Alkene halofunctionalization reactions are some of the oldest and most commonly employed reactions in organic chemistry. These transformations make it possible to rapidly build complex molecules from simple alkene starting materials and provide functional handles for further elaboration.
Halofunctionalization of alkenes is a classical method for olefin difunctionalization. It gives rise to adducts which are found in many natural products and biologically active molecules, and offers a synthetic handle for further manipulation. Classically, this reaction is performed with an electrophilic halogen source and leads to regioselective formation of the halofunctionalized adducts.
In work published in Angewandte Chemie, researchers in the Nicewicz Group demonstrate a reversal of the native regioselectivity for alkene halofunctionalization through the use of an acridinium photooxidant in conjunction with a copper cocatalyst. In doing so, the group has developed a new dual catalytic system consisting of an acridinium photooxidant and a copper cocatalyst for the halofunctionalization of unsaturated carboxylic acids with opposite regioselectivity to that observed under classical halolactonization conditions. These conditions are capable of producing both intra- and intermolecular adducts. The reserchers believe this class of reactions could be valuable for the synthesis of complex natural products and medicinal agents.