Eburnane derivatives, process for their preparation and pharmaceutical compositions containing them

A process for the preparation of a compound of the Formula (I) ##STR5## wherein R.sup.1 is ethyl;

• or a pharmaceutically acceptable acid addition salt thereof, which comprises the step of oxidizing a compound of the Formula (II) ##STR6## wherein R.sup.2 is hydrogen or C.sub.1 to C.sub.6 alkyl, or a metal carboxylate salt or acid addition salt thereof, in an aqueous solution of an alkali metal hydroxide or an alkaline earth metal hydroxide by passing an oxygen-containing gas therethrough at a temperature between 60.degree. C. and 150.degree. C.

A process for the preparation of a compound of the Formula (I) ##STR7## wherein R.sup.1 is ethyl;

• or a pharmaceutically acceptable acid addition salt thereof, which comprises the step of oxidizing a compound of the Formula (II) ##STR8## wherein R.sup.2 is hydrogen or C.sub.1 to C.sub.6 alkyl, or a metal carboxylate salt or acid addition salt thereof, in an aqueous solution of an alkali metal hydroxide or alkaline earth metal hydroxide by adding hydrogen peroxide thereto at a temperature of between 60.degree. C. and 150.degree. C.

A process for the preparation of a compound of the Formula (I) ##STR9## wherein R.sup.1 is ethyl;

• or a pharmaceutically acceptable acid addition salt thereof, which comprises the step of oxidizing a compound of the Formula (II) ##STR10## wherein R.sup.2 is hydrogen or C.sub.1 to C.sub.6 alkyl, or a metal carboxylate salt or acid addition salt thereof, in an aqueous solution of an alkali metal or an alkaline earth metal hydroxide by employing a salt of copper or manganese as oxidizing agent in at least an equimolar amount at a temperature of between 60.degree. C. and 150.degree. C.