Cavicularin is a
natural phenol
In biochemistry, naturally occurring phenols are natural products containing at least one phenol functional group. Phenolic compounds are produced by plants and microorganisms. Organisms sometimes synthesize phenolic compounds in response to eco ...
ic
secondary metabolite isolated from the
liverwort ''
Cavicularia densa
''Cavicularia densa'' is the only species in the liverwort genus ''Cavicularia''. The species was first described in 1897 by Franz Stephani, and is endemic to Japan, where it grows on fine moist soil.
Plants are thalloid and flattened, with dis ...
''. This
macrocycle is unusual because it was the first compound isolated from nature displaying
optical activity
Optical rotation, also known as polarization rotation or circular birefringence, is the rotation of the orientation of the plane of polarization about the optical axis of linearly polarized light as it travels through certain materials. Circul ...
solely due to the presence of
planar chirality and
axial chirality
Axial may refer to:
* one of the anatomical directions describing relationships in an animal body
* In geometry:
:* a geometric term of location
:* an axis of rotation
* In chemistry, referring to an axial bond
* a type of modal frame, in music
* ...
. The
specific rotation
In chemistry, specific rotation ( �'') is a property of a chiral chemical compound. It is defined as the change in orientation of monochromatic plane-polarized light, per unit distance–concentration product, as the light passes through a sampl ...
for (+)-cavicularin is +168.2°. 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.
The
liverwort was obtained from
Mount Ishizuchi in the district of
Shikoku. The material was dried for one day, ground to a powder and 5 grams were
refluxed in
methanol
Methanol (also called methyl alcohol and wood spirit, amongst other names) is an organic chemical and the simplest aliphatic alcohol, with the formula C H3 O H (a methyl group linked to a hydroxyl group, often abbreviated as MeOH). It is a ...
for 4 months
'reference needed''/sup> to yield 2.5 mg (0.049%) of cavicularin after column chromatography and preparative TLC
Thin-layer chromatography (TLC) is a chromatography technique used to separate non-volatile mixtures.
Thin-layer chromatography is performed on a sheet of an inert substrate such as glass, plastic, or aluminium foil, which is coated with a ...
.
Total synthesis
In 2005 and again in 2011, the compound was prepared by total synthesis together with the unstrained compound riccardin C
Riccardin C is a macrocyclic bis(bibenzyl). It is a secondary metabolite isolated from the Siberian cowslip subspecies '' Primula veris subsp. macrocalyx'', in '' Reboulia hemisphaerica'' and in the Chinese liverwort '' Plagiochasma intermedium'' ...
. In 2013, several other syntheses were reported for it and a racemic synthesis.
References
{{Phenanthrenes
Dihydrostilbenoids
Phenanthrenoids
Macrocycles
Diphenyl ethers
Total synthesis
Cyclophanes