Process for the preparation of indole derivatives

Abstract

The present invention provides a process for the preparation of 4-hydroxyindole derivatives of the general formula: ##STR1## in which R.sub.1 is a hydrogen atom or an alkyl radical containing up to 6 carbon atoms and R.sub.2 is a hydrogen atom or an alkyl radical containing up to 6 carbon atoms, wherein a compound of the general formula: ##STR2## in which R.sub.2 has the same meaning as above, is reacted with a compound of the general formula: R.sub.3 --CH.sub.2 --CO--COOR.sub.1 (III) in which R.sub.1 has the same meaning as above and R.sub.3 is a reactive residue, to give a 2-(2-imino-6-oxocyclohexylidene)-propionic acid derivative of the general formula: ##STR3## in which R.sub.1, R.sub.2 and R.sub.3 have the same meanings as above, which is then cyclized in known manner to give a compound of the general formula: ##STR4## in which R.sub.1 and R.sub.2 have the same meaning as above, which is subsequently dehydrated. The present invention also provides new 4-hydroxyindoles of general formula (I'), as well as new 4-Oxo-4,5,6,7-tetrahydroindoles of general formula (IV).

Dependencies are inferred from the claim text.