One‐ and two‐dimensional gradient‐selected HSQMBC NMR experiments for the efficient analysis of long‐range heteronuclear coupling constants

Three new gradient-selected NMR experiments for the analysis of long-range heteronuclear coupling constants are presented. They are demonstrated on a series of compounds including sucrose, strychnine and a complex macrolide, phormidolide, isolated from a marine cyanobacterium. These 1D and 2D heteronuclear single quantum multiple bond correlation (HSQMBC) experiments provide pure absorption, antiphase lineshapes for precise, direct measurement of nJ(C,H) coupling constants. The example compounds were chosen to demonstrate the high sensitivity and ease of spectral interpretation provided by these HSQMBC experiments. In addition, suppression of one-bond CH correlations has been introduced into the HSQMBC pulse sequence. Copyright © 2000 John Wiley & Sons, Ltd.