Patent ID: 6066741
Filing Date: 2000-05-23
Classification: C07D

Abstract:
In a process for the preparation of etodolac, comprising:a) reacting 7-ethyl-tryptophol of formula (II) ##STR8## with methyl 3-oxo-pentanoate of formula (III) in an apolar solvent ##STR9## thereby obtaining the methyl 1,8-diethyl-1,3,4,9-tetrahydropyrano [3,4-bis] indole-1-acetate of formula (IV) ##STR10## b) subsequent hydrolysing of the intermediate compound of formula (IV) to etodolac (I), ##STR11## the improvement consisting of carrying out step (a) at temperatures comprised between -20.degree. C. and +50.degree. C. in the presence of a concentrated mineral acid, the molar ratio of said mineral acid to 7-ethyl-tryptophol being comprised between 0.5 and 5.