Abstract: The use of indolines of formula (I): in which R1, R2, R3, R4 and R5 independently of one another represent hydrogen or C1-4 alkyl groups, or R4 and R5 together with the oxygen atoms to which they are attached may represent an alkylenedioxy group containing 1 to 4 carbon atoms, or their salts, as oxidation dye precursors gives natural brown hair colorings. The indolines of formula (I) are also suitable as couplers in oxidation hair dyes with a conventional primary intermediate, in which they result in a modification of the tints obtainable with the primary intermediate. They are used in conventional carriers, e.g., in gel or emulsion form, preferably mixed before use or on the hair with an oxidizing agent to develop the color.

Abstract: Novel compounds with structures corresponding to the formula: ##STR1## in which n=0 or 1 and R.sup.1 is hydrogen, a C.sub.1 -C.sub.4 alkyl or hydroxyalkyl group, or an amino group, and salts of such compounds, are superior to previously known couplers for oxidation hair dyes to produce a variety of colors, especially reds, when used with standard developer components. With 2,4,5,6-tetraaminopyrimidine developer for example, these novel compounds produce red to brown hair colors and, with p-tolylenediamine developer, red to blue-violet hair colors.

Abstract: Oxidation hair-dyeing preparations which contain as couplers N-(2-4dihydroxbenzylidene)-amino compounds corresponding to the following formula ##STR1## in which A is a group corresponding to one of the following formulae ##STR2## or salts thereof and the developers normally present in oxidation hair dyes. p-Phenylenediamine and derivatives thereof are particularly suitable as developers. Yellow to olive-brown colors of high fastness are obtained.