Photocatalysis in Organic Synthesis
Iodobenzene-catalyzed photochemical heteroarylation of alcohols by rupture of inert C–H and C–C bondsA Minisci-type reaction catalyzed by iodobenzene is disclosed here for the first time. The heteroarylation of unprotected aliphatic alcohols proceeds via alkoxy radical-induced homolytic cleavage of C–H and C–C bonds under photochemical conditions. The use of m-CPBA as the oxidant allows the oxidation of iodobenzene to a hypervalent iodine species, driving the catalytic cycle. The method features mild reaction conditions, broad scope of heteroarenes and alcohols, and scaled up preparations. This approach provides a notable supplement to iodobenzene-catalyzed ionic reactions, and opens up a new avenue for its application in radical chemistry.
Stereoconvergent, photocatalytic cyclopropanation reactions of β-substituted styrenes with ethyl diazoacetateCyclopropanes constitute a pivotal molecular scaffold in medicinal and agrochemical research and find broad applications in marketed drugs and other bioactive compounds. Their synthesis commonly relies on metal-catalyzed carbene transfer reactions that necessitate the utilization of stereochemically defined olefin starting materials, which in turn requires a high stereochemical fidelity in the olefin synthesis step. Herein, we report on a photocatalytic strategy that allows the use of a mixture of the E- and Z-isomers of such olefins and gives access to a single isomer of the cyclopropane product in a stereoconvergent reaction.
Visible-light-mediated interrupted Cloke-Wilson rearrangement of cyclopropyl ketones to construct oxy-bridged macrocyclic frameworkCloke-Wilson rearrangement has been well studied, in which cyclopropyl ketones or cyclopropyl imines could be transformed to dihydrofuran or dihydropyrrole derivatives through a tandem ring-opening/recyclization process. Herein, we report a new version of Cloke-Wilson rearrangement, in which the ring-opening/recyclization of cyclopropyl ketones upon visible-light-induced photoredox catalysis can provide oxy-bridged macrocyclic frameworks under mild reaction conditions, and the reagent XRf plays dual roles in the catalytic cycle.