Selective J-resolved-HMQC-1 and -2, new methods for measuring proton–proton coupling constants in strongly coupled spin systems
✍ Scribed by Kazuo Furihata; Mitsuru Tashiro
- Publisher
- John Wiley and Sons
- Year
- 2011
- Tongue
- English
- Weight
- 405 KB
- Volume
- 49
- Category
- Article
- ISSN
- 0749-1581
- DOI
- 10.1002/mrc.2778
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✦ Synopsis
Abstract
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.