Absolute Configuration Assignment of Norcamphor-Derived Furyl Hydroperoxide Using Density Functional Theory Calculations of Optical Rotation and Vibrational Circular Dichroism

Density functional theory (DFT) calculations of sodium d line specific rotation and of vibrational circular dichroism (VCD) have been used to assign the absolute configuration of a recently prepared (1<i>S</i>,4<i>R</i>)-norcamphor-derived furyl hydroperoxide, (+)-<b>3</b>, introduced as a stereoselective oxidant. Both approaches give the same absolute configuration to the newly generated stereogenic carbon at position 2, i.e., (1<i>S</i>,2<i>S</i>,4<i>R</i>)-(+)-<b>3</b>, thus providing a confident assignment in a case made difficult by the large conformational flexibility and the small difference between the computed optical rotations of the two possible diastereoisomers. Although the computed IR absorption spectra of (1<i>S</i>,2<i>S</i>,4<i>R</i>)-<b>3</b> and (1<i>S</i>,2<i>R</i>,4<i>R</i>)-<b>3</b> are practically indistinguishable, a number of significant differences in the VCD spectra of these two nonmirror-image isomers can be observed, which allows the structural identification of the synthesized compound. This is clearly shown here for the first time.