Whereas treatment of the allylic mesylates of N-protected 2-alkyl-4-amino-(E)-2-alken-1-ols with sodium hydride in DMF yields exclusively the corresponding thermodynamically less stable 2,3-trans-2-alkenyl-3-alkylaziridines, exposure of the methyl carbonates of N-protected 2-alkyl-4-amino-(E)-2-alken-1-ols to a catalytic amount of Pd(PPh3)4 in THF or 1,4-dioxane affords predominantly the corresponding thermodynamically more stable 2,3-cis-2-alkenyl-3-alkylaziridines. The kinetically favored trans-selective aziridination would be attributed to the allylic 1,3-strain in aza-anionic intermediates. The conformational analysis of the sterically highly congested 2-alkenylaziridines thus obtained is also presented.
而用氢化
钠在
DMF 中处理 N-保护的 2-烷基-4-
氨基-(E)-2-烯-1-醇的烯丙基
甲磺酸酯仅产生相应的热力学不稳定的 2,3-反式-2-烯基-3-烷基
氮丙啶,将N-保护的2-烷基-4-
氨基-(E)-2-链烯-1-醇的
碳酸甲酯暴露于催化量的Pd(PPh3)4的THF或1,4-溶液中
二恶烷主要提供相应的热力学更稳定的2,3-顺-2-烯基-3-烷基
氮丙啶。动力学上有利的反式选择性
氮丙啶化归因于氮杂阴离子中间体中的烯丙基1,3-应变。还介绍了由此获得的空间高度拥挤的2-烯基
氮丙啶的构象分析。