Stereodivergent Catalysis

This review covers diastereo- and enantiodivergent catalyzed reactions in acyclic and cyclic systems using metal complexes or organocatalysts. Among them, nucleophilic addition to carbon-carbon and carbon-nitrogen double bonds, α-functionalization of carbonyl compounds, allylic substitutions, and ring opening of oxiranes and aziridines are considered. The diastereodivergent synthesis of alkenes from alkynes is also included. Finally, stereodivergent intramolecular and intermolecular cycloadditions and other cyclizations are also reported.

A Copper-Catalyzed Reductive Defluorination of β-Trifluoromethylated Enones via Oxidative Homocoupling of Grignard Reagents

An efficient copper-catalyzed reductive defluorination of β-trifluoromethylated enones via an oxidative homocoupling of Grignard reagents is reported. The reaction proceeded smoothly with a wide range of substrates, including the ones bearing aromatic heterocycles, such as furyl and thienyl ring systems in high yields (80-92%, except one example) under mild conditions. This provides a practical method for synthesis of gem-difluoroolefin ketones. It is also worth noting that this homocoupling process of Grignard reagents using β-trifluoromethylated enones as "oxidizing reagents" is effective for both the Csp²-Csp² and Csp³-Csp³ bond formations, including for substrates whose β-hydride elimination of the corresponding transition metal alkyl complex is particularly facile, affording coupling products with high yields (83-95%), simultaneously.

[2.2]Paracyclophane-derived monodentate phosphoramidite ligands for copper-catalyzed asymmetric conjugate addition of diethylzinc to substituted chalcones

Copper-catalyzed asymmetric conjugate addition of diethylzinc to chalcones could be realized by using [2.2]paracyclophane-derived monodentate phosphoramidite ligands. The excellent yield and enantioselectivity (up to 98% yield and 95% enantiomeric excess) could be realized with low catalyst loading of 1.0 mol % and low ligand loading of 1.2%.

New advances in dual stereocontrol for asymmetric reactions

Achieving dual stereocontrol in asymmetric reactions using a single enantiomer for the building of the chiral catalyst or auxiliary is a very important goal in enantioselective synthesis as it eliminates the need for having available the two enantiomers of the auxiliary or catalyst designed. Recent strategies and advances towards this goal during the last four years will be discussed throughout this review.