A novel type of catalysts for the asymmetric C-C bond formation based on chiral stereochemically inert cationic Co iii complexes

Chiral Cobalt(III) Complexes as Bifunctional Brønsted Acid–Lewis Base Catalysts for the Preparation of Cyclic Organic Carbonates

“…Additionally,t he counter anionso ft he complexes were involved in the activation of another substrate in bimolecular reactions, such as cyanosilylation of aldehydes. [17] We believed that other important reactions, involving simultaneous catalysis by both nucleophilic and electrophilic groups of the catalysts, could also be efficiently promoted with our cationic complexes.T herefore, we decided to investigate the atom efficient coupling of carbon dioxide and oxiranes leading to cyclic carbonates.Cyclic carbonatesh ave applications as solvents in organic synthesis, electrolytes for lithium-ion batteries, and as chemical intermediates for biodegradable polymer synthesis. [18][19][20][21][22] Catalysis of this reaction is generally believed to proceeda ss hown in Scheme 1, with both the nucleophilic openingo ft he oxirane( usually by ah alide anion)a nd electrophilic activationo fb oth epoxide and carbond ioxide( by strong Lewisa cids or Brønsted acids) involved in the transition states.…”

“…Thus, the complexes became “Brønsted acids in disguise”. Additionally, the counter anions of the complexes were involved in the activation of another substrate in bimolecular reactions, such as cyanosilylation of aldehydes …”

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 …”

Expanding the Family of Octahedral Chiral-at-Metal Cobalt(III) Catalysts by Introducing Tertiary Amine Moiety into the Ligand

“…Chiral stereochemically inert, coordinatively saturated metal complexes of Co, Cr, Rh, Ir or Ru presented a perspective class of "organic catalysts in disguise" which were applied in various asymmetric organic reactions [1][2][3][4]. In these complexes, the metal center can play several important roles: (1) to activate the coordinated ligands converting them into efficient hydrogen bond donors/acceptors ; (2) to serve as a chiral center (metal-centered chirality) providing a well-defined chiral environment [35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51] (in case of octahedral geometry of the complexes due to the mutual meridional arrangement of the chiral or achiral ligands around the metal ion with Λ-(left-handed propeller) or ∆configurations (right-handed propeller)) [1][2][3][4][5][6][7][8][9][10][11][13][14][15][16][17][18][19][20][21][22]…”

“…Earlier, we prepared diastereoisomerically pure cobalt(III) complexes from the Schiff bases of substituted salicylaldehydes with chiral 1,2-diamines and Co(III) salts [6,8,10]. The complexes (Figure 1a) possess both chirality at the ligand and metal-center [3,8,10,13].…”