Preparation of chiral building blocks and auxiliaries by chromatography on cellulose triacetate (CTA I): Indications for the presence of multiple interaction sites in CTA I

Due to the increasing demand for optically active compounds, the development of methods supplying optically pure isomers is intensively progressing. Among these methods the chromatographic resolution on chiral stationary phases is very promising, although only a limited number of preparative applications have been reported so far. In this work, we demonstrate that especially cellulose triacetate I (CTA I) as a chiral phase presents a number of advantages for this purpose. The broad applicability and the high loading capacity of CTA I are particularly important features for preparative chromatography. Nevertheless, slight structural modifications of the racemates to be resolved can often strongly improve the resolution. This strategy has been applied to numerous practical problems and is illustrated in this work taking as examples some chiral building blocks and auxiliaries. Moreover, a systematic investigation of the influence of a substituent in the para ‐position of the phenyl ring for different series of aromatic compounds led to the conclusion that a large number of different interaction sites must be present in the chiral environment of CTA I.