Robby Vroemans

A rhodium-catalyzed enantioselective click cycloaddition of azides and alkynes for rapid and modular access to atropisomeric triazoles is reported. This click process features very mild reaction conditions, superior efficiency and enantioselectivity, broad substrate scope and facile scalability. The racemization study and further derivatizations demonstrate the good configurational stability of obtained axially chiral triazole products.

Abstract

The cycloaddition of azides and alkynes is the leading click chemistry technology and has been widely used in drug discovery, biology and material sciences. However, the development of a modular and scalable enantioselective click cycloaddition remains a long-standing challenge. Herein, we report a rhodium-catalyzed enantioselective click cycloaddition of azides and alkynes for rapid and modular access to atropisomeric triazoles in excellent yields and enantioselectivities. The process is mild, efficient and scalable, and features broad substrate scope.

A manganese biopolymer-supported catalyst is reported for hydrogen/deuterium exchange in anilines, phenols, heterocycles, and electron-rich arenes. Notably, taking advantage of deuterium oxide as easy-to-handle isotope source, deuterated compounds are obtained in high yields in a practical manner.

Abstract

There is a constant need for deuterium-labelled products for multiple applications in life sciences and beyond. Here, a new class of heterogeneous catalysts is reported for practical deuterium incorporation in anilines, phenols, and heterocyclic substrates. The optimal material can be conveniently synthesised and allows for high deuterium incorporation using deuterium oxide as isotope source. This new catalyst has been fully characterised and successfully applied to the labelling of natural products as well as marketed drugs.

Synlett
DOI: 10.1055/a-1806-5999

The synthesis and characterization of a novel class of pillar[4]arene[1]thioarenes (P[4]A[1]SMe) are reported. An oxidation–thionation strategy was used to replace a single dialkoxybenzene panel in the parent pillar[5]arene. 1H NMR spectroscopic titration experiments, supported by density functional theory computational studies, revealed that P[4]A[1]SMe show starkly modulated host–guest binding properties for electron-deficient aliphatic guests.
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Nature Catalysis, Published online: 26 April 2022; doi:10.1038/s41929-022-00773-8

Nature, Published online: 25 April 2022; doi:10.1038/d41586-022-01134-y

An oxidative cross-coupling between two alkenes under the dual action of a Pd^II catalyst and a transient directing group (TDG) is demonstrated. The reaction involves TDG-mediated C(alkenyl)−H activation to generate an endo-palladacycle intermediate, whose formation is promoted by a tailored carboxylic acid additive.

Abstract

Palladium(II)-catalyzed C(alkenyl)−H alkenylation enabled by a transient directing group (TDG) strategy is described. The dual catalytic process takes advantage of reversible condensation between an alkenyl aldehyde substrate and an amino acid TDG to facilitate coordination of the metal catalyst and subsequent C(alkenyl)−H activation by a tailored carboxylate base. The resulting palladacycle then engages an acceptor alkene, furnishing a 1,3-diene with high regio- and E/Z-selectivity. The reaction enables the synthesis of enantioenriched atropoisomeric 2-aryl-substituted 1,3-dienes, which have seldom been examined in previous literature. Catalytically relevant alkenyl palladacycles were synthesized and characterized by X-ray crystallography, and the energy profiles of the C(alkenyl)−H activation step and the stereoinduction model were elucidated by density functional theory (DFT) calculations.

A series of atomically dispersed and nitrogen coordinated dual-metal sites (e.g., Ni-Fe, Fe-Co, and Ni-Co) was designed. Among all possible dual-metal site configurations, the predicted 2N-bridged (Fe-Ni)N₆ sites exhibited the highest CO₂RR activity and promising stability. The optimal dual-metal sites can decrease the energy barriers for the *COOH adsorption (−0.34 eV) and the *CO desorption (0.39 eV), facilitating CO₂ reduction to CO.

Abstract

Carbon-supported nitrogen-coordinated single-metal site catalysts (i.e., M−N−C, M: Fe, Co, or Ni) are active for the electrochemical CO₂ reduction reaction (CO₂RR) to CO. Further improving their intrinsic activity and selectivity by tuning their N−M bond structures and coordination is limited. Herein, we expand the coordination environments of M−N−C catalysts by designing dual-metal active sites. The Ni-Fe catalyst exhibited the most efficient CO2RR activity and promising stability compared to other combinations. Advanced structural characterization and theoretical prediction suggest that the most active N-coordinated dual-metal site configurations are 2N-bridged (Fe-Ni)N₆, in which FeN₄ and NiN₄ moieties are shared with two N atoms. Two metals (i.e., Fe and Ni) in the dual-metal site likely generate a synergy to enable more optimal *COOH adsorption and *CO desorption than single-metal sites (FeN₄ or NiN₄) with improved intrinsic catalytic activity and selectivity.