Ring-opening reactions of simple gem-difluorocyclopropanes using molecular iodine

Abstract

We previously reported an efficient method for the ring-opening 1,3-difunctionalization of gem-difluorinated cyclopropanes (F2CPs) using KBr in the presence of ceric ammonium nitrate or potassium persulfate, resulting in the formation of 3-bromo-2,2-difluoropropanes with a bromine atom or a hydroxy group at the 1 position by the highly regioselective cyclopropane bond cleavage. In spite of the usefulness of this process, the concern of the use of these irritant oxidants and the insufficient reactivity of Br incorporated at the 1 position allowed us to modify this system to find out that the environmentally friendly as well as easy-to-handle reagent, an iodine molecule, works quite efficiently, enabling the successful introduction of not only a hydroxy group but also alkoxy, sulfenyl, and aryl groups at the 1 position of products.