A simple and efficient method has been established for the synthesis of asymmetrical
               2,6-diarylpyridines by cyclization of α,β,γ,δ-unsaturated ketones with ammonium formate
               under air atmosphere. The reaction is metal-free and operationally convenient from
               readily available starting materials. Thirty-three examples have been presented, most
               of which show good yields.
            
         Key words
regioselectivity - Michael addition - annulations - 2,4-dien-1-one - asymmetrical
            pyridine