The methylation of N-cyano N-methyl hydrazones: A new access to 2-aminoimidazoles through an in situ 1,3,4-triaza cope rearrangement

The reaction of 1-methyl-1-cyanohydrazones with methyl trifluoromethane sulfonate allows the direct preparation of 2-(methylamino)-1-methyl imidazoles as their triflic acid salts. The reaction pathway is believed to involve the formation of the 1-cyano-1,2-dimethyl ene-hydrazine derivative, which then undergoes a [3,3] rearrangement at room temperature, followed by an in situ cyclisation. None of the intermediates could be isolated or observed by H-1 NMR. Thus, the 2-(methylamino)-1-methyl imidazoles are obtained in good to average yields In two steps from the corresponding ketones and 1-methyl-1-cyanohydrazine.