Patent ID: 8865742

Claim:
A process for the preparation of a compound formula (I), or a salt thereof, wherein R 1 is selected from hydrogen, methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl and allyl; R 2 is selected from methyl, ethyl, n-propyl, iso-propyl, methoxy, ethoxy, halogen, trifluoromethyl and trifluoromethoxy; R 3 is hydrogen; or R 2 and R 3 together are selected from methylenedioxy, ethylenedioxy and isopropylidenedioxy; the process comprising the steps of: a) reacting an anthranilate derivative of formula (7A) wherein R is an alkyl, aryl or alkylaryl, with a 3-oxopropanoic acid derivative of formula (8A) wherein X is OH or a leaving group, so as to obtain a compound of formula (9A): b) optionally, saponifying the ester group CO 2 R in compound (9A) to the corresponding carboxylic acid CO 2 H so as to obtain a compound formula (10A), and converting acid (10A) to an activated derivative thereof of formula (11A): wherein Y is a leaving group; and c) converting compound (9A) obtained in step (a), or compound (11A) obtained in step (b) to a compound of formula (I) or a salt thereof in the presence of a base.