Regioselectivity and Reactivity of Intramolecular [2+2] Cycloaddition Reactions of Acyl Ketenes: Experimental and Theoretical Studies
作者:Mahboobeh Zahedifar、Hassan Sheibani、Vahid Saheb
DOI:10.1055/s-0037-1610198
日期:2018.9
intramolecular [2+2] cycloaddition reaction of acyl ketenes formed from metastable mesoionic 1,3-oxazinium-4-olates was investigated by experimental and theoretical methods. The ring opening of the mesoionic N -allyl-2-(2-arylvinyl)-1,3-oxazinium-4-olates led to the formation of unstable acyl ketenes. Although there are four possible paths for an intramolecular [2+2] cycloaddition reaction involving the
通过实验和理论方法研究了由亚稳态介离子 1,3-oxazinium-4-olates 形成的酰基烯酮的分子内 [2+2] 环加成反应的区域选择性。介离子 N-allyl-2-(2-arylvinyl)-1,3-oxazinium-4-olates 的开环导致不稳定酰基烯酮的形成。尽管涉及两个双键(乙烯基和烯丙基)的分子内 [2+2] 环加成反应有四种可能的路径,但只有通过乙烯基双键的分子内 [2+2] 交叉环加成反应发生了 3-烯丙基-3-氮杂双环[3.1.1]庚烷-2,4,6-三酮衍生物。当丙烯酰胺或苯甲酰胺的芳基上存在强吸电子基团时,不会形成这些产物。为了理解反应机理,进行了 M06-2X/6-31+G(d) 水平的密度泛函理论计算。这些表明一些初步中间体的形成在中离子 1,3-oxazinium-4-olates 的形成中起着重要作用。