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

Abstract

An overview about the principles, applications and perspectives on the catalytic use of chiral metal-templated complexes that operate as “chiral organocatalysts in disguise” is presented.

Rhodium(III) Werner Complexes with 1,2‐Diphenylethylenediamine Ligands: Syntheses, Structures, and Applications as Chiral Hydrogen Bond Donor Catalysts and Agents for Enantiomer Purity Determinations

“…There has been enormous recent interest in developing hydrogen bond donor catalysts for enantioselective organic reactions, [1] and several investigators have focused on a subclass containing "spectator" metal fragments. [2][3][4][5][6] In our laboratory, we have been particularly interested in helically chiral tris(1,2diamine) species, [6,7] for which Werner complexes of the type [Co(en) 3 ] 3 + 3X À (1 3 + 3X À , Figure 1) represent the classical archetype. [8] Such trications have D 3 symmetry, with the enantiomers designated Λ and Δ, and feature a principal C 3 axis and three C 2 axes in a perpendicular plane.…”

An electron-deficient MOF as an efficient electron-transfer catalyst for selective oxidative carbon–carbon coupling of 2,6-di-tert-butylphenol

“…These organocatalysts are efficient, less toxic, inexpensive, and readily available. 5 Among these organocatalysts, electron-deficient π-acid catalysts, such as dicyanoketene acetal derivatives, tetracyanoethylene, and dichlorodicyanobenzoquione, are the most attractive class. 6 Unlike common organocatalysts that generally use an empty orbital atom to extract electrons from the reaction substrate, electron-deficient π-acid organocatalysts are based on a linear or planar π-conjugated system, which can remove the electrons through an electron-deficient π-conjugated system, undoubtedly increasing their probability of collision with the substrates.…”

Synthesis and a Catalytic Study of Diastereomeric Cationic Chiral-at-Cobalt Complexes Based on (R,R)-1,2-Diphenylethylenediamine

“…Generally, the chiral centers in molecules are presented by carbon, nitrogen, silicon, phosphorus, and sulfur atoms, but there is also a plethora of examples with a chirality at metal centers (metal centrochirality) in the literature. , Metal complexes may exhibit a chirality owing to the different arrangement of (a)­chiral ligands around the metal center, and these are called “ chiral-at-metal ” or “ stereogenic-at-metal ” complexes. , In case the metal complexes have an octahedral geometry, they are designated as Λ (a left-handed propeller) and Δ (a right-handed propeller) configurations. , It was demonstrated that the chiral-at-metal complexes (mostly based on cobalt, iridium, rhodium, ruthenium, iron, etc.) are an efficient and promising class of chiral catalysts for different enantioselective reactions. ,− …”