Catalytic Enantioselective Alkyne Addition to Nitrones Enabled by Tunable Axially Chiral Imidazole-Based P,N-Ligands.

Although catalytic enantioselective alkyne addition is an established method for the synthesis of chiral propargylic alcohols and amines, addition to nitrones presents unique challenges, and no general chiral catalyst system has been developed. In this manuscript, we report the first Cu-catalyzed enantioselective alkyne addition to nitrones utilizing tunable axially chiral imidazole-based ,-ligands. Our approach effectively overcomes difficulties in both reactivity and selectivity, resulting in a simple Cu-catalyzed protocol.

Catalytic Enantioselective Synthesis of Axially Chiral Imidazoles by Cation-Directed Desymmetrization.

Axially chiral five-membered heterobiaryls synthesized by enantioselective catalysis typically feature large ortho-substituents or a heteroatom in the chiral axis to maintain a stable configuration. Herein we report a cation-directed catalytic enantioselective desymmetrization method that enables rapid access to axially chiral imidazoles with the basic nitrogen at the ortho position and efficiently integrates π-stacking moieties to ensure a stable axial configuration for further applications. The process is operationally simple, is highly enantioselective, and can be performed on the gram scale.

-Selective iridium-catalyzed cross-coupling of allylic carbonates and α-diazo esters.

A well-defined Ir-allyl complex catalyzes the -selective cross-coupling of allyl carbonates with α-aryl diazo esters. The process overrides the large thermodynamic preference for -products typically observed in metal-mediated coupling reactions to enable the synthesis of ,-dieneoates in good yield with selectivities consistently approaching or greater than 90 : 10. This transformation represents the first productive merger of Ir-carbene and Ir-allyl species, which are commonly encountered intermediates in allylation and cyclopropanation/E-H insertion catalysis.

Ambient Decarboxylative Arylation of Malonate Half-Esters via Oxidative Catalysis.

We report decarboxylative carbonyl α-arylation by coupling of arylboron nucleophiles with malonic acid derivatives. This process is enabled by the merger of aerobic oxidative Cu catalysis with decarboxylative enolate interception reminiscent of malonyl-CoA reactivity in polyketide biosynthesis. This method enables the synthesis of monoaryl acetate derivatives containing electrophilic functional groups that are incompatible with existing α-arylation reactivity paradigms.