Seeds alkaloid conversion

The beanlike seeds of the trees and shrubs of the genus Erythrina, a member of the legume family, contain substances that possess curare-like activity. The plants are widely distributed in the tropical and subtropical areas of the American continent, Asia, Africa, and Australia, but apparently they are not used by the natives in the preparation of arrow poisons. Of 105 known species, the seeds from more than 50 have been tested, and all were found to contain alkaloids with curariform properties. Erythroidine, from E. americana, was the first crystalline alkaloid of the group to be isolated. It consists of at least two isomeric alkaloids, a and P-erythroidine both are dextrorotatory. Most experimental and clinical study has centered on the b form because it is more readily obtainable in pure state. P-Erythroidine is a tertiary nitrogenous base. Several hydrogenated derivatives of p-erythroidine have been prepared of these, dihydro-P-erythroidine has been studied most carefully and subjected to clinical trial. Conversion of P-erythroidine into the quaternary metho salt (p-erythroidine methiodide) does not enhance, but rather almost entirely, abolishes its curariform activity this constitutes a notable exception to the rule that conversion of many alkaloids into quaternary metho salts results in the appearance of curare-like action. 

Calycanthine is the chief alkaloid in the seeds of these plants. It is not an indole alkaloid, but its facile conversion to indoles and the fact that most of its congeners are indoles is justification for treating it in this volume. 

Vasicinone (37) is an oxidation product of vasicine. Mehta et al. 136) have found that the crude total alkaloids from Adhatoda vasica contain predominantly vasicine, but that gradual conversion of vasicine to vasicinone takes place during countercurrent distribution and partition chromatography, probably as a result of autooxidation. Pure vasicine similarly undergoes autooxidation to vasicinone. (37) has also been isolated from the seeds 121, 122, 136) and other parts 163, cf. 775) of Peganum harmala as well as Linaria transiliensis 164). The physical properties are as follows uv, max 227, 272, 302 and 315 nm ir, the short wavenumber part of the spectrum contains absorptions at 3115, 2924, 1658, 1454, 1385, 1331, 1291, 1209, 1179, 1104, 1080, 1028, 987, 970, 896, 883, 867, 854, 774, 749, 720, 694 cm H-nmr (CF3COOH), 5 7.3—7.8, aromatic protons 8.05, C8-H 5.56, C3-H 2.64-h2.21, C2-H2 3.92-h4.32, CI-H2. 

Literature concerning the chemistry of loline alkaloids was first reviewed in 1972 (20). Robbins et al. (21), using much milder isolation procedures than those of Yates and Tookey (18), also reported the occurrence of AT-acetylloline (6), AT-acetylnorloline (7), and N-formylloline (9) in F. arundinacea seed. Procedures for multiple-gram scale isolation of loline dihydrochloride from F. arundinacea seed, and its conversion in high yield to any of the monomeric... 

The erythrina alkaloids form a widely distributed family that lately has received considerable attention as a result of their unique tetracychc skeleton and biological activities. Erythrocarine (46) [27, 28], erythravine (50) [29], and (-l-)-jS-erythroidine (59) [30] are three members of this family that have been synthesized with metathesis as a key step. The molecular structures of erythrocarine, found in the seeds of Erythrina carihaea, and erythravine, isolated from Erythrina cochleata, are related. As a result, the total syntheses independently proposed by, respectively, Mori et al. and Hatakeyama et al. proceeded via the comparable intermediates 45 and 49, respectively, as shown in Scheme 2.11. Ene-yne 45 was synthesized in a number of steps. This substrate was subjected to HCl, followed by [Ru]-I catalyst (10mol%) to induce a tandem enyne-RCM process to yield the acetylated natural product in a quantitative conversion as a 1 1 mixture of diastereoisomers. After... 

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