Synthesis of bench-stable diarylmethylium tetrafluoroborates

Bench-stable non-symmetric diarylcarbenium tetrafluoroborates have been isolated via the direct coupling of aryl (or heteroaryl) aldehydes and N-heteroarenes, and fully characterised. They have proven to be highly stable in the presence of both EDG and EWG substituents. An (E)-iminium vinylogous substructure has been shown as the common cation scaffold by X-ray analysis and by n.O.e. determination.