Macrocyclic quinolizidines

Macrocyclic quinolizidine or 1-oxaquinolizidine alkaloids, aragu-spongines B-H (236-242) and J (243) (206) and aragupetrosine A (244) (207) were isolated from an Okinawan sponge (Xestospongia sp.) together with the previously known petrosin (245) (208) and petrosin A (246) (209). These alkaloids show vasodilating activity. 

Aragupetrosine A, A new Vasodilative Macrocyclic Quinolizidine Alkaloid from an Okinawan Marine Sponge Xestospongia sp. Kobayashi, M. Kawazoe, K. and Kitagawa, I. Tetrahedron Lett. 1989, 30, 4149. 

After the recent considerable activity in the synthesis of macrocyclic Lythraceae alkaloids, published work this year has been confined to the isolation of the new aryl-quinolizidine alkaloids desmethoxyabresoline (28) and 10-ep/-desmethoxyabresoline (29) from Heimia salicifolia The structure of alkaloid (28) was established by spectroscopy and by conversion into two known compounds, the alcohol (27) (c/. Vol. 6, p. 97) obtained by basic hydrolysis and... 

There is no uniform classification for the A. In the literature divisions according to origin (examples Aconitum, Amaryllidaceae, Aspidosperma, cactus, Catharanthus, Cephalotaxus, Cinchona, coca, Corydalis, curare, Dendrobates, ergot, Erythrina, Iboga, Lycopodium, Maytenus, opium, Rauvol-fia, Senecio, Strychnos, tobacco, Vinca alkaloids, salamander, Solanum, Veratrum steroid alkaloids) in addition to divisions according to chemical structure (examples aporphine, benzylisoquinoline, bis-benzylisoquinoline, berberine, carboline, diterpene, inudazole, indole, indolizidine, isoquinoline, lupinane, macrocyclic, morphine, peptide, / -phenyl-ethylamine, piperidine, purine, pyridine, pyrrolidine, pyrrolizidine, quinoline, quinolizidine, quinucli-dine, spermine, spermidine, steroid, terpene, tro-pane, tropolone alkaloids) are used. 

Lythraceous alkaloids include several 4-arylquinolizidin-2-ols and their esters, as well as a variety of piperidine- and quinolizidine-based macrocyclic variants (macrolides, cyclophanes) possessing biaryl linkages. Only the former group is relevant to this review. No new simple quinolizidine metabolites have been reported for over two decades, and recent publications have dealt almost exclusively with the synthesis of four alkaloids, lasubine I (909), lasubine II (910), and their 3,4-dimethoxycinnamate esters subcosine I (911) and subcosine II (912) (Fig. 17). The naturally occurring enantiomers are represented in the diagrams. 

From the methanolic extract of sun-dried specimens of the sponge Petrosia seriata Braekman et al. 194) isolated a novel type of bis-quinolizidine alkaloid, the ichthyotoxic petrosin (312), and determined its structure by X-ray diffraction. 312, which contains a C-16 macrocycle, was toxic to the fish Lebistes reticulatus (LD = 50mg/L). Later,... 

Petrosines A and B, which were isolated in 1982 from the Papua New Guinea species Petrosia seriata, are symmetrical macrocycles with two quinolizidines (Braekman, Daloze, and Macedo De Abreu, 1982 Braekman et al, 1984). The presence of substituents in the quinoUzidine or 1-oxaquinolizidine rings implies the existence of numerous conformers, most of which were found later in Australian and Japanese Xestospongia as enantiomers or in racemic mixtures. 

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