Structural discrimination from in situ measurement of 1 DCH and 2 DHH residual dipolar coupling constants.

A fast residual dipolar coupling constant-assisted strategy involving the simultaneous determination of scalar and total coupling constants from a single 1 JCH /2 JHH -resolved NMR spectrum is reported. It is shown that the concerted use of the directly measured 1 DCH (for all CHn multiplicities) and 2 DHH residual dipolar couplings allows an on-the-fly assignment of diastereotopic CH2 protons, as well as of an efficient discrimination between diastereoisomeric structures of strychnine which contains six stereocenters. Copyright © 2017 John Wiley & Sons, Ltd.