtue of the previous correlation (93) of kobusine with pseudokobusine, structure 87 was assigned to pseudokobusine. The latter was also isolated along with kobusine from A. yesoense Nakai and A. lucidusculum Nakai (97). The chemistry of kobusine and pseudokobusine has been discussed (6) in a previous chapter in this treatise. 

Vakognavine is the first example of an N, C-19-seco-diterpenoid alkaloid reported and an interesting alkaloid for biogenetic speculation. The authors (116) suggested that the C-19 aldehyde may be a plausible alternate to the pseudokobusine structure as an intermediate in the biosynthesis of the modified atisine-type skeletons such as hetisine. The C-19 hydroxyl of vakognavine hydriodide (119) is reminiscent of the oxazolidine oxygen of isoatisine. 

Kobusine (C20H27NO2) and Pseudokobusine (C20H27NO3). The structure of kobusine seemed reasonably secure on chemical and spectroscopic grounds. However, the configuration of the hydroxy-groups on the bicyclo[2,2,2]octane system was uncertain. An X-ray analysis of kobusine methiodide has now shown it to have structure (9). It follows that pseudokobusine has structure (10) (ref. 1, pp. 182—185). 

Acetylation of pseudokobusine gave besides the normal 0-acetate, an V-acetyl-seco derivative (CCXX) [1596, 1700 cm i 299 (e 33) ... 

The correlation of kobusine and pseudokobusine has been effected by still other routes. Dihydropseudokobusine (CCXXXV) on reduction with sodium in propanol gave dihydrokobusine (CCXXXVI). Also, reduction of either kobusine or pseudokobusine with sodium in propanol gave the same alcohol (CCXVII). 

Alkaloids of Aaonitum yesoense Nakai.- Takayama and coworkers S have reported an extensive reinvestigation of the alkaloids of this species. Kobusine (92), pseudokobusine (93), lucidusculine (94), neoline (19), chasmanine (29), mesaconitine (10), and jesaconitine (13) had previously been reported from A. yesoense. These com-... 

Pseudokobusine, like kobusine but unlike hetisine, gives a crystalline diacetyl derivative, and like both kobusine and hetisine, a dihydro compound the properties of this and of its hydrochloride correspond so well to those of dihydrohetisine and its hydrochloride that the possibility of identity of the substances will have to be examined. Dihydropseudokobusine, however, may be characterized as a triacetyl derivative, a reaction not hitherto recorded for dihydrohetisine. In boiling thionyl chloride, two hydroxyl groups of pseudokobusine are replaced and a dichloro compound results. 

---