Evidence and exploitation of dicationic ammonium-nitrilium superelectrophiles: direct synthesis of unsaturated piperidinones.

Exploiting superacid activation, the reactivity of aminonitriles was enhanced through the transient formation of highly reactive ammonium-nitrilium superelectrophiles. Demonstrated by using in situ low-temperature NMR experiments and confirmed by X-ray diffraction analysis, these dications can be intramolecularly trapped by non-activated alkenes to generate unsaturated piperidinones, including enantioenriched ones, in a straightforward way.

Tuning the Anomeric Effect in Sulfamide with Superacids.

This study shows that the anomeric effect (negative hyperconjugation) that arises in sulfamide, as a result of the relatively short S-N bonds, can be tuned by the utilization of superacidic media. Sulfamide was reacted in binary superacidic systems XF/MF (M=As, Sb; X=H, D) and HF/BF . The colorless salts formed, [X NSO NX ] [MF ] and [H NSO NH ] [BF ] were characterized by low-temperature vibrational spectroscopy.

Diprotonation of Guanidine in Superacidic Solutions.

Guanidinium chloride reacts with the superacidic solutions HF/MF (M=As, Sb) at a molar ratio of 1:2 under formation of the diprotonated guanidinium salts [C(NH ) (NH )][AsF ] and [C(NH ) (NH )][SbF ] . The compounds were characterized by using infrared and Raman spectroscopy. Furthermore, single-crystal X-ray structure analysis of the guanidinium(2+) salts [C(NH ) (NH )][SbF ] ⋅HF, [C(NH ) (NH )] [Ge F ]⋅HF, and [C(NH ) (NH )] [Ge F ]⋅2 HF and the guanidinium(1+) salt [C(NH ) ][SbF ] is reported.