[R2S-CH2-OTf]+ OTf as a Reagent with an Optionally Mono- or Biselectrophilic Csp3 Center

G em inal Bisonium Salts, SN-R eaction, Synthesis, Regioselectivity, X -Ray D ata Sulfonium salts [R2S-CH2-OTf]+ O T fla,b are synthetically versatile 1,1-biselectrophiles featuring the sulfonioand triflato-substituents as leaving groups of differential nucleofugic power. R eactions with a num ber of neutral nucleophiles INu yield a series of novel sulfoniom ethylated onium salts [R2S-CH 2-Nu]2+ 2 0 T f_ 2 -8 under very mild conditions. Structures of salts 2a, 5a and 6b were confirm ed by X-ray analysis. W ith certain N -hetarenes exchange of both nucleofuges in la was achieved, yielding the sym metrical 1,1-bisonium salts 9 and 10. W ith pyridine(derivatives) selective substitution of the sulfoniofunction in 1,1-bisonium systems 2a and 5a was also realized. These reactions represent typical examples of nucleophilic substitutions at geminally bisonio substituted Csp3 centers, which we recently have in tro­ duced as a novel variant of SN2 reactivity.