Heteroyohimbine types

These observations, together with the co-occurrence of quinamine (93) and the occurrence of aricine (heteroyohimbine type) in Cinchona pelletieriana Wedd. (C. pubescens Vahl), led to the proposal of the alternative structures A and B for these probably stereoisomeric alkaloids. 

CHCI3) of serpentinine also shows a hydrogen-bonded NH (3330 cm ) the standard NH group in heteroyohimbine types absorbs at 3445-3475 cm. ... 

The oxindole [both stereoisomers at C(7)] rearrangement products of an intermediate used previously in syntheses10 of d/e trans-heteroyohimbine types, were converted into their imino-ethers (30). A cyclization, C(16) as nucleophile... 

J. Stockigt, in J. D. Phillipson and M. H. Zenk (Dds.), Indole and biogenetically related alkaloids. The biosynthesis of heteroyohimbine-type alkaloids. Academic Press, London, 1980, pp. 113-141. 

Pawelka and Stockigt (5S5) identified eight different indole alkaloids from cell suspension cultures of O. elliptica. The pattern of the alkaloids found was quite different from the above-mentioned results reported by Kuoadio and co-workers (779). The alkaloids identified were tetrahydroal-stonine, cathenamine, pleiocarpamine and two other methoxy-substituted heteroyohimbine alkaloids Corynanthe/heteroyohimbine type), norfluo-rocurarine Strychnos type), and apparicine and epchrosine Aspi-dosperma type). The last mentioned alkaloid was a new compound (729) not known from intact plants. 

Kitajima M, Nakayama T, Kogure N, Wongseripipatana S, Takayama H. New heteroyohimbine-type oxindole alkaloid from the leaves of Thai Mitragyna hirsuta. J Nat Med 2007 61(2) 192-5. 

In the first slide I summarized what I am going to talk today, the list of target indole alkaloids. My talk consists of two parts, the first part is on the synthesis of yohimbine and its group and the second part on the synthesis of corynantheine and heteroyohimbine types of alkaloids. 

The stereochemistry of the heteroyohimbine types resembles that of the yohimbines but with an additional chiral centre at C19. It is again probable that only (155) type compounds occur naturally and there are thus again 4 basic skeletal types, normal (e.g. ajmalicine K9.7, pseudo, alio and epiallo, each of which may in addition have the (19i ) or (195) configuration [4]. ORD of heteroyohimbine alkaloids [5]. 

Cathenamine and 4,21-dehydrogeissoschizine have both been demonstrated to be the central intermediates in the enzymatic production of heteroyohimbine-type alkaloids - ajmalicine, 19-epiajmalicine, and tetrahydroalsonine (128, 152) (Fig. 

Enzymatic Formation of Monoterpenoid Indole Alkaloids 2.1 Heteroyohimbine /Sarpagine /Ajmaline Type Alkaloids... 

From these data, the structure XXX has been proposed for alstonidine (70). Although this structure is consistent with the known properties of this alkaloid, further work is desirable in order to establish the precise nature of the dihydropyran residue, which was formulated in this way partly by analogy with the structure of the heteroyohimbine bases. In particular, a facile conversion of a structure such as XXX into a close relative of alstonine should be feasible. Unfortunately, lack of material has so far precluded all attempts at a structural correlation of this type (70). 

RETENTION TIMES OF HETEROYOHIMBINE- AND OXtNDOLE-TYPE ALKALOIDS77... 

The transformation of indole into corresponding oxindole alkaloids has been possible for some time now the reverse sequence has been achieved. The type of 2,3-seco-intermediate (47) arrived at by total synthesis above has been pro-duced " and then cyclized, in both heteroyohimbine (Scheme 12) and yohimbine... 

Synthesis of the heteroyohimbine aikaioid, ajmalicinej outlined below is a classic example of van Tamelen s biogenetic-type synthesis of natural products. The non-aromatic part of the molecule is condensed with formaldehyde and tryptamine in a biogenetically patterned key step, serving to assemble the essential skeletal features of the alkaloid at the very outset. 

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