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1H and 13C NMR conformational study of N-substituted hexahydrocyclopent[e][1,3]-oxazin-4-ones and hexahydro-2H-1,3-benzoxazin-4-ones

✍ Scribed by Roustem A. Shaikhutdinov; Karel D. Klika; Ferenc Fülöp; Kalevi Pihlaja

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

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✦ Synopsis

Abstract

A ^1^H and ^13^C NMR conformational study of four cis‐fused N‐substituted hexahydrocyclopent[e][1,3]oxazin‐4‐ones and four cis‐fused hexahydro‐2__H__‐1,3‐benzoxazin‐4‐ones at various temperatures revealed several dynamic conformational processes to be in effect. These included a clear conformational equilibrium between the O‐in (major conformer) and O‐out ring forms in the hexahydro‐2__H__‐1,3‐benzoxazin‐4‐ones, an equilibrium consisting of two intramolecularly hydrogen bonded forms (between the hydroxyl proton and the carbonyl oxygen attached to C4 or the ethereal oxygen) and a non‐hydrogen bonded form in two compounds, and a restricted rotation about the amide C N bond in the CH~2~OCONHC~6~H~4~X‐p substituents (X = H, Cl) in three other compounds. Copyright © 2001 John Wiley & Sons, Ltd.

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