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Selective J ‐resolved‐HMQC‐1 and ‐2, new methods for measuring proton–proton coupling constants in strongly coupled spin systems
Author(s) -
Furihata Kazuo,
Tashiro Mitsuru
Publication year - 2011
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.2778
Subject(s) - chemistry , pulse sequence , coupling constant , proton , pulse (music) , spin (aerodynamics) , excited state , excitation , coupling (piping) , analytical chemistry (journal) , nuclear magnetic resonance , atomic physics , optics , detector , organic chemistry , nuclear physics , physics , thermodynamics , mechanical engineering , particle physics , quantum mechanics , engineering
Efficient pulse sequences for measuring 1 H– 1 H coupling constants ( J HH ) in strongly coupled spin systems, named selective J ‐resolved‐HMQC‐1 and ‐2, have been developed. In the strongly coupled spin systems such as ‐CH 2 ‐CH A (OH)‐CH B (OH)‐CH 2 ‐, measurements of 3 J HAHB are generally difficult owing to the complicated splitting caused by the adjacent CH 2 protons. For easier and accurate measurements of 3 J HAHB in such a spin system, a selective excitation pulse is incorporated into the J ‐resolved HMQC pulse sequence. In the proposed methods, only two strongly coupled protons, H A and H B which are excited by a selective pulse, are observed as J ‐resolved HMQC signals. The cross peaks of H A and H B appear as doublets owing to 3 J HAHB along the F 1 dimension in the selective J ‐resolved HMQC‐1 and ‐2 experiments. The efficiency of the proposed pulse sequences has been demonstrated in application to the stereochemical studies of the complicated natural product, monazomycin. Copyright © 2011 John Wiley & Sons, Ltd.