Sceletium Alkaloids Research Articles

Synthesis of Alkaloids, (±)-Sceletium Alkaloid A4 and (±)-N-Acetyltortuosamine

Synthesis of Alkaloids, (±)-Sceletium Alkaloid A4 and (±)-N-Acetyltortuosamine

Sceletium (Aizoaceae) Alkaloids : Short Total Synthesis of Racemic O-methyljoubertiamine by the Arylacetonitrile Route

Abstract Renewed synthetic interest in the mesembrane alkaloids3,4 has resulted from the recent characterization of several new bases found in various Southwest African Sceletium (Aizoaceae) species used in the elaboration of the pharmacollogicalPy interesting preparation known a8 “Channa” or “Kougoed”4. These include, amongst others, the seco-mesembrane alkaloids joubertiamine (Ia), dihydrojoubertiamine (11) and dehydrojoubertiamine (III)5.

Sceletium (aizoaceae) alkaloids: total synthesis of racemic mesembranone, joubertinamine and epijoubertinamine

The total synthesis of the Sceletium alkaloids mesembranone, joubertinamine and epijoubertinamine via the intramolecular cyclization of an enone to a benzensulfo n amide grouping under the conditions of a dissolving metal reduction is described.

ChemInform Abstract: A CONVERGENT APPROACH TO THE SYNTHESIS OF (.+‐.)‐O‐METHYLJOUBERTIAMINE USING ORGANOIRON COMPLEXES

AbstractDer Eisen‐Komplex (I) und das Enolat (II) ergeben das Addukt (III), das auf denn im Formelschema beschriebenen Weg zur Vorstufe (VII) von O‐Methyljoubertiamin (VIII) führt.

Sceletium alkaloids. Part 11. Aza-ring expansion of cis-bicyclo[4.2.0]octanones and related compounds. A regiospecific synthesis of cis-octahydroindolones

Sceletium alkaloids. Part 11. Aza-ring expansion of cis-bicyclo[4.2.0]octanones and related compounds. A regiospecific synthesis of cis-octahydroindolones

Sceletium alkaloids. Part 10. Synthesis of 1-substituted cis-bicyclo[4.2.0]octanones through [2+2] cycloadditions of dichloroketene to alkenes. Structural characterization of cycloadducts by oxa-ring expansion

Sceletium alkaloids. Part 10. Synthesis of 1-substituted cis-bicyclo[4.2.0]octanones through [2+2] cycloadditions of dichloroketene to alkenes. Structural characterization of cycloadducts by oxa-ring expansion

Sceletium alkaloids. Structures of five new bases from Sceletium namaquense

Sceletium alkaloids. Structures of five new bases from Sceletium namaquense

A convergent approach to the synthesis of (±)-O-methyljoubertiamine using organoiron complexes

Application of tricarbonyl (2-methoxycyclohexadienylium)iron hexafluorophosphate (4) as a readily available synthetic equivalent of the p-methoxyphenyl cation is exploited in a synthetic approach to the sceletium alkaloid (±)-O-methyljoubertiamine.

TOTAL SYNTHESIS OF SCELETIUM (AIZOACEAE) ALKALOIDS. THE CINNAMONITRILE ROUTE. THE TOTAL SYNTHESIS OF RACEMIC O-METHYL JOUBERTIAMINE AND MESEMBRINE

Abstract A new method of synthesis of Sceletium (Aizoaceae) alkaloids based on the introduction of a “formyl anion” equivalent at the β-position of a cinnamonitrile, followed by Robinson annulation and final modification of the resulting cyanomethyl side chain is described. The method has been successfully applied to the total synthesis of racemic O-methyljoubertiamine (1) and mesembrine (2).

Applications of substituted arylacetaldehydes in the total synthesis of mesembrane alkaloids. Part 2. An alternative synthesis of (±)-sceletium alkaloid A4

The substituted arylacetaldehydes (±)-2-(3,4-dimethoxyphenyl)pent-4-enal (1c) is shown to serve as a precursor in the total synthesis of the mesembrane alkaloid (±)-sceletium alkaloid A4.

Isolation and structure of a new Sceletium alkaloid containing a dihydropyridone ring

Isolation and structure of a new Sceletium alkaloid containing a dihydropyridone ring

Further applications of endocyclic enamine-enone annulations : The total syntheses of rac-Sceletium alkaloid A 4 and 3'-demethoxy sceletium alkaloid A 4

The total synthesis of rac-sceletium alkaloid A 4 1a and of its 3'-demethoxy analogue 1b via the annulation of endocyclic enamines 4a–b is presented. The Michael acceptor 5a is a useful synthon for the two-step synthesis of 2,3-disubstituted pyridines from Δ 2-pyrrolines.

Sceletium alkaloids. Part 7. Structure and absolute stereochemistry of (–)-mesembrane and 3′-methoxy-4′-O-methyljoubertiamine, two minor bases from S. namaquense L. Bolus: X-ray analysis of (–)mesembrane hydrochloride monohydrate

From S. namaquense L. Bolus, we have isolated the known base tortuosamine (7) and two new alkaloids, 3′methoxy-4′-O-methyljoubertiamine (6) and (–)-mesembrane (2) the structures of which have been established by spectroscopic and X-ray methods. Previous suggestions concerning the absolute configuration of alkaloids of the 3a-aryl-cis-octahydroindole ring system are confirmed by an X-ray analysis of (–)-mesembrane hydrochloride monohydrate which crystallizes in the monoclinic system, space group P21, with a= 14.50(1), b= 8.02(1), c= 7.57(1)A, β= 93.4(1)°, Z= 2. The crystal structure was solved by direct methods and refined by least-squares calculations to R 0.055 over 1 158 reflections from diffractometer measurements. The absolute configuration was established by the anomalous dispersion effect. The c.d. spectrum of (–)-mesembrine, considered as an axial β-aminoketone, is shown to exhibit normal octant behaviour.

The total syntheses of [formula omitted]-sceletium alkaloid A 4 and its 3′-demethoxy analogue

The total syntheses of [formula omitted]-sceletium alkaloid A 4 and its 3′-demethoxy analogue

Mass spectra of Sceletium alkaloids

AbstractThe mass spectra of several naturally occuring Sceletium alkaloids, as well as several synthetic variants, have been investigated. Techniques used include high resolution mass measurements, analysis of metastable transitions by the technique of ion defocusing and specific deuterium labeling in conjunction with low resolution mass spectrometry. Characteristic major fragmentation pathways have been determined for four basic structure types studied: the cis‐3a‐aryl‐octahydroindole ring system, exemplified by mesembrine; its 2,3‐pyrido analog, Sceletium A4; the seco series of pyridine bases, represented by tortuosamine; and the seco analog of the mesembrine‐type represented by tortuosamine; and the seco analog of the mesembrine‐type represented by dehydrojoubertiamine.

General methods of alkaloid synthesis. XI. Total synthesis of the sceletium alkaloid A-4 and an improved synthesis of (+/-)-mesembrine.

General methods of alkaloid synthesis. XI. Total synthesis of the sceletium alkaloid A-4 and an improved synthesis of (+/-)-mesembrine.

General methods of alkaloid synthesis. X. The total synthesis of the sceletium alkaloids ( )-joubertiamine, ( )-O-methyljoubertiamine, and ( )-dihydrojoubertiamine.

General methods of alkaloid synthesis. X. The total synthesis of the sceletium alkaloids ( )-joubertiamine, ( )-O-methyljoubertiamine, and ( )-dihydrojoubertiamine.

Crystal and molecular structure of sceletium alkaloid A4 by X-ray analysis

Sceletium Alkaloid A4, (1), C20H24N2O2, isolated from Sceletium namaquense L. Bolus crystallizes in the monoclinic system, space group P21, with a= 8·33(2), b= 14·74(3), c= 7·18(2)A, β= 95·04(20)°, and Z= 2. The structure was solved from photographic X-ray data by direct phase-determining methods and refined by full-matrix least-squares calculations to R 0·100 over 1523 observed reflexions. The alkaloid which contains a 2,3-disubstituted pyridine moiety is representative of a third structure variant in Sceletium species.

The structures of partial racemic Sceletium alkaloid A4 and tortuosamine, pyridine alkaloids from Sceletium tortuosum N. E. Br.

The structures of partial racemic Sceletium alkaloid A4 and tortuosamine are shown by spectral and chemical evidence to represent a new structural type of Sceletium alkaloid.

The structure of sceletium alkaloid A4, a pyridine alkaloid from Sceletium namaquense: direct method X-ray determination

The structure of the title alkaloid is shown by spectral evidence and direct method X-ray analysis to embody a 2,3-disubstituted pyridine ring in a novel variant of the known alkaloid ring system of the mesembrine series.