Corynantheane

According to KisakQrek and Hesse (4), eight of these types are named vin-cosan, vallesiachotaman, corynanthean, strychnan aspidospermatan (all these... 

Alkaloids of plumeran, aspidospermatan, corynanthean, and ibogan types are conveniently subdivided into subtypes depending on further variations of the terpenic portion or, in very few cases, of the indole portion of the fundamental skeleton. The subtypes are named according to the most representative member, even if this is not found in Tabemaemontana. 

E. Bisindole Alkaloids 1. Corynanthean-Aspidospermatan-Type Alkaloids... 

Wolff-Kishner reduction gave the open-chain alcohol LXXX. Elimination of the hydroxyl via the corresponding ketone generated dihydro-corynantheane (XV) (50). 

The stereochemistry of ajmaline (II) has been the subject of discussion (41, 42), although no later experimental evidence to support these deductions has been formulated. It is, of course, clear that except for centers at 17, 20, and 21, it is largely a problem of the absolute stereochemistry, since the hexacyclic system can only be put together in two ways, epimerization being possible at C-2. The absolute stereochemistry has been derived (16) (Chart III) as a result of a stereospecific chemical unfolding of 21-deoxyisoajmaline to 1 -methyltetradehydrodihydro-corynantheane (XVI epimeric 20-ethyl) whose absolute stereochemistry... 

Vinorelbine Yohimbine la(corynanthean) Corynanthe johimbe a-adrenergic blocker... 

The pharmacological significance of ajmalicine stems from its use in the treatment of hypertension and obstructive circulatory diseases. Serpentine and ajmalicine can easily be transformed into each other by means of, respectively, simple reduction or oxidation. The yearly production of ajmalicine is estimated to be about 3600 kg (2). Ajmalicine and serpentine are the major alkaloids found in cell and tissue cultures of C. roseus. Both are representatives of corynanthean-type indole alkaliods, of which more than 25 different compounds are isolated from C. roseus cultures (592). 

Alstonia alkaloids. A group of over 250 differing monomeric and dimeric monoterpenoid indole alkaloids from the genus Alstonia (Apocynaceae) having aspidospermidine, corynanthean, heteroyohimbane, and related indole skeletons. The A. a. are isolated from leaves, roots, and bark of wild Alstonia species (bushes, often fairly large evergreen trees) with the exception of A. scholaris which can be cultivated. 

C = corynanthean-type of alkaloid I = ibogan-type of alkaloid S = strychnan-type of alkaloid... 

According to the classification of Leeuwenberg (1980), the Rubiaceae may be divided into four subfamilies the Rub-ioideae, Cinchonoideae, Guettardoideae, and Hillioideae. Indole alkaloids of the corynanthean type are the most common in the family. The tribe Cinchoneae of the subfamily Cinchonoideae is the only group to contain alkaloids with a nonrear-... 

The alkaloids imder discussion share a common Corynanthe-type nucleus derived from secologanin. Yohimbine is a carbocyclic variant of ajmalicine, and the enzymes that convert deglycosylated strictosidine to yohimbine have not been identified [124, 125]. Strychnine and bmcine are synthesized from the preakuammicine structure by hydrolysis, decarboxylation, and condensation reactions to aldehyde (Wieland-Gumlich), and subsequently reaction with acetyl-CoA to make a hemiacetal form of aldehyde (Wieland-Gumlich) and strychnine and brucine. Brucine is a dimethoxy form of strychnine. Ellipticine is a representative member of pyrido[4,3-b] carbozole alkaloid, and the formation of ellipticine is from ajmalicine (corynanthean skeleton) [126] (Fig. 20.8). 

The situation with alkaloids containing the dihydro-corynantheane skeleton is similar there are four stereoisomeric types, normal (e.g. corynantheine YAAA, pseudo, alio (e.g. corynantheidine K9.5) and epiallo. Their stereochemistry has been fully discussed [2]. On the basis of this work a corynantheine type alkaloid can be allotted to one of the four classes by spectroscopic measurement, making the same assumption about Cys) configuration [2]. 

The quasidimer longicaudatine (8), with a corynanthean-strychnan skeleton, is present in a variety of African and Asian Strychnos species and has now been found for the first time in an American species, S. trinervis (Table 1.4). Its structure is based largely on interpretation of its NMR spectra, especially the spectrum, which is very similar to those of the relevant parts of geissoschizine and strychnine. The compound is presumed to be derived via an enamine coupling between Wieland-Gumlich aldehyde and geissoschizal (475, 479). 

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