Conformational preferences of the aldol adducts of oxadiazinones. 1H NMR spectroscopy and computational studies of N4-methyl and N4-isopropyloxadiazinones
作者:James R. Burgeson、Delvis D. Dore、Jean M. Standard、Shawn R. Hitchcock
DOI:10.1016/j.tet.2005.08.097
日期:2005.11
The conformational properties of the aldol adducts of some N4-isopropyl-oxadiazinones have been investigated by 1HNMR spectroscopy and computational studies. An earlier study of the syn-aldol adducts of N4-methyl-oxadiazinone 2 led to the conclusion that the solution and solid state conformation of these compounds involve syn-parallel arrangement of the C2- and N3-carbonyls of the oxadiazinones. However
1 H NMR光谱和计算研究已经研究了一些N 4-异丙基-恶二嗪酮的醛醇加合物的构象性质。N 4-甲基-恶二嗪酮2的顺式-羟醛加合物的较早研究得出的结论是,这些化合物的溶液和固态构象涉及恶二嗪酮的C 2-和N 3-羰基的顺式平行排列。但是,N 3-氢肉桂酰基-N 4-异丙基-恶二嗪酮4的合成和不对称羟醛反应产生了羟醛加合物5a –e,其中C 2-和N 3-羰基的取向最有可能处于反平行排列。这些羟醛加合物已经通过1 H NMR光谱研究,并且观察到的屏蔽方面清楚地表明存在反平行排列。A N的批4 - d 6 -异丙基团进一步证实这一说法。计算研究支持以下结论:N 4-甲基和N 4-异丙基-恶二嗪酮的溶液状态构象涉及抗-固态羰基与氧杂二嗪酮2的X射线晶体学数据相反。