293. The crystal structure of (–)-aspidospermine N(b)-methiodide

Abstract

A three-dimensional X-ray crystal structure analysis of the N(b)-methiodide of the alkaloid aspidospermine shows the molecular structure to have been correctly ascertained by chemical methods apart from the location of one ethyl group.T H E alkaloid aspidospermine obtained from the bark of Aspidosperma quebracho-blanco Schlect. was first examined chemically by Ewins in 1914, but serious attempts to elucidate

Absolute Konfiguration von Alkaloiden der Aspidospermin‐Gruppe

“…suure-tetramethylester ( V I I I ) .a) 528,6 mg (1 mMol) 1,4,5,8-Tetramcthy1-9,10-diathyliden-1,2,3,4,5,6,7,8-octahydroanthracen-2, 3,6,7-tetracarbonsaure-tetramethylester (VI) wurden in 400 ml Methanol mit 0,5 g RANEY-Nickel [6] unter Ruhren bis zu bccndeter Wasserstoffaufnahme (38 Std., 24,6 ml H,, 719, 6 Torr,21,s') bei 50-52" hydriert. Der Katalysator wurde unter Riihren vorhydriert und anschliessend die Substanz in einem Schiffchen ohne Unterbruch der Operation mittels einer Kippvorrichtung zugegeben.…”

“…kleinere Wellenlange; fur 11 /I in entsprechender Weise (-) und (+). Anschliessend seien die Argumente zusammengefasst, die zur Ableitung der Konfiguration der anderen Zentren dienen: 1) Die relative Stereochemie von (-)-Aspidospermin (Xc) steht auf Grund der RoNTGEN-StrUktUIanalySe im Sinne der Formel Xc fest [6] ; bei einer Sesselkonformation der Ringe C und D gibt sje Anlass zu einer infraroten trans-Bande bei 2750-2800 cm-1 (axiales H-Atom an C-19) [7]. Durch kontrollierte Permanganat-Oxydation von (+)-N-Deacetylaspidospermin (Xb) (aus (-)-Xc) erhalt man in etwa 10% Aus-beute (+)-l,2-Dehydro-N-deacetyl-aspidospermin (Vb) 3), das, wie an der rm.-Verbindung gezeigt wurde, mit Lithiumaluminiumhydrid in Ather, gefolgt von Acetylierung, Aspidospermin (Xc) liefert [8] [9].…”

Conformational Space and Dynamic Stereochemistry of Overcrowded Homomerous Bistricyclic Aromatic Enes − A Theoretical Study

“…[38] Thermochromism has also been found in the solid state. [47,48] The A Ǟ B transformation can be triggered not only by heating, photoexcitation, and pressure, but also by electrochemical redox cycles. [2,49Ϫ59] The important role of conformational equilibrium and kinetics in electrode reactions in the bianthrone series has been noted.…”

“…[63] Red bifluorenylidene (2), with central five-membered rings, adopts a twisted conformation. [7,35,64Ϫ67] Yellow dixanthylene (3) [7,47,48,68] and bianthrone (4), [7,69Ϫ71] with central sixmembered rings, are anti-folded with boat-shaped central rings. Colorless 5,5Ј-bi-5H-dibenzo[a,d]cycloheptenylidene (11), with central seven-membered rings, can adopt both an anti-folded and a syn-folded conformation.…”

Fastigiatine, a lycopodium alkaloid with a new ring system

“…This surprisingly large number of alkaloids and ring systems has been derived from an estimated -(2) 10% of the extant Lycopodium species. Recently, a number 12 of species native to New Zealand have been investigated in this R-N laboratory (3) and from one of them, Lycopodium fastigiatum R. Br., two new alkaloids, fastigiatine 1 (Cl9HZ8N20) and 10 …”