Process for the synthesis of vincamine and related indole alkaloids
AssigneePaolo Corvi Mora
InventorsSilvano Paracchini, Paolo C. Mora
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Abstract
A process is taught for the synthesis of vincamine and related indole alkaloids, according to which, through only two steps and through a novel synthesis intermediate, namely the glycidic ester, having the formula ##STR1## wherein R" represents --COOCH.sub.3 or --COOCH.sub.2 CH.sub.3, 1-ethyl-1,2,3,4,5,6,7,12b-octahydroindole[2,3-a]quinolizine-1-carboxaldehy de is reacted with a haloester in the presence of a base and the glycidic ester is converted to vincamine or apovincamine or like esters by reaction with a Lewis acid or a mineral acid, the reaction products being subsequently separated by chromatography.
Claims6
A process for the preparation of vincamine and related indole alkoloids of the formula (I) ##STR9## wherein:
- (a) R is --OH, R' is H, and R" is COOY wherein Y is selected from the group consisting of --CH.sub.3 and --CH.sub.2 CH.sub.3 ;
- (b) R is --OH, and both R' and R" are H;
- or
- (c) R" is COOY, and R and R' together form a double bond, said process comprising reacting a compound of the formula (II) ##STR10## with an alpha-halo-ester of the formula CH.sub.2 X-R" wherein X is selected from the group consisting of Cl, Br, and I and R" is COOY, in the presence of a base containing at least one member selected from the group comprising alkaline alcoholates and metal amides where the metal is selected from the group consisting of Na, K, or Li, according to the Darzens reaction conditions, to give the corresponding glycidic esters of the formula (III) ##STR11## and thereafter treating the glycidic ester with a Lewis acid in an inert solvent and/or with a mineral acid in alcoholic solution to produce a compound of formula (I).
Glycidic esters represented by the formula (III):
- ##STR12## wherein R" is --COOCH.sub.3 or --COOCH.sub.2 CH.sub.3.
Dependencies are inferred from the claim text.