金属转移
化学
亲核细胞
还原消去
区域选择性
烯丙基重排
脱质子化
异构化
艾伦
钯
多烯
金属化
药物化学
光化学
组合化学
催化作用
有机化学
离子
作者
Jing Zhang,Chunhui Shan,Kang Lv,Lei Zhu,Yuanyuan Li,Tao Liu,Yu Lan
出处
期刊:Chemcatchem
[Wiley]
日期:2019-01-23
卷期号:11 (4): 1228-1237
被引量:20
标识
DOI:10.1002/cctc.201801934
摘要
Abstract Density functional theory calculations were performed to reveal the mechanisms of Pd‐catalyzed cascade carbocyclization‐borylation and arylation reactions. The computational results indicate that the reactions start with allylic C−H cleavage through concerted metalation‐deprotonation and an intramolecular exo‐type allene insertion to form a six‐membered carbocycle intermediate. The regioselectivity of insertion could be explained by frontier molecular orbital theory and natural population analysis calculation. In the absence of extra nucleophiles, η 1 /η 3 ‐isomerization followed by acetate‐assisted deprotonation could yield polyene product. When nucleophile was added to the reaction system, transmetalation and subsequent reductive elimination could give the exo‐substituted triene as major product. Meanwhile, η 1 /η 3 ‐isomerization, transmetalation, and reductive elimination could afford the endo‐isomer as side product. The regioselectivity of further functionalization is controlled by the competition of transmetalation and η 1 /η 3 ‐isomerization. The computational results show that both exo‐ and endo‐boronation product could be observed when bis(pinacolato)diboron is added as nucleophile. However, only exo‐phenylation product is observed when phenylboronic acid is used as nucleophile because of the high free‐energy barrier for reductive elimination from aryl η 3 ‐allylic palladium.
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