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Effect of hydroxyl and carbonyl groups on long-range proton—carbon coupling constants

✍ Scribed by Teodor Parella; Francisco Sánchez-Ferrando; Albert Virgili

Publisher
John Wiley and Sons
Year
1994
Tongue
English
Weight
754 KB
Volume
32
Category
Article
ISSN
0749-1581

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✦ Synopsis

Abstract

Long‐range ^1^H^13^C coupling constants were measured for some simple, rigid model compounds containing hydroxyl, bromine or carbonyl groups. These were performed using the recently proposed selective J‐resolved SPININEP and SDEPT‐2D experiments. The geminal and vicinal heteronuclear coupling constant values were analysed in terms of the nature of substituent, the position along the coupling path and the orientation of the substituent relative to the bounds. In some cases, through‐space interactions of the substituent group were also observed. Sizeable substituent effects are associated with the electronegativity and lone pair of the oxygen nucleus in the hydroxyl and carbonyl systems. In addition, the π‐system of the carbonyl group may also be important. Such substituent effects may be as large at ±5 Hz. Since ^n^J~CH~ constants rarely exceed 10 Hz, these effects can produce important deviations in ^n^J~CH~ magnitudes and therefore are essential for applications to stereochemical and conformational analysis.

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