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Endoperoxides chemistry

In this context it must be noted that the natural prostaglandin endoperoxide 4 does give rise to malonaldehyde and 12-hydroxy-5,8,10-heptadecatrienoic acid 67 under biological conditions66 (Eq. 54), which connects with the chemistry of the... [Pg.158]

Doubtless attempts will now be made to prepare more sophisticated model compounds that more closely resemble the natural prostaglandin endoperoxides. Thus the influence of endo-5-allyl and/or cxo-6-vinyl groups upon the chemistry of the [2.2.1] system is clearly of interest. However, it seems likely that the next major effort in this area will involve a thorough and systematic investigation of the reactions of the first generation of bicyclic peroxides that has now been obtained. [Pg.160]

The keto endoperoxide 90 has been synthesised from 1,4-cyclohexadiene through its photooxygenation, reduction of the resulting diastereoisomeric mixture of endoperoxides 89 and subsequent oxidation (Scheme 60). Some chemistry of 90 is described . [Pg.333]

Endohedral fullerenes, 12 230-231 chemistry of, 12 253 Endonucleases, artificial, 17 636 Endoperoxides, 18 442—443 Endopolygalacturonase, 11 598 Endo-receptors, convergent, 16 774 Endosseous dental implants, 8 344 Endothall (Aquathol Granular, Aquathol K), 13 315... [Pg.314]

Ziffer H, Highet RJ, Klayman DL. (1997) An endoperoxidic antimalarial from Artemisia Annua L. In Herz W, Kirby GW, Moore RE, Steglich W. (eds). Progress in the Chemistry of Organic Natural Products, pp. 121-202, Spinger-Verlag, Wien. [Pg.128]

Biomimetic Fe(ll) chemistry and synthetic studies on antimaiarial and antitumour endoperoxides... [Pg.1279]

It should be emphasized that virmaUy all of the above discussion is based on biomimetic chemistry, where the Fe(II) source varies from salts such FeS04 to the more reactive FeCla-THaO as well as heme mimetics (TPP) and ester hematin variants. When heme models are used, since porphyrin alkylation is a favoured process, end-product distributions of products can be very different from when a free ferrous ion source is employed. Furthermore, solvent has been shown to have a profound effect on the rate of reaction and product distributions obtained in iron-mediated endoperoxide degradation. Thus all of these studies are truly only approximate models of the actual events within the malaria parasites. Future work is needed to correlate the results of biomimetic chemistry with the actual situation within the parasite. In general, most workers do accept the role of carbon-centred radicals in mediating the antimalarial activity of the endoperoxides, but the key information defining (a) the chemical mechanism by which these species alkylate proteins and (b) the basis for the high parasite selectivity remains to be unequivocally established. [Pg.1309]

Table 1 summarizes the synthetic and antimalarial profiles of selected endoperoxides. Clearly, synthetic organic chemistry has enabled several excellent potential drng candidates to be prepared, some of which have outstanding antimalarial properties. At the forefront of these efforts are the trioxolanes prepared by Vennerstrom and colleagnes. The challenge in this field in future years will be to construct additional endoperoxide templates that can be prepared in a few steps using scalable synthesis and have similar pharmacological profiles to lead semi-synthetic artemisinins and trioxolanes (e.g. 6). [Pg.1332]

Antimalarial endoperoxides biological targets, 1311-13 biomimetic Fe(II) chemistry, 1279-332, 1338, 1342... [Pg.1443]

In addition to the CIEEL mechanism, peroxides and endoperoxides are key intermediates in a number of chemical and biological processes. There are a growing number of examples where ET to the 0-0 bond in these systems is accepted as an important step in their activity. For example, it is now generally agreed that the first step in the bioactivity of the recently discovered potent antimalarial, artemisinin, involves an ET from Fe-heme to the 0-0 bond, leading to fragmentation and a number of psytotoxic radical intermediates. " In contrast to the enormous amount of literature on the thermal and photochemical reactivity of peroxides, there is relatively little known about their ET chemistry. It is this lack of kinetic data on ET to peroxides and endoperoxides and the possible relationship of this data to Saveant s model for dissociative ET that initiated our own interest in this chemistry.22 23 2 - - - ... [Pg.117]

This chapter comprises an update on the chemistry of 1,2-dioxepines, 1,2-oxathiepines, and 1,2-dithiepines which appeared in Chapter 9.10 in CHEC-II(1996). It is evident that the structural nature, in terms of construction and/or stability of each of these seven-membered heterorings, which include a relatively weak O-O, O-S, or S-S bond, lies behind the paucity of publications in this area. However, the literature on the effective antimalarial artemisinin 1, a remarkably stable endoperoxide, and especially its derivatives more than make up for this deficiency. [Pg.299]

Mamett LJ, Goodwin DC, Rowlinson SW, Kalgutkar AS and Landino LM (1999) Structure, function, and inhibition of prostaglandin endoperoxide synthases. Comprehensive Natural Products Chemistry, Vol 5. Elsevier, Amsterdam, pp 225-261. [Pg.118]

New assignment of the electronically excited states of anthracene-9,10-endoperoxide and its derivatives. Journal of Physical Chemistry A, 104, 164—165. [Pg.381]

Quantitative rearrangement of monocyclic endoperoxides to furans catalyzed by cobalt(II). Journal of Organic Chemistry, 54 (14), 3475-3477. [Pg.381]

Clennan, E.L. and Heah, P.C. (1984) Bicydic dioxaphosphorane. 4. A kinetic investigation of the reactions of trivalent phosphorus compounds with bicydic endoperoxides. Journal of Organic Chemistry, 49, 2284—2286. [Pg.383]


See other pages where Endoperoxides chemistry is mentioned: [Pg.156]    [Pg.156]    [Pg.851]    [Pg.127]    [Pg.129]    [Pg.913]    [Pg.240]    [Pg.292]    [Pg.190]    [Pg.190]    [Pg.951]    [Pg.1279]    [Pg.1281]    [Pg.1323]    [Pg.679]    [Pg.190]    [Pg.190]    [Pg.951]    [Pg.1279]    [Pg.1281]    [Pg.1309]    [Pg.1323]    [Pg.100]    [Pg.523]    [Pg.109]    [Pg.363]    [Pg.377]    [Pg.382]    [Pg.383]   


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