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Indolizidine alkaloids allopumiliotoxins

A new synthesis of the indolizidine alkaloid (+)-allopumiliotoxin 323B was achieved through intramolecular 13-DC of the (Z)-A -alkenylnitrone 84. The major cycloadduct 85,... [Pg.241]

An alternative intramolecular cyclization protocol, Ni(COD)2/PBu3/Et3SiH, was developed for the consideration of avoiding the 1,2-addition of EtjZn to the aldehyde when a complexed substrate was used. The synthesis of indolizidine alkaloid, (-i-)-allopumiliotoxin 267A, was accomplished using this protocol [197]. [Pg.431]

SAM, samandarines BTX, batrachotoxins HTX, histrionicotoxins PTX, pumiliotoxins aPTX, allopumiliotoxins hPTX, homopumiliotoxins DHQ, 2,5-disubstituted decahydroquinolines 3,5-P, 3,5-d [substituted pyrrolizidines 3,5-1 and 5,8-1, disubstituted indolizidines 1,4-Q, 1,4-disubstituted quinolizidines Epi, epibatidine Pseudophry, pseudophrynamines. With the exception of 3,5-P and 3,5-1, these alkaloids are not known to occur in arthropods (see text). Histrionicotoxins may occur in Minyobates and Mantella, but the evidence is not conclusive. [Pg.29]

Cyclization of P-allenylamine systems to six-membered ring products has been observed recently. Cyclization of terminally substituted p-allenylamides with silver tetrafluoroborate produced lactam products (equation 137).267 The cyclization shown in equation (138) was used to generate the indolizidine ring system of allopumiliotoxin alkaloids.2676... [Pg.411]

Indolizidine and quinolizidine alkaloids found in amphibians and ants were studied by Daly and co-workers who classified them in two different classes, A and B, Fig. (1) [2,15-17]. The former include 3,5- and 5,8-disubstituted indolizidines, 5,6,8-trisubstituted indolizidines and 1,4- and 4,6-disubstituted quinolizidines that can be derived from straight-chain carbon precursors. The latter contain one or more isoprene units, and include pumiliotoxins (PTX-A), allopumiliotoxins (a//o-PTX-A or... [Pg.234]

Besides the main alkaloids, about 20 minor P. A with different side chains, 15 allopumiliotoxins (with an OH-group at C-7 of the indolizine system), and 10 ho-mopumiliotoxins (with a quinolizidine system instead of indolizidine as the skeleton) as well as about 25 decahydroquinolines have been found however, the exact structures of some of them are still unknown. The minor alkaloids differ from the P. in the side chains which may be hydrogenated, oxidized, methylated, or shortened P. A and B exhibit cardiotonic and myotonic activities and are thus of pharmaceutical interest. Furthermore they have an effect on sodium ion channels. Subcutaneous injections of 50 pg P. A or 20 pg P. B in mice are lethal. The decahydroquinolines on the other hand are less toxic (injection of 400 pg P. C causes death of mice) and influence nicotine receptors as well as sodium and potassium channels. [Pg.527]

Edwards MW, Daly JW, Myers CW (1988) Akaloids from a Panamanian poison frog, Dendrobates speciosus identification of pumiliotoxin-A and allopumiliotoxin class alkaloids, 3,5-disubstituted indolizidines, 5-substituted 8-methylindolizidines, and a 2-methyl-6-nonyl-4-hydroxypiperidine. J Nat Prod 51 1188-1197 Emsley L, Bodenhausen G (1989) Self-refocusing effect of 270° Gaussian pulses. Applications to selective two-dimensional exchange spectroscopy. J Magn Reson 82 211-221... [Pg.86]

Figure 39 Some alkaloids common to arthropods and frogs allopumiliotoxin 323B (1714) indolizidine 217B (1715) indolizidine 239Q (1716) indolizidine 235B (1717) allopumiliotoxin 267A (1718). Figure 39 Some alkaloids common to arthropods and frogs allopumiliotoxin 323B (1714) indolizidine 217B (1715) indolizidine 239Q (1716) indolizidine 235B (1717) allopumiliotoxin 267A (1718).

See other pages where Indolizidine alkaloids allopumiliotoxins is mentioned: [Pg.13]    [Pg.23]    [Pg.527]    [Pg.33]    [Pg.838]    [Pg.389]    [Pg.213]    [Pg.213]    [Pg.221]    [Pg.178]    [Pg.205]    [Pg.178]    [Pg.205]    [Pg.433]    [Pg.448]    [Pg.304]   
See also in sourсe #XX -- [ Pg.424 , Pg.430 , Pg.431 , Pg.432 , Pg.433 ]




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