Isotope Effects Reveal the Catalytic Mechanism of the Archetypical Suzuki-Miyaura Reaction.

Experimental and theoretical C kinetic isotope effects (KIEs) are utilized to obtain atomistic insight into the catalytic mechanism of the Pd(PPh)-catalyzed Suzuki-Miyaura reaction of aryl halides and aryl boronic acids. Under catalytic conditions, we establish that oxidative addition of aryl bromides occurs to a 12-electron monoligated palladium complex (Pd-(PPh)). This is based on the congruence of the experimental KIE for the carbon attached to bromine (KIE = 1.

A Designed Approach to Enantiodivergent Enamine Catalysis.

The rational design and implementation of enantiodivergent enamine catalysis is reported. A simple secondary amine catalyst, 2-methyl-l-proline, and its tetrabutylammonium salt function as an enantiodivergent catalyst pair delivering the enantiomers of α-functionalized aldehyde products in excellent enantioselectivities. This novel concept of designed enantiodivergence is applied to the enantioselective α-amination, aldol, and α-aminoxylation/α-hydroxyamination reactions of aldehydes.