| 摘要 |
The invention relates to a new process for the preparation of apovincaminic acid esters. More particularly, the invention concerns a process for preparing racemic and optionally active vincaminic acid esters of the formula (I) <IMAGE> (I) in which R1 and R2 independently stand for alkyl having from one to 6 carbon atoms, and 14-epimers thereof. According to the invention an octahydroindolo[2,3-a]quinolizine-oxime ester of the formula (II) <IMAGE> (II) in which R1 and R2 have the same meaning as defined above, is reacted with an aqueous solution of sulfurous acid or a salt thereof at a temperature of 80 DEG to 110 DEG C. and the 14-epimeric mixture obtained is epimerized or separated in a known manner and if desired, the racemic vincaminic acid esters are resolved. The valuable, pharmaceutically active compounds of the formula (I) can be prepared according to the invention in a considerably improved yield and the undesired side reactions can be suppressed and/or the by-products can easily be converted into other pharmaceutically active materials. |
