Condylocarpine-type alkaloids

Third, and most important, direct structural information may be obtained. It is often possible, especially when the method is used in conjunction with NMR and with deuteration, to determine the exact position of substituents and also to establish the nature of new skeletons without in many cases having to make any extensive degradations. The importance of this will be seen particularly in the sections on aspido-fractinine-, aspidoalbine-, and condylocarpine-type alkaloids (Sections III, IV, and V), whose structures do not lend themselves to easy degradation by classical methods, owing to the presence of quaternary centers. 

Tubotaiwine (168), a condylocarpine-type indole alkaloid, obtained from Tabernaemontana dichotoma of Sri Lankan origin, was subjected to a stereochemical investigation with extensive NMR studies involving NOE dif-... 

Although the alkaloids of Aspidosperma populifolium are preponderantly of the aspidofractinine type, one of them (CCXXIV-A) was clearly excluded from this class by its IR- (ACHCl3 5.98 and 6.25 p, MeC C—C=C) and UV- (Table III) spectra. The latter was somewhat similar to that of condylocarpine (CCXV), the differences being accountable to an aromatic methoxyl group whose presence was indicated by the NMR-spectrum (OCH3, 3.74 S, coincident with the CC Me peak 3 aromatic protons only). A further difference from condylocarpine and akuammicine lay in the presence of an ethyl (0.70 S, triplet) rather than ethylidene side chain. 

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... 

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