Optimization of the preparative separation of a chiral pharmaceutical intermediate by high performance liquid chromatography.

The prediction of optimal conditions of the preparative HPLC separation of the enantiomers of a pharmaceutical intermediate was accomplished by employing analytical chromatographic data, i.e. sample injections at low concentrations. Various temperatures and mobile phase conditions were studied. It was assumed that the sample loadability of the stationary phase is constant for a constant value of the separation factor and different mobile phase conditions and temperatures. Using this assumption, possible production rates can be compared for different method conditions. Overloading experiments were carried out to verify that the procedure employed is adequate. It was found that the optimization approach used, changing the mobile phase composition and temperature to achieve the shortest cycle time while keeping the separation factor constant, could be applied to improve the production rate of the separation.

Isolation and characterization of the major equilibrium product of FK-520.

The existence of an isomeric form in equilibrium with the major component of FK-520 in polar solutions has been demonstrated. This minor component has been isolated in high yield and purity by a novel crystallization strategy and preparative HPLC. The equilibrium product was characterized by NMR and MS.