Finally in an effort to understand how Selectfluor is transformed
in these reactions (Scheme 8 and Supplementary data) NMR spectra
of ‘spent’ Selectfluor (the solid formed in the reaction upon addition
of TMSX and collected after completion of the reaction) (see
Supplemental file) were compared with: (a) an authentic sample
of Selectfluor (i); (b) an authentic sample of the monocation salt
(ii) synthesized by refluxing DABCO in CH2Cl2; and (c) the dication
(iii) generated by protonation of (ii) with TFAH (X = CF3CO2
). Based
on this comparison (Suppl. data) it may be concluded that
Selectfluor (i) is transformed into dication salt iii (the source of
H+ is likely hydrolysis of TMSX).
In summary the potential of Selectfluor to act as mediator and
oxidant for mild dihalogenation and dithiocyanation of