Determination of absolute configuration using circular dichroism: Tröger’s Base revisited using vibrational circular dichroism

A new methodology for predicting the Vibrational Circular Dichroism (VCD) spectra of chiral molecules using Density Functional Theory (DFT) and Gauge-Invariant Atomic Orbitals (GIAOs) permits the direct determination of the absolute configuration of organic molecules in solution; application to Tröger’s Base leads to the opposite absolute configuration from that deduced from electronic CD, confirming the conclusion arrived at from X-ray analysis of a diastereoisomeric salt.