Cyanine dyes from derivatives of 4-, 5-, and 6-trifluoromethylindolenines

The synthesis of 2,3-dimethyl-5- and -6-trifluoromethylindoles and 2,3,3-trimethyl-4-, -5-, and -6-trifluoromethylindolenines, from which quaternary salts, as well as indocarbo- and di- and tricarbocyanine dyes were obtained, is described. The effect of the introduction of a trifluoromethyl group in the 4, 5, and 6 positions on the color of the indocyanine dyes is examined.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 47–51, January, 1982.