Aspidosperma marcgravianum

An investigation of Aspidosperma marcgravianum (23) led to the isolation of 18,19-dihydroantirhine (14). The quaternary Ab-(3-methochloride derivative of 14 (compound 15) was previously found in Hunteria eburnea Pichon (22). 

Tetradehydro-18,19-dihydrocorynantheol (16) has been isolated from Aspidosperma marcgravianum (23). The structure of 16 has been determined on the basis of spectral data and by comparing the alkaloid with a semisynthetic... 

Dihydrocorynantheol (21), first isolated from Aspidosperma marcgravianum (147), is the simplest corynanthe alkaloid. The members of this type of alkaloid have three stereo centers in the D ring of the indolo[2,3-a]quinolizine skeleton. This substitution pattern allows four possible relative arrangements for the C-3, C-15, and C-20 stereo centers, the names of which are normal, pseudo, alio, and epiallo, respectively. 

Verpoorte, R., Kos-Kuick, E., Tsin a Tsoi, A., Ruigrok, C. L. M., de Jong, G. and Baerheim Svendsen, A. 1983. Medicinal plants of Suriname. IB. Antimicrobially active alkaloids from Aspidosperma marcgravianum. Planta Medica, 48 283-289. 

Alstonia constricta F. Muell. (36) alstonine, R. vomitoria (37) aricine, Aspidosperma marcgravianum Woodson (37) reserpiline, R. decurva Hook. (38) isoreserpiline, R. cambodiana Pierre (39), R. decurva, and Ochrosia poweri F. M. Bailey serpentinine, R. vomitoria (37) and R. javanica (34). 

Since oxidized derivatives of secodine appear to be involved as late intermediates in the biosynthesis of the aspidospermidine and pseudoas-pidospermidine alkaloids, it is logical to begin with those secodine derivatives that have been found to occur naturally. Tetrahydrosecodine (1) occurs in the root bark of Aspidosperma marcgravianum Woodson (5) and has been detected in cell-suspension cultures of Rhazya stricta Decaisne (6) its demethoxycarbonyl derivative (2) also occurs in A. marcgravianum (5), and in Haplophyton crooksii L. Benson (7,8) and the roots of R. stricta (9). The two isomeric carbonyl derivatives, 2-ethyl-3-[2-(3-acetyl-V-piperidino)ethyl]indole (3) and crooksidine (4), occur, respectively, in A. marcgravianum (5) and H. crooksii (7,8). 

Verpoorte R, Ruigrok CLM, Baerheim Svendsen A. Medicinal plants of Suriname. Antimicrobial active alkaloids from Aspidosperma marcgravianum. Planta Med 1982 46 149-52. 

Scheme 47, use of R)- 2 as a catalyst in the first step should therefore give access to the natural product dihydrocorynantheol, a compound isolated from Aspidosperma marcgravianum showing activity against Gram-positive bacteria (J80). 

Aspidosperma marcgravianum L. Quinidine, dibydroquinidine, (methoxy) dihydrocOTynantheol, aricine [54,55,56]... 

The enamine (/dienamine)-iminium cycle-specific cascade catalysis is an important constituent of amine-catalyzed cascade reactions [10]. This strategy has been explored extensively and also applied to natural product synthesis. One such example is the total synthesis of dihydrocorynantheol, which was first isolated from the bark of Aspidosperma marcgravianum in 1967 [29]. This indole alkaloid is a member of the corynantheine and was found to exhibit antiparasitic, antiviral, or analgetic activities, which have attracted considerable attention from the synthetic community. Among those reported total syntheses, Itoh et al. developed a Mannich-Michael cascade reaction catalyzed by L-proline 52 for the total synthesis of ent-dihydrocorynantheol 54 (Scheme 3.8) [30], The cascade reaction of 3-ethyl-3-buten-2-one 51 with dihydro-P-carboline 50 catalyzed by 30mol% of (S)-proline afforded the tetracyclic core structure 53 in 85% yield. Excellent stereoselectivity was achieved in this cascade reaction (99% enantiomeric excess and almost complete diastereomeric control). Therefore, this organocascade reaction could lead expeditiously to construction of the core structure, which enabled the authors to accomplish the total synthesis of enl-dihydrocorynantheol 54 in just five steps. 

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