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DOI: 10.1055/s-0030-1258874
Synthesis of endo-6-Aryl-8-oxabicyclo-[3.2.1]oct-3-en-2-one
Rezensent(en):Steven V. Ley, James R. FrostHokkaido University, Sapporo and Rigaku Corporation, Tokyo, Japan
Catalytic Asymmetric Synthesis of the endo-6-Aryl-8-oxabicyclo[3.2.1]oct-3-en-2-one Natural Product from Ligusticum chuanxing via 1,3-Dipolar Cycloaddition of a Formyl-Derived Carbonyl Ylide Using Rh2(S-TCPTTL)4
J. Org. Chem. 2010, 75: 6039-6042
Publikationsverlauf
Publikationsdatum:
22. November 2010 (online)
Key words
1,3-dipolar cycloaddition - ylides - catalytic asymmetric synthesis
Significance
This is the first example of an enantioselective 1,3-dipolar cycloaddition of a cyclic formyl carbonyl ylide. This methodology was successfully applied to the synthesis of endo-6-aryl-8-oxabicyclo[3.2.1]oct-3-en-2-one, which was isolated from Ligusticum chuanxing Hort., a traditional Chinese medicine used to promote blood circulation.
Comment
The enantioselective 1,3-dipolar cycloaddition proceeds with impressive er (97.5:2.5) to form E. The reduced product F could then be recrystallized and the er upgraded to 99.5:0.5. The circular dichroism of the natural product differed from the synthetic sample, leading the authors to speculate that the natural product may be biosynthesized in racemic form.