Nickel-Catalyzed Secondary Alkylations and Fluoroalkylations via C–H Activation

by Sebastian Lackner
Doctoral thesis
Date of Examination:2016-06-29
Date of issue:2016-07-15
Advisor:Prof. Dr. Lutz Ackermann
Referee:Prof. Dr. Lutz Ackermann
Referee:Prof. Dr. Konrad Koszinowski
Persistent Address: http://dx.doi.org/10.53846/goediss-5738

 

 

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Abstract

English

In the past several decades, transition metal-catalyzed cross-coupling reactions proved to be of utmost importance within organic synthesis. However, required prefunctionalization of substrates remained as a major disadvantage of this methodology. A solution to this are direct C–H functionalizations, which have emerged in recent years as a viable synthetic tools. The focus within this thesis was on the development of atom- and step-economic nickel-catalyzed C–H alkylation reactions utilising challenging, unactivated alkyl halides with β-hydrogen or β-fluorine atoms. In the first part, a protocol for the direct C–H secondary alkylation of benzamides under bidentate assistance was devised for a variety of alkyl bromides. Second, investigations on a novel trifluoroethylation were conducted. Third, focus was shifted to utilising simpler and biologically relevant directing groups for direct C–H secondary alkylation. For this a simple catalytic system was developed for the efficient ortho-alkylation of aniline derivatives. The involved nickelacycle is presumed to be an unusual six-membered metalacycle. Finally, the novel C–H trifluoroethylation was applied to aniline derivatives as well.
Keywords: Nickel; C–H Activation; Homogeneous Catalysis; Alkylation; Trifluoroethylation
 
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