Process for the preparation of optically-active compounds

A method of preparation of a (±)-3a,6,6,9a-tetramethyl-dodecahydro-naphtho[2,1b]furan (“TDNF”) mixture having a proportion of one isomer greater than 50%, comprising the steps of:

• 1. reacting a compound selected from (E,E)-homofarnesic acid and (E)-monocyclohomofarnesic acid with a chiral alcohol of formula R*OH, wherein the chiral alcohol R*OH is of formula
• in which:
• R1, R2 and R3 are individually selected from H, alkyl, alkenyl, alkinyl, cycloakyl, cycloalkenyl, cycloalkylalkyl, alkylcycloakyl, cycloakylalkenyl, alkylcycloalkenyl, aryl, alkylaryl, alkenylaryl, arylalkyl, arylalkenyl and cyclic moieties of these types that include at least one heteroatom, preferably selected from N, O, S, Si, R1, R2 and R3 optionally additionally comprising at least one substituent preferably selected from OH, CHO, CO2H, CO2R4, CONH2, CONHR5, CONR5R6, NO2, CN;
• R4, R5 and R6 being independently C1-C6 alkyl;
• with the proviso that the residues R1, R2 and R3 are different, to form a compound selected from the group consisting of compounds of formula III and formula IV:
• wherein R* is the residue of a chiral alcohol R*OH,
• 2. reacting the result of step 1 with an acid to form one of the compounds of formula V
• 3. reacting the result of step 2 with a reducing agent, to form an alcohol;
• and
• 4. treating the alcohol of step 3 with an acid to form compounds of the formulae VI and VII