The present invention provides indole derivatives of the general formula: ##STR1## wherein R.sub.1 is a hydrogen atom or an alkyl, alkenyl, cycloalkyl, cycloalkenyl, carboxyl, cyano, alkylcarbonyl, alkoxycarbonyl, aminocarbonyl, alkylaminocarbonyl, dialkylaminocarbonyl or aryl radical, R.sub.2 is a hydrogen atom or an alkyl, trihalogenomethyl, hydroxyl, cycloalkyl, cyano, carboxyl, alkoxycarbonyl, alkylcarbonyl, aminocarbonyl, alkylaminocarbonyl or dialkylaminocarbonyl radical; R.sub.2 is a heterocyclic five-membered ring containing 1 to 4 heteroatoms or a heterocyclic six-membered ring containing 1 to 5 heteroatoms, the heteroatoms of the five- and six-membered rings being the same or different and being nitrogen, oxygen or sulphur and one or more of the nitrogen atoms optionally carrying an oxygen atom, the said five- and six-membered rings optionally being substituted by one or more alkyl, alkoxy, alkylthio, oxo, hydroxyl, nitro, amino, halogen or cyano groups; or R.sub.2 is ##STR2## the tautomers thereof and the physiologically acceptable salts thereof with inorganic and organic acids.The present invention also provides processes for the preparation of these compounds and pharmaceutical compositions containing them.Furthermore, the present invention provides intermediates of the general formula: ##STR3## in which R.sub.1, R.sub.2, A and X have the same meanings as above, and processes for the preparation of these intermediates.