Oxidative cross-coupling is a powerful synthetic strategy for forming a carbon−carbon bond from two nucleophiles having C−H bonds. However, controlling the coupling selectivity (homovs cross-coupling) and the chemo-(C−C vs C−O) and regioselectivity in the reaction of two distinct enolizable substrates under aerobic conditions is notoriously challenging. Here, we present a regiodivergent oxidative cross-coupling reaction between catechols and carbonyl compounds (2-oxindoles and benzofuranones). The oxidative cross-coupling proceeds at the C(6) position of 4-substituted catechols under catalyst-free conditions, while the Pd(II)-BINAP-μ-hydroxo catalyst promotes the reaction at the C(5) position. A series of mechanistic control experiments support a homolytic aromatic substitution mechanism for the carbon−carbon bond-forming processes in both the C(6)-and C(5)selective coupling reactions. Furthermore, computational analyses suggest that Pd(II)−catecholate is a key catalytic active species, which serves as a SOMO-phile, to facilitate the endothermic C(5)-selective carbon−carbon bond formation and the exothermic aerobic oxidative aromatization.

Reaction design in asymmetric catalysis has traditionally been predicated on a structurally robust scaffold in both substrates and catalysts, to reduce the number of possible diastereomeric transition states. Herein, we present the stereochemical dynamics in the Ni(II)-catalyzed diastereoconvergent (3 + 2) cycloadditions of isomerizable nitrile-conjugated nitrones with α-keto ester enolates. Even in the presence of multiple equilibrating species, the catalytic protocol displays a wide substrate scope to access a range of CN-containing building blocks bearing adjacent stereocenters with high enantio-and diastereoselectivities. Our computational investigations suggest that the enantioselectivity is governed in the deprotonation process to form (Z)-Ni-enolates, while the unique syn addition is mainly controlled by weak noncovalent bonding interactions between the nitrone and ligand.

Cross-coupling reactions using tertiary carboncentered radicals are an important class of transformations for constructing C(sp 3 )À C(sp 3 ) bonds, but the use of dimers as precursors of the persistent radicals is quite rare. Herein, we describe a radical-based cross-coupling reaction between dimers (prepared from 2-oxindoles and benzofuranones) and azo compounds that proceeds simply upon heating the reaction mixture. We present a conformational analysis of the dimers and we characterize the generation of a persistent radical via cleavage of the elongated C(3)À C(3') σ-bond. The behavior of the dimers in solution was characterized by spectroscopic analysis, helping to provide a basis for expanding the substrate scope of the cross-coupling reaction.