Efficient and Chemoselective Reduction of Pyridines to Tetrahydropyridines and Piperidines
Promoted by iodide anion the rhodium complex dimer, [Cp*RhCl2]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‐Et3N) mixture at 40 °C, with catalyst loadings as low as 0.005 mol% being feasible.
Document Type: Communications
Affiliations: 1: Liverpool Centre for Materials & Catalysis, Department of Chemistry, University of Liverpool, Liverpool L69 7ZD, U.K., (~jxiao), Fax: (+44)-151-794-3588, URL: http://pcwww.liv.ac.uk/ 2: Chemical R & D, Global Research & Development, Pfizer, Sandwich, Kent CT13 9NJ, U.K.
Publication date: 2013-01-14