5-substituted 3-nitro-1-vinyl-1,2,4-triazoles

A series of 5-substituted 3-nitro-1-vinyl-1,2,4-triazoles were synthesized by alkaline treatment of the corresponding 1-(2-haloethyl- or 2-nitroxyethyl)-3-nitro-1,2,4-triazoles and by transvinylation of NH acids of the same series with vinyl acetate. The scope of applicability of the transvinylation procedure was established with respect to the azole pK(a) value. The vinylic double bond on the nitrogen was shown to be inactive toward both nucleophilic and electrophilic reagents, whereas the halogen atom in position 5 exhibits enhanced reactivity. The latter factor provides the possibility for versatile structural modification via nucleophilic replacement of the 5-halogen atom by various groups, including triazolate ion.