Aza-Diels–Alder reaction catalyzed by novel chiral metalocomplex Brønsted acids

Sodium Salts of Anionic Chiral Cobalt(III) Complexes as Catalysts of the Enantioselective Povarov Reaction

“…recently showed that salicylaldehyde‐derived chiral Co III complexes can be employed to accelerate a few CC bond formation reactions by asymmetric counterion catalysis 2bd However, these transformations proceeded with low to moderate enantioselectivities2a–d owing to the limitations of unsubstituted salicylaldehydes and the meridional stereoisomers of these complexes 2e–f. We envisioned that easily prepared, structurally tunable, and stereochemically stable2g metal salts of anionic chiral Co III complexes (CCC − M + ) that are derived from salicylaldehydes with bulky substituents and L ‐amino acids would be more applicable to asymmetric catalysis than anticipated by common sense (Scheme ).…”

“…Our initial investigation started with the reaction of N ‐phenyl benzaldimine ( 1 a ) with 2,3‐dihydrofuran ( 2 a ) in the presence of the Brønsted acids of various anionic chiral Co III complexes (CCC − H + , 4 a – 4 e ; 5 mol %), which are all derived from salicylaldehydes and L ‐amino acids (Table 1, entries 1–7) 2d. Among them, Λ‐ 4 e ,8 which bears a 3,5‐di‐ tert ‐butyl‐substituted (R 1 , R 2 ) salicylaldehyde and a tert ‐butyl group (R 3 ) on the amino acid moiety, gave the highest enantiomeric ratio of 75:25 (entry 7).…”

Synthesis and Investigations of Chiral NNO Type Copper(II) Coordination Polymers

“…For the last 2 decades the interest to CPs application as catalysts is growing due to their heterogeneous nature ,. In our earlier work we used the chiral NNO and ONO type ligands based on Schiff bases of chiral diamines (or amino acids) and salicylaldehydes to construct new type of chiral octahedral inert cobalt(III) complexes . These complexes were efficient catalysts for different asymmetric reactions …”

Enantioselective “organocatalysis in disguise” by the ligand sphere of chiral metal-templated complexes

“…130 (Fig. 1b and e), 94,100,[102][103][104]106,107,115,122,123,[126][127][128][129] enamine catalysis (Fig. 1d), 99 nucleophilic catalysis, 120 and photocatalysis (Fig.…”