|Publication type:||Article in scientific journal|
|Type of review:||Peer review (publication)|
|Title:||Enantioselective synthesis of key intermediates in a novel approach towards the Iboga-alkaloid family|
|Published in:||Helvetica Chimica Acta|
|Publisher / Ed. Institution:||Wiley|
|Subjects:||Indole Alkaloids; Enantioselektive Synthesis; Ireland-Claisen Rearrangemenent|
|Subject (DDC):||540: Chemistry|
|Abstract:||Significant improvements in the realm of a recently disclosed, novel synthetic concept towards the Iboga alkaloid family are presented. The key step for the construction of the bicyclic aliphatic core consists of an intramolecular nitrone-olefin 1,3‐dipolar cycloaddition reaction of a 1 : 1 mixture 15/16 yielding the two diastereoisomeric tricyclic isoxazolidine derivatives 17 and 18. The required nitrones were prepared from the readily available (S)‐hydroxylactone 6 in twelve steps with an overall yield of 15% (average: 83.5% per step). The relative configuration of the minor isomer was deduced unambiguously by single‐crystal X‐ray analysis of the derived tricyclic carbamate 21. As four out of five asymmetric centers in the pair 17/18 have opposite configuration, destruction of the one possessing the same absolute configuration transforms the original set of diastereoisomers into a pair of enantiomers. We verified this contention by oxidizing the two alcohols 20 and 22 to yield the two antipodal forms of ketone 23. The absence of significant amounts of by‐product and the high reproducibility of the crucial cycloaddition reaction represent marked improvements over our earlier attempts. In addition, the new route, which starts from L‐glutamate, should provide access to both naturally occurring antipodal series of the targeted alkaloid class.|
|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|
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Höck, S., & Borschberg, H.-J. (2003). Enantioselective synthesis of key intermediates in a novel approach towards the Iboga-alkaloid family. Helvetica Chimica Acta, 86(5), 1397–1409. https://doi.org/10.1002/hlca.200390125
Höck, S. and Borschberg, H.-J. (2003) ‘Enantioselective synthesis of key intermediates in a novel approach towards the Iboga-alkaloid family’, Helvetica Chimica Acta, 86(5), pp. 1397–1409. Available at: https://doi.org/10.1002/hlca.200390125.
S. Höck and H.-J. Borschberg, “Enantioselective synthesis of key intermediates in a novel approach towards the Iboga-alkaloid family,” Helvetica Chimica Acta, vol. 86, no. 5, pp. 1397–1409, 2003, doi: 10.1002/hlca.200390125.
Höck, Stefan, and Hans-Jürg Borschberg. “Enantioselective Synthesis of Key Intermediates in a Novel Approach towards the Iboga-Alkaloid Family.” Helvetica Chimica Acta, vol. 86, no. 5, 2003, pp. 1397–409, https://doi.org/10.1002/hlca.200390125.
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