Enantiomers, asymmetric synthesis definition

To date, direct asymmetric synthesis of optically active chiral-at-metal complexes, which by definition leads to a mixture of enantiomers in unequal amounts thanks to an external chiral auxiUary, has never been achieved. The most studied strategy is currently indirect asymmetric synthesis, which involves (i) the stereoselective formation of the chiral-at-metal complex thanks to a chiral inductor located either on the ligand or on the counterion and then (ii) removal of this internal chiral auxiliary (Fig. 4). Indeed, when the isomerization of the stereogenic metal center is possible in solution, in-... 

This definition refers to an enantiomeric mixture produced in an asymmetric synthesis. In some cases where a diastereomeric mixture is produced, the definition has to be altered accordingly. Percent optical purity is an operational term that depends on optical rotation measurements. It is not necessarily equal to the percent enantiomeric purity (13), which is a more meaningful term and is the extent to which one enantiomer is formed in excess over the other ... 

Time reversal, mentioned above in connection with PT-enantiomers, is also at the heart of a distinction between time-dependent and time-independent enantiomorphism. In a series of publications,33-36 Laurence Barron has provided the basis for his argument that The only compelling reason for generalizing Kelvin s definition is to encompass absolute asymmetric synthesis and the concept of chirality in elementary particle physics by including motion-dependent chirality. 37 According to Barron33 ... 

Polymers having configurational chirality in the side chain or the main chain can be prepared by asymmetric synthesis polymerization or enantiomer-selective polymerization. As for the main-chain chiral polymers, it is difficult to determine a definite chiral structure and rationally connect observed chiroptical properties with the structure for most polymers. Improved analytical techniques need to be evolved to address this issue. 

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