PREPARATION OF VINCAMINE AND VINCAMINE-ANALOGUES

A new process for the preparation of vincamine and of homologues thereof containing acyl groups of 2 to 6 carbon atoms in the 14-position, wherein 1-ethyl-2,3,4,6,7,12-hexahydroindolo[2,3-a]quinolizine is reacted with an alpha -acyloxy-acrylic acid derivative of the formula (R = C15 alkyl) to obtain the corresponding 1-( beta -acyloxy- beta -R-oxycarbonyl-ethyl)-1-ethyl-1,2,3,4,6,7-hexahydro-12H-indolo[2,3-a]q uinolizine compound, this is converted by deacylation and reduction into the corresponding 1-( beta -hydroxy- beta -R-oxycarbonyl-ethyl)-1-ethyl-1,2,3,4,6,7,12,12b-octahydroindolo[2,3-a ]quinolizine; the latter is treated with an oxidizing agent to yield a mixture of the desired vincamine derivative and the 14-epimer thereof. The latter can be epimerized in a known manner; by using silver carbonate as oxidizing agent, the epimerization occurs simultaneously.