Bicyclic lupine alkaloids

The bicyclic lupine alkaloid, (-)-(3 -methoxy-4 -a-L-rhamnosyloxycinna-moyl)-epilupinine. Fig. (33), was isolated from the aerial parts of Lupiniis hirsutus [218]. 

In the course of biogenesis-type syntheses of lupin alkaloids, reduction of protected macrocyclic acyloin 50 (Scheme 15) has been found to be a second route to bicyclic aminoalcohol 14a (69JA7372). Another 11-membered ring compound, namely caprinolactam (51), on anodic oxidation in the presence of halide ions produces 6/7 bicyclic lactam 52 together with two isomeric 5/8 bicyclic lactams (87CJC2770). 

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. 

Ten of the 45 alkaloids that were gas chromatographed by Lloyd et al. in 19611 on a 2-3 % SE-30 on Chromosorb W column were lupine alkaloids. The bicyclic lupinine and the tricyclic sparteine, a-isosparteine and 13-hydroxysparteine were chromatographed at at column temperature of 160°C, the tricyclic cytisine, methylcytisine, methylcytisine-N-oxide and the tetracyclic lupanine, 13-hydroxylupanine and matrine at 204°C.The retention times of the alkaloids are listed in Table 7.1. 

Simple bicyclic compounds form a rather small subset of the lupine (or lupin) alkaloids, the overwhelming majority of which have tricyclic or tetracyclic structures based on the quinolizidine motif. These alkaloids are characteristic metabolites of the Papilionoideae, a sub-family of the Leguminosae (Fabaceae), although representative examples have also been isolated from several other plant families. The simple lupine quinolizidines were surveyed in Volume 28 of this treatise (7), while later reviews in Volumes 31 (5) and 47 (9) comprehensively covered all classes of lupine alkaloids, including those containing indolizidine components. Much relevant material is also to be found in the review on the biosynthesis of pyrrolizidine and... 

Lupins produce both tetracyclic (e.g., lupanine) and bicyclic quinolizidine alkaloids (i.e., lupinine), which typically accumulate as esters of tiglic acid, p-coumaric... 

These tetracyclic and tricyclic quinolizidine alkaloids are commonly known as lupine alkaloids. The simple bicyclic alkaloids such as lupinine are produced from two lysine units via cadaverine. Tricyclic alkaloids such as cytisine are considered to be formed from tetracyclic alkaloids through anagyrine-type alkaloids (Fig. 5.2.7). 

Lupins produce both tetracyclic (e.g. lupanine) and bicyclic quinolizidine alkaloids (i.e. lupinine) (Figure 4.15), which typically accumulate as esters of tiglic acid, p-coumaric acid, acetic acid and ferulic acid (Suzuki et al. 1996). The biological significance of these esters is not clear. Quinolizidine alkaloid esters are mainly distributed in the genera... 

Not included in the Table are the results of a colossal GC-MS chemotaxonomic survey of the alkaloidal profiles of 56 Lupinus species (embracing 90 subspecies and chemotypes) representing both Old World and New World taxa 337). Of interest in this survey is the finding that bicyclic alkaloids of the lupinine class occurred mainly in Old World species. Genetic evidence has also been obtained for a close relationship between (and probably a common ancestry for) lupines that produce the lupinine complex of metabolites 33S). 

By far the most popular asymmetric deprotonation uses sparteine as a ligand for lithium.28 Sparteine 154 is a bicyclic alkaloid from lupins and gorse and has two nitrogen atoms that can, in one favourable conformation 154a, chelate a lithium atom. In spite of appearances, it is not (quite) C2-symmetric and only one enantiomer is available. 

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