Organofluorine Family Expands Radically

Synthesis of a difluoromethyl xanthate compound has enabled a team of chemists to devise a convergent pathway to a new class of bioactive heterocyclic compounds. The difluorothiochromans, as they are called, could serve as building blocks to increase the diversity of heterocycle-based drugs. Pierre Salomon and Samir Z. Zard of École Polytechnique, in France, originally prepared the xanthate as part of the Zard group’s metal-free strategy for generating fluorine-containing radical species for addition to terminal alkenes. With the new xanthate in hand, the researchers ran a series of reactions coupling the compound with variously substituted alkenes. They discovered that further treating the adducts with a peroxide leads to a cyclization step to form the bicyclic thiochromans as shown (Org. Lett. 2014, DOI: 10.1021/ol5002939). Fluorine chemistry is enjoying a renaissance as chemists create new methods for preparing drug candidates, agrochemicals, and electronic materials. But work on fluorinated sulfides has been limited, Zard notes. Thiochromans are already used to treat acne, psoriasis, and breast cancer, he says, so the fluorinated thiochromans might serve to improve existing drugs or lead to new drugs for treating other diseases.