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Saturated amine oxides: Part 4. Steric and electric field effects on the 17O NMR chemical shifts of saturated six-membered azaheterocyclic amine oxides

✍ Scribed by Francisc Potmischil; Damian Magiera; Helmut Duddeck; Joachim Buddrus

Publisher
John Wiley and Sons
Year
2001
Tongue
English
Weight
133 KB
Volume
39
Category
Article
ISSN
0749-1581

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✦ Synopsis

Abstract

The ^17^O NMR chemical shifts of 14 N‐methylpiperidine‐N‐oxides and five N‐methyltetradecahydroacridine‐N‐oxides were measured. The effects of steric factors, such as γ‐gauche and 1,3‐syn‐axial interactions of the N^+^—O^−^ oxygen, on the ^17^O chemical shifts are discussed, and evidence for the main contribution of electrostatic interactions, rather than true steric compression, to the so‐called ‘steric effects’ on ^17^O chemical shifts of alcohols, ethers, sulfoxides and amine oxides is presented. For conformationally mobile compounds, the discussion of the chemical shifts is assisted by results from molecular mechanics (MM+) calculations. Copyright © 2001 John Wiley & Sons, Ltd.

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## Abstract The ^15^N chemical shifts of 13 __N__‐methylpiperidine‐derived mono‐, bi‐ and tricycloaliphatic tertiary amines, their methiodides and their __N__‐epimeric pairs of __N__‐oxides were measured, and the contributions of specific structural parameters to the chemical shifts were determined