Alkaloid general formula

According to Wieland, the typical lobelia alkaloids so far isolated and examined belong to three groups (Table A), all of which can be represented by the general Formula I. 

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. 

Stereoisomerism in the Cinchona Bases It was at first common practice to number the four asymmetric carbon atoms indicated in the general formula (I), 1, 2, 3 and 4, but this is now replaced by the more general system introduced by Rabe, who suggested the name ruban for (HI), which can be regarded as the parent substance of the natural cinchona alkaloids, and rubatoxan (IV) for that of the quinicines (quinatoxines). The formifiae, with notation, for ruban (III) and rubatoxan (IV) are shown below, and the general formula (I) for cinchona bases has been numbered in accordance with that scheme. 

Babe s general formula (p. 443) for the cinchona alkaloids was published in 1908 and a partial synthesis of quinine was effected by Babe and Kindler in 1918, but a complete synthesis of this alkaloid did not become available until 1945 when Woodward and Doering described their ingenious process. 

C20H3QO4 (p. 728). Ruzicka, Dalma and Scott (1941) have pointed out that formula I cannot be the basis of a general formula for the erythrophloeum alkaloids, because their degradation to 1 7 8-tri-methylphenanthrene would then imply the migration of a methyl group from C to C for which a substituent at C is essential. 

Chondrodendron polyanthum, 371 Chondrodendron tomentosum, 363, 371, 373, 377, 391 alkaloids, 376 Chondrodine, 363, 364 Chondrofoline, 364, 365 Chrycentrine, 172, 313 Chiysanthemine, 773 Chrysanthemum cineraricefoHum, 773 Chuchuara, 781 Chuehuhuasha, 781 Cicuta virosa, 13 Cinchamidine, 419, 429 Cinchene, 439 Cinchenine, 438, 439, 440 apoCinchenine, 440, 441 Cincholoipon, 438 Cincholoiponic acid, 438, 443 Cinchomeronic acid, 183 Cinchona alkaloid structure, synthesis, 457 Cinchona alkaloids, bactericidal action of some derivatives, 478 centres of asymmetry, 445 constitution, 435 formulae and characters of transformation products, 449, 451 general formula, 443 hydroxydihydro-bases, 448, 452-4 melting-points and specific rotations, 446... 

Several new syntheses of quinoline and indole Cinchona alkaloids were reported in the last few years. In these synthetic routes the quinuclidine moiety of the alkaloids was derived from various synthetic meroquinene derivatives 18. These new syntheses all proceed through intermediates of general formula 19 which are characterized by a properly positioned functional group (t.e., X) which facilitates the formation of quinuclidine ring 20. 

The alkaloids have been assembled in a series of general formulas based on the type of acid present and show an interesting structural correlation. 

The work in this branch of alkaloid chemistry has been extensive and, although a number of these bicyclic hydramines have been isolated, it must be emphasized that all possible combinations of I have not as yet been found in nature. Dioscorine, although it does fulfill the requirements of the above generalized formula, is a lactone ... 

The terpenoid indole alkaloids are a group of plant bases derived by multiple variation on the strictosidine [(79) p. 20] skeleton. Arguably the most important work in the past five years has been done on these alkaloids with enzyme preparations from plant tissue cultures, and the research is of great potential significance for other studies in alkaloid biosynthesis. The results have allowed close definition of the early stages of biosynthesis (this Report, p. 19). Use of crude enzyme preparations in this way has been extended to the study of benzylisoquinoline biosynthesis, with enzyme-catalysed formation of norlaudanosoline-1-carboxylic acid [(57) p. 16] this compound had earlier been identified as the first of the benzylisoquinolines (this Report, p. 15). It seems that amino-acids of this general formula (6) are key intermediates in the biosynthesis of all isoquinoline alkaloids. Lophocereine (7) is exceptional in that two routes (from leucine and mevalonate) may lead to it, only one of which potentially involves an acid like (6). ... 

Cinchoninone is also formed by the action of alkali on J -bromocineho-nicine, and, since cinchoninone can be reduced to cinchonine, it is possible in this way to reconvert cinchonicine into cinchonine and quinicine into quinine. On the basis of aU these results, Rabe developed the following general formula (I) for this group of alkaloids —... 

Though the Knorr-Horlein formula was generally accepted until 1923, difficulties were frequently encountered in explaining reactions of the morphine alkaloids by it, and in some cases led to suggestions for its modification. Knorr and Horlein adopted an ethylenic linkage at C to because (1) positions C and must, for the reasons given above, be... 

There are two generally accepted numbering systems for the bisindole-type alkaloids. The system used throughout the chapter is shown around formula 1 however, the biogenetic numbering system presented for vinblastine as formula lA is still in wide use. 

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