Phase-Transfer Catalysis (PTC)
Biphasic catalysis moving anions across phases with chiral quaternary ammonium salts.
Context: Practical for large-scale enantioselective alkylations.
Example: Cinchona-derived PTCs.
Related Terms: Organocatalysis, Asymmetric Catalysis.
Reference: Starks, JACS (1971); O’Donnell, Acc. Chem. Res. (2004).
Pirkle-Type CSP
Small-molecule chiral selectors relying on π–π and H-bond interactions.
Context: Versatile for aromatic enantiomers and drug-like molecules.
Example: Whelk-O columns.
Related Terms: CSP, Chiral HPLC.
Reference: Pirkle, J. Chromatogr. (1981).
Planar Chirality
Chirality resulting from the arrangement of substituents in a plane.
Context: Seen in ferrocene ligands and metallocenes used in asymmetric catalysis.
Example: Planar-chiral 1,2-disubstituted ferrocenes.
Related Terms: Helicity, Axial Chirality.
Reference: IUPAC Gold Book.
Polarimetry
Technique to measure optical rotation of chiral compounds.
Context: Rapid QC screen for enantiomeric composition when correlation is established.
Example: Measuring rotation of limonene enantiomers.
Related Terms: Optical Activity, Specific Rotation.
Reference: Atkins, Physical Chemistry.
Polysaccharide CSP
Derivatized cellulose/amylose selectors coated or immobilized on silica.
Context: Most widely used CSPs due to broad applicability.
Example: Chiralcel OD-H equivalents.
Related Terms: CSP, Chiral HPLC.
Reference: Okamoto, Chem. Rev. (2011).
Pro-R / Pro-S
Labels for enantiotopic groups whose replacement would give R or S product.
Context: Critical in enzymatic selectivity and NMR assignment.
Example: Pro-R hydrogen abstraction in alcohol dehydrogenase.
Related Terms: Prochirality, Re/Si Face.
Reference: IUPAC Gold Book.
Prochirality
An achiral entity that can become chiral by a single desymmetrizing step.
Context: Basis for enantioface/enantioselective reactions in synthesis and enzymology.
Example: Prochiral ketones undergoing enantioselective reduction.
Related Terms: Re/Si Face, Pro-R/Pro-S.
Reference: IUPAC Gold Book.
Protein Homochirality
Proteins are composed almost exclusively of L-amino acids.
Context: Drives stereoselective binding and metabolism in biology.
Example: Enzymes discriminating D- vs L-substrates.
Related Terms: Homochirality, Stereorecognition.
Reference: Blackmond, PNAS (2004).
Pseudoasymmetric Center (r/s)
A stereocenter whose configuration is defined relative to other stereocenters (lowercase r/s).
Context: Relevant in complex APIs where relayed stereochemistry affects labeling.
Example: r/s descriptors in substituted tartaric acid derivatives.
Related Terms: CIP Rules, Relative Configuration.
Reference: IUPAC Gold Book.