|Publication type:||Article in scientific journal|
|Type of review:||Peer review (publication)|
|Title:||Chirality transfer in an Ireland-Claisen rearrangement : a new approach toward the Iboga alkaloids|
|Published in:||Tetrahedron: Asymmetry|
|Publisher / Ed. Institution:||Elsevier|
|Subjects:||Indole alkaloids; Chirality transfer; Ireland-Claisen rearrangemenent|
|Subject (DDC):||572: Biochemistry|
|Abstract:||The synthesis of the isoquinuclidine core of the Iboga alkaloid family is described. This building block contains the entire stereochemical information of the targeted natural products. Starting with (S)-4-(hydroxymethyl)-4-butanolide, a derivative available in two steps from l-glutamate, (S)-4-benzyloxy-5,5-dimethoxypentanoic acid was obtained in four steps. Mitsunobu esterification with (S)-but-3-en-2-ol furnished the inverted ester, which was then subjected to an Ireland–Claisen rearrangement. This crucial step took place with a very satisfactory chirality transfer from the alcohol component to the new carbon backbone of the product. After transformation of the resulting silyl ester function into a hydroxylamino group, the dimethyl acetal moiety was hydrolyzed with 3 M sulfuric acid at 47°C. Under these conditions, the resulting cyclic nitrone could not be isolated, because it underwent a rapid intramolecular nitrone–olefin [3+2]-cycloaddition reaction to furnish the expected tricyclic isoxazolidine derivative in 67% yield. After chromatographic purification, this product was obtained enantiomerically pure and with a chemical purity of 96%. The targeted isoquinuclidine building block was thus obtained from (S)-4-(hydroxymethyl)-4-butanolide in 13 steps with an overall yield of 9.2%, which amounts to an average yield of 83.3% per step.|
|Fulltext version:||Published version|
|License (according to publishing contract):||Licence according to publishing contract|
|Departement:||Life Sciences and Facility Management|
|Organisational Unit:||Institute of Chemistry and Biotechnology (ICBT)|
|Appears in collections:||Publikationen Life Sciences und Facility Management|
Files in This Item:
There are no files associated with this item.
Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.