Abstract Promoted by iodide anion the rhodium complex dimer,[Cp* RhCl 2] 2, catalyzes efficiently the transfer hydrogenation of various quaternary pyridinium salts under mild conditions, affording not only piperidines but also 1, 2, 3, 6-tetrahydropyridines in a highly chemoselective fashion, depending on the substitution pattern at the pyridinium ring. The reduction is conducted in azeotropic formic acid/triethylamine (HCOOH-Et 3 N) mixture at ...
