CD-spectroscopic confirmation of the absolute configuration of a conformationally flexible aldehyde ester containing a quarternary stereogenic center

The absolute configuration of the conformationally flexible aldehyde ester methyl-2-formyl-2-(phenylsulfanyl)-3-(3,4,5-trimethoxyphenyl)-propanoate wa s determined by comparison of measured and calculated CD spectra. The spectra were calculated by means of the so-called matrix method assumin g R configuration at the stereogenic center. Calculated and observed signs of the first three most intense CD bands agree. Therefore, it was concluded that the absolute configuration of the compound was also R, which is in pe rfect agreement with the results of an X-ray structure determination.