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Conformational Analysis of Benzoannulated Nine-Membered Rings, 5. 1,2,6,7-Tetrahydro-4H-3,5-benzodioxonin

✍ Scribed by Rys, Barbara ;Szneler, Edward ;Duddeck, Helmut

Publisher
John Wiley and Sons
Year
2006
Tongue
English
Weight
334 KB
Volume
1996
Category
Article
ISSN
0947-3440

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✦ Synopsis

Abstract

Temperature‐dependent ^1^H‐ and ^13^C‐NMR spectra of the title compound are presented. Coalescence effects are discussed and assigned to two dynamic processes: (a) ring inversion of the nine‐membered ring, (b) racemization of the enantiomeric ground‐state conformations of the nine‐membered ring. The barriers are 52 and 35 kJ mol^−1^, respectively. The stability of the ground state conformation is discussed in terms of transannular hydrogen interactions and anomeric effects. An assignment of the proton signals in the groundstate conformation is proposed.

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