The regioselectivity of nitrone and nitrile oxide cycloadditions to alkylidenecyclopropanes
作者:Alberto Brandi、Franca M. Cordero、Francesco De Sarlo、Remo Gandolfi、Andrea Rastelli、Marisa Bagatti
DOI:10.1016/0040-4020(92)85008-3
日期:1992.1
The 1,3-dipolar cycloaddition of nitrile oxides and a nitrone to alkylidencyclopropanes 1–5,used as model for methylenecyclopropanes substituted with aryl group (1), electron-releasing groups (2 and 3) and electron-attracting groups (4 and 5) is reported. The cycloaddition to alkylidenecyclopropanes 1–3 gives prevalently or exclusively adducts bearing the cyclopropane ring on the C4 position of the
腈和硝酮与亚烷基环丙烷1–5的1,3-偶极环加成反应,用作被芳基(1),电子释放基团(2和3)和电子吸引基团(4和5)取代的亚甲基环丙烷的模型)被报告。亚烷基环丙烷1-3的环加成反应会普遍或仅在异恶唑啉(异恶唑烷)环的C4位置带有环丙烷环的加合物,而甲氧羰基取代的亚甲基环丙烷4和5产生与区域化学相反的加合物。在二烷基取代的亚甲基环丙烷的情况下观察到的高区域选择性提出了亚环丙基在这些环加成中所起的作用的问题。基于半经验和从头算的FMO方法无法解释这种“环亚丙基效应”。