Pyrolizidine alkaloids

Pyrolizidine alkaloids Heliotropium crassifolium SiOj CHCI3 + MeOH + NH3 aqueous DragendorlTs reagent Ehrlich s reagent Isolation 15... 

A further example is given in reference [88] Selective esterification of retronecine, the dialcoholic component of a pyrolizidine alkaloid, by the imidazolide method was found to be superior to the acid chloride/pyridine method. Acylation of the 9-position of retronecine with tiglic acid, pivalic acid, isobutyric acid, and propionic acid was investigated concerning the steric requirement of the carboxylic acid. 

Pyrolizidine alkaloids fagomine 6-epi-castanospermine castanospermine australine 3-epi-fagomine 2,3-diepi-australine 2,3,7-triepi-australine 3-epi-australine 2R-hydroxymethyl-3S-hydroxypyrrolidine castanospermine-8-O-D-glucopyranoside 1-epi-australine-2-O-D-glucopyranosideand 1-epi-australine [32]. 

Rose described the toxicity of the senecio plant in 1972 [24]. It is the most common plant species to contain the pyrolizidine alkaloids. Toxicity includes hepatic necrosis and later intrahepatic veno-occlusion. A major secondary component is ATN. There are over 50 species of senecio plants in the south east of South Africa. The plants are used extensively as enemas and purgatives. Rose mentions that, despite the deaths resulting from the use of these plants, the local inhabitants are not aware of the danger these plants pose to their well-being. 

Tropea, J E, Molyneux, R J, Kaushal, G P, Pan, Y T, Mitchell, M, Elbein, A D, Austrahne, a pyrolizidine alkaloid that inhibits amyloglucosidase and glycoprotein processing. Biochemistry, 28, 2027-2034, 1989. 

In the alkaloid domain, several hydroxylated alkaloids were chosen to demonstrate that arene cw-dihydrodiols can serve as synthons in heterocyclic synthesis. The first venture into this area was the enantiodivergent synthesis of pyrolizidine triols from erythruronolactone 30, as shown in Figure 8 (30-32). The same principles of enantiodivergent design of the pinitols were applied here to yield the two enantiomeric azido dienes 40 and 41, which were then transformed to the alkaloids by previously documented azide-diene cycloaddition followed by vinylaziridine- yrroline rearrangement (33). 

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