Synthesis of perfluoroalkylated bipyridines - New ligands for oxidation reactions under fluorous triphasic conditions

Fluorous soluble bipyridines bearing two perfluoroalkylated side chains in the 6,6'- or 4,4'-positions have been prepared in good yields via etherification of 6,6'-bis(chloromethyl)-2,2'-bipyridine or C-alkylation of 6,6'-dimethyl-2,2'-bipyridine. The new ligands L exhibit amphiphilic behaviour with respect to certain fluorous-organic biphasic systems. Nevertheless, their ruthenium complexes (RuLn)X generated in situ are efficient catalysts for the epoxidation of trans-stilbene in a fluorous triphasic system CH2Cl2/H2O/C8F18 in the presence of NaIO4. The fluorous phase, where (RuLn)X is trapped, can be used up to four times without major loss of catalytic activity. (C) 1999 Elsevier Science Ltd. All rights reserved.