Matched Pair
Substrate and chiral reagent/catalyst whose stereochemical preferences reinforce each other.
Context: Delivers higher selectivity than mismatched combinations.
Example: (S)-substrate with (S)-auxiliary.
Related Terms: Mismatched Pair, Double Stereodifferentiation.
Reference: Seebach, Angew. Chem. (1979).
Memory of Chirality
Retention of stereochemical information through achiral or planar intermediates via conformational constraints.
Context: Enables net stereospecificity where racemization might be expected.
Example: Acylium ion cyclizations retaining chirality.
Related Terms: Stereomutation, Enantiospecificity.
Reference: Houk, Angew. Chem. (2001).
Meso Compound
An achiral molecule with stereocenters and an internal plane/center of symmetry.
Context: No net optical activity, important in planning stereoselective routes.
Example: Meso-tartaric acid.
Related Terms: Symmetry, Diastereomer.
Reference: Eliel & Wilen (1994).
Mismatched Pair
Substrate and chiral reagent/catalyst with opposing preferences.
Context: Reduces stereoselectivity; addressed by switching catalyst or substrate.
Example: (S)-substrate with (R)-auxiliary.
Related Terms: Matched Pair, Stereoselectivity.
Reference: Evans, JACS (1981).
Molar Rotation (Φ)
Specific rotation multiplied by molar mass.
Context: Allows comparison of chiroptical responses across compounds.
Example: Molar rotation trends within homologous series.
Related Terms: Specific Rotation, Optical Activity.
Reference: Barron, Molecular Light Scattering (2004).
Molecular Imprinting
Template-directed polymerization producing cavities complementary to a target enantiomer.
Context: Creates synthetic receptors for separations and sensing.
Example: Imprinted polymers for S-propranolol.
Related Terms: Chiral Recognition, CSP.
Reference: Sellergren, Chem. Rev. (2000).
Mosher’s Method
Use of MTPA esters/amides to assign absolute configuration by Δδ patterns.
Context: Gold-standard for alcohols and amines in small-molecule analysis.
Example: Δδ analysis of secondary alcohols.
Related Terms: CDA, NMR.
Reference: Dale & Mosher, JACS (1973).