TY  - JOUR
A1  - Hansen, Poul Erik
A1  - Koch, Andreas
A1  - Kleinpeter, Erich
T1  - Ring current and anisotropy effects on OH chemical shifts in resonance-assisted intramolecular H-bonds
JF  - Tetrahedron letters
N2  - Ring current effects on resonance-assisted and intramolecularly bridged hydrogen bond protons for 10-hydroxybenzo[h]quinoline 1 and a number of related compounds were calculated and the through-space NMR shieldings (TSNMRS) obtained hereby visualized as iso-chemical-shielding surfaces (ICSS) of various size and direction. These calculations revealed that this through-space effect is comparably large (up to 2 ppm) dependent on the position of the intramolecularly bridged OH proton, and therefore, contribute considerably to the chemical shift of the latter making it questionable to use delta(OH)/ppm in the estimation of intramolecular hydrogen bond strength without taking this into account. Furthermore, the anisotropy effects of additional groups on the aromatic moiety (e.g. the carbonyl group in salicylaldehyde or in o-hydroxyacetophenone of ca. 0.6 ppm deshielding) should also be considered. These through-space effects need to be taken into account when using OH chemical shifts to estimate hydrogen bond strength.
KW  - RA-intramolecular hydrogen bond
KW  - Through-space NMR shieldings (TSNMRS)
KW  - Iso-chemical-shielding surfaces (ICSS)
KW  - Ring current effect
KW  - Anisotropy effect
Y1  - 2018
U6  - https://doi.org/10.1016/j.tetlet.2018.05.006
SN  - 0040-4039
VL  - 59
IS  - 23
SP  - 2288
EP  - 2292
PB  - Elsevier
CY  - Oxford
ER  -