Cavicularin

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Cavicularin
Cavicularin.svg
Identifiers
CAS number 178734-41-3 YesY
ChemSpider 26323925 YesY
Jmol-3D images Image 1
Properties
Molecular formula C28H22O4
Molar mass 422.47 g mol−1
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

Cavicularin is a natural phenolic secondary metabolite isolated from the liverwort Cavicularia densa. This macrocycle is unusual because it was the first compound isolated from nature displaying optical activity solely due to the presence of planar chirality and axial chirality. The specific rotation for (+)-cavicularin is +168.2°.[1] It is also a very strained molecule. The para-substituted phenol ring is bent about 15° out of planarity, adopting a somewhat boat-like geometry. This type of angle strain in aromatic compounds is normally reserved for synthetic cyclophanes.

Cavicularin, three-dimensional representation

The liverwort was obtained from Mt. Ishizuchi in the district of Shikoku. The material was dried for one day, ground to a powder and 5 grams were refluxed in methanol for 4 months to yield 2.5 mg (0.049%) of cavicularin after column chromatography and preparative TLC.

Riccardin C, flat molecule representation

Total synthesis[edit]

In 2005 and again in 2011, the compound was prepared by total synthesis together with the unstrained compound riccardin C.[2][3] The strategy used was a radical reaction. In 2013 several procedures have been reported, one based on transannulation,[4] one based on a Diels-Alder reaction [5] and one (racemic) based on a coupling reaction.[6]

References[edit]

  1. ^ M. Toyota, T. Yoshida, Y. Kan, S. Takaoka, Y. Asakawa (1996). "(+)-Cavicularin: A Novel Optically Active Cyclic Bibenzyl-Dihydrophenanthrene Derivative from the Liverwort Cavicularia densa Steph". Tetrahedron Letters 37 (27): 4745–4748. doi:10.1016/0040-4039(96)00956-2. 
  2. ^ David C. Harrowven, Timothy Woodcock , Peter D. Howes (2005). "Total Synthesis of Cavicularin and Riccardin C: Addressing the Synthesis of an Arene That Adopts a Boat Configuration". Angewandte Chemie 44 (25): 3899–3901. doi:10.1002/anie.200500466. PMID 15900530. 
  3. ^ Kostiuk, S. L., Woodcock, T., Dudin, L. F., Howes, P. D. and Harrowven, D. C. (2011), Unified Syntheses of Cavicularin and Riccardin C: Addressing the Synthesis of an Arene Adopting a Boat Configuration. Chemistry - A European Journal, 17: 10906–10915. doi:10.1002/chem.201101550
  4. ^ Takiguchi, H., Ohmori, K. and Suzuki, K. (2013), Synthesis and Determination of the Absolute Configuration of Cavicularin by a Symmetrization/Asymmetrization Approach . Angew. Chem. Int. Ed., 52: 10472–10476. doi:10.1002/anie.201304929
  5. ^ Total Synthesis of (±)-Cavicularin: Control of Pyrone Diels–Alder Regiochemistry Using Isomeric Vinyl Sulfones Peng Zhao and Christopher M. Beaudry Organic Letters 2013 15 (2), 402-405 doi:10.1021/ol303390a
  6. ^ Kenichi Harada, Kosho Makino, Naoki Shima, Haruka Okuyama, Tomoyuki Esumi, Miwa Kubo, Hideaki Hioki, Yoshinori Asakawa, Yoshiyasu Fukuyama, Total synthesis of riccardin C and (±)-cavicularin via Pd-catalyzed Ar–Ar cross couplings, Tetrahedron, Volume 69, Issue 34, 26 August 2013, Pages 6959-6968, ISSN 0040-4020, http://dx.doi.org/10.1016/j.tet.2013.06.064.