diastereoelektiivisyys

Diastereoelektiivisyys, a Finnish term, refers to a type of stereoselectivity in chemical reactions where a reaction preferentially forms one or more diastereomers over others. Diastereomers are stereoisomers that are not mirror images of each other. This phenomenon is crucial in organic chemistry, particularly in the synthesis of complex molecules where precise control over the spatial arrangement of atoms is necessary.

In a diastereoselective reaction, the starting materials or intermediates already possess stereocenters, or stereocenters are created during the reaction. The presence of existing stereocenters can influence the stereochemical outcome of the reaction, leading to a higher proportion of a specific diastereomer. This influence can arise from various factors, including steric hindrance, electronic effects, or the formation of transient intermediates that favor a particular conformation.

The degree of diastereoselectivity is often quantified by the diastereomeric ratio (dr) or the diastereomeric excess (de). A high dr or de indicates that the reaction has strongly favored the formation of one diastereomer. Understanding and controlling diastereoselectivity is vital for medicinal chemists and synthetic organic chemists aiming to produce specific enantiomers or diastereomers of target molecules, as different stereoisomers can exhibit vastly different biological activities or physical properties.