Olefination with Sulfonyl Halides and Esters: Synthesis of Unsaturated Sulfonyl Fluorides

Methanedisulfonyl fluoride, CH2(SO2F)(2), transforms aromatic aldehydes into beta-arylethenesulfonyl fluorides, useful substrates for the SuFEx click-type transformations. The reaction mimics mechanism of the Horner-Wadsworth-Emmons olefination, which runs via addition of the carbanion, followed by cyclization-fragmentation of the four-membered ring intermediate. In the absence of base, electron-rich aldehydes follow an alternative pathway of the Knoevenagel condensation to provide unsaturated 1,1-disulfonyl fluorides. We demonstrate also trapping of elusive ethene-1,1-disulfonyl fluoride, CH2=C(SO2F)(2), with 4-(dimethylamino)pyridine (DMAP) that forms zwitterionic adduct, characterized with X-ray studies.

Automated summary

Methanedisulfonyl fluoride can convert aromatic aldehydes into useful substrates and mimic the mechanism of Horner-Wadsworth-Emmons olefination. In the absence of base, electron-rich aldehydes can also undergo Knoevenagel condensation to yield unsaturated 1,1-disulfonyl fluorides. Additionally, elusive ethene-1,1-disulfonyl fluoride can be trapped with 4-(dimethylamino)pyridine to form a zwitterionic adduct as characterized by X-ray studies.