Process for preparing compounds derived from 4-(3-ethoxy-4-hydroxyphenyl)butan-2-one

Process for preparing at least one compound of formula (I) below:

• in which formula (I):
• R1 represents a linear or branched, saturated or unsaturated hydrocarbon group comprising from 1 to 6 carbon atoms;
• preferably R1 represents a C1-C4 alkyl group, more preferentially a C2-C4 alkyl group, such as ethyl;
• R2 represents a hydrogen atom or a C2-C4 alkyl group, such as methyl or ethyl;
• preferably R2 represents a hydrogen atom;
• R3 represents a linear or branched, saturated or unsaturated hydrocarbon group comprising from 1 to 12 atoms, optionally substituted with an aryl group;
• the aryl group preferably being a phenyl group optionally substituted with one or more groups chosen from hydroxyl, C1-C4 alkyl group, C1-C4 alkoxy group and combinations thereof;
• preferably R3 represents a C1-C6 alkyl group;
• preferably a C1-C4 alkyl group;
• and also one of the optical isomers or geometrical isomers thereof, and/or one of the salts thereof with an organic or inorganic acid or base, and/or one of the solvates thereof, such as the hydrates;
• said process taking place according to the following synthesis scheme (1):
• in which synthetic pathway (1):
• X represents a heteroatom chosen from oxygen and sulfur, preferably an oxygen atom,
• R1, R2 and R3 have the same meanings as in the formula (I);
• said process being characterised in that it comprises:
• at least one step (i) of reacting the compound of formula (II) in the presence of:
• at least one compound of formula (III),
• at least one (non)polar (a)protic solvent, and
• at least one alkaline agent in an excess molar amount relative to the compound of formula (II),
• in order to result in the formation of at least one precipitate including at least one compound of formula (IV), geometrical isomers thereof and/or one of the one of the salts thereof with an organic or inorganic base;
• and
• at least one step (i1) of separating the precipitate from the reaction medium of step (i), then
• at least one step (i2) of acidifying the precipitate using at least one inorganic or organic, preferably inorganic acidifying agent, before carrying out the reaction step (ii).