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Published on: August 12, 2019
Roxbin B is cuspinin: structural revision and total synthesis
Sayuri Yamaguchi1, Tsukasa Hirokane, Takashi Yoshida
1School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda 669-1337, Japan.
Roxbin B, initially synthesized and found different from its natural form, was re-examined. Structural analysis and total synthesis confirmed Roxbin B is identical to cuspinin, a rare natural product with (R)-axial chirality.
Area of Science:
- Natural Product Chemistry
- Organic Synthesis
- Structural Elucidation
Background:
- Roxbin B, a natural product, was synthesized, but the synthetic product did not match the natural compound.
- Initial structural determination and spectral data suggested a discrepancy.
Purpose of the Study:
- To resolve the structural discrepancy between synthesized and natural Roxbin B.
- To confirm the proposed structure of cuspinin through total synthesis.
Main Methods:
- Re-examination of structural determination processes and spectral data.
- Total synthesis of the proposed structure of cuspinin.
- Comparison of synthesized and natural Roxbin B.
Main Results:
- The re-examination indicated Roxbin B is likely 1-O-galloyl-2,3-(R);4,6-(S)-bis-O-hexahydroxydiphenoyl-β-d-glucose (cuspinin).
- The (R)-axial chirality in the hexahydroxydiphenoyl bridging is a rare feature in natural products.
- Total synthesis successfully confirmed the proposed structure of cuspinin.
Conclusions:
- Roxbin B is structurally identical to cuspinin.
- The total synthesis validated the proposed structure and the presence of rare (R)-axial chirality.
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