US Patent 7683190 Process for the preparation of optically-active compounds

A method of preparing enatiomerically enriched 3a,6,6,9a-tetramethyl-dodecahydro-naphtho[2,1-b]furan, formula (I), from (E,E)-homofarnesic acid or (E)-monocyclohomofarnesic acid by (a) reacting firstly with a chiral alcohol, (b) reacting the product of (a) with an acid to cause a first cyclization, (c) producing an alcohol by reacting the product of (b) with a reducing agent and (d) causing a second cyclization by reacting the product of (c) with an acid. The product of this process gives a mixture of both enantiomers with one in excess.