A new chiral anisotropic reagent, phenylglycine methyl ester (PGME), developed for the elucidation of the absolute configuration of chiral alpha,alpha-disubstituted acetic acids, has turned out to be applicable to other substituted carboxylic acids, such as chiral alpha-hydroxy-, alpha-alkoxy-, and alpha-acyloxy-alpha, alpha-disubstituted acetic acids, as well as to chiral beta, beta-disubstituted propionic acids. Because a carboxylic moiety is convertible from other functional groups, e.g., ozonolysis of an olefin and oxidative cleavage of a glycol, the present findings can expand the utility of the PGME method to the absolute configuration determination of various types of organic compounds, even those which initially lack oxygen functions. Several examples of the combination of chemical reactions and the PGME method are described.

This article describes the application of the modified Mosher’s method to a variety of natural products possessing a secondary alcohol for determining their absolute configuration. The method is generally applicable to secondary alcohols with a few exceptions where the hydroxy group is seriously hindered by neighboring substituents. Countermeasures to solve the problems are also described. Recent findings that the modified Mosher’s method can be used in solvents other than deutero-chloroform are included. Development and application of the sulfoximine method for the determination of the absolute configuration of chiral sulfoxides are also described.

Eleven new sesquiterpenes (1--11) and two thymol derivatives (12, 13), along with 12 known sesquiterpenes and monoterpenes, were isolated from the bark of Inula macrophylla. Their structures were determined on the basis of spectral evidence (especially by HREIMS and 2D NMR) as well as chemical transformations. The structure of macrophyllic acid A (1) was confirmed by X-ray analysis, and the absolute configuration of 1 was determined on the basis of the appropriate chemical conversions and the application of a modified Mosher's method.

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