Carbonyl derivatives trifluoromethanesulfonate

In addition to halides, some pseudohalides undergo facile oxidative addition to Pd and Ni complexes. Trifluoromethanesulfonates (triflates), namely aiyl triflates 3 derived from phenols and enol triflates of carbonyl compounds, are most useful. 

Reaction of benzaldehyde and its 4-nitro derivative with the enantiopure diene 796 in DCM and in presence of trimethylsilyl trifluoromethanesulfonate (TMSOTf) afforded the condensed enantiopure oxathiocanes 777 and 778 (50% yield). The reaction path began with the ionic addition of the diene 796 onto the carbon atom of the aldehyde function in 797a,b activated by trimethylsilyl cation attack to the carbonyl oxygen. 

Ene Cyclization, " The asymmetric catalysis of the intramolecular carbonyl-ene reaction not only of type (3,4) but also (2,4) employs the BINOL-derived titanium complexes [(I )-BINOL-TiX2 X = C104 or OTf], modified by the perchlorate and trifluoromethanesulfonate ligands. The tmns-... 

Cyclopropenones were protonated at the carbonyl oxygen to give the hydroxycyclo-propenylium ions in solution, e.g. the dimethylamino-substituted derivative 3 was protonated and isolated as the crystalline trifluoromethanesulfonate salt. "... 

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