approach leads to a pendant SF that is exposed, and therefore susceptible to off-target reactivity. The second option is direct late-stage SF functionalization (Figure ). Many efforts have been made to advance this area including the direct coupling of aryl halides and diazonium salts to sulfur dioxide surrogate, DABSO and various photocatalytic methods. These efforts usually result in sulfinate salts that can then be oxidized to the SF using selectfluor or N-fluorobenzenesulfonimide (NFSI). In these cases, although the late-stage installation is elegant, the parent starting material (for example an aryl bromide) must be introduced late stage and/or be compatible with previous synthetic steps.