Patent ID: 7928223

Claim:
A process for the synthesis of a compound of formula (I): wherein (3,4-dimethoxyphenyl)acetic acid of formula (IV): is converted into a compound of formula (V): wherein R 1 and R 2 , which may be the same or different, represent linear or branched (C 1 -C 6 ) alkoxy groups or, together with the carbon atom carrying them, form a 1,3-dioxane, 1,3-dioxolane or 1,3-dioxepane ring, wherein the conversion is carried out either: by means of preliminary conversion of the compound of formula (IV) into a compound of formula (VI): wherein X represents a halogen atom or a OCOR 3 group, wherein R 3 is a linear or branched (C 1 -C 6 )alkyl group, a phenyl group, a benzyl group or an imidazolyl group, in an organic solvent, and the compound of formula (VI) is subjected to a condensation reaction with a compound of formula (VII): wherein R 1 and R 7 , which may be the same or different, represent linear or branched (C 1 -C 6 )alkoxy groups or, together with the carbon atom carrying them, form a 1,3-dioxane, 1,3-dioxolane or 1,3-dioxepane ring, in the presence of a base in an organic solvent, to yield the compound of formula (V): or by reaction of the compound of formula (IV) with a compound of formula (VII): wherein R 1 and R 2 , which may be the same or different, represent linear or branched (C 1 -C 6 )alkoxy groups or, together with the carbon atom carrying them, form a 1,3-dioxane, 1,3-dioxolane or 1,3-dioxepane ring, in the presence of a coupling agent in an organic solvent, to yield the compound of formula (V): wherein the compound of formula (V) is not isolated and is directly subjected to a cyclisation reaction in an acid medium, wherein the acid medium is selected from concentrated sulphuric acid, polyphosphoric acid, concentrated hydrochloric acid in aqueous solution, concentrated hydrochloric acid in solution in acetic acid, concentrated hydrobromic acid in solution in acetic acid, and methanesulphonic acid, to yield, after isolation, the compound of formula (I).