Asymmetric radical allylation of β-keto esters with vinyl cyclopropanes by dual photoredox/nickel catalysis

Radical-involved allylation reactions have emerged as a powerful platform for construction of carbon-carbon and carbonheteroatom bonds, facilitating the strategic incorporation of diverse allyl moieties. Nevertheless, this burgeoning field still faces ongoing challenges, including limitations of radical precursors and coupling partners, and difficulties in achieving enantiocontrol. Herein, we report for the first time a highly enantioselective radical allylation involving β-keto esters with vinyl cyclopropanes utilizing a synergistic dual photoredox/nickel catalysis under visible light irradiation. The mild and redox-neutral catalytic protocol demonstrates an extensive substrate compatibility and good functional tolerance, providing access to enantioenriched β-keto esters featuring quaternary α-stereocenter with good yields and high enantioselectivities. Preliminary mechanistic studies have uncovered that the success of the reaction hinges on the dual roles of nickel catalyst, including in situ formation of photoredox sensitive substrate/Ni complex and the ensuing asymmetric radical addition step.

Intriguing magnetoelectric effect in two-dimensional ferromagnetic/perovskite oxide ferroelectric heterostructure

Two-dimensional (2D) magnets have broad application prospects in the spintronics,but how to effectively control them with a small electric field is still an issue.Here we propose that 2D magnets can be efficiently controlled in a multiferroic heterostructure composed of 2D magnetic material and perovskite oxide ferroelectric (POF) whose dielectric polarization is easily flipped under a small electric field.We illustrate the feasibility of such strategy in the bilayer CrI_(3)/BiFeO_(3)(001) heterostructure by using the first-principles calculations.Different from the traditional POF multiferroic heterostructures which have strong interface interactions,we find that the interface interaction between CrI_(3) and BiFeO_(3)(001) is van der Waals type.Whereas,the heterostructure has particular strong magnetoelectric coupling where the bilayer CrI_(3) can be efficiently switched between ferromagnetic and antiferromagnetic types by the polarized states P↑ and P↓ of BiFeO_(3)(001).We also discover the competing effect between electron doping and the additional electric field on the interlayer exchange coupling interaction of CrI_(3),which is responsible to the magnetic phase transition.Our results provide a avenue for the tuning of 2D magnets with a small electric field.