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

Accurate measurement of long-range CH residual dipolar couplings (RDCs) ( 2 D CH and 3 D CH ) 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.