Ergot, structure

L-tryptophan has been used as a starting point for partial ergot structures such as 1-benzoyl-4-(amino)-l,2,2a,3,4,5-hexahydrobenz[cd]indoles. An optically pure amine, a key intermediate, was prepared via a four-step sequence employing an intramolecular Friedel-Crafts cyclization and a C-5 deoxygenation procedure [50]. 

Of the typical ergot alkaloids, six pairs f table, p. 526) are now known. The first five pairs are more complex in structure than the sixth pair, ergometrine and eigometrinine. 

The Structure of Ergot Alkaloid, Elymoclavine. Bull, agric. chem. Soc. Japan 19, 94 (1955). 

Fig. 1. Structural similarities between ergot alkaloids and CNS neurotransmitters.

Flieger, M. et al. (1997). Ergot alkaloids — sources, structures and analytical methods. Folia Microbiol. 42(1), 3-29. Glass, J. et al. (2002). Streptococcus pneumoniae as a genomics platform for broad spectrum antibiotic discovery. Curr. Opin. Microbiol. 5(3), 338—342. 

Cyclols Stable molecules obtained by the addition of a heteroatom nucleophile to the carbonyl group of lactams are not very common. The side-chain moiety of the ergot alkaloids (e.g., 50) is one of the earliest examples of such a cyclolic structure (75FOR51) identified. This has given rise to a number of studies on the synthesis and chemical transformations of such units. The discussion below is confined to cyclols related to or arising from piperazine-2,5-diones. 

The proline-containing tricyclic system similar to the unit present in the ergot alkaloids, seems to be particularly efficient in stabilizing the cyclol structure. This is probably due to the conformational rigidity pro-... 

In addition to the effects noted above, the ergot alkaloids produce a variety of other central nervous system and peripheral effects. Detailed structure-activity analysis and appropriate semisynthetic modifications have yielded a large number of agents of interest. 

The photoaddition of water to the ergot alkaloids has been the subject of a number of studies,214,215 and the structures of the adducts have been elucidated. 

FIGURE 7 Structures of some ergot alkaloids used for the preparation of CSPs. (From Ref. 12.)... 

Ergot is a fungal disease commonly found on many wild and cultivated grasses, and is caused by species of Claviceps. The disease is eventually characterized by the formation of hard, seedlike ergots instead of normal seeds, these structures,... 

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