Marine Heterocycles

Investigation of animals from the marine enviroiunent has thrown up an intriguing variety of poly-heterocyclic products (sometimes called sea alkaloids) five representatives are variolin B (sponge, Kirkpatrickia varialosa), lamellarin B (mollusc, Lamellaria sp.), ascididemine (mnicate, Didemnum sp.), wakayin ° (ascidian, Clavelina sp.) and dendrodoine (tunicate, Dendroda grossular), a rare natural example of a multi-heteroatom compound. 

The development of synthetic routes to such systems has prompted new thinking in the construction of poly-heterocycUc systems, as a preamble to the preparation of synthetic analogues of these lead compounds , for biological evaluation. 

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Amfidinolides (unique macrolides from marine dinoflagellates) 97H(44)543. Antitumor N-, N,S-, and S-heterocycles and macrocyclic lactams from ascidi-ans 97M122. 

Biological phenomena displayed by marine microalgae and related bioactive saturated 0-heterocycles 98YGK651. 

New bioactive O- and N-heterocycles from Chinese marine organisms 99PAC1147. 

Review of oxygenated 2,11-cyclized marine cembranoids, tri- and tetracyclic bioactive 0-heterocycles with cembrane skeleton 98H(49)531. 

Synthetic studies on biological activities of marine-origin polycyclic bis-steroid systems with 0-heterocyclic and pyrazine fragments or spirooxazoline fragment 99PAC1095. 

Total synthesis of brevetoxin B, a fused polycyclic marine-derived saturated 0-heterocycle 97YGK686. 

This series in heterocychc chemistry is being introduced to collectively make available critically and comprehensively reviewed hterature scattered in various journals as papers and review articles. All sorts of heterocyclic compounds originating from synthesis, natural products, marine products, insects, etc. will be covered. Several heterocyclic compounds play a significant role in maintaining life. Blood constituents hemoglobin and purines, as well as pyrimidines, are constituents of nucleic acid (DNA and RNA). Several amino acids, carbohydrates, vitamins, alkaloids, antibiotics, etc. are also heterocyclic compounds that are essential for life. Heterocyclic compounds are widely used in clinical practice as drugs, but all applications of heterocyclic medicines can not be discussed in detail. In addition to such applications, heterocyclic compounds also find several applications in the plastics industry, in photography as sensitizers and developers, and the in dye industry as dyes, etc. 

Berlinck RGS (2007) Polycyclic Diamine Mkaloids from Marine Sponges. 10 211-238 Besson T, Thiery V (2006) Microwave-Assisted Synthesis of Sulfiu and Nitrogen-Containing Heterocycles. 2 59-78... 

KitaM, Uemura D (2006) Bioactive Heterocyclic Alkaloids of Marine Origin. 6 157-179 Kiyota H (2006) Synthesis of Marine Natural Products with Bicyclic and/or Spirocyclic Acetals. 5 65-95... 

Error 2 The use of CRMs is mentioned, but the type of CRMs not mentioned, nor the results of their analysis. Hellou et al. (1999) determined PCBs, DDTs, chlorda-nes, dibenzo-p-dioxins (ds), dibenzofurans (Fs), PAHs and sulphur heterocycles in marine harbor sediments. 

Reductive cleavage of the thiazoline C-S bond in heterocycle 193 with -Bu3SnH <1986T3537> followed by in situ hydrolysis of the resulting hemiaminal and protection of nitrogen as its benzyl carbamate gave 194 in 64% overall yield. This was then converted in several steps to potent marine neurotoxin Kainic acid 195 in racemic form (Scheme 27) <1994JOC2773>. 

Like pyrrole, indole is a very reactive jt-excessive heterocycle and reacts with halogens and other electrophiles extremely rapidly [1]. Nature has exploited this property to produce more than 300 halogenated indoles, mainly bromoindoles in marine organisms. A few examples are illustrated below. Chapter 2 contains references to reviews of these natural organohalogens. 

Heteropines with fused five-membered rings are structural blocks of valuable natural products and their synthetic analogs. Latonduines 424 A (R = H) and B (R = COOH) (Eigure 9), two new alkaloids with pyrrolo-pyridoazepinone heterocyclic skeletons, have been isolated from the Indonesian marine sponge... 

In 2005, Han et al. reported the isolation of a novel, naturally occurring, staurosporine analog, ZHD-0501 (321) from the fermentation broth of a marine-derived Actinomadura sp. 007. This was the first example of a staurosporine analog carrying a heterocycle fused to the pyran ring, and it has shown in vitro anticancer activity against mammalian cancer cells. In nature, this isolate was obtained in its optically active form [a]p -I- 83.2 (c 0.10, MeOH) (306). 

The chemistry of fiiians and benzofurans was a Held of lively research in the last year. There are a number of reasons for this activity. The furan ring system - both in its native as well as in its reduced form - occurs in a great number of natural products and a wide variety of these compounds has been isolated from natural sources. This subject is treated regularly with care and accuracy in Heterocycles and will not be repeated here. Therefore only a few examples will be given in this chapter. Several new furan derivatives were isolated from natural sources (-)-wistarin 1 from the marine sponge Ircinia sp. <99TA3869>,... 

As in more recent years, the chemistry of seven-membered ring systems has been dominated by the chemistry of oxygen heterocycles in the form of the marine toxins and, to a lesser extent, the antimalarial artemisinin. Indeed, if it were not for the interest in these systems it would have been a sparse year indeed. For this reason the division of this report will be into just three section, nitrogen, oxygen, and other systems. 

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