Process for preparing (R)-4-aminoindane and corresponding amides

A process for preparing a compound 1,1,3-trimethylindan-4-amine of formula (I), or a salt thereof, enriched in its (R) enantiomer:

• the process comprising:
• treating a racemic mixture of an optionally substituted 2,2,4-trimethyl-1,2,3,4-tetrahydroquinoline compound of formula (IIIa)
• comprising an (R) enantiomer of formula (IVa) and an(S) enantiomer of formula (Va):
• according to an operating sequence A, comprising:
• (A1) converting by a protection reaction, the first racemic mixture of the compound of formula (Illa) into a second racemic mixture of a compound of formula (IIIb) having a protecting PG group suitable to protect the nitrogen atom
• the racemic mixture of the compound of formula (IIIb) comprising an (R) enantiomer of formula (IVb) and an(S) enantiomer of formula (Vb)
• (A2) separating the (R) enantiomer of formula (IVb) from the(S) enantiomer of formula (Vb);
• subjecting the (R) enantiomer of formula (IVb) obtained in the separating (A2) to an acid rearrangement to form a compound of formula (VI)
• substituting the PG group of the compound of formula (VI) with a hydrogen atom to obtain the (R) enantiomer of the compound of formula (I);
• wherein, in the formulas,
• * indicates an asymmetric carbon atom,
• X is a fluorine atom,
• n is 1,
• PG is a —COR1 group or a —COOR2 group,
• R1 is methyl,
• R2 is methyl or a benzyl group wherein, the optical purity of the compound of formula (VI) is greater than 97% ee.