A variety of alkynylated amines, amides, and imides arereacted in the superacid system HF-S
bF
5 to give regioselectively new
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beta2.gif" BORDER=0 ALIGN="middle">
-gem-difluoroamines. The reaction, which isnot o
bserved in pure HF, is consistent with the formation ofa dicationic intermediate (i.e.,
both vinylic and adjacentprotonated
N-ammonium cations). Application to the regioselective and efficient synthesis of difluorinated cinchonaalkaloid derivatives is descri
bed.