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

Abstract

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 SF4Cl, SO2F 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. DFT calculations provided insight into the mechanistic aspects of the transformation and rationalized the observed isomeric preference towards the SF4Cl derivatives. Ultimately, this glovebox-free method selectively dispatches three classes of compounds upon reaction condition finetuning. Furthermore, first-in-class transformations are reported, including the preparation of aliphatic SF4Cl intermediates, their transformation into aliphatic sulfur pentafluoride analogs, and posttransformations that allow accessing highly complex SF4-bridged scaffolds.

An Extrusion Strategy for On-Demand SF5Cl Gas Generation from a Commercial Disulfide

“…This urged us to seek an alternative procedure for ex situ generation of SF 5 Cl relying solely on stable and commercially available precursors. Based on our recent oxidative halogenation work and further confirmed in a 2016 report by Shibata and co-workers, we realized that 4,4′-dipyridyl disulfide (DPDS, 7 ) was a potential candidate precursor for ex situ SF 5 Cl generation. This was based on the finding that DPDS, in a chlorotetrafluorosulfanylation attempt with Cl 2 and KF, did not yield 4-(chlorotetrafluoro-λ 6 -sulfanyl)­pyridine ( 8 ) at the end of the reaction.…”