Base-induced Sommelet–Hauser rearrangement of N-(α-(2-oxyethyl)branched)benzylic glycine ester-derived ammonium salts via a chelated intermediate
作者:Eiji Tayama、Kazuki Hirano、Souya Baba
DOI:10.1016/j.tet.2020.131064
日期:2020.4
formation of chelated intermediate C that stabilizes the carbanionic ylide, and the subsequent initial dearomative [2,3] sigmatropic rearrangement would be accelerated. The existence of C was supported by mechanistic experiments. This enhancement effect is not very strong or effective; however, it will expand the synthetic usefulness of ammonium ylide rearrangements.
研究了碱诱导的N-(α-支链)苄基甘氨酸酯衍生的铵盐1的Sommelet-Hauser重排。当α-支链取代基是一个简单的烷基,例如甲基或丁基时,所需的SH重排产物2低收率地形成了[1,2] Stevens重排4和Hofmann消除的产物5和6。然而,当α-支链取代基有一个-2-氧基部分,例如2-乙酰氧基乙基或2-苯甲酰氧,的产率2得到提高。这些结果可以通过形成螯合的中间体C来解释稳定了碳负离子叶立德,随后的初始脱芳香性[2,3]σ重排将被加速。机械实验证明了C的存在。这种增强效果不是很有效。然而,它将扩大内鎓盐重排的合成用途。