13794-25-7

The lithiation of N-(dialkylamino)methyl (aminal) derivatives of imidazole, benzimidazole, and pyrazole (themselves readily available from parent heterocycles, formaldehyde, and a secondary amine) occurs smoothly at 2-, 2-, and 5-positions, respectively, upon treatment with n-butyllithium in ether or tetrahydrofuran.Reaction with electrophiles, and subsequent facile acid-catalyzed hydrolysis of the protecting group, provides 2-substituted imidazoles, 2-substituted benzimidazoles, and 3(5)-substituted pyrazoles in good overall yields.