PROCESS FOR PREPARING ESTERS OF OCTAHYDROINDOLOQUINALYSINE AND INTERMEDIATE HEXAHYDROINDOLOQUINOLYSINE

The invention relates to new hydroxyamino-eburnane derivatives of the general formula (I), (I) wherein R1 and R2 each stand for a C1-6 alkyl group, as well as to pharmaceutically acceptable acid addition salts and optically active isomers of these compounds. These new compounds can be applied as peripheral vasodilatating agents or can be converted into other compounds, e.g. vincamine and apovincamine derivatives of valuable therapeutical effects. The compounds of the general formula (I) are prepared according to the invention by reacting a hexahydro-indoloquinolisinium derivative of the general formula (II), (II) wherein R2 is as defined above and X stands for an acid residue, with a methylenemalonic acid diester derivative of the general formula (III), (III) wherein R1 is as defined above, subjecting the resulting product to catalytic hydrogenation, treating the resulting product with an alkali, and reacting the resulting octahydroindoloquinolisine monoester derivative with a nitrosating agent in an acidic medium.