Acetate-derived Alkaloids

The acetate derivative of alkaloid uleine (104) obtained from its N-oxide 103 with acetyl chloride also undergoes cleavage by sodium borohydiide, giving carbazole 105 in high yield (85LA2073 Scheme 29). 

Figure 6. An example of a pseudoalkaloid. Acetate-derived alkaloid pinidine is extracted from the Pinus species, for example, from Pinus penderosa. (Photo T. Aniszewski). Pinidine has antimicrohial activity.

Acetate-derived alkaloids Umbelliferae Conium maculatum Coniine... 

Acetate derived alkaloids 12, 40 Acetyl-intennedine 7, 29, 34, 103 Acetyl-lycopsamine 7, 29, 34, 103 Acetylajmalan 175 Acetylcorydamine 22 Acetylerucifoline 17 Acetylfolifidine 24, 155 AcetyUcomavine 40, 53 Acetylleucovernine 52 Acobine 167... 

The protoberberinium alkaloids are derivatives of the 5,6-dihydrodibenzo[n,g]quin-olizinium ion (95). There exist also alkaloids which are deriyatives of berbine (5,6,13,13a-tetrahydro-8i7-dibenzo[a,g]quinolizine, 94). Ban et al. have shown that dehydrogenation of berbine with mercury(II) acetate will afford the parent protoberberinium salt (95) in 75% yield (60CPB183). 

Anthranilic acid (2-aminobenzoic acid) (see page 126) is another shikimate-derived compound which, as its CoA ester anthraniloyl-CoA, can act as a starter unit for malonate chain extension. Aromatization of the acetate-derived portion then leads to quinoline or acridine alkaloids, according to the number of acetate units incorporated (Figure 3.47). These products are similarly discussed elsewhere, under alkaloids (Chapter 6, page 376). 

Recently, Pelletier, Nowacki, and Mody 155) reported that treatment of alkaloid imine derivatives with ethylene oxide in acetic acid or methanol afforded the oxazolidine ring-containing alkaloids in excellent yield. Treatment of lindheimerine (7) with ethylene oxide in acetic acid afforded ovatine (6) in 98% yield. Similarly, veatchine azomethine acetate (10) afforded veat-chine acetate (210) in 97% yield. Formation of the oxazolidine ring in these... 

Unlike ethylene oxide, oxetane reacted very slowly with the alkaloid imine derivatives to afford low yields of tetrahydro-l,3-oxazine derivatives. Treatment of veatchine azomethine acetate (10) with oxetane in acetic acid at 50° afforded the six-membered carbinolamine ether, homoveatchine acetate (220), in 25% yield. The latter was isolated as a mixture of C-20 epimers. 

Alkaloids of Aconitum kusnezojfii Reichb.—Researchers in the Peoples Republic of China have reported studies on the alkaloids of Aconitum kusnezojfii Reichb. that had been collected in Inner Mongolia.29 The pharmacological effects of extracts of these plants were studied in several animal systems.30 The known alkaloids aconitine (55), mesaconitine (56), hypaconitine (57), and deoxyaconitine (79) were identified on the basis of comparison of their physical and chemical properties with those of authentic samples. In addition, a new base, beiwutine (C33H45N012 m.pt 196—198 °C), was reported. This base formed a perchlorate salt (m.pt 255—257 °C) and a tetra-acetate derivative (m.pt 242—244 °C). From the H and 13C n.m.r., i.r., and mass-spectral data, structure (80) was proposed for beiwutine. 

The inandenines are macrocyclic spermidine derivatives that have been isolated as ketones from Oncinot is species. The main alkaloids of the leaves of O. inandensis inandenin-12-one (53) and inandenin-13-one (54), exist as a mixture that has not yet been separated. Only by chemical degradation of the mixture to the ethylene acetal derivatives 55 and 56 it has been estab-... 

The majority of alkaloids have been found to be derived from amino acids, such as tyrosine, phenylalanine, anthranilic acid, tryptophan/tryptamine, ornithine/arginine, lysine, histidine and nicotinic acid (Fig. 2.1). However, alkaloids maybe derived from other precursors such as purines in case of caffeine, terpenoids, which become aminated after the main skeleton has been synthesized i.e. aconitine or the steroidal alkaloids, are found in the Solanaceae and Liliaceae. Alkaloids may also be formed from acetate-derived polyketides, where the amino nitrogen is introduced as in the hemlock alkaloid, coniine. 

The monomeric acridone alkaloids are derived from anthranilic acid and acetate via a polyketide. First studies, in which [ C]-acetate was utilized by cell cultures of Ruta graveolens, indicated that the C-ring of the acridone nucleus was acetate derived. Further research revealed that anthranilic acid is specifically incorporated into the A-ring of rutacridone (Baumert et al, 1982). 

The phenanthroquinolizidine alkaloid cryptopleurine (149), which is a homologue of tyrophorine (119), was synthesized by the Weinreb group via the methylol acetate derivative (146) of an inseparable mixture of ( )- and (Z)-... 

Acetate is also a precursor of several groups of alkaloids in the form of a polyketide chain that interacts with an unknown nitrogen source (as in the terpene alkaloids). Examples of acetate-derived alkaloids are coniine—the toxic principle of Conium maculatum, pinidine—from several Pinus species, and the naphthy-lisoquinoline alkaloids (e.g., ancistrocladine)—showing antimalarial and anti-HIV activity. The latter alkaloids are apparently derived from the oxidative coupling of two pentaketide units. Huperzine A, currently in clinical trials for the treatment of Alzheimer s disease and isolated from the club moss (Serrata huperzia), is derived from a polyacetate precursor (Fig. 46). 

Treatment of the quinol acetates derived from 5-, 6-, or 7-hydroxytetra-hydroisoquinolines with lead tetraacetate (LTA) in acid gives different types of alkaloids. LTA oxidation of 7-hydroxy bases 82b,c,f,g in acetic... 

Alkaloids are basically nitrogen bases. The amino acids act as building blocks for the biosynthesis of alkaloids. Majorities of the alkaloids contain a pyridine, quinoline, and isoquinoline or tropane nucleus and are responsible for physiological effects in man or in animal. The side chains in alkaloids are derived from terpene or acetate. Alkaloids have basic properties and are alkaline in reaction, turning red litmus paper blue. 

Phenylalanine and tyrosine acts as precursor for opium alkaloid biosynthesis. Tryptophan is a significant source of Vinca alkaloids. Alkaloids are derived from anthranilic acid, which is an intermediate in biosynthesis of tryptophan. Some alkaloids are derived from acetate, terpene or shikimic acid. Shikimic acid is a significant metabolite as most of the aromatic constituents are derived from shikimic acid pathway. 

The alkaloid condelphine (CCCLII) was first isolated in 1942 from Delphinium confusum Popov and was found to be an 0-acetate derivative of isotalatizidine (CCCLIII) (142). The latter alkaloid, along with its C-1 epimer talatizidine (CCCLIV), had been isolated 2 years earlier from Aconitum talassicum Popov, a rare species native to the mountainous... 

Unprecedented alkaloid from the mediterranean sponge Reniera sarai X-ray structure of an acetate derivative of Sarain-A. Cimino, G. Mattia, C. A. Mazzarella, L. Puliti, R. Scognamiglio, G. Spinella, A. and Trivellone, E. Tetrahedron 1989, 45, 3863. 

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