Synthesis of (E)-diethyl 6,6′-(diazene-1,2-diyl)bis(5-cyano-2-methyl-4-phenylnicotinates), a new type of 2,2′-azopyridine dyes

An unexpected, but simple method for the efficient synthesis of new 2.2′-azopyridine dyes, such as (E)-diethyl 6,6′-(diazene-1,2-diyl)bis(5-cyano-2-methyl-4-phenylnicotinates) (2, 4, 6, 8, 10, and 12), based on the treatment of ethyl 6-amino-5-cyano-2-methyl-4-arylnicotinates (1, 3, 5, 7, 9, and 11) with NBS/benzoyl peroxide, is described. The X-ray diffraction analysis and the UV-vis absorption spectra of dye 2 are reported and discussed.