Pyridine-Containing Alkaloids

Several early reports of pyridine-containing alkaloids have appeared describing the application of inverse-detected 2D NMR methods. In these cases, HMBC connectivities were utilized principally to link the pyridine ring of the alkaloid to long alkyl chains. 

Haliclamines A, B. Fusetani et al. (1989) reported the isolation and elucidation of the structures of a pair of tetrahydropyridine-containing macrocyclic alkaloids, haliclamines A and B (42), from a sponge of the 

Niphatesines A-D and Theonelladins A-D. A group of pyridine alkaloids, 43, isolated from the Okinawan marine sponge, Niphates sp. have been reported by Kobayashi et al. (1990c). An HMQC spectrum was utilized to establish the direct proton-carbon shift correlations followed by an HMBC 

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There is yet no definite proof of the in vivo synthesis of these pyridino-indolo-alkaloids however, several arguments militate in favor of this hypothesis, (a) Some experiments have been performed with extraction procedures involving alkalies other than ammonia. No major qualitative or quantitative difference in the alkaloid distribution has been observed (31,32). It is therefore unlikely that pyridine-containing alkaloids are artifacts. 

Oxalicine A. An interesting pyridine-containing alkaloid, oxalicine-A (25), was communicated in 1989 (Ubillas et al. 1989). The communication referred to the HMQC experiment but cited the HMBC reference of Bax and Summers (1986). Unfortunately, no details of any long-range connectivities were communicated and, to the best of our knowledge, have not been reported elsewhere. 

Contains Nitrogen.—First test the original solid ni liquid by heating in a hard-glass tube with soda-lime (p. 2), and notice if the smell is that of ammonia (ammonia salt, amide or cyanide), an amine (amine or amino-acid) or a pyridine base (alkaloid). 

Manufacturers have acknowledged the use of hundreds of chemical additives in tobacco products (Lefifingwell et al. 1972 Philip Morris 1994). Some of these additives may synergize with nicotine or demonstrate other reinforcing effects. Cocoa, for example, contains alkaloids, which may themselves have pharmacological effects when inhaled, or may modify the effects of nicotine. Pyridine is chemically a portion of the nicotine molecule, acting as a CNS depressant similar to nicotine, although it is less potent. 

A review entitled General Methods of Alkaloid Synthesis includes pyrrolidine, pyridine, and Sceletium alkaloids.1 Another summarizes nitrogen-containing compounds in tobacco and tobacco smoke, and includes some pyrroles, pyrrolidines, pyridines, and alkaloids related to nicotine.2... 

These alkaloids were isolated in yields of 0.025 and 0.007%, respectively. Descretinine, C20H23NO4 (mp 212°-214° dec.), [a]j) —371° in pyridine), contains three methoxyl groups and one phenolic hydroxyl. Its methylation with diazomethane to (— )-tetrahydropalmatine (XLI) serves to identify descretinine as a tetrahydroprotoherherine with a 2,3,9,10-oxygenation pattern. The nonidentity of descretinine with (— )-tetrahydrojatrorrhizine [(— )-corypalmine] (XLII) and ( —)-tetra-hydrocolumbamine [(— )-isocorypalmine] (XLIII) means that it is either 9- or 10-0-demethyltetrahydropalmatine. 

Asymmetric additions of alkynylzinc reagents (pyridines and alkaloids as N-containing ligands) to aldehydes and ketones 03T9873. 

The intent of this chapter is to provide an update of pyridine and piperidine alkaloid literature since this topic was last covered in Volume 3 of this series [1], The approximate time period covered by this review is 1984-1994. Due to the wealth of information available, this review had to be somewhat selective. For example, with the exception of a few selected pyridine monoterpenes, alkaloids containing a pyridine or piperidine ring fused to another ring system were excluded. The focus of this review is placed on describing new compounds isolated, biosynthesis, and biological properties. Synthesis has not been emphasized in most cases reference is made to only the most recent syntheses. 

Several new pyridine-containing natural produas were also characterized. Four new sesquiterpene pyridines were isolated from the leaves of Maytenus spinosa and characterized (F ure 1 left) (14JNP1853). Derivatives were prepared of these alkaloids, but neither original natural produas nor... 

Contains about 0.48% pyridine (piperidine) alkaloids composed mainly of lobeline, with lesser amounts of lobelanine and lobelanidine. Other alkaloids present include norlobelanine (isolobelanine), lelobanidine, norlelobanidine, norlobelanidine, lobinine, isolobinine, lobina-nidine, isolobinanidine, 8-methyl-10-ethyllo-belidiol, and 8-methyl-10-phenyllobelidiol, among others. ... 

In 1931 Ing pointed out that formula (II) and (III) do not contain methyl or potential methyl groups in j ositions 6 and 8 which they occupy in cytisoline. Further, a partially reduced quinoline ought to oxidise easily to a benzenecarboxylic acid and so far the only simple oxidation, products recorded from cytisine were ammonia, oxalic acid and isovaleric acid. Distillation of cytisine with zinc dust or soda-lime yields pyrrole and pyridine, but no quinoline. On these grounds Ing suggested that cytisine should be formulated without a quinoline nucleus, and that the reactions which indicate the presence of an aromatic nucleus in the alkaloid can be accounted for by an a-pyridone ring. This a-pyridone nucleus can... 

Aplopappus hartwegi (Gray) Blake, contains uncharacterised alkaloids and yields pyridine on steam distillation from its suspension in strong alkaline solution. (Buehrer, Mason and Crowder, Amer. J. Pharm., 1939, 111, 105.)... 

The structural relationship among the above alkaloids was indicated by catalytic hydrogenation of 50, followed by mild Cr03-pyridine oxidation. This led to a mixture containing 44 as the major product and 45. The main work on structure elucidation was performed on 50, and this involved an interesting combination of chemical degradation and spectroscopy. 

Tobacco use is primarily due to psychopharmacological effects of nicotine (Henningfleld et al. 2006). Nicotine is a tobacco alkaloid, a basic substance that contains a cychc nitrogenous nucleus. In Nicotiana plants, most alkaloids are 3-pyridyl derivatives In cured leaf of Maryland Robinson Medium Broadleaf, 24 pyridine derivatives were identified, including nicotine, nomicotine, anabasine, oxynicotine, myosmine, 3-acetylpyridine, 2,3 -dipyridyl, iticotinamide, anatabine, nicotinic acid, and unidentified pyridine alkaloids of derivatives thereof (Tso 1990). Nicotine is the principal alkaloid in commercial tobacco (this was confirmed in 34 out of 65 Nicotiana species) nomicotine, rather than nicotine, appears to be the main alkaloid in 19 out of 65 species and anabasine is the third most important. In addition to the above-mentioned principal and minor alkaloids, the presence of many trace amounts of new alkaloids or their derivatives were frequently reported, including, for example, 2.4 -dipyridyl, 4,4 -dipyridyl, N -formylanabasine, A -formylanatabine, N -acetylanatabine, N -hexanoyl-nomicotine, N -octanoyl-nomicotine, T-(6-hydroxyoctanoyl) nomicotine, and l -(7-hydroxyoctanoyl) nor-nicotine. 

Enantiomeric excess in pyridinylethanols from reduction of 2- and 4-acetyl-pyridine at mercury. The electrolyte contains an alkaloid (5 x 10 M) in aqueous acetate buffer (pH 4.5) - ethanol (1 1) at 0° C. Data from ref. [41]. 

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