Lenalidomide, a blockbuster drug for the treatment of multiple myeloma: Semipreparative separation through supercritical fluid chromatography and vibrational circular dichroism spectroscopy.

Semipreparative separation of lenalidomide has been performed through supercritical fluid chromatography. In regard to retention and resolution of lenalidomide, effects of chromatographic conditions, such as chiral stationary phases, organic co-solvents, mobile phases, and column temperature, have been studied in detail. Amylose tris(3, 5-dimethylphenylcarbamate)-coated and the single-urea-bound β-cyclodextrin chiral stationary phases exhibited good separation performances for lenalidomide in the CO2 /methanol mixture. Then, a comparative study of semipreparative separation of lenalidomide has been carried out on these two chiral stationary phases. As indicated, separation of lenalidomide on the β-cyclodextrin-bound column was much better than the other. Under the optimized conditions, the loading per injection was 30 mg, the cycle time was 5 min, and the recoveries of two enantiomers were about 81.7 and 79.5%, respectively. Moreover, the vibrational circular dichroism spectrum of the first-eluted enantiomer in d6 -dimethylsulfoxide solution was consistent with the calculated pattern based on the S configuration, revealing that it should be (S)-(-)-lenalidomide. Briefly, this separation method through supercritical fluid chromatography might provide favorable information for rapid separation, enantioselective assessment, and absolute configurations of chiral pharmaceuticals.