Synthesis and Stereochemical Assignment of Crypto-Optically Active 2-H6 -Neopentane
Résumé
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 spectroscopyinchiral aligned media and with vibra-tional circular dichroism spectroscopyofthe sixfold-deuter-ated chiral neopentane.The study of this compound presents formidable challenges since its stereogenicity is only due to small mass differences.For this purpose,weselectively prepared both enantiomers of 2H6-1 through aconcise syn-thesis utilizing multifunctional intermediates.While NMR spectroscopyinchiral 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.