Felkin–Anh Model
Predicts nucleophilic attack on carbonyls favoring approach anti to the largest substituent.
Context: Standard model for 1,2-asymmetric induction.
Example: Addition to α-chiral aldehydes.
Related Terms: Cram’s Rule, Bürgi–Dunitz Angle.
Reference: Anh & Felkin, Tetrahedron Lett. (1973).
Fischer Projection
A 2D representation where horizontal lines indicate bonds projecting forward and vertical lines project backward.
Context: Standard tool in carbohydrate and amino acid stereochemistry.
Example: D-glucose drawn in Fischer projection.
Related Terms: Newman Projection, Sawhorse Projection.
Reference: Fischer, Ber. Dtsch. Chem. Ges. (1891).
Flack Parameter (x)
Refinement parameter indicating correct absolute structure in X-ray crystallography.
Context: x ~ 0 confirms correct absolute configuration; x ~ 1 suggests inversion.
Example: Reporting Flack x for a chiral API crystal.
Related Terms: Absolute Configuration, X-ray Crystallography.
Reference: Flack, Acta Cryst. A (1983).