Aspidofractine

Aspidospermine-Aspidofractine-Eburnamine Group. The structural and biosynthetic relationships between the various alkaloids in this group, which are referred to by the authors as the plumerane alkaloids, since they occur exclusively in plants of the subfamily Plumerioidae of the Apocynaceae, have been discussed in some detail.1110... 

The principal bases are all derivatives of kopsinine (L see Table II) and are closely related to the Aspidosperma alkaloids, aspidofractine [1-formylkopsinine (42)], refractine [17-methoxy-l-formylkopsinine... 

The carbon atom, C-3, which in the kopsinine subgroup bears a carbo-methoxyl substituent, has been shown by the mass spectral evidence summarized above not to be in the six-membered ring which contains Nb. That it lies in a strained six-membered ring is indicated by degradation of the carbomethoxyl groups of refractine (CL-A) and aspidofractine (CXLIII-A) to C-3 ketones (CXLIX-P and CXLII-P), whose IR-absorption occurs at unusually low wavelengths (5.76-5.78 p) (Section III, G). 

The NMR-spectra (Table IV) showed that pleiocarpine and aspidofractine were unsubstituted in the benzene ring (note the characteristic downfield doublet with fine structure due to the C-17 aromatic proton which lies close to the V l-acyl group), while refractine had a C-17 methoxyl (position from UV- and NMR-aromatic patterns which resemble those of aspidospermine). The remaining two oxygen atoms so far unaccounted for in each of the alkaloids were located in a carbo-methoxyl group (IR-, 5.74-5.80 /a NMR-, ca. 3.7 S, methyl singlet) (82, 91, 92). 

The abundance of the fragment of mass 124 [249] produced by a hydrogen shift123 is much lower than in aspidospermidine. The typical aspidofractinine pattern facilitated the structure determination of pyrifoline,139 refractidine,139 refractine,140 aspidofractine,140 aspido-filine,141 and kopsinine.123... 

Aspidospermine-Aspidofractine-Eburnamine Group. The leaves of Pandaca minutiftora contain (+)-vincadifformine, which also occurs in the leaves of Amsonia tabernaemontana, together with ten other alkaloids [tabersonine, (+)-l,2-dehydroaspidospermidine, (—)-quebrachamine, lochnericine, ( ) and (—)-vincadine, (-)and ( )-epivincadine, (+)-14,15-dehydrovincadine, and (+)-14,15-dehydroepivincadine] the roots contain the first four alkaloids and ebumamonine. 

Aspidospermine-Aspidofractine Group, An X-ray analysis " of the N -hydrio-dide of (+)-deacetylaspidospermine has verified the prediction that the piperidine ring has a chair conformation and not a boat conformation as it has in the iVb-metho-salt used in the original structure determination. 

Aspidospermine-Aspidofractine-Eburnamine Group Ibogamine-Cleavamine Group... 

Aspidospermine-Aspidofractine-Eburnamine Group. Details of the extraction of the enantiomeric vincadines and their C-16 epimers from the leaves of Amsonia tabemaemontana have been published. ... 

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