Photocatalytic [3 + 2] cycloadditions and control of stereochemistry have remained a substantial challenge, particularly in the context of heterocycle synthesis; sporadic successful examples have involved enantioselective [3 + 2] photocycloaddition between redox-active direct group-containing cyclopropanes and alkenes for creation of cyclopentanes. Herein, we report a cooperative catalytic system comprising a chiral nickel Lewis acid catalyst and an organic photocatalyst fueled by visible-light irradiation that allows for the hitherto elusive asymmetric [3 + 2] photocycloaddition of β-keto esters with vinyl azides under redox-neutral conditions. This protocol enables highly enantioselective construction of polycyclic densely substituted 3,4-dihydro-2H-pyrrole heterocycles featuring two contiguous tetrasubstituted carbon stereocenters, including a useful chiral N,O-ketal motif that is not easily accessible with other catalytic methods. Mechanistic studies revealed that the overall reactivity relies on the seamless integration of dual roles of nickel catalysts by the catalytic formation of the substrate/Ni complex, assisting both photoredox event and enantioselective radical addition.

The asymmetric Michael addition of phosphorus nucleophiles to electron-deficient alkenes is one of the most direct and atom-economical methods to provide chiral organophosphorus compounds with high efficiency in recent years....

The transition metal catalyzed cycloaddition reaction is one of the most powerful tools for the construction of carbon- and heterocycles. Comprehensive computational studies are employed to investigate the mechanism and...

To achieve in situ dynamic fluorescence in the solid state and unveil the mechanism remain a formidable challenge. Herein, through synergizing the cavities of macrocycles for dynamic complexing and the channels of frameworks for facile transit, we construct intrinsic channels from an emissive cyclophane and realize precisely tunable emission in the solid state through the sequential guests’ exchange. Specifically, two design criteria involve (1) The twisted cyanostilbene units not only endow the systems with solid-state fluorescence but also tailor the π–π interactions in the complex to generate the desired emission and (2) the large cavity of cyclophane results in the formation of ternary complexes with controllable binding affinity which further assemble into robust channels for the guests’ exchange in the bulky state. This strategy unifies the advantages of both macrocycle and framework in one system, achieving visualization, recyclability, and easy processability simultaneously. The present study paves an easy, efficient, and general platform for constructing dynamic optical materials.

No abstract