Structural Discrimination in Small Molecules by Accurate Measurement of Long‐Range Proton–Carbon NMR Residual Dipolar Couplings

Accurate measurement of long-range CH residual dipolar couplings (RDCs) (2DCH and 3DCH) by a new selective J-scaled HSQC experiment significantly improves the structural discrimination power of RDCs in small molecules with multiple stereocenters. The extraction of the long-range couplings is clean and straightforward, and in most cases yields the sign of the RDC too. The experiment is demonstrated with 10-epi-8-deoxycumambrin B, a tricyclic natural compound with five chiral centers.