Axial chirality is a special case of chirality in which a molecule does not possess an asymmetric carbon atom (the most common form of chirality in organic compounds) but an axis of chirality - an axis about which a set of substituents is held in a spatial arrangement which is not superposable on its mirror image. Axial chirality is most commonly observed in atropisomeric biaryl compounds where the rotation about the aryl-aryl bond is restricted, for example biphenyl, binaphthyls e.g., 1,1'-bi-2-naphthol, and certain dihydroanthracenone compounds Absolute stereochemistry of fungal metabolites: Icterinoidins A1 and B1, and atrovirins B1 and B2 Melvyn Gill and Peter M. Morgan Arkivoc (RI-1154C)2004 Online article . Certain allene compounds also display axial chirality. The enantiomers of axially chiral compounds are usually given the stereochemical labels R_a and S_{a, although the plus (P) or minus (M) notation is occasionally employed.}

External links

• Axial Chirality in 6,6'-Dinitrobiphenyl-2,2'-dicarboxylic acid 3D representation Link

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