Enzymatic process for the preparation of optically active Tetrahydro-2-naphthoic acids

A process for the preparation of optically active compounds of formula (III):

• ##STR17## in which n is 0 or 1 and the asterisk denotes the chiral carbon atom in its (R) or (S) form, and their salts, which comprises the steps of:
• (a) hydrolyzing a racemic ester of the formula:
• ##STR18## in which R is a C.sub.1 -C.sub.3 -alkyl, with porcine pancreatic lipase;
• then
• (b) when about 50% of the ester has been hydrolyzed to the acid, interrupting the hydrolysis by inactivation of the lipase and recovering unreacted ester of (S) configuration of formula:
• ##STR19## then (c) either hydrolyzing said ester of formula (II') and isolating an acid of (S) configuration of formula:
• ##STR20## or isolating an acid of (R) configuration of formula:
• ##STR21## as obtained from the lipase hydrolysis reaction after interruption of the hydrolysis in step (b);
• and finally
• (d) either reacting the isomeric acids with an azide by the Curtius reaction in order to isolate an amine of formula (III) in which n is 0,
• or converting the isomeric acids (I') and (I") or the ester (II') to a corresponding amide and reducing the amide in order to isolate an amine of formula (III) in which n is 1,
• said amines being isolated in the form of the free base or one of their acid addition salts, or converted to one of their acid addition salts.