Alkaloid pyridine

Nicotinic acid Nicotinic acid-derived alkaloids True alkaloids Pyridine alkaloids Sesquiterpene pyridine alkaloids... 

Colourless liquid with a characteristic ammo-niacal smell m.p. 9 C, b.p. 106°C. Miscible with water. It is present in pepper as the alkaloid piperine from which it can be obtained by healing with alkali. It can also be prepared by the reduction of pyridine, either electrolytically or by other means. Piperidine is a strong base, behaving like the aliphatic amines. 

Tobacco Alkaloids. The relatively small number of alkaloids derived from nicotinic acid (27) (the tobacco alkaloids) are obtained from plants of significant commercial value and have been extensively studied. They are distinguished from the bases derived from ornithine (23) and, in particular, lysine (24), since the six-membered aromatic substituted pyridine nucleus common to these bases apparendy is not derived from (24). 

Ai,A/-bis(hydroxymethyl) formamide [6921-98-8] (21), which in solution is in equiUbrium with the monomethylol derivative [13052-19-2] and formaldehyde. With ben2aldehyde in the presence of pyridine, formamide condenses to yield ben2yhdene bisformamide [14328-12-2]. Similar reactions occur with ketones, which, however, requite more drastic reaction conditions. Formamide is a valuable reagent in the synthesis of heterocycHc compounds. Synthetic routes to various types of compounds like imida2oles, oxa2oles, pyrimidines, tria2ines, xanthines, and even complex purine alkaloids, eg, theophylline [58-55-9] theobromine [83-67-0], and caffeine [58-08-2], have been devised (22). 

Pyridine, pyrrole, quinoline, isoquinoline and indole alkaloids Apply sample solution and place the TLC plate in an iodine vapor chamber for 18 h, remove the excess iodine in a stream of warm air. Characterization on the basis of the iodination pattern. [53]... 

Constitution. When coniine is distilled with zinc dust or heated with silver acetate/ a new base, coiiyrine, CgH N, differing from coniine by six atoms of hydrogen, is formed. This on oxidation yields pyridine-2-carboxylic acid and, since it is not identical with 2-isopropylpyridine, must be 2-propylpyridine (I). When coniine is heated with hydriodic acid at 300° it yields w-octane (II). These and other observations due mainly to A. W. Hofmann, made it clear by 1885 that coniine was probably a-propylpiperidine (III), and this has been amply confirmed by other reactions of the alkaloid and by syntheses. Thus, Wolffenstein showed that on oxidation with hydrogen peroxide, coniine is converted into amino-w-propylvaleraldehyde (IV) ... 

A number of other syntheses of coniine have been effected, of which that of Diels and Alder is of special interest. The initial adduct of pyridine and methyl acetylenedicarboxylate, viz., tetraraethylquinolizine-1 2 3 4-tetracarboxylate (IX) on oxidation with dilute nitric acid is converted into methyl indolizinetricarboxylate (X). This, on hydrolysis and decarboxylation, furnishes indolizine, the octahydro-derivative (XI) of which, also known as octahydropyrrocoline, is converted by the cyanogen bromide method (as applied by Winterfeld and Holschneider to lupinane, p. 123) successively into the broraocyanoamide (XII), cyanoaraide (XIII) and dZ-coniine (XIV). A synthesis of the alkaloid, starting from indolizine (pyrrocoline) is described by Ochiai and Tsuda. ... 

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... 

Bebeerine, CjjHjgOjNj. This alkaloid has been described imder various names, pelosine, chondrodendrine, chondodendrine and curine (Z-form) whose origin is described elsewhere (pp. 363 and 374). It crystallises with one molecule of benzene, m.p. 161°, or 213° (solvent-free) or from methyl alcohol, m.p. 214°, and has [ajn 298° (EtOH) for the d- or Z-form (Scholtz ). Spath et recorded m.p. 221-221-5° (vac.) for both forms and + 332° and — 328° for the d- and Z-forms, in pyridine. 

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.)... 

Pyridine Group. Piperine, Piperovatine, Leucenol, Mimosine, Alkaloids of Ricinus communis, Foenugrec, vy eca Nut, Hemlock, Lobelia, Tobacco (Nicotiana spp.). Anabasis aphylla, Pomegranate Root Bark. ... 

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