Alkaloids Related to Akuammicine

There are three known types of alkaloid which contain the a-methyleneindoline carboxylic ester chromophore, those which are typified by tabersonine (XCII), akuammicine (CCXXV), and condylocarpine (CCXV), respectively. The first is excluded since it has a C20 skeleton as against the C19 skeleton of mossambine. The molecular formula of 

It is of interest that iVb-metho salts of mossambine sometimes exhibit a carbonyl band in the IR-spectrum (1698 cm-1), pointing to a possible Hofmann cleavage (122, 121). 

Among the seven alkaloids that were isolated from Diplorrhyncus mossambicensis was a base C19H20N2O with unusually high rotation (— 1230° in chloroform). Its carbonyl activity and UV-spectrum (A, 242, 299, 360 mp) were reminiscent of fluorocurarine (Chapter 15, Refs. 133-137) and comparison of the methochloride of the new base with fluorocurarine demonstrated complete identity. The alkaloid is therefore norfluorocurarine (CCXL, 116, 132). 

Three related alkaloids have been found in the leaves of Pleiocarpa tubicina. One is the known compound 19,20-dihydroakuammicine (CCXXXVII, 70, 69, 137a), while the other two, tubifoline and tubi-folidine, are respectively its decarbomethoxy derivative, the indolenine, CCXXXIX, and the corresponding dihydroindole, CCIII (119). A compound strychene of structure CCXXXIX has been prepared from dihydrodeoxyisostrychnine (67, 125). 

The bark of Aspidosperma compactinervium, contains an alkaloid, compactinervine, whose high negative rotation, UV- (A 237, 297, 331) and IR-spectra (conjugated C02Me, 6.04 p conjugated double bond, 

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