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Synthesis 2015; 47(18): 2819-2825
DOI: 10.1055/s-0034-1380430
DOI: 10.1055/s-0034-1380430
special topic
Asymmetric Total Synthesis of Tylophorine through a Formal [2+2] Cycloaddition Followed by Migrative Ring Opening of a Cyclobutane
Weitere Informationen
Publikationsverlauf
Received: 28. April 2015
Accepted after revision: 12. Mai 2015
Publikationsdatum:
01. Juli 2015 (online)


Abstract
The asymmetric total synthesis of phenanthroindolizidine alkaloid (–)-tylophorine was achieved by asymmetric transfer hydrogenation of a cyclic imine. The cyclic imine with a pendant phenanthrene core was synthesized by a TfOH-promoted domino ring-contraction/ring-opening sequence of a cyclobutanol bearing an azide group, which was constructed by a formal [2+2] cycloaddition of a 2′-vinyl-1,1′-biaryl-2-yl ketone enolate. Catalytic asymmetric hydrogenation of the cyclic imine intermediate allowed the late-stage construction of the asymmetric center.
Key words
heterocycles - natural products - cycloaddition - asymmetric synthesis - anticancer agentsSupporting Information
- Supporting information for this article is available online at http://dx.doi.org/10.1055/s-0034-1380430.
- Supporting Information