De-Risking S-F Bond Formation: A Gas Cylinder-Free Strategy to Access S(IV) and S(VI) Fluorinated Compounds

The sulfur-fluorine partnership occupies a privileged position in fluorine chemistry given the functional versatility that it imparts to organic structures. Despite this, available methodologies to forge S-F bonds are limited compared to C-F bond formation. Here, we describe a synthetic protocol that selectively enables the oxidative halogenation of aliphatic, aromatic, and heteroaromatic thiols to their corresponding SF₄ Cl, SO₂ F and SF₃ derivatives. Selective oxidation of thiols to either S(IV)-F or S(VI)-F compounds is achieved by employing bench-stable calcium hypochlorite as chlorine surrogate (CLOgen), in the presence of KF as fluoride source. Density functional theory (DFT) calculations provided insight into the mechanistic aspects of the transformation and rationalized the observed isomeric preference towards the SF₄ Cl derivatives. Ultimately, this glovebox-free method selectively dispatches three classes of compounds upon reaction condition fine-tuning. Furthermore, first-in-class transformations are reported, including the preparation of aliphatic SF₄ Cl intermediates, their transformation into aliphatic sulfur pentafluoride analogs, and post-functionalizations that allow accessing highly complex SF₄ -bridged scaffolds.