Homonuclear long-range correlation spectra from HMBC experiments by covariance processing

Abstract

We present a new application of covariance nuclear magnetic resonance processing based on 1H-13C-HMBC experiments which provides an effective way for establishing indirect 1H-1H and 13C-13C nuclear spin connectivity at natural isotope abundance. The method, which identifies correlated spin networks in terms of covariance between one-dimensional traces from a single decoupled HMBC experiment, derives 13C-13C as well as 1H- 1H spin connectivity maps from the two-dimensional frequency domain heteronuclear long-range correlation data matrix. The potential and limitations of this novel covariance NMR application are demonstrated on two compounds: eugeny1-β-D-glucopyranoside and an emodin-derivative. Copyright © 2007 John Wiley & Sons, Ltd.