Pyridine-related alkaloids

Apart from these structurally related alkaloids, P. Lyallii contains a number of other compounds exhibiting, instead of a pyridine unit, either a dihydropyridine ring or a pyridone ring, both of which have a characteristic methylcarboxy group at the C-16 position. Lyaline (10) and lyadine (11) (79), which are representative of the dihydropyridine-bearing class of compounds, are found in all parts of P. Lyallii, while lyalidine (12) and hydroxylyalidine (13) (20) are extracted exclusively from root bark. 

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... 

The formation of C-alkaloid D from C-dihydrotoxiferine I by aerial oxidation in dilute aqueous mineral acid has already been mentioned. This is one of several important reactions which show that many of the calabash curare and Strychnos alkaloids can be grouped together in so-called families containing mutually related alkaloids. Thus, C-dihydrotoxiferine I is converted into C-curarine by irradiation of the solid alkaloid in the presence of oxygen (110) similar irradiation of a solution of the alkaloid in the presence of eosin gives C-calebassine (110). C-Calebassine is also formed from C-dihydrotoxiferine I by the action of hot acetic acid in pyridine in the presence of oxygen (111). The production of C-fluorocurarine from C-calebassine and from C-curarine has already been noted. These reactions are summarized in Scheme 2. 

A number of various derivatization reactions have been used, as shown in Table 14.25. The derivatization has been carried out as off-column or on-column derivatization, mostly in order to give morphine and related alkaloids with phenolic or alcoholic hydroxyl groups better gas chromatographic properties. Especially for quantitative determination of morphine in opium or biological material such derivatization was necessary. Street et al. found, however, that the problem of adsorption of a phenolic alkaloid, such as morphine, because of "active sites" on the solid support could be solved by deactivation of the solid support by treatment of it (diatomaceous earth) with benzoyl chloride in pyridine before coating it with the stationary phase. 

Pyridine and piperidine strategies of syntheses of the Sedum and related alkaloids 02T5957. 

Pyrrole, Imidazole, Pyrrolizidine, Pyridine, and Related Alkaloids... 

The principal pyrolysis products of nicotine and related alkaloids are myosmine, nicotyrine, cotinine, bipyridine, and a series of simpler pyridine derivatives. Besides pyridine itself, the major derivatives are alkyl-substituted pyridines which include 3-ethenylpyridine, 3-picoline (along with the 2- and 4- isomers), and the various isometric lutidines (Kuhn 1965). Structures of the most important tobacco and tobacco smoke alkaloids are illustrated in Fig. 1. Because of the extreme dilution of ETS in most indoor environments, many of these alkaloids are virtually nondetectable in real-world settings. 

Tobacco is derived from the leaves of Nicotiana tabacum (Solanaceae), and it was used to treat headache and toothache. However, it is not used as a medicine now, and smoking tobacco is now a global addictive habit. Tobacco leaf contains a large amount of nicotine (2-8%), and the nicotine extracted as nicotine sulfate is used as an insecticide in agriculture. Tobacco leaf contains more than ten related alkaloids other than nicotine, and all of these alkaloids possess a pyridine skeleton with 3-substitution. The main alkaloids other than nicotine, anabasine and nor-nicotine, are isolated from the leaf material, and these alkaloids also possess insecticidal activity. 

Mescaline and Related Alkaloids Gramine Psilocybin Pyridine Alkaloids Nicotine... 

Dioscorea and Related Alkaloids Other Pyridine Alkaloids References... 

Pinder, a. R., Pyrrole, pyrrolidine, pyridine, piperidine and related alkaloids, in Alkaloids and Sulphur Compounds (P. G. Waterman, ed.), Vol. 8 of Methods in Plant Biochemistry (P. M. Dey and J. B. Harborne, eds.), 241-269, Academic Press, London, 1993. 

Nicotinic acid is a precursor of the pyridine ring of nicotine and related alkaloids such as anabasine. The carboxy-group is lost at some stage in the biosynthetic sequence leading to nicotine. A particulate fraction has been isolated from N. rustica roots which catalyses the decarboxylation of nicotinic acid. This particulate fraction which contained mitochondria was assayed by measuring the release of from [7- C]nicotinic acid. Oxygen was... 

A variety of l,2,3,4-tetrahydro-j8-carbolines have been prepared from 3-piperidone phenylhydrazone derivatives. Used initially to obtain pentacyclic derivatives (35) related to the yohimbe alkaloids, this route was later extended to the synthesis of tetracyclic compounds (36). l-Methyl-5,6,7,8-tetrahydro-j8-carboline (37) was prepared in low yield by heating cyclohexanone 2-methyl-3-pyridylhydrazone with zinc chloride, a synthesis probably based on the similar preparation of the tetracyclic compound 38 starting from the corresponding quinolylhydrazine. Abramovitch and Adams extended this approach to the cyclization of cyclohexanone 3-pyri-dylhydrazone (39) itself. The main product was 6,7,8,9-tetrahydro-8-carboline (40), a smaller amount of the j8-isomer (41) also being obtained. This provides a convenient and readily reproducible route to the otherwise difficultly accessible 8-carboline ring system. The favored attack at carbon-2 over carbon-4 of the pyridine nucleus... 

Heptynenitrile was incorporated into the indole system giving a pyridine derivative related to the ergot alkaloids (87MI4) [Eq.(32)]. 

Areca nuts (betel nuts) are the seeds of Areca catechu (Palmae/Arecaceae), a tall palm cultivated in the Indian and Asian continents. These nuts are mixed with lime, wrapped in leaves of the betel pepper (Piper betle) and then chewed for their stimulant effect, and subsequent feeling of well-being and mild intoxication. The teeth and saliva of chewers stain bright red. The major stimulant alkaloid is arecoline (up to 0.2%) (Figure 6.36), the remainder of the alkaloid content (total about 0.45%) being composed of related reduced pyridine... 

From cultures of a mold, Penicillium concavo-rugulosum, two new alkaloids as well as chanoclavine-I (4) were isolated by routine procedures (9). The new compounds were called rugulovasine-A (C16H16N202 mp 138° [a]D 0° in pyridine hydrochloride, mp 225° oxalate, mp 224°) and rugulovasine-B (C16H16N202 amorphous [ ]D 0° in pyridine hydrochloride, mp 187° oxalate, mp 217°). They proved to be closely related to each other since they were easily interconvertible when heated in alcohol solution. 

Pyridines attached to another aryl or hetaryl ring also introduce the possibility of restricted rotation about the biaryl linkage. Typically, this requires three substituents at the or/ o-positions on the biaryl as in the case of the naphthyl derivatives 48, where the stereochemistry is determined by NMR spectroscopy <2001J(P1)1785>. Other methods of determining conformations, such as the comparison of experimental and computed circular dichroism spectra, have been applied to the related Yaoundamine alkaloids such as the derivative 49 <1997T2817>. 

Among compounds related to uleine that have been isolated from A. dasycarpon are X-noruleine (CCLVII-B), dasycarpidone (CCLVII-A), the corresponding alcohol, dasycarpidol, X-nordasycarpidone, and 1,1 -dihydro-l -hydroxyuleine. Dasycarpidone may be obtained from uleine by ozonolysis, or from dasycarpidol by oxidation with chromium trioxide in pyridine. l,l -Dihydro-l -hydroxyuleine has been synthesized from uleine by hydroboration (143b). Apparicine, an alkaloid of novel skeleton present in A. dasycarpon and several other species, has been shown to have the structure CCLVII-U (37). 

Myosmine (3[2-pyrrolidinyl]pyridine) and nicotine (3[l-methyl-2-pyrrolidinyl]pyridine) and a variety of related pyrrolidinylpyridine compounds notably occur in Mcotiana tabacum (tobacco) (Solanaceae) and are discussed in Section xii under pyridine alkaloids. 

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