Perturbation, chiral covalent

Obtaining high asymmetric induction therefore requires the placement of every reactant molecule next to a chiral inductor molecule (type B situation) i.e., enhancement of the ratio of type B cages to the sum of types A and C. In the chiral auxiliary method (CAM) the chiral perturber is connected to the reactant via a covalent bond [186,187,197-205]. In this... 

The most obvious stimulus to ehiral induction is the use of stereogenie eenters, but external perturbation, such as physical fields ean also be used to induce chirality. The term is applied to traditional asymmetric synthesis through covalent bonds as well as to supramolecular synthesis, which is our interest here. Mention the word "chirality" to any chemist, and thoughts will be conjured of the right-handed B-DNA double helix, the right-handed a-helices formed by peptides of the natural L-amino acids, of thalidomide, and other emblematic and dramatic examples of the importanee of stereochemistry. It is clear that the chirality of the eomponents of biological systems play a key role in their function, in which induction of chirality through noncovalent bonds is inherent. But beyond natural systems and related phenomena, there is a wealth of unnatural chemical systems that display remarkable and important properties. 

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