Umpolung of a Diazo Sulfonyl Fluoride Surrogate Expands Diversity-Oriented Clicking to Cyclopropanes

Herein, we report the synthesis of a new hypervalent iodine reagent, ((((( tert butyldimethylsilyl)oxy)methyl)sulfonyl)(diazo)methyl)(phenyl)- λ 3-iodaneyl trifluoromethanesulfonate (HIR 3 ), from the Diversity-Oriented Clicking (DOC) hub tert -butyl(((diazomethyl)sulfonyl)methoxy)dimethylsilane ( t Bu-DMSM), thereby reversing the native reactivity of its diazo carbon. Reaction of 3 with nucleophilic silyl enol ethers affords β-diazosulfones in good to excellent yields. Subsequent rhodium-catalysed intramolecular 1,3-C–H insertion provides novel cyclopropanes bearing a masked sulfonyl fluoride group in good to excellent yields and diastereoselectivities. Unmasking of this group enables the late-stage formation of cyclopropyl sulfonyl fluorides, either from the isolated cyclopropanes or through a one-pot, two-step sequence from the βdiazosulfones. We further demonstrate that the major cyclopropane diastereomer undergoes base-mediated epimerisation to afford an otherwise inaccessible diastereomer, which participates in sulfur(VI) fluoride exchange (SuFEx) reactions to furnish the corresponding sulfonates. Finally, trapping of the intermediate sulfinate with benzyl bromide electrophiles, rather than conversion into the sulfonyl fluoride, provides access to structurally diverse sulfones.