Direct Light Activation of Hypervalent Iodine Reagents: Substrate-Controlled C-C or C-H Alkynylation of Cyclopropanes

We report the direct light activation of ethynylbenziodoxolone (EBX) reagents for the oxyalkynylation of aryl- and amino-cyclopropanes as well as styrenes. Irradiation with visible light at 440 nm promoted the reaction without the need of a photocatalyst. By the choice of the aryl group on the cyclopropane, it was possilbe to completely switch the outcome of the reaction from the oxyalkynylation of the C-C bond to the alkynylation of the C-H bond. This effect has been speculatively attributed to the conformational control induced by the aryl group on the cyclopropane ring