Lobeline group

LOBELINE GROUP. The inter-relationships of the five members of this group have been given in Table A by reference to the general Formula I. The chief data on which this formula is based are as follows — ... 

Syntheses of members of the lobeline group have been effected by Wieland and Drishaus and by Seheuing and Winterhalder. JiorLobelane was prepared by the former authors by condensing 2 6-dimethylpyridine with benzaldehyde to 2 6-distyrylpyridine (IX), which was then reduced by sodium in alcohol, giving a mixture of meso-and trans- forms of 2 6-di-(3-phenylethylpiperidine (worlobelane). From this by crystallisation of the mixed hydrochlorides, meso-norlobelane was separated, which on A-methylation yielded lobelane (X) as the methiodide. 

The principal characteristics of the naturally occurring members of the lobeline group (see also Table A, p. 23) are as follows —... 

LELOBINE AND LOBININE GROUPS. These include the minor alkaloids of lobelia isolated from factory residues accumulated during the manufacture of lobeline. Their isolation and separation involve complicated processes of fractionation for which the original paper should be consulted. Their inter-relationships (Table A, p. 23 and general formula, I, p. 24) are similar to those among members of the lobeline group, but the effect of the presence of three or more asymmetric carbon atoms is more evident, thus there are already known six forms of the basic dihydric alcohol, lelobaiiidine. 

Exhaustive Methylation. As in the lobeline group it is the diketo-bases, lelobanines (p. 30) in the lelobine series and lobinanines (p. 31) in the lobinine group, which give methiodides amenable to this mode of degradation. They are decomposed by alkali yielding an unsaturated neutral oil, which is hydrogenated and then, if necessary, oxidised to the saturated open chain diketone, e.g., see under lelobanine. 

Lobeline group Lobeline, isolobeline, sedamine Synapsotropic, analeptic, secretolytic... 

The presence of alkaloids in Lobelia injlata, Linn., was first recorded by Proctor. Lobeline was prepared by Lewis as a basic oil from which Siebert made and analysed a series of salts and proposed the formula, CigHjsOjN. In 1921 Bohringer and Sohne protected a process for the isolation and separation of three alkaloids, a-, 3 and y-lobelines. In the same year Wieland published the first of a series of papers in which is described the isolation of several groups of alkaloids, to most of which constitutional formulae have been assigned and, in some cases, confirmed... 

The carbonyl groups in the diketo- and keto-aleohol bases are not readily detected by the usual reagents and as these bases can be reduced to the dihydrie alcohols, it was assumed at first that lobeline and lobelanine contained one and two ether linkages respectively and formulse based on this assumption, and satisfying the other experimental evidence then available, were put forward by Wieland, Schopf and Hermsen, of which that for lobeline (II) may be quoted as an example. 

This plant yielded (— )-lobeline and a new base, eampedine (C14H17O2N), whose structure (26) is based on physical methods and diagnostic chemical tests for the methylenedioxy group (35). 

Lobelanine, which is optically inactive, can be obtained by oxidation of optically active lobeline and also by oxidation of optically inactive lobelanidine. This makes it possible to eliminate some of the above formulas although all four would be consistent with the results of the Hofmann degradation. Because of the relationship of the three alkaloids, it is evident that the optical activity of lobeline must be attributed to the asymmetry of the C-atom involved in the secondary alcohol group in this keto-alcoholic base. The optical activity of lobeline is lost when the... 

A group of choline esters (acetylcholine, methacholine, carbachol, and bethanechol) and a second group of naturally occurring alkaloids (muscarine, pilocarpine, nicotine, lobeline) comprise this subclass. Newer drugs are occasionally introduced for special applications. The members differ in their... 

Lobelin (-)-lobelin, cfr-8,10-diphenyl-lobelionol, the main Lobelia alkaloid (see). Structurally, it is a lo-belionol, in which both Rj and R2 are phenyl (-C H ) groups. L. crystallizes as colorless needles, m.p. 130-131 °C, [o]d-43° (c = 1, ethanol). It is isolated from Lobelia inflata, and is used medicinally as a respiratory analeptic. On account of its nicotine-like properties, it is also used in the treatment of smoking addiction. Simultaneous administration of nicotine and L. has an additive effect, leading to nausea and aversion. 

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