The scandium-bipyridine-catalyzedenantioselective addition of anilines and O-alkyl hydroxylamines to meso-epoxides has been optimized and extended to a broad range of epoxides and amines. Whereas aromatic meso-epoxides generally furnished the corresponding 1,2-amino alcohols in excellent enantioselectivities, aliphatic meso-epoxides only gave rise to moderate enantioselectivities in the aminolysis
The newly prepared bipyridine (S,S)‐2 was then tested as a chiral ligand in metal‐catalyzed enantioselectivereactions. Out of the studied reactions the most promising results were obtained in epoxide ring opening (82% yield, 98% ee) and Mukaiyama aldolreaction (>96% yield, 99/1 dr, 92% ee). In the case of Mukaiyama‐aldolreaction as well as in the Michael addition, novel ligand 2 proved its robustness
derivatives. These new macrocycles have been showed to be strong complexing agents for primary organic ammonium salts (with K up to 4.83×105 M−1 and −ΔG0 up to 32.4 kJ mol−1) and also useful chromophores for UV–vis titration studies. These macrocyclic hosts exhibited enantioselective binding towards the (S)-enantiomer of phenylglycine methyl ester hydrochloride (Am1) with K(S)/K(R) up to 2.10 (ΔΔG0=−1.84 kJ mol−1)