Synthesis and<sup>1</sup>H and<sup>13</sup>C NMR structural analysis of<i>cis</i>- and<i>trans</i>-2-imino-1,3- and -3,1-perhydrobenzoxazines and their 3- and 1-<i>N</i>-methyl derivatives
作者:Kalevi Pihlaja、Jari Sinkkonen、Ferenc Fülöp
DOI:10.1002/mrc.1194
日期:2003.6
cis- and trans-2-imino-1,3- and -3,1-perhydrobenzoxazines and the N-methyl derivatives of the latter were synthesized from the corresponding cyclic 1,3-amino alcohol with cyanogen bromide. The configurations of the studied compounds were confirmed by 1H and 13C NMR spectra. All trans-fused compounds exist in biased chair–chair conformations as expected, whereas the cis-fused 1,3-benzoxazines attain exclusively the O-in conformations. The cis-fused 3,1-benzoxazines, especially the 1-methyl-substituted derivatives, tend to favor the N-out form, obviously owing to the favorable axial orientation of this N-methyl. Copyright © 2003 John Wiley & Sons, Ltd.
顺式和反式-2-亚氨基-1,3-和-3,1-全氢苯并恶嗪以及后者的 N-甲基衍生物是由相应的环 1,3- 氨基醇与溴化氰合成的。1H 和 13C NMR 光谱证实了所研究化合物的构型。所有反式融合的化合物都如预期的那样以偏椅椅构象存在,而顺式融合的 1,3-苯并噁嗪则完全是 O-内构象。顺式融合的 3,1-苯并噁嗪,尤其是 1-甲基取代的衍生物,倾向于 N 出构型,这显然是由于 N-甲基的轴向取向有利。Copyright © 2003 John Wiley & Sons, Ltd. All Rights Reserved.