Lupanine structure

Kirch et al. (1995) examined individual plants collected in Corsica, Elba, Sardinia, Liguria, and Provence for alkaloids and observed four groups, one characterized by sparteine [119] (see Fig. 2.34 for structures 119-124), one characterized by lupanine-based alkaloids [120 and 121], one that had a very low level of alkaloid production, and one that lacked sparteine and lupanine-based compounds, but did accumulate other alkaloids such as anagyrine [122], ammodendrine [123], and compounds based on cytisine [124], their outlier group. The distribution of these four chemotypes is presented in Table 2.10. 

The crystal structures of lupanine (15) and its derivatives were investigated as free bases (54-56) as well as protonated forms (57-60). In all structures examined ring A was a half-chair. The conformation of ring C is a boat, and rings B and D have chair conformations. In other cases rings B, C, and D had chair conformations (54-57,59). Lupanine derivatives mamanine (16) and pohakuline (17), possible metabolites in the biosynthesis of sparteine, were studied by... 

Other isolation studies are summarized in Table l 2-7 five new alkaloids have been obtained this year. Cell suspension cultures of Baptisia australis, Lupinus polyphyllus, and Sarothamnus scoparius produce lower yields of alkaloids than the differentiated plants, with lupanine as the main component8 (cj Vol. 11, p. 63). Examination of the leaf alkaloids of B. australis by g.l.c. and by g.l.c.-m.s. resulted in the identification of eleven constituents, including two new alkaloids.2 The structures and the distribution of some quinolizidine alkaloids that may be used as systematic markers in the Leguminosae have now been supplemented by more recent data.9... 

Bitterness varies with the chemical structure of an alkaloid. With the quinolizidine alkaloids (QAs) the following scale was assessed for man Mean detection levels are 0.00085% for sparteine, 0.0021% for lupanine, and 0.017% for hydroxylupanine (503). Whereas we know a few parameters of olfactory qualities in Homo sapiens, often much less or hardly anything is known for most other vertebrates. 

Figure 7.10 Structures of the quinolizidine alkaloids, lupinine (21), lupanine (22), cytisine (23) and multiflorine (24) and of a dipiperidine alkaloid of the ammodendrine type (25).

The most common group of alkaloids possessing a quinolizidine nucleus is that of the lupine alkaloids which can simply be classified as bicyclic (lupinine/epilupinine type), tricyclic (cytisine type) or tetracyclic, (sparteine/lupanine or matrine type). Fig. (23). This grouping is made according to structure complexity and without considering biosynthesis, as the detailed biosynthetic pathways are still not completely understood. 

Fig. (34). Structures of the tetracyclic lupine alkaloids (-)-6a-hydroxylupanine [219], 4a-hydroxy-13 P-methoxy lupanine, 3P,4a-dihydroxy-13 P-methoxy lupanine and...

Comparison of the NMR data of 4a-hydroxy-13 P-methoxy lupanine and 3P,4a-dihydroxy-13P-methoxylupanine with that of 13P-hydroxylupanine led the authors to propose the depicted structures the hydroxyl group of 4a-hydroxy-13 P-methoxy lupanine was evident in the mass fragment at m/z 294 (C16H26N2O3) and resonances at 5 3.92 ppm and 5 63.2 ppm, the latter replacing the C-4 resonance (6 19.4 ppm) in the C NMR spectrum of 13 P-methoxy lupanine, and its a orientation was determined on the basis of the H-4 multiplicity and magnitude of the observed upfield shift of the C-4 and downfield shift of the C-3 and the C-5 resonances, when compared to a known 4P-hydroxylupanine derivative (4P-hydroxy-13a-0-(2 -pyrroyl-carbonyl)-lupanine). 

New accounts of oxo- derivatives of lupanine include the (+)-15P-hydroxy-17-oxolupanine, isolated fi-om seeds of Lupinus albus [221], and the two structures proposed for 10-oxo- and 17-oxolupanine, isolated from an East Afiican legume, Dicraeopetalum stipulare Harms, Fig. (35) [222]. 

New reports of lupanine esters concern the isolation and characterisation of the new structures (-)-3P-hydroxy-13a-tigloyl-oxylupanine from the seedlings of Cytisus scoparius [223] and cineroctine from twigs of Genista cinerea subsp. Cinerea [224], Fig. (36). The full C NMR characterisation of the previously known cineverine was also reported[224]. 

Fig. (36). Structures of the lupanine esters (-)-3 i-hydroxy-13a-tigloyloxylupanine [223], cineroctine [224] and cineverine [224].

The structure of Beckels ethoxylupanine (LXXV), which prepared by the reaction of bromine on lupanine in ethanol, has been elucidated (68). 17-Hydroxy lupanine is readily obtainable from it. 

Lupanine is comparatively easily dehydrogenated with mercuric acetate 62, 69), a property not usual for cis-quinolizidine structures. The conformation, with ring C in boat form, appears to be the favored conformation equilibrium (5, 35, 70). 

Lupinine Group.—A new lupinine ester (1) obtained from seedhngs of Lupinus luteus contained traces of the c -isomer, which could be obtained from the trans-derivative by irradiation. The structure of the alkaloid was established by hydrolysis and by synthesis from (-)-lupanine and trans-4-acetoxycinnamyl chloride. ... 

The conversion of lupanine into camoensidine may represent a biosynthetic pathway, and cleavage of the C-16 C-17 bond of a tetracyclic quinolizidine [cf. mamanine (3)] followed by carbon-carbon cyclization could lead to tetracyclic derivatives containing terminal piperidine rings. New alkaloids of this type have been obtained recently. Aloperine was first isolated from Sophora alopercuroides over forty years ago, and structure (12) has now been assigned to the alkaloid on the basis of spectral studies. Allylaloperine (13) is a constituent of the same species. Nitraramine (14) and 7V-hydroxynitraramine (15) from Nitraria schoberi are... 

Lupanine Dodecahydro-7tl4-methano 4Hf6H di-pyrido[It2-a r,2 e][lt5]diQzocin-4 one. Cl5HMNaO mol wt 248,36, C 72.54% H 9.74%, N 11.28%, O 6,44%. Racemic lupanine is found in white lupins, d-tupanine is found in blue lupins /-lupanine has been prepd from the natural racemic fnrm. Structure Davis, Arch. Pharm. 235, 199,... 

Full confirmation of the proposed structure came from the enzymatic synthesis of (-)-3(3-hydroxy-13a-tigloyloxylupanine from (-)-3(3,13a-dihydroxylupanine, tigloyl-CoA and DHLTase [(-)-3 P, 13 a-dihydroxy lupanine 13-0-tigloyloxyltransferase]. 

Lupanine iV-oxide perchlorate exists in anhydrous and hydrated forms of these, the cation in the anhydrous form has been shown by X-ray crystal structure analysis to have the conformation depicted in (21). Lupanine forms only one... 

Since, in the H-NNIR spectra of lupin alkaloids, most signals of alicyclic hydrogens appear in the range of S 1-2.5, it is not easy to assign all overlapping signals. However, several characteristic features in the spectra are helpful for structural elucidation. In the IH-NMR spectra of lupanine-type alkaloids, only the signal of Hjoa... 

The structure of the alkaloids will be considered in the above order of increasing complexity. Related and isomeric alkaloids will be discussed within these five main groups lupinine, cytisine, sparteine, lupanine, and anagyrine. 

Mention of lupanine (XCIV) has already been made in consideration of the structure proof of sparteine (XCI) and in relation to the vari-... 

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