Annulation of ketones with vinamidinium hexafluorophosphate salts: An efficient preparation of trisubstituted pyridines

[GRAPHICS] alpha-Aryl ketones react with vinamidinium hexafluorophosphate salts to giv e access to the corresponding 3-arylpyridines, The annulation reactions pro ceed in good to excellent yields with vinamidinium salts containing electro n-withdrawing groups at the beta-position (R-2). The reaction was applied t o the preparation of the COX-2 specific inhibitor 5-chloro-3-(4-methylsulfo nyl)phenyl-2-(2-methyl-5-pyridynl)pyridine (1), as well as a series of anal ogues.