ИСТИНА

Chiral organocatalysts are environmentally friendly, easily available, and cheap catalytic systems which extensively applied in many asymmetric transformations. However, one of the main problems in their case is the need of high catalyst loadings (up to 50 mol%) to achieve high asymmetric induction. Recently, a new class of stereochemically inert transition metal complexes has been proposed as an alternative, named “organocatalysts in disguise”. These metal-templated complexes have shown high catalytic activity and enantiocontrol even at 0.001 mol% loading (ppm level). In this work, we have developed a new class of octahedral Co(III) complexes of Λ and Δ-configurations based on commercially available (1R,2R)-cyclohexanediamine and (1R,2R)-diphenylethylenediamine and various salicylaldehydes (Figure). In these complexes, the amino groups become effective hydrogen bond donors (or Brønsted acids) due to the coordination with the metal ion. The resulting chiral complexes efficiently catalyzed various asymmetric reactions with enantioselectivity up to 96% ee. The high efficiency can be traced back to the fact that these catalysts activate their substrates via (non-)covalent interactions (in particular, via multiple cooperative hydrogen-bonding interactions) within the chiral, rigid propeller-shaped ligand sphere of these catalysts.