Base-switched annuloselectivity in the reactions of ethyl malonyl chloride and imines
作者:Zhanhui Yang、Siqi Li、Zhong Zhang、Jiaxi Xu
DOI:10.1039/c4ob01454e
日期:——
and [2 + 2 + 2] selectivity, in the reactions of ethyl malonyl chloride and imines is successfully realized. In the presence of the weak nucleophilic base 2-chloropyridine, the reactions deliver ethyl trans-β-lactam-3-carboxylates as the exclusive [2 + 2] products in up to 93% yields, while with the strong nucleophilic N-methylimidazole as the base, the reactions give rise to 2,3-dihydro-1,3-oxazin-4-one
在乙基丙二酰氯与亚胺的反应中,成功实现了碱基转换的环选择性,即[2 + 2]和[2 + 2 + 2]选择性。在弱亲核碱2-氯吡啶存在下,反应以最高[93%]的产率提供反式-β-内酰胺-3-羧酸乙酯作为独家[2 + 2]产物,而强亲核N-甲基咪唑在此基础上,通过涉及一个分子的分子的正式[2 + 2 + 2]环加成反应,以唯一的产物形式生成2,3-二氢-1,3-恶嗪-4-酮衍生物,唯一产率高达99%。亚胺和由丙二酰氯生成的两个烯酮分子。值得注意的是,乙基反式-β-内酰胺-3-羧酸酯是第一次直接由乙基丙二酰氯与亚胺的反应合成。机理讨论表明,环选择性是由有机碱的亲核性控制的。