Contribution Powerful Novel Chiral Acids for Enantioresolution, Determination of Absolute Configuration, and MS Spectral Determination of Enantiomeric Excess

It is well recognized that molecular chirality is essential to life processes, and that most biologically active compounds controlling physiological functions of living organisms are chiral. Hence, in the structural study of biologically active compounds, including natural products, determination of absolute configuration becomes the first major issue. The second issue is chiral synthesis of natural products and biologically active compounds that become pharmaceutical targets and how efficiently the desired enantiomers can be synthesized with 100% enantiopurity or enantiomeric excess (% ee). Furthermore, studies on chiral functional molecules and molecular machines, such as the light-powered chiral molecular motor developed in our laboratory, has been apidly progressing in recent years. Therefore, the unambiguous determination of the absolute configuration of a molecule as well as that in the chiral synthesis are of vital importance in the field of material science. We have recently developed chiral carboxylic acids as novel chiral auxiliaries proven to be powerful molecular tools for enantioresolution and unambiguous determination of the absolute configuration of various alcohols. Those chiral acids are very useful for the facile synthesis of the enantiomers with 100% ee and also for the absolute configurational assignment. The methods using these chiral acids have been successfully applied to various compounds and their methodologies and applications are explained throughout this contribution.