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Cavicularin
Cavicularin is a natural phenolic secondary metabolite Secondary metabolites, also called specialised metabolites, toxins, secondary products, or natural products, are organic compounds produced by any lifeform, e.g. bacteria, fungi, animals, or plants, which are not directly involved in the norma ... isolated from the Marchantiophyta, 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°. It is also a very strain (chemistry), strained molecule. The ''para''-substituted phenol ring is bent about 15° out of planarity, adopting a somewhat cyclohexane conformation, boat-like geometry. This type of Ring strain, angle strain in aromatic compounds is normally reserved for synthetic cyclophanes. The Marchantiophyta, liverwort was obtained from Mount Ishizuchi in the dist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cavicularin
Cavicularin is a natural phenolic secondary metabolite Secondary metabolites, also called specialised metabolites, toxins, secondary products, or natural products, are organic compounds produced by any lifeform, e.g. bacteria, fungi, animals, or plants, which are not directly involved in the norma ... isolated from the Marchantiophyta, 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°. It is also a very strain (chemistry), strained molecule. The ''para''-substituted phenol ring is bent about 15° out of planarity, adopting a somewhat cyclohexane conformation, boat-like geometry. This type of Ring strain, angle strain in aromatic compounds is normally reserved for synthetic cyclophanes. The Marchantiophyta, liverwort was obtained from Mount Ishizuchi in the dist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Planar Chirality
Planar chirality, also known as 2D chirality, is the special case of chirality for two dimensions. Most fundamentally, planar chirality is a mathematical term, finding use in chemistry, physics and related physical sciences, for example, in astronomy, optics and metamaterials. Recent occurrences in latter two fields are dominated by microwave and terahertz applications as well as micro- and nanostructured planar interfaces for infrared and visible light. In chemistry This term is used in chemistry contexts, e.g., for a chiral molecule lacking an asymmetric carbon atom, but possessing two non-coplanar rings that are each dissymmetric and which cannot easily rotate about the chemical bond connecting them: 2,2'-dimethylbiphenyl is perhaps the simplest example of this case. Planar chirality is also exhibited by molecules like (''E'')-cyclooctene, some di- or poly-substituted metallocenes, and certain monosubstituted paracyclophanes. Nature rarely provides planar chiral molecules, c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 2005, the compound was prepared by total synthesis together with the strained compound cavicularin Cavicularin is a natural phenolic secondary metabolite Secondary metabolites, also called specialised metabolites, toxins, secondary products, or natural products, are organic compounds produced by any lifeform, e.g. bacteria, fungi, animal ....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. References {{Dihydrostilbenoid Dihydrostilbenoids Macrocycles Cyclophanes Heterocyclic compounds with 5 rings Oxygen heteroc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyclophane
In organic chemistry, a cyclophane is a hydrocarbon consisting of an aromatic unit (typically a benzene ring) and a chain that forms a bridge between two non-adjacent positions of the aromatic ring. More complex derivatives with multiple aromatic units and bridges forming cagelike structures are also known. Cyclophanes are well-studied examples of strained organic compounds. Cyclophanes Structures Paracyclophanes adopt the boat conformation normally observed in cyclohexanes. Smaller value of n lead to greater distortions. X-ray crystallography on ' aracyclophane' shows that the aromatic bridgehead carbon atom makes an angle of 20.5° with the plane. The benzyl carbons deviate by another 20.2°. The carbon-to-carbon bond length alternation has increased from 0 for benzene to 39 pm. Despite their distorted structures, cyclophanes retain their aromaticity, as determined by UV-vis spectroscopy. Reactivity With regards to their reactivity, cyclophanes often exhibit diene-li ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 ecological pressures such as pathogen and insect attack, UV radiation and wounding. As they are present in food consumed in human diets and in plants used in traditional medicine of several cultures, their role in human health and disease is a subject of research. Some phenols are germicidal and are used in formulating disinfectants. Classification Various classification schemes can be applied. A commonly used scheme is based on the number of carbons and was devised by Jeffrey Harborne and Simmonds in 1964 and published in 1980: C6-C7-C6 Diarylheptanoids are not included in this Harborne classification. They can also be classified on the basis of their number of phenol groups. They can therefore be called ''simple phenols'' or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 distinct upper and lower surfaces and a faint central strand. Thin scales grow from the underside in two rows, and in the region between the scales and the central strand are small ear-shaped ''domatia'' which harbor colonies of the blue-green alga ''Nostoc''. The plants are dioicous, with the male antheridia and female archegonia produced by separate plants. Plants may also reproduce asexually from multicellular gemmae produced in crescent-shaped receptacles on the thallus surface. The spores are spherical and apolar, with a surface devoid of ornamentation except for tiny papillae. Gametophyte development is endosporic, so that cell divisions begin inside the spore wall. This pattern of development is normally found in liverworts from xeri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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. Circular birefringence and circular dichroism are the manifestations of optical activity. Optical activity occurs only in chiral materials, those lacking microscopic mirror symmetry. Unlike other sources of birefringence which alter a beam's state of polarization, optical activity can be observed in fluids. This can include gases or solutions of chiral molecules such as sugars, molecules with helical secondary structure such as some proteins, and also chiral liquid crystals. It can also be observed in chiral solids such as certain crystals with a rotation between adjacent crystal planes (such as quartz) or metamaterials. When looking at the source of light, the rotation of the plane of polarization may be either to the right (dextrorota ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 light, volatile, colourless, flammable liquid with a distinctive alcoholic odour similar to that of ethanol (potable alcohol). A polar solvent, methanol acquired the name wood alcohol because it was once produced chiefly by the destructive distillation of wood. Today, methanol is mainly produced industrially by hydrogenation of carbon monoxide. Methanol consists of a methyl group linked to a polar hydroxyl group. With more than 20 million tons produced annually, it is used as a precursor to other commodity chemicals, including formaldehyde, acetic acid, methyl tert-butyl ether, methyl benzoate, anisole, peroxyacids, as well as a host of more specialised chemicals. Occurrence Small amounts of methanol are present in normal, healthy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diphenyl Ethers
Biphenyl (also known as diphenyl, phenylbenzene, 1,1′-biphenyl, lemonene or BP) is an organic compound that forms colorless crystals. Particularly in older literature, compounds containing the functional group consisting of biphenyl less one hydrogen (the site at which it is attached) may use the prefixes xenyl or diphenylyl. It has a distinctively pleasant smell. Biphenyl is an aromatic hydrocarbon with a molecular formula (C6H5)2. It is notable as a starting material for the production of polychlorinated biphenyls (PCBs), which were once widely used as dielectric fluids and heat transfer agents. Biphenyl is also an intermediate for the production of a host of other organic compounds such as emulsifiers, optical brighteners, crop protection products, and plastics. Biphenyl is insoluble in water, but soluble in typical organic solvents. The biphenyl molecule consists of two connected phenyl rings. Properties and occurrence Biphenyl occurs naturally in coal tar, crude oil, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Macrocycles
Macrocycles are often described as molecules and ions containing a ring of twelve or more atoms. Classical examples include the crown ethers, calixarenes, porphyrins, and cyclodextrins. Macrocycles describe a large, mature area of chemistry. Synthesis The formation of macrocycles by ring-closure is called macrocylization. Pioneering work was reported for studies on terpenoid macrocycles. The central challenge to macrocyclization is that ring-closing reactions do not favor the formation of large rings. Instead, small rings or polymers tend to form. This kinetic problem can be addressed by using high-dilution reactions, whereby intramolecular processes are favored relative to polymerizations. Some macrocyclizations are favored using template reactions. Templates are ions, molecules, surfaces etc. that bind and pre-organize compounds, guiding them toward formation of a particular ring size. The crown ethers are often generated in the presence of an alkali metal cation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phenanthrenoids
Phenanthrenoids are chemical compounds formed with a phenanthrene backbone. These compounds occur naturally in plants, although they can also be synthesized. Phenanthrols Phenanthrols are any of five isomeric phenols derived from phenanthrene (1-phenanthrol, 2-phenanthrol, 3-phenanthrol, 4-phenanthrol, 9-phenanthrol). These molecules can be biomarkers of smoking and/or PAH worker exposure. Chemistry Under UV irradiation, stilbene and its derivatives undergo intramolecular cyclization to form dihydrophenanthrenes. Natural occurrences Phenanthrenes have been reported from flowering plants, mainly in the family Orchidaceae, and a few in the families Dioscoreaceae, Combretaceae and Betulaceae, as well as in the lower plant class Marchantiophyta (liverworts). The rhizome of '' Dioscorea communis'' contains phenanthrenes ( 7-hydroxy-2,3,4,8-tetramethoxyphenanthrene, 2,3,4-trimethoxy-7,8-methylenedioxyphenanthrene, 3-hydroxy-2,4,-dimethoxy-7,8-methylenedioxyphenanthrene, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dihydrostilbenoids
Dihydrostilbenoids (bibenzyls) are natural phenols formed from the dihydrostilbene ( bibenzyl) backbone. Examples Dihydro-resveratrol is a natural phenol with a bibenzyl structure found in wine. It is also a metabolite of trans-resveratrol formed in the intestine by the hydrogenation of the double bond by microflora. Combretastatin and combretastatin B-1 are two dihydrostilbenoids found in ''Combretum caffrum'', an African tree. Isonotholaenic acid is another dihydrostilbenoid found in the Andean fern '' Argyrochosma nivea''. Bibenzyls ( 3,4'-dihydroxy-5,5'-dimethoxybibenzyl, 3,3'-dihydroxy-5-methoxybibenzyl ( batatasin III)) can be found in the orchid '' Bulbophyllum vaginatum''. Bis(bibenzyls) and macrocyclic bis(benzyls) can be found in bryophytes, such as the compounds plagiochin E, 13,13'-O-isoproylidenericcardin D, riccardin H, marchantin E, neomarchantin A, marchantin A and marchantin B in the Chinese liverwort ''Marchantia polymorpha''. Prenylated bibenzyls ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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