Determination of the absolute configurations of isotopically chiral molecules using vibrational circular dichroism (VCD) spectroscopy: the isotopically chiral sulfoxide, perdeuteriophenyl-phenyl-sulfoxide

The (+) and (−) enantiomers of the isotopically chiral sulfoxide, perdeuteriophenyl-phenyl-sulfoxide, 1, have been synthesized by the reaction of the diastereomers of O-menthyl benzenesulfinate with C6D5MgBr. Their absolute configurations have been determined by comparison of the vibrational circular dichroism (VCD) spectra of (R)-1 and (S)-1, predicted using ab initio DFT, to the experimental VCD spectrum of 1. The absolute configuration of 1 is shown to be (S)(+)/(R)(−). This is the first application of VCD to the determination of the absolute configuration of an isotopically chiral sulfoxide.

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Perdeuteriophenyl-phenyl-sulfoxideC12H5D5SOEe = 98.4%[α]400 = +3.08 (c 2.11, CH2Cl2)Source of chirality: VCD spectroscopyAbsolute configuration: S