Inhaltsstoffe aus Clausena anisata (Willd.) Oliv. (Rutaceae), IV. Synthese des Mupamins

Abstract

Die Synthese des Pyranocarbazolalkaloids Mupamin (6) aus der Wurzelrinde von Clausenu anisata wird mitgeteilt. Constituents of Chusena anisata (Willd.) Oliv. (Rutaceae), IV1). -Synthesis of MupamineThis contribution reports on the synthesis of mupamine (6), a pyranocarbazole alkaloid from the root bark of Clausena anisata.Eine friihere Mitteilung2) befal3te sich mit der Isolierung des Mupamins aus der Wurzelrinde von Clausenu unisutu (Willd.) Oliv. (Rutaceae). Dem neuen Alkaloid konnte kiirzlich aufgrund seiner spektralen Daten die Struktur 10-Methoxy-3,3 ,Strimethyl-3,l l-dihydropyrano[3,2-u]carbazol(6) zugeordnet werden3). Nun folgt ein Bericht iiber die Synthese des Mupamins, durch die die vorgeschlagene Struktur 6 bestatigt wird.Ausgangsverbindung der Synthese war das 1,2-Cyclohexandion-(3-hydroxy-4methylphenylhydrazon) (l), welches durch Kondensieren von 2-Hydroxymethylencyclohexanon mit 3-Hydroxy-4-methylbenzoldiazoniumchlorid zuganglich ist . Die Indolisierung nach der Methode von Chukruborty und Mitarbeitern4) fiihrt hauptsachlich zum 7-Hydroxy-6-methyl-I ,2,3,4-tetrahydro-l-carbazolon (2a); als Nebenprodukt tritt das isomere 5-Hydroxy-6-methyl-1,2,3,4-tetrahydro-l-carbazolon (2b) auf.

Total Synthesis of 7‐ and 8‐Oxygenated Pyrano[3,2‐a]carbazole and Pyrano[2,3‐a]carbazole Alkaloids via Boronic Acid‐Catalyzed Annulation of the Pyran Ring

“…Boronic acid-catalyzed reaction of 35 with prenal led to mupamine (2), isolated by Mester and Reisch from the root bark of Clausena anisata. [23,24] The structural assignment for our synthetic mupamine (2) has been additionally confirmed by an X-ray crystal structure determination (Figure 1). [25] The boronic acid-catalyzed annulation of 35 and citral provided murrayamine-B (5), isolated by Wu from the leaves of Murraya euchrestifolia.…”

“…Reaction of the 2-hydroxycarbazole 14 with citral in the presence of 20 mol % of boronic acid and an excess of propanoic acid afforded the desired O-(triisopropylsilyl)mahanine (23) in 51 % yield along with O-(triisopropylsilyl)murrayamine-D (24) in 27 % yield (Scheme 4, Table 2). The proton-catalyzed conversion of homoprenyl-substituted pyrano[3,2-a]carbazoles to the corresponding cyclized monoterpenoid pyrano[3,2a]carbazoles has been confirmed recently.…”

“…Greger et al described the stress-induced formation of this phytoalexin in Glycosmis parviflora and isolated it from the leaves of that plant. [22,23] Carbalexin-B (35) exhibits a strong antifungal activity. Boronic acid-catalyzed reaction of 35 with prenal led to mupamine (2), isolated by Mester and Reisch from the root bark of Clausena anisata.…”

Synthesis of Tetranuclear Palladium(II) Complexes and Their Catalytic Activity for Cross‐Coupling Reactions

“…Finally,w ea lso prepared the non-natural biscarbalexine B ( 5). The corresponding carbalexin B ( 20)w as first mentioned as as ynthetic compound by Reisch in 1980, [66] later isolated by Greger from Glycosmis pentaphylla in 2001, [61] and obtained by our total synthesis in 2014. [35,36] Treatment of 20 with di-tert-butyl peroxide in chlorobenzenea tr eflux led to the 8,8'-dimethoxy-1,1'-bicarbazole in only 23 %yield accompanied by extensive decomposition.…”

Inhaltsstoffe aus Clausena anisata (Willd.)Oliv. (Rutaceae), III [1,2]13C-NMR-Spektren des Mupamins, des Carbazols und einiger Carbazol-Derivate / Constituents of Clausena anisata (Willd.) Oliv . (Rutaceae) , III [1,2] 13C NMR Spectra of Mupamine , Carbazole and Some Carbazole Derivatives

“…Für die völlige Aufschlüsselung des Mupamin-Spektrums wurden die Spektren des Carbazols und einiger Modellsubstanzen benötigt. Derartige Modellsubstanzen, das sind die Tetrahydrocarbazole la-d und 2, sowie die Carbazole 3b-d. fielen nun bei der Gegensynthese des Mupamins an [6].…”