Beyond DP4: an Improved Probability for the Stereochemical Assignment of Isomeric Compounds using Quantum Chemical Calculations of NMR Shifts

The DP4 probability is one of the
most sophisticated and popular
approaches for the stereochemical assignment of organic molecules
using GIAO NMR chemical shift calculations when only one set of experimental
data is available. In order to improve the performance of the method,
we have developed a modified probability (DP4+), whose main differences
from the original DP4 are the inclusion of unscaled data and the use
of higher levels of theory for the NMR calculation procedure. With
these modifications, a significant improvement in the overall performance
was achieved, providing accurate and confident results in establishing
the stereochemistry of 48 challenging isomeric compounds.