Recent Development of Bis-Cyclometalated Chiral-at-Iridium and Rhodium Complexes for Asymmetric Catalysis

Abstract

The field of asymmetric catalysis has been developing to access synthetically efficacious chiral molecules from the last century. Although there are many sustainable ways to produce nonracemic molecules, simplified and unique methodologies are always appreciated. In the recent developments of asymmetric catalysis, chiral-at-metal Lewis acid catalysis has been recognized as an attractive strategy. The catalysts coordinatively activate a substrate while serving the sole source of chirality by virtue of its helical environment. These configurationally stable complexes were utilized in a large number of asymmetric transformations, ranging from asymmetric Lewis acid catalysis to photoredox and electrocatalysis. Here we provide a comprehensive review of the current advancements in asymmetric catalysis utilizing iridium and rhodium-based chiral-at-metal complexes as catalysts. First, the asymmetric transformations via LUMO and HOMO activation assisted by a chiral Lewis acid catalyst are reviewed. In the second part, visible-light-induced asymmetric catalysis is summarized. The asymmetric transformation via the electricity-driven method is discussed in the final section.

The Photocatalytic Degradation Mechanism for Organic Pollutants in Seawater and the Fabrication of Catalyst-Loaded Floating Spheres for Effectively Removing Tetracycline

“…According to previous results, ,− the obvious differences in the photodegradation performance between chiral M-TiO 2 and achiral M-TiO 2 were due to their structural differences. Based on the Brunauer–Emmett–Teller (BET) analysis (Figures S8 and S9 and Table S2), both chiral M-TiO 2 and achiral M-TiO 2 had a large specific surface area and mesoporous channel structure.…”

Strategies toward the Difunctionalizations of Enamide Derivatives for Synthesizing α,β-Substituted Amines

“…Moreover, modest ee was observed with less nucleophilic pyrazoles 35 , possibly due to partial racemization of the intermediary imine 36 . Interestingly, Bach et al, in 2005, disclosed a powerful combination of photocatalysis with enantioselective organocatalysis by merging, in the same congested tricyclic structure, a hydrogen bond donor/acceptor with a photosensitizer. , We decided to transpose this approach to chiral phosphoric acids by substituting their 3- and 3′-positions with photosensitizers. We assumed that the resulting polyfunctional species could catalyze the three steps of our sequence .…”

Post-Modification of Octahedral Chiral-at-Metal Cobalt(III) Complexes by Suzuki–Miyaura Cross-Coupling and Evaluation of Their Catalytic Activity

“…Impressive advances in asymmetric catalysis are achieved through a continually updated library of chiral catalysts which provide high levels of enantioselectivity, diastereoselectivity, and diversity . Despite numerous efficient chiral organocatalysts and metal complex catalysts featuring chiral organic ligands, there are still underexplored challenging asymmetric transformations in organic synthesis that requires the development of novel breakthrough and universal catalytic systems. In most cases for creating of chiral complex molecules with high enantiocontrol (especially with quaternary stereogenic centers), the catalysts have to be complicated with bulky groups .…”