Reaction of Selectfluor (F-TEDA-BF4) with chloromethylated-DABCO monocation salts (X = BF4, NTf2) and other nitrogen bases (Et3N; piperidine; basic ionic liquid); unexpected formation of symmetrical [N−H−N]+ trication salts

Selectfluor reacts with N-chloromethylated DABCO monocation BF4 or NTf2 salts in MeCN (rt to 80 °C) to give symmetrical [N−H−N]+ trication salts. The same dimeric adducts are formed via the reaction of Selectfluor with Et3N, piperidine, or a basic-IL (imidazolium with an alkyl-piperidine tether). The resulting stable salts were studied by multinuclear NMR, 15N/1H HMBC, electrospray-MS, and by chemical reactivity. This hitherto unreported reactivity behavior contrasts the well documented ‘transfer fluorination’ by Selectfluor to quinuclidine and the quinuclidinic nitrogen of cinchona alkaloids.