Mechanism of rhodium(Ⅲ)-catalyzed formal C(sp^3)-H activation/spiroannulation of a-arylidene pyrazolones with alkynes:A computational study  

作　　者：Hongyan Zou Zhong-Liang Wang Yang Cao Genping Huang 

机构地区：[1]Tianjin Key Laboratory of Water Resources and Environment, Tianjin Normal University, Tianjin 300387, China [2]Department of Chemistry, School of Science, Tianjin University, Tianjin 300072, China [3]Institute of New Energy, Shenzhen 518031, China

出　　处：《Chinese Chemical Letters》2018年第9期1355-1358,共4页中国化学快报（英文版）

基　　金：supported by the National Natural Science Foundation of China(No.21503143);the Tianjin Natural Science Foundation(Nos.16JCQNJC05600 and 16JCYBJC43600);the Talent Research Start-up Fund of Tianjin Normal University(No.5RL139);support from the Shenzhen Peacock Plan(No.1208040050847074)

摘　　要：The rhodium-catalyzed formal C（sp^3）-H activation/spiroannulation of α-arylidene pyrazolones with alkynes was investigated by means of density functional theory calculations. The calculations indicate that the spiroannulation through the proposed C-C reductive elimination is kinetically unfeasible, Instead, the C-C coupling from the eight-membered rhodacycle was proposed to account for the experimental results. The overall catalytic cycle consists of six steps： （1） the keto-enol isomerization; （2） the O-H deprotonation, （3） the C（sp^2）-H bond cleavage; （4） the migratory insertion of alkyne into the Rh-C bond; （5） the C-C coupling and （6） the regeneration of the active catalyst.The rhodium-catalyzed formal C（sp^3）-H activation/spiroannulation of α-arylidene pyrazolones with alkynes was investigated by means of density functional theory calculations. The calculations indicate that the spiroannulation through the proposed C-C reductive elimination is kinetically unfeasible, Instead, the C-C coupling from the eight-membered rhodacycle was proposed to account for the experimental results. The overall catalytic cycle consists of six steps： （1） the keto-enol isomerization; （2） the O-H deprotonation, （3） the C（sp^2）-H bond cleavage; （4） the migratory insertion of alkyne into the Rh-C bond; （5） the C-C coupling and （6） the regeneration of the active catalyst.

关 键 词：RHODIUM Spiroannulation C-H activation Reaction mechanism DFT calculations 

分 类 号：O621.251[理学—有机化学]