Synthesis and Stereochemical Assignment of Crypto-Optically Active ²H₆-Neopentane

The determination of the absolute configuration of chiral molecules is at the heart of asymmetric synthesis. Here we probe the spectroscopic limits for chiral discrimination with NMR spectroscopy in chiral aligned media and with vibrational circular dichroism spectroscopy of the sixfold-deuterated chiral neopentane. The study of this compound presents formidable challenges since its stereogenicity is only due to small mass differences. For this purpose, we selectively prepared both enantiomers of ²H₆-1 through a concise synthesis utilizing multifunctional intermediates. While NMR spectroscopy in chiral aligned media could be used to characterize the precursors to ²H₆-1, the final assignment could only be accomplished with VCD spectroscopy, despite the fleetingly small dichroic properties of 1. Both enantiomers were assigned by matching the VCD spectra with those computed with density functional theory.