Enzymatic reactions can gain this property by binding to dirigent proteins. Catalysis of reactions with this property is often initiated by “privileged” ligands with C2 (“C-two”) symmetry as exemplified by DIPAMP. Proline is used as an organocatalyst to grant this property to aldol condensations. Cram’s rule and the Felkin–Anh model describe how nucleophilic attacks on carbonyls cause this property’s induction. Reactions often maintain this property through the incorporation of “auxiliaries.” The products of reactions with this property have nonzero optical rotation, while reactions without this property produce racemic mixtures. For 10 points, (-5[1])name this property of reactions that preferentially form one chiral stereoisomer over another. (10[1])■END■ (10[1]0[1])