化学
二烯
电泳剂
取代基
反应性(心理学)
迁移插入
催化作用
密度泛函理论
药物化学
共轭体系
轨道能级差
亚甲基
光化学
环加成
还原消去
计算化学
有机化学
分子
替代医学
聚合物
天然橡胶
病理
医学
作者
Yike Zou,Shuming Chen,K. N. Houk
摘要
The (3+2) cycloadditions between electron-deficient Pd-oxyallyls and conjugated dienes have been investigated with density functional theory calculations. A stepwise mechanism with C–C bond formation occurring first is supported by computations. The key electron-withdrawing ester substituent on the Pd-oxyallyl species decreases the migratory insertion barrier by both lowering the LUMO energy and enabling a less-strained six-membered coordination mode. The lack of (3+2) reactivity with monoenes is attributed to higher migratory insertion barriers due to a lower-energy HOMO, as well as high C–O reductive elimination barriers, which become rate-determining. Conjugated dienes enable the formation of a highly electrophilic η3 Pd-allyl species and greatly facilitates C–O formation.
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