NMR Studies of Hindered Rotation. The Diels-Alder Adduct of 4-Methyl-1, 2, 4-triazoline-3, 5-dione with Phencyclone: Restricted Motion of Unsubstituted Bridgehead Phenyls.
作者:
Kevin Bynum,
Robert Rothchild,
期刊:
Spectroscopy Letters
(Taylor Available online 1997)
卷期:
Volume 30,
issue 8
页码: 1713-1732
ISSN:0038-7010
年代: 1997
DOI:10.1080/00387019708006754
出版商: Taylor & Francis Group
关键词: Dynamic NMR;1H NMR;13C NMR;One-and two-dimensional NMR;COSY;DEPT;Restricted rotation;Stereochemistry;Anisotropy
数据来源: Taylor
摘要:
4-Methyl-1, 2, 4-triazoline-3, 5-dione was produced by lead tetraacetate oxidation of 4-methylurazole and allowed to react with phencyclone,1-The resulting Diels-Alder adduct,2, has been characterized by one-and two-dimensional1H and13C NMR at 300 and 75 MHz, respectively, at ambient temperatures in different solvents. The NMR data are consistent with hindered rotation of the bridgehead unsubstituted phenyl groups about the C(sp2)-C(sp3) bonds, based on numbers of absorption signals in the1H and13C NMR aryl region, together with magnetic anisotropic effects in the1H spectrum. The spectral simplicity suggests further that stereochemistry at the ring junction nitrogens involves only a single isomer or very rapidly interconverting “exo”/“endo” isomers (if the ring junction nitrogens are pyramidalized).
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