Silver-catalyzed [3 + 2] domino reaction: an efficient strategy to synthesize imidazole-5-carbaldehydes.

An unprecedented regioselective silver-catalyzed [3 + 2] domino reaction of amidines and ynals for the formation of C-N bonds has been developed. The reaction provided a new route to prepare imidazole-5-carbaldehydes which are important intermediates for the construction of fine chemicals. The reaction proceeds smoothly with a broad range of substrates to give imidazoles in good yields.