Solid-phase Zincke route to pyridinium, tetrahydropyridine, and piperidine derivatives: vesamicol analogs

Optically active derivatives of vesamicol are prepared using solid-phase chemistry. Zincke coupling of resin-bound amino ethers (trityl linker) with 2,4-dinitrophenyl pyridinium salts delivers Zincke products which can be (1) liberated from the resin (TFA) or (2) reduced (NaBH4) to tetrahydropyridine derivatives and liberated. Subsequent reduction (H2/Pd) gives piperidines.