The derivation of carbon–proton internuclear distances in organic natural products from 13C relaxation rates and nuclear overhauser effects

Abstract

The precise definition of the hydrogen bonding patterns of natural product organic molecules and biopolymers in solution has hitherto been very difficult. It is demonstrated here that proton–carbon n.O.e. difference spectroscopy and carbon relaxation rates readily yield carbon assignments, the donor and acceptor groups of hydrogen bonds, and the cis- and trans- stereochemistry around C–O and C–N single bonds.

N.O.e. ratio methods and cross-relaxation rates gave proton–carbon distances that are in good agreement with the corresponding crystallographically derived distances.