Stereodivergent Synthesis of Chiral 2-Alkenylaziridines: Palladium(0)-Catalyzed 2,3-cis-Selective Aziridination and Base-Mediated 2,3-trans-Selective Aziridination
作者:Hiroaki Ohno、Yoshiji Takemoto、Nobutaka Fujii、Tetsuaki Tanaka、Toshiro Ibuka
DOI:10.1248/cpb.52.111
日期:——
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。