Total synthesis of the antileukaemic lignan (±)-steganacin

Becker, D.; Hughes, Laura E.; Raphael, R. A.

doi:10.1039/p19770001674

Cited by 51 publications

(11 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…So wurde das durch [6p]-Photocyclisierung erhaltene Phenanthren 31 in das Lignan (AE)-Steganacin (32) verwandelt. [51] Oxidative Spaltung, [55] Die [6p]-Photocyclisierung eines Vinylbenzols wurde erstmals in der Synthese der Alkaloide Sanguinarin und Chelerythrin genutzt. [56] In jüngster Zeit wurde die [6p]-Photocyclisierung eines ortho-Pyridinylstyrols von Kelly et al zur Synthese des Alkaloids Santiagonamin angewendet.…”

Section: Aufsätzeunclassified

Photochemische Reaktionen als Schlüsselschritte in der Naturstoffsynthese

2011

View full text Add to dashboard Cite

Photochemische Reaktionen bereichern in signifikanter Weise das Repertoire zur Knüpfung von Kohlenstoff‐Kohlenstoff‐Bindungen und machen ungewöhnliche, auf herkömmlichem Weg nicht erhältliche Molekülgerüste zugänglich. In diesem Aufsatz werden die wichtigsten Umsetzungen der Photochemie vorgestellt, die auf breiter Front Einzug in die Naturstoffsynthese gehalten haben. Beispielhaft werden einzelne Totalsynthesen diskutiert, wobei besonderes Augenmerk auf den photochemischen Schlüsselschritt sowie dessen Stereoselektivität gerichtet ist. Dabei wird das photochemisch erzeugte Molekül in Relation zur Struktur des Naturstoffs gebracht, und Folgereaktionen werden, wo notwendig, illustriert und klassifiziert.

show abstract

Section: Aufsätzeunclassified

Photochemische Reaktionen als Schlüsselschritte in der Naturstoffsynthese

2011

View full text Add to dashboard Cite

show abstract

“…EXPERIMENTAL General: 2-Oxobutanoic acid and 1-butanoyl chloride were commercial products from Aldrich. 2-Bromo-4,5-methylenedioxybenzoic acid was prepared from piperonal according to the reported procedure [23]. 1 H and 13 C NMR spectra (δ) were recorded in CDCl 3 at 400 and 100 MHz, respectively (Bruker AM-100).…”

Section: Resultsmentioning

confidence: 99%

A Single-Step Synthesis of Xyridins A and B, Metabolites from Xyris indica

Saeed

2005

Chem Heterocycl Compd

View full text Add to dashboard Cite

A facile single-step synthesis of the title isocoumarins isolated from Xyris indica has been elaborated. Condensation of butanoyl chloride and 2-oxobutanoyl chloride with 3,4-methylenedioxyhomophthalic acid afforded xyridin A and xyridin B, respectively. Xyridin A was saponified to the corresponding keto acid, which on reduction gave the (±)-3,4-dihydro-6,7-methylenedioxy-3-propylisocoumarin in which diastereotopy of the methylenic protons around the stereogenic center was observed. A mass fragmentation mechanism for xyridins has also been suggested.In 1995, Ruangrungsi et al. isolated from the nonpolar fraction of the chloroform extract of the flowering heads of the weed Xyris indica two new isocoumarins, which they named xyridins A and B [1]. Xyris indica L. (tall yellow-eyed grass) is one of the five species of the genus Xyris found throughout Thailand and is known locally as "Kra thin thung". In Bengal the plant has been used in folk medicine as a cure for ring worm, itch, and leprosy. The structures of xyridin A and B were established by modern spectroscopic techniques as 6,7-methylenedioxy-3-propylisocoumarin (1a) and 6,7-methylenedioxy-3-(1-oxopropyl)isocoumarin (1b), respectively. O O O O X 1a,b 1 a X = H 2 , b X = OAlthough xyridins A and B, like the majority of other naturally occurring isocoumarins derived biogenetically from acetate via the acetate-polymalonate pathway, possess a C(8) or C(6) and C(8) oxygenation, xyridins A and B are unique in being 3-alkyl/acyl-substituted 6,7-methylenedioxyisocoumarins. In the literature unsubstituted 4,5-, 6,7-methylenedioxyisocoumarins and 4,5-, 5,6-, 6,7-methylenedioxy-3,4-dihydroisocoumarins are known along with 3-methyl-6,7-methylenedioxy-3,4-dihydroisocoumarin as the only example of a 3-alkyl-substituted 6,7-methylenedioxyisocoumarin [2][3][4]. Some important examples of other natural products bearing a 6,7-methylenedioxydihydroisocoumarin moiety are hippeastrine [5], tetrabenzylcorricidin [6], lycoricidin [7], pancratistatin [8,9], and tazettine [10]. Peshawarine contains an 3-aryl-7,8-methylenedioxy-3,4-dihydroisocoumarin skeleton [11]. __________________________________________________________________________________________

show abstract

“…The commercial starting compounds purchased from Aldrich were 2-oxobutanoic acid and butanoyl chloride. 2-Bromo-4,5methylenedioxybenzoic acid was prepared from piperonal according to the reported procedure [17]. 1 A stirred solution of xyridin A (1a) 0.095 g (0.40 mmol) in 10 ml ethanol was treated with 20 ml of 5% potassium hydroxide and the mixture was refluxed for 4 h. After cooling the reaction mixture, 10 ml cold water was added and the mixture acidified with dilute hydrochloric acid and immediately extracted with dichloromethane (2x 30 mL).…”

Section: Methodsmentioning

confidence: 99%