chiralauxiliarijärjestelmiä

Chiral auxiliary systems refer to a class of reagents used in organic synthesis to control the stereochemistry of a reaction. These auxiliaries are chiral molecules that are temporarily attached to a substrate. Their presence directs the incoming reagent to attack from a specific face of the molecule, leading to the formation of a predominantly one enantiomer of the product. After the reaction is complete, the chiral auxiliary is typically cleaved off and can often be recovered and reused.

The effectiveness of a chiral auxiliary system relies on several factors, including the steric bulk and electronic properties of the auxiliary, the nature of the substrate, and the reaction conditions. Common chiral auxiliaries are derived from readily available chiral starting materials like amino acids, terpenes, or carbohydrates. Examples include Evans' oxazolidinones, Oppolzer's sultams, and Myers' pseudoephedrine amides. These systems are particularly valuable for asymmetric synthesis, enabling the production of enantiomerically pure compounds that are crucial in pharmaceuticals, agrochemicals, and materials science. The development of efficient and recyclable chiral auxiliary systems remains an active area of research in organic chemistry.