Process for the preparation of 11-bromo-vincaminic acid ester derivatives and their use in protecting animals against cerebral hypoxy

A process for the preparation of a racemic or optically active 11-bromo-vincaminic acid ester of the formula (I), ##STR16## wherein R.sup.1 and R.sup.2 each represent a C.sub.1-6 alkyl group, or a pharmaceutically acceptable acid addition salt thereof, characterized in that

• (a) an optically active or racemic 1-alkyl-1-alkoxy-carbonylethyl-octahydroindoloquinolizine of the formula (II), ##STR17## wherein R.sup.2 is as defined above and R.sup.3 stands for a C.sub.1-6 alkyl group, or an acid addition salt thereof as treated with a brominating agent, the resulting mixture of the optically active or racemic 10-bromo- and 8-bromo-1-alkyl-1-alkoxycarbonylethyl-octahydroindoloquinolizine of the formulae (IIIa) and (IIIb) ##STR18## wherein R.sup.2 and R.sup.3 are as defined above, is treated with an alkaline agent, or
• (b) an optically active homoeburnane derivative of the formula (IV), ##STR19## wherein R.sup.2 is as defined above, or a racemate or salt thereof is treated with a brominating agent,
• and the 9-bromo- and 11-bromo compounds are separated from the resulting mixture of the optically active or recemic 11-bromo- and 9-bromo-14-oxo-E-homoeburnane derivatives of the formulae (Va) and (Vb), ##STR20## wherein R.sup.2 is as defined above, or salts thereof, and the resulting racemic or optically active 11-bromo-14-oxo-E-homo-eburnane derivative of the formula (Va), ##STR21## wherein R.sup.2 is as defined above, or an acid addition salt thereof is reacted with a nitrosating agent, the resulting racemic or optically active 11-bromo-14-oxo-15-hydroxyimino-E-homo-eburnane derivative of the formula (VI), ##STR22## wherein R.sup.2 is as defined above, or an acid addition salt thereof is subjected to deoxyimination, the resulting racemic or optically active 11-bromo-14,15-dioxo-E-homo-eburnane derivative of the formula (VII), ##STR23## wherein R.sup.2 is as defined above, or an acid addition salt thereof is treated with a base in an alcohol of the formula R.sup.1 OH, wherein R.sup.1 is as defined above, and, if desired, the resulting 11-bromo-vincaminic acid ester of the formula (I) is converted into its pharmaceutically acceptable acid addition salt.