Three-bond Couplings to Hydrogen

The combined use of the DFT calculated and experimentally determined Jhh and Vhc couplings complemented by the NOE s results has allowed Woods and co-workers to elucidate correctly the conformation of (lR,6R,7R,8S)-7,8-dihydroxy-7-thia-l-thioniabicyclo[4.3.0]nonane chloride, a member of the sul-fonium salt class inhibitors. 

More examples of peptides and proteins for which these couplings have been 

A conformational analysis of a guaiacyl p-O-4 lignin model compound has been performed by Besombes et by the combined use of vicinal proton- 

A recently developed approach based inter alia on molecular modelling and on analysis of NMR data including vicinal proton-carbon couplings has been tested by Tanaka et alP They used one of the synthetic chiral dihydrofuro-angelicines, 4-methyl-8(2- -phenylethenyl)-8,9-dihydro-2H-furo[2.3-/i]-l-ben-zopyran-2-one, as a model compound and extended the method to establish the absolute stereochemistry of six new dihydrofuroangelicins bearing C-8 substituted double bonds. 

The one- and three-bond H-C couplings of the Me2N group in 8-dimethylamino-napht-l-yl phosphines and their derivatives have been found by Schiemenz et alP to be useful indicators of the N-P interactions in these compounds. 

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Three-bond coupling to vicinal hydrogens generally leads to a pentet signal, meaning that coupling to the equatorial fluorines of the SF5 substituent, as mentioned earlier, is much greater than to its axial fluorine. 

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