Amide rotamers of N-acetyl-1,3-dimethyltetrahydroisoquinolines: synthesis, variable temperature NMR spectroscopy and molecular modelling
作者:Charles B de Koning、Willem A.L van Otterlo、Joseph P Michael
DOI:10.1016/j.tet.2003.09.001
日期:2003.10
Mercury(II)-mediated ring closure of N-[1-(2-allyl-3-benzyloxy-4,6-dimethoxyphenyl)ethyl]acetamide 9 afforded N-acetyl-5-benzyloxy-6,8-dimethoxy-1,3-trans-dimethyl-1,2,3,4-tetrahydroisoquinoline 8. The product was shown to exist as a mixture of amide rotamers by NMR spectroscopy, since signals coalesced at higher temperatures. Variable temperature NMR spectroscopy and molecular modelling were used
汞(II)介导的N- [1-(2-烯丙基-3-苄氧基-4,6-二甲氧基苯基)乙基]乙酰胺9的闭环提供N-乙酰基-5-苄氧基-6,8-二甲氧基-1, 3-反式-二甲基-1,2,3,4-四氢异喹啉8。NMR光谱显示产物以酰胺旋转异构体的混合物形式存在,因为信号在较高温度下会聚。使用可变温度NMR光谱学和分子模型研究了这些旋转异构体,并给出了旋转势垒的平均值,范围为15–16 kcal mol -1。2- [2- [1-(乙酰氨基)乙基] -6-(苄氧基)-3,5-二甲氧基苯基] -1-甲基乙基甲磺酸酯17也用氢化钠环化,得到相同的旋转异构体的产品具有相同的四氢异喹啉骨架,但由于1,3-混合物反式-和顺式-二甲基异构体。