Article: Intramolecular hydrogen bonding of novel o-hydroxythioacetophenones and related compounds evaluated by deuterium isotope effects on (13)C chemical shifts

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Intramolecular hydrogen bonding of novel o-hydroxythioacetophenones and related compounds evaluated by deuterium isotope effects on (13)C chemical shifts
Trung Thanh Nguyen, Thach Ngoc Le, Fritz Duus, Bjarke K. V. Hansen and
Poul Erik Hansen

Magn. Reson. Chem. 2007; 45: 245–252

Abstract:
A new class of compounds, the 2-hydroxythioacetophenones, and related compounds have recently been synthesized. The hydrogen-bond system has been characterized by NMR chemical shifts and deuterium isotope effects on these as well as by DFT calculations. Use of solid-state (13)C NMR has enabled measurements of the intrinsic deuterium isotope effects of the most abundant tautomer of -thioxoketones. The compounds show very interesting long-range deuterium isotope effects on the thiocarbonyl carbon. The intramolecular hydrogen bonds of o-hydroxythioacetophenones are found to be slightly stronger than those of the corresponding acetophenones. The reactivity and stability of the compounds can be related to hydrogen bonding and to the presence of electron donating substituents.

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