A unique high-performance liquid chromatographic (HPLC) workflow specifically designed for the rigors of process development has been developed. A key feature of the workflow is the creation of an HPLC software-hardware platform designed to automatically and systematically screen samples using a matrix of columns and eluents to aggressively search for impurities. The workflow platform was assembled from commercial hardware components and both custom and commercial HPLC software.
View Article and Find Full Text PDF[reaction: see text] A novel crystallization-induced chiral inversion of (S)-2-bromo-3-phenylpropanoic acid to its (R)-enantiomer with excellent enantiomeric excess (96-99%) is achieved. Optically pure (S)-2-acetylthio-3-phenylpropanoic acid can be prepared in good yield from inexpensive and commercially available l-phenylalanine via diazotization/bromination, chiral inversion, and thioacetate substitution reactions.
View Article and Find Full Text PDFHerein we present a novel route to enantiomerically enriched chiral alpha-substituted carboxylic acids by crystallization-induced dynamic resolution (CIDR) of their diastereomeric salts with chiral amines. Thus, the racemic alpha-bromo acid 3 is converted reliably with (1R,2S)-2-amino-1,2-diphenylethanol in the presence of a catalytic amount of tetrabutylammonium bromide into its R-enantiomer 4 in 90% yield with 88% ee. Similarly, the racemic alpha-thiobenzoyl acid 5 could be resolved to 90% ee in 74% yield.
View Article and Find Full Text PDF