Patent ID: 7678938

Claim:
A process for the optical resolution of (±)-3-(carbamoylmethyl)-5-methyl-hexanoic acid (CMH-racemate), comprising: a) combining CMH-racemate; a solvent selected from the group consisting of C 3 -C 6 ketone, C 1-4 alcohol, and mixtures thereof; and a chiral resolving reagent of selected from ephedrine, ephedrine salt, norephedrine, and norephedrine salt to obtain a precipitate; b) isolating the precipitate; and c) adding to the precipitate a solvent selected from the group consisting of ketone, C 1-8 alcohol, water and mixtures thereof, and a strong mineral acid; wherein the precipitate comprises a CMH salt that contains less than about 7% area by HPLC of the (S)—CMH salt and more that about 93% area by HPLC of the corresponding (R)-CMH salt.